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Sample records for attenuation corrected cardiac

  1. Practical method of breast attenuation correction for cardiac SPECT

    International Nuclear Information System (INIS)

    Oliveira, Anderson de; Nogueira, Tindyua; Gutterres, Ricardo Fraga; Megueriam, Berdj Aram; Santos, Goncalo Rodrigues dos

    2007-01-01

    The breast attenuation effects on SPECT (Single Photon Emission Tomography) myocardium perfusion procedures have been lately scope of continuous inquiry. The requested attenuation correction factors are usually achieved by transmission analysis, making up the exposure of a standard external source to the SPECT, as a routine step. However, its high cost makes this methodology not fully available to the most of nuclear medicines services in Brazil and abroad. To overcome the problem, a new trend is presented in this work, implementing computational models to balance the breast attenuation effects on the left ventricle anterior wall, during myocardium perfusion scintigraphy procedures with SPECT. A neural network was put on in order to provide the attenuation correction indexes, based upon the following patients individual biotypes features: mass, age, height, chest and breast thicknesses, heart size, as well as the imparted activity intake levels. (author)

  2. Practical method of breast attenuation correction for cardiac SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Anderson de; Nogueira, Tindyua; Gutterres, Ricardo Fraga [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil). Coordenacao Geral de Instalacoes Medicas e Industriais (CGMI)]. E-mails: anderson@cnen.gov.br; tnogueira@cnen.gov.br; rguterre@cnen.gov.br; Megueriam, Berdj Aram [Instituto Nacional do Cancer (INCA), Rio de Janeiro, RJ (Brazil)]. E-mail: megueriam@hotmail.com; Santos, Goncalo Rodrigues dos [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)]. E-mail: goncalo@cnen.gov.br

    2007-07-01

    The breast attenuation effects on SPECT (Single Photon Emission Tomography) myocardium perfusion procedures have been lately scope of continuous inquiry. The requested attenuation correction factors are usually achieved by transmission analysis, making up the exposure of a standard external source to the SPECT, as a routine step. However, its high cost makes this methodology not fully available to the most of nuclear medicines services in Brazil and abroad. To overcome the problem, a new trend is presented in this work, implementing computational models to balance the breast attenuation effects on the left ventricle anterior wall, during myocardium perfusion scintigraphy procedures with SPECT. A neural network was put on in order to provide the attenuation correction indexes, based upon the following patients individual biotypes features: mass, age, height, chest and breast thicknesses, heart size, as well as the imparted activity intake levels. (author)

  3. Sources of attenuation-correction artefacts in cardiac PET/CT and SPECT/CT.

    Science.gov (United States)

    McQuaid, Sarah J; Hutton, Brian F

    2008-06-01

    Respiratory motion during myocardial perfusion imaging can cause artefacts in both positron emission tomography (PET) and single-photon emission computed tomography (SPECT) images when mismatches between emission and transmission datasets arise. In this study, artefacts from different breathing motions were quantified in both modalities to assess key factors in attenuation-correction accuracy. Activity maps were generated using the NURBS-based cardiac-torso phantom for different respiratory cycles, which were projected, attenuation-corrected and reconstructed to form PET and SPECT images. Attenuation-correction was performed with maps at mismatched respiratory phases to observe the effect on the left-ventricular myocardium. Myocardial non-uniformity was assessed in terms of the standard deviation in scores obtained from the 17-segment model and changes in uniformity were compared for each mismatch and modality. Certain types of mismatch led to artefacts and corresponding increases in the myocardial non-uniformity. For each mismatch in PET, the increases in non-uniformity relative to an artefact-free image were as follows: (a) cardiac translation mismatch, 84% +/- 11%; (b) liver mismatch, 59% +/- 10%, (c) lung mismatch from diaphragm contraction, 28% +/- 8%; and (d) lung mismatch from chest-wall motion, 6% +/- 7%. The corresponding factors for SPECT were (a) 61% +/- 8%, (b) 34% +/- 8%, (c) -2% +/- 7)% and (d) -4% +/- 6%. Attenuation-correction artefacts were seen in PET and SPECT images, with PET being more severely affected. The most severe artefacts were produced from mismatches in cardiac and liver position, whereas lung mismatches were less critical. Both cardiac and liver positions must, therefore, be correctly matched during attenuation correction.

  4. Ultra-low Dose CT for Attenuation Correction of 82Rb Cardiac PET

    DEFF Research Database (Denmark)

    Sørensen, Maria Balshøj; Bouchelouche, Kirsten; Tolbod, Lars Poulsen

    Aim: Myocardial perfusion imaging (MPI) using cardiac PET with tracers like 82Rb and 15O-water is substantially lower in radiation dose than classic MIBI-based SPECT. However, for cardiac PET, the dose contribution of CT for attenuation correction (CTAC) is typically 20-30% of the total dose....... To reduce the total radiation dose of cardiac PET further, we set out to examine if the use of ultra-low dose CTAC (UL-CTAC) would affect the accuracy of the quantitative parameters related to MPI. Furthermore, we examined whether the low quality of the UL-CTAC would affect the technologist’s ability...... to perform manual adjustment for misalignment between PET and CTAC. The CT reconstruction algorithm Q.AC was used to improve quality and consistency of the CTAC. Method: 23 consecutive clinical patients (BMI: 26.9 [range: 15.4-38.8]) referred for 82Rb PET rest and stress imaging were included in the study...

  5. MR-based attenuation correction for cardiac FDG PET on a hybrid PET/MRI scanner: comparison with standard CT attenuation correction

    Energy Technology Data Exchange (ETDEWEB)

    Vontobel, Jan; Liga, Riccardo; Possner, Mathias; Clerc, Olivier F.; Mikulicic, Fran; Veit-Haibach, Patrick; Voert, Edwin E.G.W. ter; Fuchs, Tobias A.; Stehli, Julia; Pazhenkottil, Aju P.; Benz, Dominik C.; Graeni, Christoph; Gaemperli, Oliver; Herzog, Bernhard; Buechel, Ronny R.; Kaufmann, Philipp A. [University Hospital Zurich, Department of Nuclear Medicine, Zurich (Switzerland)

    2015-09-15

    The aim of this study was to evaluate the feasibility of attenuation correction (AC) for cardiac {sup 18}F-labelled fluorodeoxyglucose (FDG) positron emission tomography (PET) using MR-based attenuation maps. We included 23 patients with no known cardiac history undergoing whole-body FDG PET/CT imaging for oncological indications on a PET/CT scanner using time-of-flight (TOF) and subsequent whole-body PET/MR imaging on an investigational hybrid PET/MRI scanner. Data sets from PET/MRI (with and without TOF) were reconstructed using MR AC and semi-quantitative segmental (20-segment model) myocardial tracer uptake (per cent of maximum) and compared to PET/CT which was reconstructed using CT AC and served as standard of reference. Excellent correlations were found for regional uptake values between PET/CT and PET/MRI with TOF (n = 460 segments in 23 patients; r = 0.913; p < 0.0001) with narrow Bland-Altman limits of agreement (-8.5 to +12.6 %). Correlation coefficients were slightly lower between PET/CT and PET/MRI without TOF (n = 460 segments in 23 patients; r = 0.851; p < 0.0001) with broader Bland-Altman limits of agreement (-12.5 to +15.0 %). PET/MRI with and without TOF showed minimal underestimation of tracer uptake (-2.08 and -1.29 %, respectively), compared to PET/CT. Relative myocardial FDG uptake obtained from MR-based attenuation corrected FDG PET is highly comparable to standard CT-based attenuation corrected FDG PET, suggesting interchangeability of both AC techniques. (orig.)

  6. Attenuation correction for SPECT

    International Nuclear Information System (INIS)

    Hosoba, Minoru

    1986-01-01

    Attenuation correction is required for the reconstruction of a quantitative SPECT image. A new method for detecting body contours, which are important for the correction of tissue attenuation, is presented. The effect of body contours, detected by the newly developed method, on the reconstructed images was evaluated using various techniques for attenuation correction. The count rates in the specified region of interest in the phantom image by the Radial Post Correction (RPC) method, the Weighted Back Projection (WBP) method, Chang's method were strongly affected by the accuracy of the contours, as compared to those by Sorenson's method. To evaluate the effect of non-uniform attenuators on the cardiac SPECT, computer simulation experiments were performed using two types of models, the uniform attenuator model (UAM) and the non-uniform attenuator model (NUAM). The RPC method showed the lowest relative percent error (%ERROR) in UAM (11 %). However, 20 to 30 percent increase in %ERROR was observed for NUAM reconstructed with the RPC, WBP, and Chang's methods. Introducing an average attenuation coefficient (0.12/cm for Tc-99m and 0.14/cm for Tl-201) in the RPC method decreased %ERROR to the levels for UAM. Finally, a comparison between images, which were obtained by 180 deg and 360 deg scans and reconstructed from the RPC method, showed that the degree of the distortion of the contour of the simulated ventricles in the 180 deg scan was 15 % higher than that in the 360 deg scan. (Namekawa, K.)

  7. Evaluation of attenuation correction in cardiac PET using PET/MR.

    Science.gov (United States)

    Lau, Jeffrey M C; Laforest, R; Sotoudeh, H; Nie, X; Sharma, S; McConathy, J; Novak, E; Priatna, A; Gropler, R J; Woodard, P K

    2017-06-01

    Simultaneous acquisition Positron emission tomography/magnetic resonance (PET/MR) is a new technology that has potential as a tool both in research and clinical diagnosis. However, cardiac PET acquisition has not yet been validated using MR imaging for attenuation correction (AC). The goal of this study is to evaluate the feasibility of PET imaging using a standard 2-point Dixon volume interpolated breathhold examination (VIBE) MR sequence for AC. Evaluation was performed in both phantom and patient data. A chest phantom containing heart, lungs, and a lesion insert was scanned by both PET/MR and PET/CT. In addition, 30 patients underwent whole-body 18 F-fluorodeoxyglucose PET/CT followed by simultaneous cardiac PET/MR. Phantom study showed 3% reduction of activity values in the myocardium due to the non-inclusion of the phased array coil in the AC. In patient scans, average standardized uptake values (SUVs) obtained by PET/CT and PET/MR showed no significant difference (n = 30, 4.6 ± 3.5 vs 4.7 ± 2.8, P = 0.47). There was excellent per patient correlation between the values acquired by PET/CT and PET/MR (R 2  = 0.97). Myocardial SUVs PET imaging using MR for AC shows excellent correlation with myocardial SUVs obtained by standard PET/CT imaging. The 2-point Dixon VIBE MR technique can be used for AC in simultaneous PET/MR data acquisition.

  8. The Value of Attenuation Correction in Hybrid Cardiac SPECT/CT on Inferior Wall According to Body Mass Index

    International Nuclear Information System (INIS)

    Tamam, Muge; Mulazimoglu, Mehmet; Edis, Nurcan; Ozpacaci, Tevfik

    2016-01-01

    The purpose of this study was to evaluate the diagnostic value of attenuation-corrected single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) on the inferior wall compared to uncorrected (NC) SPECT MPI between obese and nonobese patients. A total of 157 consecutive patients (122 males and 35 females, with median age: 57.4 ± 11 years) who underwent AC technetium 99m-methoxyisobutylisonitrile (AC Tc99m-sestamibi) SPECT MPI were included to the study. A hybrid SPECT and transmission computed tomography (CT) system was used for the diagnosis with 1-day protocol, and stress imaging was performed first. During attenuation correction (AC) processing on a Xeleris Workstation using Myovation cardiac software with ordered subset expectation maximization (OSEM), iterative reconstruction with attenuation correction (IRAC) and NC images filtered back projection (FBP) were used. For statistical purposes, P < 0.05 was considered significant. This study included 73 patients with body mass index (BMI) <30 and 84 patients with BMI ≥ 30. In patients with higher BMI, increased amount of both visual and semiquantitative attenuation of the inferior wall was detected. IRAC reconstruction corrects the diaphragm attenuation of the inferior wall better than FBP. AC with OSEM iterative reconstruction significantly improves the diagnostic value of stress-only SPECT MPI in patients with normal weight and those who are obese, but the improvements are significantly greater in obese patients. Stress-only SPECT imaging with AC provides shorter and lower radiation exposure

  9. Measured attenuation correction methods

    International Nuclear Information System (INIS)

    Ostertag, H.; Kuebler, W.K.; Doll, J.; Lorenz, W.J.

    1989-01-01

    Accurate attenuation correction is a prerequisite for the determination of exact local radioactivity concentrations in positron emission tomography. Attenuation correction factors range from 4-5 in brain studies to 50-100 in whole body measurements. This report gives an overview of the different methods of determining the attenuation correction factors by transmission measurements using an external positron emitting source. The long-lived generator nuclide 68 Ge/ 68 Ga is commonly used for this purpose. The additional patient dose from the transmission source is usually a small fraction of the dose due to the subsequent emission measurement. Ring-shaped transmission sources as well as rotating point or line sources are employed in modern positron tomographs. By masking a rotating line or point source, random and scattered events in the transmission scans can be effectively suppressed. The problems of measured attenuation correction are discussed: Transmission/emission mismatch, random and scattered event contamination, counting statistics, transmission/emission scatter compensation, transmission scan after administration of activity to the patient. By using a double masking technique simultaneous emission and transmission scans become feasible. (orig.)

  10. A Generalized Correction for Attenuation.

    Science.gov (United States)

    Petersen, Anne C.; Bock, R. Darrell

    Use of the usual bivariate correction for attenuation with more than two variables presents two statistical problems. This pairwise method may produce a covariance matrix which is not at least positive semi-definite, and the bivariate procedure does not consider the possible influences of correlated errors among the variables. The method described…

  11. Segmented attenuation correction using artificial neural networks in positron tomography

    International Nuclear Information System (INIS)

    Yu, S.K.; Nahmias, C.

    1996-01-01

    The measured attenuation correction technique is widely used in cardiac positron tomographic studies. However, the success of this technique is limited because of insufficient counting statistics achievable in practical transmission scan times, and of the scattered radiation in transmission measurement which leads to an underestimation of the attenuation coefficients. In this work, a segmented attenuation correction technique has been developed that uses artificial neural networks. The technique has been validated in phantoms and verified in human studies. The results indicate that attenuation coefficients measured in the segmented transmission image are accurate and reproducible. Activity concentrations measured in the reconstructed emission image can also be recovered accurately using this new technique. The accuracy of the technique is subject independent and insensitive to scatter contamination in the transmission data. This technique has the potential of reducing the transmission scan time, and satisfactory results are obtained if the transmission data contain about 400 000 true counts per plane. It can predict accurately the value of any attenuation coefficient in the range from air to water in a transmission image with or without scatter correction. (author)

  12. Patient position alters attenuation effects in multipinhole cardiac SPECT.

    Science.gov (United States)

    Timmins, Rachel; Ruddy, Terrence D; Wells, R Glenn

    2015-03-01

    Dedicated cardiac cameras offer improved sensitivity over conventional SPECT cameras. Sensitivity gains are obtained by large numbers of detectors and novel collimator arrangements such as an array of multiple pinholes that focus on the heart. Pinholes lead to variable amounts of attenuation as a source is moved within the camera field of view. This study evaluated the effects of this variable attenuation on myocardial SPECT images. Computer simulations were performed for a set of nine point sources distributed in the left ventricular wall (LV). Sources were placed at the location of the heart in both an anthropomorphic and a water-cylinder computer phantom. Sources were translated in x, y, and z by up to 5 cm from the center. Projections were simulated with and without attenuation and the changes in attenuation were compared. A LV with an inferior wall defect was also simulated in both phantoms over the same range of positions. Real camera data were acquired on a Discovery NM530c camera (GE Healthcare, Haifa, Israel) for five min in list-mode using an anthropomorphic phantom (DataSpectrum, Durham, NC) with 100 MBq of Tc-99m in the LV. Images were taken over the same range of positions as the simulations and were compared based on the summed perfusion score (SPS), defect width, and apparent defect uptake for each position. Point sources in the water phantom showed absolute changes in attenuation of ≤8% over the range of positions and relative changes of ≤5% compared to the apex. In the anthropomorphic computer simulations, absolute change increased to 20%. The changes in relative attenuation caused a change in SPS of position-dependent changes were removed with attenuation correction. Translation of a source relative to a multipinhole camera caused only small changes in homogeneous phantoms with SPS changing position-dependent changes in attenuation.

  13. Patient position alters attenuation effects in multipinhole cardiac SPECT

    International Nuclear Information System (INIS)

    Timmins, Rachel; Ruddy, Terrence D.; Wells, R. Glenn

    2015-01-01

    Purpose: Dedicated cardiac cameras offer improved sensitivity over conventional SPECT cameras. Sensitivity gains are obtained by large numbers of detectors and novel collimator arrangements such as an array of multiple pinholes that focus on the heart. Pinholes lead to variable amounts of attenuation as a source is moved within the camera field of view. This study evaluated the effects of this variable attenuation on myocardial SPECT images. Methods: Computer simulations were performed for a set of nine point sources distributed in the left ventricular wall (LV). Sources were placed at the location of the heart in both an anthropomorphic and a water-cylinder computer phantom. Sources were translated in x, y, and z by up to 5 cm from the center. Projections were simulated with and without attenuation and the changes in attenuation were compared. A LV with an inferior wall defect was also simulated in both phantoms over the same range of positions. Real camera data were acquired on a Discovery NM530c camera (GE Healthcare, Haifa, Israel) for five min in list-mode using an anthropomorphic phantom (DataSpectrum, Durham, NC) with 100 MBq of Tc-99m in the LV. Images were taken over the same range of positions as the simulations and were compared based on the summed perfusion score (SPS), defect width, and apparent defect uptake for each position. Results: Point sources in the water phantom showed absolute changes in attenuation of ≤8% over the range of positions and relative changes of ≤5% compared to the apex. In the anthropomorphic computer simulations, absolute change increased to 20%. The changes in relative attenuation caused a change in SPS of <1.5 for the water phantom but up to 4.2 in the anthropomorphic phantom. Changes were larger for axial than for transverse translations. These results were supported by SPS changes of up to six seen in the physical anthropomorphic phantom for axial translations. Defect width was also seen to significantly increase. The

  14. Scatter and attenuation correction in SPECT

    International Nuclear Information System (INIS)

    Ljungberg, Michael

    2004-01-01

    The adsorbed dose is related to the activity uptake in the organ and its temporal distribution. Measured count rate with scintillation cameras is related to activity through the system sensitivity, cps/MBq. By accounting for physical processes and imaging limitations we can measure the activity at different time points. Correction for physical factor, such as attenuation and scatter is required for accurate quantitation. Both planar and SPECT imaging can be used to estimate activities for radiopharmaceutical dosimetry. Planar methods have been the most widely used but is a 2D technique. With accurate modelling for imagine in iterative reconstruction, SPECT methods will prove to be more accurate

  15. Attenuation correction using simultaneous emission - transmission tomography

    International Nuclear Information System (INIS)

    Ljubenov, V.; Marinkovic, P.

    1998-01-01

    In order to reduce degrading influence of attenuation on SPECT image quality, possibility for correction, based on simultaneous emission / transmission measurements, is discussed. Numerical photon transport simulations through the phantom and acquisition of of tomographic projections are performed by using Monte Carlo code MCNP-4A. Amount of contamination in transmission data due to photon Compton scattering for emission energy window is specially analyzed and appropriate spatial depending 'noise / signal' factors for three different external sources, applied with Tc-99m, are determined (author)

  16. Is attenuation correction of myocardial SPECT scans worth the effort?

    International Nuclear Information System (INIS)

    Bui, C.; Nguyen, D.; Dixson, H.; Saunders, C.; Cook, P.; Burnett, P.; Croll, F.; Dunn, R.; Hasche, E.; Kelleher, P.; Nasser, F.; Wilson, D.; Lee, K.

    2000-01-01

    Full text: Gated (GS), attenuation-corrected (AC) and non-attenuation-corrected (NAC) myocardial SPECT scans were performed after injection of 99 Tc m -Sestamibi (MIBI) at peak stress in 253 patients between September 1998 and March 1999. 60 patients have undergone cardiac catheterisation (37 males, 23 females, age range 34-80). For whole heart analysis, significant coronary disease was defined as 50% or greater diameter narrowing in any of the coronary arteries and/or documented myocardial infarction. For vascular territory analysis, significant coronary disease was defined as 50% or greater diameter narrowing of any artery in that territory. The three coronary artery territories were assigned as: left anterior descending (LAD), left circumflex (LCA) and right coronary (RCA). The septum, apex and anterior wall; the lateral wall; and the inferior wall were assigned to the LAD; LCA; and RCA territories respectively. In conclusion for this selected subgroup of patients with angiographic follow-up, NAC, AC and GS were of similar accuracy in the detection of significant CAD in both whole heart analysis and individual vascular territory analysis. AC and GS were of superior specificity when compared with NAC in both whole heart analysis and individual vascular territory analysis. AC and GS may be of additional diagnostic value in improving the specificity of NAC. Further outcome data will be presented. Copyright (2000) The Australian and New Zealand Society of Nuclear Medicine Inc

  17. Effects of attenuation map accuracy on attenuation-corrected micro-SPECT images

    NARCIS (Netherlands)

    Wu, C.; Gratama van Andel, H.A.; Laverman, P.; Boerman, O.C.; Beekman, F.J.

    2013-01-01

    Background In single-photon emission computed tomography (SPECT), attenuation of photon flux in tissue affects quantitative accuracy of reconstructed images. Attenuation maps derived from X-ray computed tomography (CT) can be employed for attenuation correction. The attenuation coefficients as well

  18. Pentoxifylline Attenuates Cardiac Remodeling Induced by Tobacco Smoke Exposure

    Energy Technology Data Exchange (ETDEWEB)

    Minicucci, Marcos; Oliveira, Fernando; Santos, Priscila; Polegato, Bertha; Roscani, Meliza; Fernandes, Ana Angelica; Lustosa, Beatriz; Paiva, Sergio; Zornoff, Leonardo; Azevedo, Paula, E-mail: paulasa@fmb.unesp.br [Faculdade de Medicina de Botucatu, Universidade Estadual Paulista, São Paulo, SP (Brazil)

    2016-05-15

    Tobacco smoke exposure is an important risk factor for cardiac remodeling. Under this condition, inflammation, oxidative stress, energy metabolism abnormalities, apoptosis, and hypertrophy are present. Pentoxifylline has anti‑inflammatory, anti-apoptotic, anti-thrombotic and anti-proliferative properties. The present study tested the hypothesis that pentoxifylline would attenuate cardiac remodeling induced by smoking. Wistar rats were distributed in four groups: Control (C), Pentoxifylline (PX), Tobacco Smoke (TS), and PX-TS. After two months, echocardiography, invasive blood pressure measurement, biochemical, and histological studies were performed. The groups were compared by two-way ANOVA with a significance level of 5%. TS increased left atrium diameter and area, which was attenuated by PX. In the isolated heart study, TS lowered the positive derivate (+dp/dt), and this was attenuated by PX. The antioxidants enzyme superoxide dismutase and glutathione peroxidase were decreased in the TS group; PX recovered these activities. TS increased lactate dehydrogenase (LDH) and decreased 3-hydroxyacyl Coenzyme A dehydrogenases (OH-DHA) and citrate synthase (CS). PX attenuated LDH, 3-OH-DHA and CS alterations in TS-PX group. TS increased IL-10, ICAM-1, and caspase-3. PX did not influence these variables. TS induced cardiac remodeling, associated with increased inflammation, oxidative stress, apoptosis, and changed energy metabolism. PX attenuated cardiac remodeling by reducing oxidative stress and improving cardiac bioenergetics, but did not act upon cardiac cytokines and apoptosis.

  19. Evaluation of respiratory and cardiac motion correction schemes in dual gated PET/CT cardiac imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lamare, F., E-mail: frederic.lamare@chu-bordeaux.fr; Fernandez, P. [Univ. Bordeaux, INCIA, UMR 5287, F-33400 Talence (France); CNRS, INCIA, UMR 5287, F-33400 Talence (France); Service de Médecine Nucléaire, Hôpital Pellegrin, CHU de Bordeaux, 33076 Bordeaux (France); Le Maitre, A.; Visvikis, D. [INSERM, UMR1101, LaTIM, Université de Bretagne Occidentale, 29609 Brest (France); Dawood, M.; Schäfers, K. P. [European Institute for Molecular Imaging, University of Münster, Mendelstr. 11, 48149 Münster (Germany); Rimoldi, O. E. [Vita-Salute University and Scientific Institute San Raffaele, Milan, Italy and CNR Istituto di Bioimmagini e Fisiologia Molecolare, Milan (Italy)

    2014-07-15

    Purpose: Cardiac imaging suffers from both respiratory and cardiac motion. One of the proposed solutions involves double gated acquisitions. Although such an approach may lead to both respiratory and cardiac motion compensation there are issues associated with (a) the combination of data from cardiac and respiratory motion bins, and (b) poor statistical quality images as a result of using only part of the acquired data. The main objective of this work was to evaluate different schemes of combining binned data in order to identify the best strategy to reconstruct motion free cardiac images from dual gated positron emission tomography (PET) acquisitions. Methods: A digital phantom study as well as seven human studies were used in this evaluation. PET data were acquired in list mode (LM). A real-time position management system and an electrocardiogram device were used to provide the respiratory and cardiac motion triggers registered within the LM file. Acquired data were subsequently binned considering four and six cardiac gates, or the diastole only in combination with eight respiratory amplitude gates. PET images were corrected for attenuation, but no randoms nor scatter corrections were included. Reconstructed images from each of the bins considered above were subsequently used in combination with an affine or an elastic registration algorithm to derive transformation parameters allowing the combination of all acquired data in a particular position in the cardiac and respiratory cycles. Images were assessed in terms of signal-to-noise ratio (SNR), contrast, image profile, coefficient-of-variation (COV), and relative difference of the recovered activity concentration. Results: Regardless of the considered motion compensation strategy, the nonrigid motion model performed better than the affine model, leading to higher SNR and contrast combined with a lower COV. Nevertheless, when compensating for respiration only, no statistically significant differences were

  20. Attenuation correction strategies for multi-energy photon emitters using SPECT

    International Nuclear Information System (INIS)

    Pretorius, P.H.; King, M.A.; Pan, T.S.

    1996-01-01

    The aim of this study was to investigate whether the photopeak window projections from different energy photons can be combined into a single window for reconstruction or if it is better to not combine the projections due to differences in the attenuation maps required for each photon energy. The mathematical cardiac torso (MCAT) phantom was modified to simulate the uptake of Ga-67 in the human body. Four spherical hot tumors were placed in locations which challenged attenuation correction. An analytical 3D projector with attenuation and detector response included was used to generate projection sets. Data were reconstructed using filtered backprojection (FBP) reconstruction with Butterworth filtering in conjunction with one iteration of Chang attenuation correction, and with 5 and 10 iterations of ordered-subset maximum-likelihood expectation-maximization reconstruction. To serve as a standard for comparison, the projection sets obtained from the two energies were first reconstructed separately using their own attenuation maps. The emission data obtained from both energies were added and reconstructed using the following attenuation strategies: (1) the 93 keV attenuation map for attenuation correction, (2) the 185 keV attenuation map for attenuation correction, (3) using a weighted mean obtained from combining the 93 keV and 185 keV maps, and (4) an ordered subset approach which combines both energies. The central count ratio (CCR) and total count ratio (TCR) were used to compare the performance of the different strategies. Compared to the standard method, results indicate an over-estimation with strategy 1, an under-estimation with strategy 2 and comparable results with strategies 3 and 4. In all strategies, the CCR's of sphere 4 were under-estimated, although TCR's were comparable to that of the other locations. The weighted mean and ordered subset strategies for attenuation correction were of comparable accuracy to reconstruction of the windows separately

  1. Attenuation correction for the NIH ATLAS small animal PET scanner

    CERN Document Server

    Yao, Rutao; Liow, JeihSan; Seidel, Jurgen

    2003-01-01

    We evaluated two methods of attenuation correction for the NIH ATLAS small animal PET scanner: 1) a CT-based method that derives 511 keV attenuation coefficients (mu) by extrapolation from spatially registered CT images; and 2) an analytic method based on the body outline of emission images and an empirical mu. A specially fabricated attenuation calibration phantom with cylindrical inserts that mimic different body tissues was used to derive the relationship to convert CT values to (I for PET. The methods were applied to three test data sets: 1) a uniform cylinder phantom, 2) the attenuation calibration phantom, and 3) a mouse injected with left bracket **1**8F right bracket FDG. The CT-based attenuation correction factors were larger in non-uniform regions of the imaging subject, e.g. mouse head, than the analytic method. The two methods had similar correction factors for regions with uniform density and detectable emission source distributions.

  2. Attenuation correction method for single photon emission CT

    Energy Technology Data Exchange (ETDEWEB)

    Morozumi, Tatsuru; Nakajima, Masato [Keio Univ., Yokohama (Japan). Faculty of Science and Technology; Ogawa, Koichi; Yuta, Shinichi

    1983-10-01

    A correction method (Modified Correction Matrix method) is proposed to implement iterative correction by exactly measuring attenuation constant distribution in a test body, calculating a correction factor for every picture element, then multiply the image by these factors. Computer simulation for the comparison of the results showed that the proposed method was specifically more effective to an application to the test body, in which the rate of attenuation constant change is large, than the conventional correction matrix method. Since the actual measurement data always contain quantum noise, the noise was taken into account in the simulation. However, the correction effect was large even under the noise. For verifying its clinical effectiveness, the experiment using an acrylic phantom was also carried out. As the result, the recovery of image quality in the parts with small attenuation constant was remarkable as compared with the conventional method.

  3. The Self Attenuation Correction for Holdup Measurements, a Historical Perspective

    International Nuclear Information System (INIS)

    Oberer, R. B.; Gunn, C. A.; Chiang, L. G.

    2006-01-01

    Self attenuation has historically caused both conceptual as well as measurement problems. The purpose of this paper is to eliminate some of the historical confusion by reviewing the mathematical basis and by comparing several methods of correcting for self attenuation focusing on transmission as a central concept

  4. Attenuation and scatter correction in SPECT

    International Nuclear Information System (INIS)

    Pant, G.S.; Pandey, A.K.

    2000-01-01

    While passing through matter, photons undergo various types of interactions. In the process, some photons are completely absorbed, some are scattered in different directions with or without any change in their energy and some pass through unattenuated. These unattenuated photons carry the information with them. However, the image data gets corrupted with attenuation and scatter processes. This paper deals with the effect of these two processes in nuclear medicine images and suggests the methods to overcome them

  5. The usefulness and the problems of attenuation correction using simultaneous transmission and emission data acquisition method. Studies on normal volunteers and phantom

    International Nuclear Information System (INIS)

    Kijima, Tetsuji; Kumita, Shin-ichiro; Mizumura, Sunao; Cho, Keiichi; Ishihara, Makiko; Toba, Masahiro; Kumazaki, Tatsuo; Takahashi, Munehiro.

    1997-01-01

    Attenuation correction using simultaneous transmission data (TCT) and emission data (ECT) acquisition method was applied to 201 Tl myocardial SPECT with ten normal adults and the phantom in order to validate the efficacy of attenuation correction using this method. Normal adults study demonstrated improved 201 Tl accumulation to the septal wall and the posterior wall of the left ventricle and relative decreased activities in the lateral wall with attenuation correction (p 201 Tl uptake organs such as the liver and the stomach pushed up the activities in the septal wall and the posterior wall. Cardiac dynamic phantom studies showed partial volume effect due to cardiac motion contributed to under-correction of the apex, which might be overcome using gated SPECT. Although simultaneous TCT and ECT acquisition was conceived of the advantageous method for attenuation correction, miss-correction of the special myocardial segments should be taken into account in assessment of attenuation correction compensated images. (author)

  6. Magnitude corrections for attenuation in the upper mantle

    International Nuclear Information System (INIS)

    Anon.

    1978-01-01

    Since 1969, a consistent discrepancy in seismic magnitudes of nuclear detonations at NTS compared with magnitudes of detonations elsewhere in the world has been observed. This discrepancy can be explained in terms of a relatively high seismic attenuation for compressional waves in the upper mantle beneath the NTS and in certain other locations. A correction has been developed for this attenuation based on a relationship between the velocity of compressional waves at the top of the earth's mantle (just beneath the Mohorovicic discontinuity) and the seismic attenuation further down in the upper mantle. Our new definition of body-wave magnitude includes corrections for attenuation in the upper mantle at both ends of the teleseismic body-wave path. These corrections bring the NTS oservations into line with measurements of foreign events, and enable one to make more reliable estimates of yields of underground nuclear explosions, wherever the explosion occurs

  7. An attenuation correction method for PET/CT images

    International Nuclear Information System (INIS)

    Ue, Hidenori; Yamazaki, Tomohiro; Haneishi, Hideaki

    2006-01-01

    In PET/CT systems, accurate attenuation correction can be achieved by creating an attenuation map from an X-ray CT image. On the other hand, respiratory-gated PET acquisition is an effective method for avoiding motion blurring of the thoracic and abdominal organs caused by respiratory motion. In PET/CT systems employing respiratory-gated PET, using an X-ray CT image acquired during breath-holding for attenuation correction may have a large effect on the voxel values, especially in regions with substantial respiratory motion. In this report, we propose an attenuation correction method in which, as the first step, a set of respiratory-gated PET images is reconstructed without attenuation correction, as the second step, the motion of each phase PET image from the PET image in the same phase as the CT acquisition timing is estimated by the previously proposed method, as the third step, the CT image corresponding to each respiratory phase is generated from the original CT image by deformation according to the motion vector maps, and as the final step, attenuation correction using these CT images and reconstruction are performed. The effectiveness of the proposed method was evaluated using 4D-NCAT phantoms, and good stability of the voxel values near the diaphragm was observed. (author)

  8. Attenuation correction for flexible magnetic resonance coils in combined magnetic resonance/positron emission tomography imaging.

    Science.gov (United States)

    Eldib, Mootaz; Bini, Jason; Calcagno, Claudia; Robson, Philip M; Mani, Venkatesh; Fayad, Zahi A

    2014-02-01

    Attenuation correction for magnetic resonance (MR) coils is a new challenge that came about with the development of combined MR and positron emission tomography (PET) imaging. This task is difficult because such coils are not directly visible on either PET or MR acquisitions with current combined scanners and are therefore not easily localized in the field of view. This issue becomes more evident when trying to localize flexible MR coils (eg, cardiac or body matrix coil) that change position and shape from patient to patient and from one imaging session to another. In this study, we proposed a novel method to localize and correct for the attenuation and scatter of a flexible MR cardiac coil, using MR fiducial markers placed on the surface of the coil to allow for accurate registration of a template computed tomography (CT)-based attenuation map. To quantify the attenuation properties of the cardiac coil, a uniform cylindrical water phantom injected with 18F-fluorodeoxyglucose (18F-FDG) was imaged on a sequential MR/PET system with and without the flexible cardiac coil. After establishing the need to correct for the attenuation of the coil, we tested the feasibility of several methods to register a precomputed attenuation map to correct for the attenuation. To accomplish this, MR and CT visible markers were placed on the surface of the cardiac flexible coil. Using only the markers as a driver for registration, the CT image was registered to the reference image through a combination of rigid and deformable registration. The accuracy of several methods was compared for the deformable registration, including B-spline, thin-plate spline, elastic body spline, and volume spline. Finally, we validated our novel approach both in phantom and patient studies. The findings from the phantom experiments indicated that the presence of the coil resulted in a 10% reduction in measured 18F-FDG activity when compared with the phantom-only scan. Local underestimation reached 22% in

  9. A promising hybrid approach to SPECT attenuation correction

    International Nuclear Information System (INIS)

    Lewis, N.H.; Faber, T.L.; Corbett, J.R.; Stokely, E.M.

    1984-01-01

    Most methods for attenuation compensation in SPECT either rely on the assumption of uniform attenuation, or use slow iteration to achieve accuracy. However, hybrid methods that combine iteration with simple multiplicative correction can accommodate nonuniform attenuation, and such methods converge faster than other iterative techniques. The authors evaluated two such methods, which differ in use of a damping factor to control convergence. Both uniform and nonuniform attenuation were modeled, using simulated and phantom data for a rotating gamma camera. For simulations done with 360 0 data and the correct attenuation map, activity levels were reconstructed to within 5% of the correct values after one iteration. Using 180 0 data, reconstructed levels in regions representing lesion and background were within 5% of the correct values in three iterations; however, further iterations were needed to eliminate the characteristic streak artifacts. The damping factor had little effect on 360 0 reconstruction, but was needed for convergence with 180 0 data. For both cold- and hot-lesion models, image contrast was better from the hybrid methods than from the simpler geometric-mean corrector. Results from the hybrid methods were comparable to those obtained using the conjugate-gradient iterative method, but required 50-100% less reconstruction time. The relative speed of the hybrid methods, and their accuracy in reconstructing photon activity in the presence of nonuniform attenuation, make them promising tools for quantitative SPECT reconstruction

  10. Investigation of Compton scattering correction methods in cardiac SPECT by Monte Carlo simulations

    International Nuclear Information System (INIS)

    Silva, A.M. Marques da; Furlan, A.M.; Robilotta, C.C.

    2001-01-01

    The goal of this work was the use of Monte Carlo simulations to investigate the effects of two scattering correction methods: dual energy window (DEW) and dual photopeak window (DPW), in quantitative cardiac SPECT reconstruction. MCAT torso-cardiac phantom, with 99m Tc and non-uniform attenuation map was simulated. Two different photopeak windows were evaluated in DEW method: 15% and 20%. Two 10% wide subwindows centered symmetrically within the photopeak were used in DPW method. Iterative ML-EM reconstruction with modified projector-backprojector for attenuation correction was applied. Results indicated that the choice of the scattering and photopeak windows determines the correction accuracy. For the 15% window, fitted scatter fraction gives better results than k = 0.5. For the 20% window, DPW is the best method, but it requires parameters estimation using Monte Carlo simulations. (author)

  11. Bulk sample self-attenuation correction by transmission measurement

    International Nuclear Information System (INIS)

    Parker, J.L.; Reilly, T.D.

    1976-01-01

    Various methods used in either finding or avoiding the attenuation correction in the passive γ-ray assay of bulk samples are reviewed. Detailed consideration is given to the transmission method, which involves experimental determination of the sample linear attenuation coefficient by measuring the transmission through the sample of a beam of gamma rays from an external source. The method was applied to box- and cylindrically-shaped samples

  12. Improvement of quantitation in SPECT: Attenuation and scatter correction using non-uniform attenuation data

    International Nuclear Information System (INIS)

    Mukai, T.; Torizuka, K.; Douglass, K.H.; Wagner, H.N.

    1985-01-01

    Quantitative assessment of tracer distribution with single photon emission computed tomography (SPECT) is difficult because of attenuation and scattering of gamma rays within the object. A method considering the source geometry was developed, and effects of attenuation and scatter on SPECT quantitation were studied using phantoms with non-uniform attenuation. The distribution of attenuation coefficients (μ) within the source were obtained by transmission CT. The attenuation correction was performed by an iterative reprojection technique. The scatter correction was done by convolution of the attenuation corrected image and an appropriate filter made by line source studies. The filter characteristics depended on μ and SPEC measurement at each pixel. The SPECT obtained by this method showed the most reasonable results than the images reconstructed by other methods. The scatter correction could compensate completely for a 28% scatter components from a long line source, and a 61% component for thick and extended source. Consideration of source geometries was necessary for effective corrections. The present method is expected to be valuable for the quantitative assessment of regional tracer activity

  13. Gamma-ray self-attenuation corrections in environmental samples

    International Nuclear Information System (INIS)

    Robu, E.; Giovani, C.

    2009-01-01

    Gamma-spectrometry is a commonly used technique in environmental radioactivity monitoring. Frequently the bulk samples that should be measured differ with respect to composition and density from the reference sample used for efficiency calibration. Correction factors should be applied in these cases for activity measurement. Linear attenuation coefficients and self-absorption correction factors have been evaluated for soil, grass and liquid sources with different densities and geometries.(authors)

  14. On self-attenuation corrections in gamma-ray spectrometry

    International Nuclear Information System (INIS)

    Bolivar, J.P.; Garcia-Leon, M.; Garcia-Tenorio, R.

    1997-01-01

    In this paper we discuss and justify the dependence on the sample density and gamma energy of the self-attenuation correction factor, f, in the transmission method for the full energy peak efficiency calibration of Ge detectors. It is suggested as a method for the direct computing of f in the case that the sample composition is known. (Author)

  15. Attenuation correction of myocardial SPECT by scatter-photopeak window method in normal subjects

    International Nuclear Information System (INIS)

    Okuda, Koichi; Nakajima, Kenichi; Matsuo, Shinro; Kinuya, Seigo; Motomura, Nobutoku; Kubota, Masahiro; Yamaki, Noriyasu; Maeda, Hisato

    2009-01-01

    Segmentation with scatter and photopeak window data using attenuation correction (SSPAC) method can provide a patient-specific non-uniform attenuation coefficient map only by using photopeak and scatter images without X-ray computed tomography (CT). The purpose of this study is to evaluate the performance of attenuation correction (AC) by the SSPAC method on normal myocardial perfusion database. A total of 32 sets of exercise-rest myocardial images with Tc-99m-sestamibi were acquired in both photopeak (140 keV±10%) and scatter (7% of lower side of the photopeak window) energy windows. Myocardial perfusion databases by the SSPAC method and non-AC (NC) were created from 15 female and 17 male subjects with low likelihood of cardiac disease using quantitative perfusion SPECT software. Segmental myocardial counts of a 17-segment model from these databases were compared on the basis of paired t test. AC average myocardial perfusion count was significantly higher than that in NC in the septal and inferior regions (P<0.02). On the contrary, AC average count was significantly lower in the anterolateral and apical regions (P<0.01). Coefficient variation of the AC count in the mid, apical and apex regions was lower than that of NC. The SSPAC method can improve average myocardial perfusion uptake in the septal and inferior regions and provide uniform distribution of myocardial perfusion. The SSPAC method could be a practical method of attenuation correction without X-ray CT. (author)

  16. Attenuation correction factors for cylindrical, disc and box geometry

    International Nuclear Information System (INIS)

    Agarwal, Chhavi; Poi, Sanhita; Mhatre, Amol; Goswami, A.; Gathibandhe, M.

    2009-01-01

    In the present study, attenuation correction factors have been experimentally determined for samples having cylindrical, disc and box geometry and compared with the attenuation correction factors calculated by Hybrid Monte Carlo (HMC) method [ C. Agarwal, S. Poi, A. Goswami, M. Gathibandhe, R.A. Agrawal, Nucl. Instr. and. Meth. A 597 (2008) 198] and with the near-field and far-field formulations available in literature. It has been observed that the near-field formulae, although said to be applicable at close sample-detector geometry, does not work at very close sample-detector configuration. The advantage of the HMC method is that it is found to be valid for all sample-detector geometries.

  17. Is Necessary Attenuation Correction for Cat Brain PET?

    International Nuclear Information System (INIS)

    Kim, Jin Su; Lee, Jae Sung; Park, Min Hyun; Im, Ki Chun; Oh, Seung Ha; Lee, Dong Soo; Moon, Dae Hyuk

    2007-01-01

    Photon attenuation and scatter corrections (AC and SC) were necessary for quantification of human PET. However, there is no consensus on whether AC and SC are necessary for the cat brain PET imaging. Since post-injection transmission (TX) PET scans are not permitted or provided to microPET scanner users at present, additional time for performing TX scan and awaiting FDG uptake is required for attenuation and scatter corrections. Increasing probability of subject movement and possible biological effect of long term anesthesia would be the problem in additional TX scan. The aim of this study was to examine the effect of AC and SC for the quantification of cat brain PET data

  18. Validation of attenuation-corrected equilibrium radionuclide angiographic determinations of right ventricular volume: comparison with cast-validated biplane cineventriculography

    International Nuclear Information System (INIS)

    Dell'Italia, L.J.; Starling, M.R.; Walsh, R.A.; Badke, F.R.; Lasher, J.C.; Blumhardt, R.

    1985-01-01

    To determine the accuracy of attenuation-corrected equilibrium radionuclide angiographic determinations of right ventricular volumes, the authors initially studied 14 postmortem human right ventricular casts by water displacement and biplane cineventriculography. Biplane cineventriculographic right ventricular cast volumes, calculated by a modification of Simpson's rule algorithm, correlated well with right ventricular cast volumes measured by water displacement (r = .97, y = 8 + 0.88x, SEE = 6 ml). Moreover, the mean volumes obtained by both methods were no different (73 +/- 28 vs 73 +/- 25 ml). Subsequently, they studied 16 patients by both biplane cineventriculography and equilibrium radionuclide angiography. The uncorrected radionuclide right ventricular volumes were calculated by normalizing background corrected end-diastolic and end-systolic counts from hand-drawn regions of interest obtained by phase analysis for cardiac cycles processed, frame rate, and blood sample counts. Attenuation correction was performed by a simple geometric method. The attenuation-corrected radionuclide right ventricular end-diastolic volumes correlated with the cineventriculographic end-diastolic volumes (r = .91, y = 3 + 0.92x, SEE = 27 ml). Similarly, the attenuation-corrected radionuclide right ventricular end-systolic volumes correlated with the cineventriculographic end-systolic volumes (r = .93, y = - 1 + 0.91x, SEE = 16 ml). Also, the mean attenuation-corrected radionuclide end-diastolic and end-systolic volumes were no different than the average cineventriculographic end-diastolic and end-systolic volumes (160 +/- 61 and 83 +/- 44 vs 170 +/- 61 and 86 +/- 43 ml, respectively)

  19. Is attenuation correction of myocardial SPET scans worth the effort?

    International Nuclear Information System (INIS)

    Nguyen, D.; Saunders, C.; Dixson, H.; Cook, P.; Burnett, P.; Croll, F.; Dunn, R.; Hasche, E.; Kelleher, P.; Nasser, F.; Wilson, D.; Lee, K.

    1999-01-01

    Full text: In this prospective study, we compared gated (GS), attenuation-corrected (AC) and non-attenuation-corrected (NAC) myocardial SPET scans. 119 consecutive patients were scanned after 800 MBq 99 Tc m -Sestamibi (MIBI) injected at peak stress. AC studies were performed using a Siemens Multispect 3 triple-headed camera with a MμSIC attenuation correction system. Transmission data were provided by an Am241 line source mounted opposite an offset fan beam collimator. Simultaneous emission data were collected from all 3 heads over a 360deg rotation (acquisition time 25 min). The NAC and GS studies were performed using a Siemens ECAM variable-angle dual-headed gamma camera using 8 gating frames over a 90deg rotation (acquisition time 15 min). The myocardium was divided into 9 segments and the studies were reported separately by two observers. Clinical data and angiography results were obtained when available. For GS, myocardial segments with normal systolic wall thickening were considered to have normal perfusion. AC studies were used as the standard for measuring myocardial perfusion. In the 119 patients studied, the overall sensitivity, specificity and accuracy for NAC vs AC were 100%, 25%, 54% and for GS vs AC were 86%, 84% and 85% respectively. There were 265 abnormal segments on NAC. GS demonstrated normal thickening in 90/265 segments and AC demonstrated normal perfusion in 94/265 segments. There were 33 segments with discordant GS and AC. 16/33 segments (9 inferior, 3 anterior, 4 other) with normal thickening had abnormal perfusion on AC and 17/33 segments (9 inferior, 6 anterior, 2 other) with abnormal thickening had normal perfusion on AC. Weight and sex did not predict discordance. In conclusion, attenuation artefacts are common and are not predicted by body habitus or sex. They are usually accurately identified by normal systolic wall thickening on GS. GS is strongly recommended when AC is not available. AC provides additional information, particularly

  20. Photon attenuation correction technique in SPECT based on nonlinear optimization

    International Nuclear Information System (INIS)

    Suzuki, Shigehito; Wakabayashi, Misato; Okuyama, Keiichi; Kuwamura, Susumu

    1998-01-01

    Photon attenuation correction in SPECT was made using a nonlinear optimization theory, in which an optimum image is searched so that the sum of square errors between observed and reprojected projection data is minimized. This correction technique consists of optimization and step-width algorithms, which determine at each iteration a pixel-by-pixel directional value of search and its step-width, respectively. We used the conjugate gradient and quasi-Newton methods as the optimization algorithm, and Curry rule and the quadratic function method as the step-width algorithm. Statistical fluctuations in the corrected image due to statistical noise in the emission projection data grew as the iteration increased, depending on the combination of optimization and step-width algorithms. To suppress them, smoothing for directional values was introduced. Computer experiments and clinical applications showed a pronounced reduction in statistical fluctuations of the corrected image for all combinations. Combinations using the conjugate gradient method were superior in noise characteristic and computation time. The use of that method with the quadratic function method was optimum if noise property was regarded as important. (author)

  1. Attenuation correction for the HRRT PET-scanner using transmission scatter correction and total variation regularization

    DEFF Research Database (Denmark)

    Keller, Sune H; Svarer, Claus; Sibomana, Merence

    2013-01-01

    scatter correction in the μ-map reconstruction and total variation filtering to the transmission processing. Results: Comparing MAP-TR and the new TXTV with gold standard CT-based attenuation correction, we found that TXTV has less bias as compared to MAP-TR. We also compared images acquired at the HRRT......In the standard software for the Siemens high-resolution research tomograph (HRRT) positron emission tomography (PET) scanner the most commonly used segmentation in the μ -map reconstruction for human brain scans is maximum a posteriori for transmission (MAP-TR). Bias in the lower cerebellum...

  2. Filtering of SPECT reconstructions made using Bellini's attenuation correction method

    International Nuclear Information System (INIS)

    Glick, S.J.; Penney, B.C.; King, M.A.

    1991-01-01

    This paper evaluates a three-dimensional (3D) Wiener filter which is used to restore SPECT reconstructions which were made using Bellini's method of attenuation correction. Its performance is compared to that of several pre-reconstruction filers: the one-dimensional (1D) Butterworth, the two-dimensional (2D) Butterworth, and a 2D Wiener filer. A simulation study is used to compare the four filtering methods. An approximation to a clinical liver spleen study was used as the source distribution and algorithm which accounts for the depth and distance dependent blurring in SPECT was used to compute noise free projections. To study the effect of filtering method on tumor detection accuracy, a 2 cm diameter, cool spherical tumor (40% contrast) was placed at a known, but random, location with the liver. Projection sets for ten tumor locations were computed and five noise realizations of each set were obtained by introducing Poisson noise. The simulated projections were either: filtered with the 1D or 2D Butterworth or the 2D Wiener and then reconstructed using Bellini's intrinsic attenuation correction, or reconstructed first, then filtered with the 3D Wiener. The criteria used for comparison were: normalized mean square error (NMSE), cold spot contrast, and accuracy of tumor detection with an automated numerical method. Results indicate that restorations obtained with 3D Wiener filtering yielded significantly higher lesion contrast and lower NMSE values compared to the other methods of processing. The Wiener restoration filters and the 2D Butterworth all provided similar measures of detectability, which were noticeably higher than that obtained with 1D Butterworth smoothing

  3. Cardiac expression of microsomal triglyceride transfer protein is increased in obesity and serves to attenuate cardiac triglyceride accumulation.

    Directory of Open Access Journals (Sweden)

    Emil D Bartels

    Full Text Available Obesity causes lipid accumulation in the heart and may lead to lipotoxic heart disease. Traditionally, the size of the cardiac triglyceride pool is thought to reflect the balance between uptake and beta-oxidation of fatty acids. However, triglycerides can also be exported from cardiomyocytes via secretion of apolipoproteinB-containing (apoB lipoproteins. Lipoprotein formation depends on expression of microsomal triglyceride transfer protein (MTP; the mouse expresses two isoforms of MTP, A and B. Since many aspects of the link between obesity-induced cardiac disease and cardiac lipid metabolism remain unknown, we investigated how cardiac lipoprotein synthesis affects cardiac expression of triglyceride metabolism-controlling genes, insulin sensitivity, and function in obese mice. Heart-specific ablation of MTP-A in mice using Cre-loxP technology impaired upregulation of MTP expression in response to increased fatty acid availability during fasting and fat feeding. This resulted in cardiac triglyceride accumulation but unaffected cardiac insulin-stimulated glucose uptake. Long-term fat-feeding of male C57Bl/6 mice increased cardiac triglycerides, induced cardiac expression of triglyceride metabolism-controlling genes and attenuated heart function. Abolishing cardiac triglyceride accumulation in fat-fed mice by overexpression of an apoB transgene in the heart prevented the induction of triglyceride metabolism-controlling genes and improved heart function. The results suggest that in obesity, the physiological increase of cardiac MTP expression serves to attenuate cardiac triglyceride accumulation albeit without major effects on cardiac insulin sensitivity. Nevertheless, the data suggest that genetically increased lipoprotein secretion prevents development of obesity-induced lipotoxic heart disease.

  4. Air slab-correction for Γ-ray attenuation measurements

    Science.gov (United States)

    Mann, Kulwinder Singh

    2017-12-01

    Gamma (γ)-ray shielding behaviour (GSB) of a material can be ascertained from its linear attenuation coefficient (μ, cm-1). Narrow-beam transmission geometry is required for μ-measurement. In such measurements, a thin slab of the material has to insert between point-isotropic γ-ray source and detector assembly. The accuracy in measurements requires that sample's optical thickness (OT) remain below 0.5 mean free path (mfp). Sometimes it is very difficult to produce thin slab of sample (absorber), on the other hand for thick absorber, i.e. OT >0.5 mfp, the influence of the air displaced by it cannot be ignored during μ-measurements. Thus, for a thick sample, correction factor has been suggested which compensates the air present in the transmission geometry. The correction factor has been named as an air slab-correction (ASC). Six samples of low-Z engineering materials (cement-black, clay, red-mud, lime-stone, cement-white and plaster-of-paris) have been selected for investigating the effect of ASC on μ-measurements at three γ-ray energies (661.66, 1173.24, 1332.50 keV). The measurements have been made using point-isotropic γ-ray sources (Cs-137 and Co-60), NaI(Tl) detector and multi-channel-analyser coupled with a personal computer. Theoretical values of μ have been computed using a GRIC2-toolkit (standardized computer programme). Elemental compositions of the samples were measured with Wavelength Dispersive X-ray Fluorescence (WDXRF) analyser. Inter-comparison of measured and computed μ-values, suggested that the application of ASC helps in precise μ-measurement for thick samples of low-Z materials. Thus, this hitherto widely ignored ASC factor is recommended to use in similar γ-ray measurements.

  5. Correction of time resolution of an ambulatory cardiac monitor (VEST)

    International Nuclear Information System (INIS)

    Kumita, Shin-ichiro; Nishimura, Tsunehiko; Hayashida, Kohei; Uehara, Toshiisa

    1990-01-01

    Using ambulatory cardiac monitor (VEST) at exercise study, its time resolution is very important factor. We evaluated the time resolution of VEST using pulsate cardiac baloon phantom. Four analysis were carried out; no smoothing (NS) method, 3 points smoothing (3S) method, short sampling interval (SS) method, and digital filter (DF) method. By comparison of |ΔEF| (|EF:HR120-EF: HR60|) among 4 analysis methods, |ΔEF| by DF method was significant small (NS:3.58±3.01, 3S: 4.46±0.95, SS: 3.35±3.26, DF: 1.11±1.28%). We conclude that correction of time resolution by digital filter is necessary when we use VEST during exercise. (author)

  6. Comparison of MR-based attenuation correction and CT-based attenuation correction of whole-body PET/MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Izquierdo-Garcia, David [Mount Sinai School of Medicine, Translational and Molecular Imaging Institute, New York, NY (United States); Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA (United States); Sawiak, Stephen J. [University of Cambridge, Wolfson Brain Imaging Centre, Cambridge (United Kingdom); Knesaurek, Karin; Machac, Joseph [Mount Sinai School of Medicine, Division of Nuclear Medicine, Department of Radiology, New York, NY (United States); Narula, Jagat [Mount Sinai School of Medicine, Department of Cardiology, Zena and Michael A. Weiner Cardiovascular Institute and Marie-Josee and Henry R. Kravis Cardiovascular Health Center, New York, NY (United States); Fuster, Valentin [Mount Sinai School of Medicine, Department of Cardiology, Zena and Michael A. Weiner Cardiovascular Institute and Marie-Josee and Henry R. Kravis Cardiovascular Health Center, New York, NY (United States); The Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid (Spain); Fayad, Zahi A. [Mount Sinai School of Medicine, Translational and Molecular Imaging Institute, New York, NY (United States); Mount Sinai School of Medicine, Department of Cardiology, Zena and Michael A. Weiner Cardiovascular Institute and Marie-Josee and Henry R. Kravis Cardiovascular Health Center, New York, NY (United States); Mount Sinai School of Medicine, Department of Radiology, New York, NY (United States)

    2014-08-15

    The objective of this study was to evaluate the performance of the built-in MR-based attenuation correction (MRAC) included in the combined whole-body Ingenuity TF PET/MR scanner and compare it to the performance of CT-based attenuation correction (CTAC) as the gold standard. Included in the study were 26 patients who underwent clinical whole-body FDG PET/CT imaging and subsequently PET/MR imaging (mean delay 100 min). Patients were separated into two groups: the alpha group (14 patients) without MR coils during PET/MR imaging and the beta group (12 patients) with MR coils present (neurovascular, spine, cardiac and torso coils). All images were coregistered to the same space (PET/MR). The two PET images from PET/MR reconstructed using MRAC and CTAC were compared by voxel-based and region-based methods (with ten regions of interest, ROIs). Lesions were also compared by an experienced clinician. Body mass index and lung density showed significant differences between the alpha and beta groups. Right and left lung densities were also significantly different within each group. The percentage differences in uptake values using MRAC in relation to those using CTAC were greater in the beta group than in the alpha group (alpha group -0.2 ± 33.6 %, R{sup 2} = 0.98, p < 0.001; beta group 10.31 ± 69.86 %, R{sup 2} = 0.97, p < 0.001). In comparison to CTAC, MRAC led to underestimation of the PET values by less than 10 % on average, although some ROIs and lesions did differ by more (including the spine, lung and heart). The beta group (imaged with coils present) showed increased overall PET quantification as well as increased variability compared to the alpha group (imaged without coils). PET data reconstructed with MRAC and CTAC showed some differences, mostly in relation to air pockets, metallic implants and attenuation differences in large bone areas (such as the pelvis and spine) due to the segmentation limitation of the MRAC method. (orig.)

  7. Comparison of MR-based attenuation correction and CT-based attenuation correction of whole-body PET/MR imaging

    International Nuclear Information System (INIS)

    Izquierdo-Garcia, David; Sawiak, Stephen J.; Knesaurek, Karin; Machac, Joseph; Narula, Jagat; Fuster, Valentin; Fayad, Zahi A.

    2014-01-01

    The objective of this study was to evaluate the performance of the built-in MR-based attenuation correction (MRAC) included in the combined whole-body Ingenuity TF PET/MR scanner and compare it to the performance of CT-based attenuation correction (CTAC) as the gold standard. Included in the study were 26 patients who underwent clinical whole-body FDG PET/CT imaging and subsequently PET/MR imaging (mean delay 100 min). Patients were separated into two groups: the alpha group (14 patients) without MR coils during PET/MR imaging and the beta group (12 patients) with MR coils present (neurovascular, spine, cardiac and torso coils). All images were coregistered to the same space (PET/MR). The two PET images from PET/MR reconstructed using MRAC and CTAC were compared by voxel-based and region-based methods (with ten regions of interest, ROIs). Lesions were also compared by an experienced clinician. Body mass index and lung density showed significant differences between the alpha and beta groups. Right and left lung densities were also significantly different within each group. The percentage differences in uptake values using MRAC in relation to those using CTAC were greater in the beta group than in the alpha group (alpha group -0.2 ± 33.6 %, R 2 = 0.98, p 2 = 0.97, p < 0.001). In comparison to CTAC, MRAC led to underestimation of the PET values by less than 10 % on average, although some ROIs and lesions did differ by more (including the spine, lung and heart). The beta group (imaged with coils present) showed increased overall PET quantification as well as increased variability compared to the alpha group (imaged without coils). PET data reconstructed with MRAC and CTAC showed some differences, mostly in relation to air pockets, metallic implants and attenuation differences in large bone areas (such as the pelvis and spine) due to the segmentation limitation of the MRAC method. (orig.)

  8. Cardiac ankyrin repeat protein attenuates cardiac hypertrophy by inhibition of ERK1/2 and TGF-β signaling pathways.

    Directory of Open Access Journals (Sweden)

    Yao Song

    Full Text Available AIMS: It has been reported that cardiac ankyrin repeat protein is associated with heart development and diseases. This study is aimed to investigate the role of CARP in heart hypertrophy in vivo. METHODS AND RESULTS: We generated a cardiac-specific CARP-overexpressing transgenic mouse. Although such animals did not display any overt physiological abnormality, they developed less cardiac hypertrophy in response to pressure overload than did wildtype mice, as indicated by heart weight/body weight ratios, echocardiographic and histological analyses, and expression of hypertrophic markers. These mice also exhibited less cardiac hypertrophy after infusion of isoproterenol. To gain a molecular insight into how CARP attenuated heart hypertrophy, we examined expression of the mitogen-activated protein kinase cascade and found that the concentrations of phosphorylated ERK1/2 and MEK were markedly reduced in the hearts of transgenic mice subjected to pressure overload. In addition, the expressions of TGF-β and phosphorylated Smad3 were significantly downregulated in the hearts of CARP Tg mice in response to pressure overload. Furthermore, addition of human TGF-β1 could reverse the inhibitory effect of CARP on the hypertrophic response induced by phenylephrine in cardiomyocytes. It was also evidenced that the inhibitory effect of CARP on cardiac hypertrophy was not attributed to apoptosis. CONCLUSION: CARP attenuates cardiac hypertrophy, in which the ERK and TGF-β pathways may be involved. Our findings highlight the significance of CARP as an anti-hypertrophic factor in therapy of cardiac hypertrophy.

  9. Noise suppressed partial volume correction for cardiac SPECT/CT

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Chung; Liu, Chi, E-mail: chi.liu@yale.edu [Department of Radiology and Biomedical Imaging, Yale University, New Haven, Connecticut 06520 (United States); Liu, Hui [Department of Radiology and Biomedical Imaging, Yale University, New Haven, Connecticut 06520 and Key Laboratory of Particle and Radiation Imaging (Tsinghua University), Ministry of Education, Beijing 100084 (China); Grobshtein, Yariv [GE Healthcare, Haifa 3910101 (Israel); Stacy, Mitchel R. [Department of Internal Medicine, Yale University, New Haven, Connecticut 06520 (United States); Sinusas, Albert J. [Department of Radiology and Biomedical Imaging, Yale University, New Haven, Connecticut 06520 and Department of Internal Medicine, Yale University, New Haven, Connecticut 06520 (United States)

    2016-09-15

    Purpose: Partial volume correction (PVC) methods typically improve quantification at the expense of increased image noise and reduced reproducibility. In this study, the authors developed a novel voxel-based PVC method that incorporates anatomical knowledge to improve quantification while suppressing noise for cardiac SPECT/CT imaging. Methods: In the proposed method, the SPECT images were first reconstructed using anatomical-based maximum a posteriori (AMAP) with Bowsher’s prior to penalize noise while preserving boundaries. A sequential voxel-by-voxel PVC approach (Yang’s method) was then applied on the AMAP reconstruction using a template response. This template response was obtained by forward projecting a template derived from a contrast-enhanced CT image, and then reconstructed using AMAP to model the partial volume effects (PVEs) introduced by both the system resolution and the smoothing applied during reconstruction. To evaluate the proposed noise suppressed PVC (NS-PVC), the authors first simulated two types of cardiac SPECT studies: a {sup 99m}Tc-tetrofosmin myocardial perfusion scan and a {sup 99m}Tc-labeled red blood cell (RBC) scan on a dedicated cardiac multiple pinhole SPECT/CT at both high and low count levels. The authors then applied the proposed method on a canine equilibrium blood pool study following injection with {sup 99m}Tc-RBCs at different count levels by rebinning the list-mode data into shorter acquisitions. The proposed method was compared to MLEM reconstruction without PVC, two conventional PVC methods, including Yang’s method and multitarget correction (MTC) applied on the MLEM reconstruction, and AMAP reconstruction without PVC. Results: The results showed that the Yang’s method improved quantification, however, yielded increased noise and reduced reproducibility in the regions with higher activity. MTC corrected for PVE on high count data with amplified noise, although yielded the worst performance among all the methods

  10. Improvements to the Chebyshev expansion of attenuation correction factors for cylindrical samples

    International Nuclear Information System (INIS)

    Mildner, D.F.R.; Carpenter, J.M.

    1990-01-01

    The accuracy of the Chebyshev expansion coefficients used for the calculation of attenuation correction factors for cylinderical samples has been improved. An increased order of expansion allows the method to be useful over a greater range of attenuation. It is shown that many of these coefficients are exactly zero, others are rational numbers, and others are rational frations of π -1 . The assumptions of Sears in his asymptotic expression of the attenuation correction factor are also examined. (orig.)

  11. MRI-guided attenuation correction in whole-body PET/MR. Assessment of the effect of bone attenuation

    International Nuclear Information System (INIS)

    Akbarzadeh, A.; Ay, M.R.; Ahmadian, A.; Riahi Alam, N.; Zaidi, H.

    2013-01-01

    Hybrid positron emission tomography (PET)/MRI presents many advantages in comparison with its counterpart PET/CT in terms of improved soft-tissue contrast, decrease in radiation exposure, and truly simultaneous and multi-parametric imaging capabilities. However, the lack of well-established methodology for MR-based attenuation correction is hampering further development and wider acceptance of this technology. We assess the impact of ignoring bone attenuation and using different tissue classes for generation of the attenuation map on the accuracy of attenuation correction of PET data. This work was performed using simulation studies based on the XCAT phantom and clinical input data. For the latter, PET and CT images of patients were used as input for the analytic simulation model using realistic activity distributions where CT-based attenuation correction was utilized as reference for comparison. For both phantom and clinical studies, the reference attenuation map was classified into various numbers of tissue classes to produce three (air, soft tissue and lung), four (air, lungs, soft tissue and cortical bones) and five (air, lungs, soft tissue, cortical bones and spongeous bones) class attenuation maps. The phantom studies demonstrated that ignoring bone increases the relative error by up to 6.8% in the body and up to 31.0% for bony regions. Likewise, the simulated clinical studies showed that the mean relative error reached 15% for lesions located in the body and 30.7% for lesions located in bones, when neglecting bones. These results demonstrate an underestimation of about 30% of tracer uptake when neglecting bone, which in turn imposes substantial loss of quantitative accuracy for PET images produced by hybrid PET/MRI systems. Considering bones in the attenuation map will considerably improve the accuracy of MR-guided attenuation correction in hybrid PET/MR to enable quantitative PET imaging on hybrid PET/MR technologies. (author)

  12. Effects of scatter and attenuation corrections on phantom and clinical brain SPECT

    International Nuclear Information System (INIS)

    Prando, S.; Robilotta, C.C.R.; Oliveira, M.A.; Alves, T.C.; Busatto Filho, G.

    2002-01-01

    Aim: The present work evaluated the effects of combinations of scatter and attenuation corrections on the analysis of brain SPECT. Materials and Methods: We studied images of the 3D Hoffman brain phantom and from a group of 20 depressive patients with confirmed cardiac insufficiency (CI) and 14 matched healthy controls (HC). Data were acquired with a Sophy-DST/SMV-GE dual-head camera after venous injection of 1110MBq 99m Tc-HMPAO. Two energy windows, 15% on 140keV and 30% centered on 108keV of the Compton distribution, were used to obtain corresponding sets of 128x128x128 projections. Tomograms were reconstructed using OSEM (2 iterations, 8 sub-sets) and Metz filter (order 8, 4 pixels FWHM psf) and FBP with Butterworth filter (order 10, frequency 0.7 Nyquist). Ten combinations of Jaszczak correction (factors 0.3, 0.4 and 0.5) and the 1st order Chang correction (u=0.12cm -1 and 0.159cm -1 ) were applied on the phantom data. In all the phantom images, contrast and signal-noise ratio between 3 ROIs (ventricle, occipital and thalamus) and cerebellum, as well as the ratio between activities in gray and white matters, were calculated and compared with the expected values. The patients images were corrected with k=0.5 and u=0.159cm -1 and reconstructed with OSEM and Metz filter. The images were inspected visually and blood flow comparisons between the CI and the HC groups were performed using Statistical Parametric Mapping (SPM). Results: The best results in the analysis of the contrast and activities ratio were obtained with k=0.5 and u=0.159cm -1 . The results of the activities ratio obtained with OSEM e Metz filter are similar to those published by Laere et al.[J.Nucl.Med 2000;41:2051-2062]. The method of correction using effective attenuation coefficient produced results visually acceptable, but inadequate for the quantitative evaluation. The results of signal-noise ratio are better with OSEM than FBP reconstruction method. The corrections in the CI patients studies

  13. Deconvolution based attenuation correction for time-of-flight positron emission tomography

    Science.gov (United States)

    Lee, Nam-Yong

    2017-10-01

    For an accurate quantitative reconstruction of the radioactive tracer distribution in positron emission tomography (PET), we need to take into account the attenuation of the photons by the tissues. For this purpose, we propose an attenuation correction method for the case when a direct measurement of the attenuation distribution in the tissues is not available. The proposed method can determine the attenuation factor up to a constant multiple by exploiting the consistency condition that the exact deconvolution of noise-free time-of-flight (TOF) sinogram must satisfy. Simulation studies shows that the proposed method corrects attenuation artifacts quite accurately for TOF sinograms of a wide range of temporal resolutions and noise levels, and improves the image reconstruction for TOF sinograms of higher temporal resolutions by providing more accurate attenuation correction.

  14. Fuzzy clustering-based segmented attenuation correction in whole-body PET

    CERN Document Server

    Zaidi, H; Boudraa, A; Slosman, DO

    2001-01-01

    Segmented-based attenuation correction is now a widely accepted technique to reduce noise contribution of measured attenuation correction. In this paper, we present a new method for segmenting transmission images in positron emission tomography. This reduces the noise on the correction maps while still correcting for differing attenuation coefficients of specific tissues. Based on the Fuzzy C-Means (FCM) algorithm, the method segments the PET transmission images into a given number of clusters to extract specific areas of differing attenuation such as air, the lungs and soft tissue, preceded by a median filtering procedure. The reconstructed transmission image voxels are therefore segmented into populations of uniform attenuation based on the human anatomy. The clustering procedure starts with an over-specified number of clusters followed by a merging process to group clusters with similar properties and remove some undesired substructures using anatomical knowledge. The method is unsupervised, adaptive and a...

  15. Attenuation correction for the HRRT PET-scanner using transmission scatter correction and total variation regularization.

    Science.gov (United States)

    Keller, Sune H; Svarer, Claus; Sibomana, Merence

    2013-09-01

    In the standard software for the Siemens high-resolution research tomograph (HRRT) positron emission tomography (PET) scanner the most commonly used segmentation in the μ -map reconstruction for human brain scans is maximum a posteriori for transmission (MAP-TR). Bias in the lower cerebellum and pons in HRRT brain images have been reported. The two main sources of the problem with MAP-TR are poor bone/soft tissue segmentation below the brain and overestimation of bone mass in the skull. We developed the new transmission processing with total variation (TXTV) method that introduces scatter correction in the μ-map reconstruction and total variation filtering to the transmission processing. Comparing MAP-TR and the new TXTV with gold standard CT-based attenuation correction, we found that TXTV has less bias as compared to MAP-TR. We also compared images acquired at the HRRT scanner using TXTV to the GE Advance scanner images and found high quantitative correspondence. TXTV has been used to reconstruct more than 4000 HRRT scans at seven different sites with no reports of biases. TXTV-based reconstruction is recommended for human brain scans on the HRRT.

  16. Evaluation of attenuation correction, scatter correction and resolution recovery in myocardial Tc-99m MIBI SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Larcos, G.; Hutton, B.F.; Farlow, D.C.; Campbell- Rodgers, N.; Gruenewald, S.M.; Lau, Y.H. [Westmead Hospital, Westmead, Sydney, NSW (Australia). Departments of Nuclear Medicine and Ultrasound and Medical Physics

    1998-06-01

    Full text: The introduction of transmission based attenuation correction (AC) has increased the diagnostic accuracy of Tc-99m MIBI myocardial perfusion SPECT. The aim of this study is to evaluate recent developments, including scatter correction (SC) and resolution recovery (RR). We reviewed 13 patients who underwent Tc-99m MIBI SPECT (two day protocol) and coronary angiography and 4 manufacturer supplied studies assigned a low pretest likelihood of coronary artery disease (CAD). Patients had a mean age of 59 years (range: 41-78). Data were reconstructed using filtered backprojection (FBP; method 1), maximum likelihood (ML) incorporating AC (method 2), ADAC software using sinogram based SC+RR followed by ML with AC (method 3) and ordered subset ML incorporating AC,SC and RR (method 4). Images were reported by two of three blinded experienced physicians using a standard semiquantitative scoring scheme. Fixed or reversible perfusion defects were considered abnormal; CAD was considered present with stenoses > 50%. Patients had normal coronary anatomy (n=9), single (n=4) or two vessel CAD (n=4) (four in each of LAD, RCA and LCX). There were no statistically significant differences for any combination. Normalcy rate = 100% for all methods. Physicians graded 3/17 (methods 2,4) and 1/17 (method 3) images as fair or poor in quality. Thus, AC or AC+SC+RR produce good quality images in most patients; there is potential for improvement in sensitivity over standard FBP with no significant change in normalcy or specificity

  17. Minocycline attenuates cardiac dysfunction in tumor-burdened mice.

    Science.gov (United States)

    Devine, Raymond D; Eichenseer, Clayton M; Wold, Loren E

    2016-11-01

    Cardiovascular dysfunction as a result of tumor burden is becoming a recognized complication; however, the mechanisms remain unknown. A murine model of cancer cachexia has shown marked increases of matrix metalloproteinases (MMPs), known mediators of cardiac remodeling, in the left ventricle. The extent to which MMPs are involved in remodeling remains obscured. To this end a common antibiotic, minocycline, with MMP inhibitory properties was used to elucidate MMP involvement in tumor induced cardiovascular dysfunction. Tumor-bearing mice showed decreased cardiac function with reduced posterior wall thickness (PWTs) during systole, increased MMP and collagen expression consistent with fibrotic remodeling. Administration of minocycline preserved cardiac function in tumor bearing mice and decreased collagen RNA expression in the left ventricle. MMP protein levels were unaffected by minocycline administration, with the exception of MMP-9, indicating minocycline inhibition mechanisms are directly affecting MMP activity. Cancer induced cardiovascular dysfunction is an increasing concern; novel therapeutics are needed to prevent cardiac complications. Minocycline is a well-known antibiotic and recently has been shown to possess MMP inhibitory properties. Our findings presented here show that minocycline could represent a novel use for a long established drug in the prevention and treatment of cancer induced cardiovascular dysfunction. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Direct cone-beam cardiac reconstruction algorithm with cardiac banding artifact correction

    International Nuclear Information System (INIS)

    Taguchi, Katsuyuki; Chiang, Beshan S.; Hein, Ilmar A.

    2006-01-01

    Multislice helical computed tomography (CT) is a promising noninvasive technique for coronary artery imaging. Various factors can cause inconsistencies in cardiac CT data, which can result in degraded image quality. These inconsistencies may be the result of the patient physiology (e.g., heart rate variations), the nature of the data (e.g., cone-angle), or the reconstruction algorithm itself. An algorithm which provides the best temporal resolution for each slice, for example, often provides suboptimal image quality for the entire volume since the cardiac temporal resolution (TRc) changes from slice to slice. Such variations in TRc can generate strong banding artifacts in multi-planar reconstruction images or three-dimensional images. Discontinuous heart walls and coronary arteries may compromise the accuracy of the diagnosis. A β-blocker is often used to reduce and stabilize patients' heart rate but cannot eliminate the variation. In order to obtain robust and optimal image quality, a software solution that increases the temporal resolution and decreases the effect of heart rate is highly desirable. This paper proposes an ECG-correlated direct cone-beam reconstruction algorithm (TCOT-EGR) with cardiac banding artifact correction (CBC) and disconnected projections redundancy compensation technique (DIRECT). First the theory and analytical model of the cardiac temporal resolution is outlined. Next, the performance of the proposed algorithms is evaluated by using computer simulations as well as patient data. It will be shown that the proposed algorithms enhance the robustness of the image quality against inconsistencies by guaranteeing smooth transition of heart cycles used in reconstruction

  19. Correction of Hemodynamic Disorders in the Complex Surgical Correction of Acquired Cardiac Valvular Defects

    Directory of Open Access Journals (Sweden)

    A. I. Lenkin

    2011-01-01

    Full Text Available Objective: to compare the efficiency of using the values of transpulmonary (PiCCO and prepulmonary (Swan-Ganz catheter thermodilution as guides to targeted therapy for hemodynamic disorders in the surgical correction of mixed cardiac valvular defects. Subjects and methods. The study enrolled 40 patients operated on for acquired cardiac diseases who were randomized to two matched groups. Hemodynamics was monitored by means of a Swan-Ganz catheter in Group 1 and by transpulmonary thermodilution in Group 2. Anesthesia was maintained with propofol and fentanyl. Infusion therapy was performed using crystalloid and colloid solutions. Continuous intravenous infusion of inotropic agents was used when heart failure was developed. Hemodynamic, clinical, and laboratory parameters were estimated intraoperatively and within 24 hours postoperatively. Results. The groups did not differ in the degree of baseline heart failure, the duration of an operation and myocardial ischemia, and the length of extracorporeal circulation. In the PiCCO group, postoperative infusion volume was 33% higher than that in the Swan-Ganz group, which ensured increases in stroke volume and oxygen delivery in the early postoperative period (p<0.05. Respiratory support was 26% shorter in the PiCCO group (p<0.04. Conclusion. After surgical interventions for mixed cardiac defects, the targeted therapy algorithm based on transpulmonary thermodilution provided more steady-state values of hemodynamics and oxygen transport, which was followed by the increased scope of infusion therapy and the shorter length of postoperative mechanical ventilation than that based on hemodynamics being corrected from the values of prepul-monary thermodilution. Key words: transpulmonary thermodilution, targeted therapy, prepulmonary ther-modilution, acquired heart disease.

  20. Effect of attenuation correction on surface amplitude distribution of wind waves

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.

    Some selected wave profiles recorded using a ship borne wave recorder are analysed to study the effect of attenuation correction on the distribution of the surface amplitudes. A new spectral width parameter is defined to account for wide band...

  1. Effects of methods of attenuation correction on source parameter determination

    Science.gov (United States)

    Sonley, Eleanor; Abercrombie, Rachel E.

    We quantify the effects of using different approaches to model individual earthquake spectra. Applying different approaches can introduce significant variability in the calculated source parameters, even when applied to the same data. To compare large and small earthquake source parameters, the results of multiple studies need to be combined to extend the magnitude range, but the variability introduced by the different approaches hampers the outcome. When studies are combined, there is large uncertainty and large scatter and some systematic differences have been neglected. We model individual earthquake spectra from repeating earthquakes (M˜2) at Parkfield, CA, recorded by a borehole network. We focus on the effects of trade-offs between attenuation (Q) and corner frequency in spectral fitting and the effect of the model shape at the corner frequency on radiated energy. The trade-off between attenuation and corner frequency can increase radiated energy by up to 400% and seismic moment by up to 100%.

  2. Attenuation correction for freely moving small animal brain PET studies based on a virtual scanner geometry

    International Nuclear Information System (INIS)

    Angelis, G I; Kyme, A Z; Ryder, W J; Fulton, R R; Meikle, S R

    2014-01-01

    Attenuation correction in positron emission tomography brain imaging of freely moving animals is a very challenging problem since the torso of the animal is often within the field of view and introduces a non negligible attenuating factor that can degrade the quantitative accuracy of the reconstructed images. In the context of unrestrained small animal imaging, estimation of the attenuation correction factors without the need for a transmission scan is highly desirable. An attractive approach that avoids the need for a transmission scan involves the generation of the hull of the animal’s head based on the reconstructed motion corrected emission images. However, this approach ignores the attenuation introduced by the animal’s torso. In this work, we propose a virtual scanner geometry which moves in synchrony with the animal’s head and discriminates between those events that traversed only the animal’s head (and therefore can be accurately compensated for attenuation) and those that might have also traversed the animal’s torso. For each recorded pose of the animal’s head a new virtual scanner geometry is defined and therefore a new system matrix must be calculated leading to a time-varying system matrix. This new approach was evaluated on phantom data acquired on the microPET Focus 220 scanner using a custom-made phantom and step-wise motion. Results showed that when the animal’s torso is within the FOV and not appropriately accounted for during attenuation correction it can lead to bias of up to 10% . Attenuation correction was more accurate when the virtual scanner was employed leading to improved quantitative estimates (bias < 2%), without the need to account for the attenuation introduced by the extraneous compartment. Although the proposed method requires increased computational resources, it can provide a reliable approach towards quantitatively accurate attenuation correction for freely moving animal studies. (paper)

  3. Cardiac Fibroblasts Adopt Osteogenic Fates and Can Be Targeted to Attenuate Pathological Heart Calcification.

    Science.gov (United States)

    Pillai, Indulekha C L; Li, Shen; Romay, Milagros; Lam, Larry; Lu, Yan; Huang, Jie; Dillard, Nathaniel; Zemanova, Marketa; Rubbi, Liudmilla; Wang, Yibin; Lee, Jason; Xia, Ming; Liang, Owen; Xie, Ya-Hong; Pellegrini, Matteo; Lusis, Aldons J; Deb, Arjun

    2017-02-02

    Mammalian tissues calcify with age and injury. Analogous to bone formation, osteogenic cells are thought to be recruited to the affected tissue and induce mineralization. In the heart, calcification of cardiac muscle leads to conduction system disturbances and is one of the most common pathologies underlying heart blocks. However the cell identity and mechanisms contributing to pathological heart muscle calcification remain unknown. Using lineage tracing, murine models of heart calcification and in vivo transplantation assays, we show that cardiac fibroblasts (CFs) adopt an osteoblast cell-like fate and contribute directly to heart muscle calcification. Small-molecule inhibition of ENPP1, an enzyme that is induced upon injury and regulates bone mineralization, significantly attenuated cardiac calcification. Inhibitors of bone mineralization completely prevented ectopic cardiac calcification and improved post injury heart function. Taken together, these findings highlight the plasticity of fibroblasts in contributing to ectopic calcification and identify pharmacological targets for therapeutic development. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Evaluation of attenuation and scatter correction requirements in small animal PET and SPECT imaging

    Science.gov (United States)

    Konik, Arda Bekir

    Positron emission tomography (PET) and single photon emission tomography (SPECT) are two nuclear emission-imaging modalities that rely on the detection of high-energy photons emitted from radiotracers administered to the subject. The majority of these photons are attenuated (absorbed or scattered) in the body, resulting in count losses or deviations from true detection, which in turn degrades the accuracy of images. In clinical emission tomography, sophisticated correction methods are often required employing additional x-ray CT or radionuclide transmission scans. Having proven their potential in both clinical and research areas, both PET and SPECT are being adapted for small animal imaging. However, despite the growing interest in small animal emission tomography, little scientific information exists about the accuracy of these correction methods on smaller size objects, and what level of correction is required. The purpose of this work is to determine the role of attenuation and scatter corrections as a function of object size through simulations. The simulations were performed using Interactive Data Language (IDL) and a Monte Carlo based package, Geant4 application for emission tomography (GATE). In IDL simulations, PET and SPECT data acquisition were modeled in the presence of attenuation. A mathematical emission and attenuation phantom approximating a thorax slice and slices from real PET/CT data were scaled to 5 different sizes (i.e., human, dog, rabbit, rat and mouse). The simulated emission data collected from these objects were reconstructed. The reconstructed images, with and without attenuation correction, were compared to the ideal (i.e., non-attenuated) reconstruction. Next, using GATE, scatter fraction values (the ratio of the scatter counts to the total counts) of PET and SPECT scanners were measured for various sizes of NEMA (cylindrical phantoms representing small animals and human), MOBY (realistic mouse/rat model) and XCAT (realistic human model

  5. Cardiac Effects of Attenuating Gsα - Dependent Signaling.

    Directory of Open Access Journals (Sweden)

    Marcus R Streit

    Full Text Available Inhibition of β-adrenergic signalling plays a key role in treatment of heart failure. Gsα is essential for β-adrenergic signal transduction. In order to reduce side-effects of beta-adrenergic inhibition diminishing β-adrenergic signalling in the heart at the level of Gsα is a promising option.We analyzed the influence of Gsα on regulation of myocardial function and development of cardiac hypertrophy, using a transgenic mouse model (C57BL6/J mice overexpressing a dominant negative Gsα-mutant under control of the α-MHC-promotor. Cardiac phenotype was characterized in vivo and in vitro and under acute and chronic β-adrenergic stimulation. At rest, Gsα-DN-mice showed bradycardia (602 ± 13 vs. 660 ± 17 bpm, p<0.05 and decreased dp/dtmax (5037 ± 546- vs. 6835 ± 505 mmHg/s, p = 0.02. No significant differences were found regarding ejection fraction, heart weight and cardiomyocyte size. β-blockade by propranolol revealed no baseline differences of hemodynamic parameters between wildtype and Gsα-DN-mice. Acute adrenergic stimulation resulted in decreased β-adrenergic responsiveness in Gsα-DN-mice. Under chronic adrenergic stimulation, wildtype mice developed myocardial hypertrophy associated with increase of LV/BW-ratio by 23% (4.4 ± 0.2 vs. 3.5 ± 0.1 mg/g, p<0.01 and cardiac myocyte size by 24% (14927 ± 442 px vs. 12013 ± 583 px, p<0.001. In contrast, both parameters were unchanged in Gsα-DN-mice after chronic isoproterenol stimulation.Overexpression of a dominant negative mutant of Gsα leads to decreased β-adrenergic responsiveness and is protective against isoproterenol-induced hypertrophy. Thus, Gsα-DN-mice provide novel insights into β-adrenergic signal transduction and its modulation in myocardial overload and failure.

  6. Blueberry Anthocyanins-Enriched Extracts Attenuate Cyclophosphamide-Induced Cardiac Injury.

    Directory of Open Access Journals (Sweden)

    Yunen Liu

    Full Text Available We sought to explore the effect of blueberry anthocyanins-enriched extracts (BAE on cyclophosphamide (CTX-induced cardiac injury. The rats were divided randomly into five groups including normal control, CTX 100 mg/kg, BAE 80mg/kg, CTX+BAE 20mg/kg and CTX+BAE 80mg/kg groups. The rats in the three BAE-treated groups were administered BAE for four weeks. Seven days after BAE administration, rats in CTX group and two BAE-treated groups were intraperitoneally injected with a single dose of 100 mg/kg CTX. Cardiac injury was assessed using physiological parameters, Echo, morphological staining, real-time PCR and western blot. In addition, cardiotoxicity indices, inflammatory cytokines expression and oxidative stress markers were also detected. Four weeks 20mg/kg and 80mg/kg dose of BAE treatment following CTX exposure attenuated mean arterial blood pressure, heart rate and activities of heart enzymes, improved cardiac dysfunction, left ventricular hypertrophy and fibrosis. Importantly, BAE also attenuated CTX-induced LV leukocyte infiltration and inflammatory cytokines expression, ameliorated oxidative stress as well as cardiomyocyte apoptosis. In conclusion, BAE attenuated the CTX-induced cardiac injury and the protective mechanisms were related closely to the anti-inflammatory, antioxidant and anti-inflammatory characteristics of BAE.

  7. Efficiency and attenuation correction factors determination in gamma spectrometric assay of bulk samples using self radiation

    International Nuclear Information System (INIS)

    Haddad, Kh.

    2009-02-01

    Gamma spectrometry forms the most important and capable tool for measuring radioactive materials. Determination of the efficiency and attenuation correction factors is the most tedious problem in the gamma spectrometric assay of bulk samples. A new experimental and easy method for these correction factors determination using self radiation was proposed in this work. An experimental study of the correlation between self attenuation correction factor and sample thickness and its practical application was also introduced. The work was performed on NORM and uranyl nitrate bulk sample. The results of proposed methods agreed with those of traditional ones.(author)

  8. Attenuation correction for the large non-human primate brain imaging using microPET

    International Nuclear Information System (INIS)

    Naidoo-Variawa, S; Lehnert, W; Kassiou, M; Banati, R; Meikle, S R

    2010-01-01

    Assessment of the biodistribution and pharmacokinetics of radiopharmaceuticals in vivo is often performed on animal models of human disease prior to their use in humans. The baboon brain is physiologically and neuro-anatomically similar to the human brain and is therefore a suitable model for evaluating novel CNS radioligands. We previously demonstrated the feasibility of performing baboon brain imaging on a dedicated small animal PET scanner provided that the data are accurately corrected for degrading physical effects such as photon attenuation in the body. In this study, we investigated factors affecting the accuracy and reliability of alternative attenuation correction strategies when imaging the brain of a large non-human primate (papio hamadryas) using the microPET Focus 220 animal scanner. For measured attenuation correction, the best bias versus noise performance was achieved using a 57 Co transmission point source with a 4% energy window. The optimal energy window for a 68 Ge transmission source operating in singles acquisition mode was 20%, independent of the source strength, providing bias-noise performance almost as good as for 57 Co. For both transmission sources, doubling the acquisition time had minimal impact on the bias-noise trade-off for corrected emission images, despite observable improvements in reconstructed attenuation values. In a [ 18 F]FDG brain scan of a female baboon, both measured attenuation correction strategies achieved good results and similar SNR, while segmented attenuation correction (based on uncorrected emission images) resulted in appreciable regional bias in deep grey matter structures and the skull. We conclude that measured attenuation correction using a single pass 57 Co (4% energy window) or 68 Ge (20% window) transmission scan achieves an excellent trade-off between bias and propagation of noise when imaging the large non-human primate brain with a microPET scanner.

  9. Respiratory and cardiac motion correction in dual gated PET/MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Fayad, Hadi; Monnier, Florian [LaTIM, INSERM, UMR 1101, Brest (France); Odille, Freedy; Felblinger, Jacques [INSERM U947, University of Nancy, Nancy (France); Lamare, Frederic [INCIA, UMR5287, CNRS, CHU Bordeaux, Bordeaux (France); Visvikis, Dimitris [LaTIM, INSERM, UMR 1101, Brest (France)

    2015-05-18

    Respiratory and cardiac motion in PET/MR imaging leads to reduced quantitative and qualitative image accuracy. Correction methodologies involve the use of double gated acquisitions which lead to low signal-to-noise ratio (SNR) and to issues concerning the combination of cardiac and respiratory frames. The objective of this work is to use a generalized reconstruction by inversion of coupled systems (GRICS) approach, previously used for PET/MR respiratory motion correction, combined with a cardiac phase signal and a reconstruction incorporated PET motion correction approach in order to reconstruct motion free images from dual gated PET acquisitions. The GRICS method consists of formulating parallel MRI in the presence of patient motion as a coupled inverse problem. Its resolution, using a fixed-point method, allows the reconstructed image to be improved using a motion model constructed from the raw MR data and two respiratory belts. GRICS obtained respiratory displacements are interpolated using the cardiac phase derived from an ECG to model simultaneous cardiac and respiratory motion. Three different volunteer datasets (4DMR acquisitions) were used for evaluation. GATE was used to simulate 4DPET datasets corresponding to the acquired 4DMR images. Simulated data were subsequently binned using 16 cardiac phases (M1) vs diastole only (M2), in combination with 8 respiratory amplitude gates. Respiratory and cardiac motion corrected PET images using either M1 or M2 were compared to respiratory only corrected images and evaluated in terms of SNR and contrast improvement. Significant visual improvements were obtained when correcting simultaneously for respiratory and cardiac motion (using 16 cardiac phase or diastole only) compared to respiratory motion only compensation. Results were confirmed by an associated increased SNR and contrast. Results indicate that using GRICS is an efficient tool for respiratory and cardiac motion correction in dual gated PET/MR imaging.

  10. Attenuation correction for the collimated gamma ray assay of cylindrical samples

    International Nuclear Information System (INIS)

    Patra, Sabyasachi; Agarwal, Chhavi; Goswami, A.; Gathibandhe, M.

    2015-01-01

    The Hybrid Monte Carlo (HMC) method developed earlier for attenuation correction of non-collimated samples [Agarwal et al., 2008, Nucl. Instrum. Methods A 597, 198], has been extended to the segmented gamma ray assay of cylindrical samples. The method has been validated both experimentally and theoretically. For experimental validation, the results of HMC calculation have been compared with the experimentally obtained attenuation correction factors. The HMC attenuation correction factors have also been compared with the results obtained from literature available near-field and far-field formulae at two sample-to-detector distances (10.3 cm and 20.4 cm). The method has been found to be valid at all sample-to-detector distances over a wide range of transmittance. On the other hand, the literature available near-field and far-field formulae have been found to work over a limited range of sample-to detector distances and transmittances. The HMC method has been further extended to circular collimated geometries where analytical formula for attenuation correction does not exist. - Highlights: • Hybrid Monte Carlo method for attenuation correction developed for SGA system. • Method found to work for all sample-detector geometries for all transmittances. • The near-field formula applicable only after certain sample-detector distance. • The far-field formula applicable only for higher transmittances (>18%). • Hybrid Monte Carlo method further extended to circular collimated geometry

  11. Correlation of the myocardial perfusion corrected by attenuation with the coronariography. Preliminary results

    International Nuclear Information System (INIS)

    Garcia C, S.E.; Garcia O, R.

    2005-01-01

    The attenuation that suffers the radiation in the soft tissues of the hinders the appropriate interpretation of the myocardial perfusion studies, for what have been implemented attenuation correction systems to reduce the attenuation for soft tissues and to provide myocardial perfusion images more accurate in the diagnosis of coronary illness. The objective was to evaluate the utility of an attenuation correction system (with source of Gadolinium 153) to minimize the devices that look like true defects of myocardial perfusion, caused by soft tissues (mammary tissue, thoracic wall, abdomen, left hemi diaphragm), and to compare those interpretations of the studies with the interpretations of the corresponding coronariographies. The method consists of 95 electronic files which were revised with the concept of heart catheterization, being identified 20 patients from the masculine sex to those that underwent coronariography among May 1999 and December 2002, and that they had study of myocardial perfusion in a maximum period of 3 months foresaw to the invasive procedure. (Author)

  12. Impact of attenuation correction and gated acquisition in SPECT myocardial perfusion imaging: results of the multicentre SPAG (SPECT Attenuation Correction vs Gated) study

    International Nuclear Information System (INIS)

    Genovesi, Dario; Giorgetti, Assuero; Gimelli, Alessia; Kusch, Annette; D'Aragona Tagliavia, Irene; Casagranda, Mirta; Marzullo, Paolo; Cannizzaro, Giorgio; Giubbini, Raffaele; Bertagna, Francesco; Fagioli, Giorgio; Rossi, Massimiliano; Romeo, Annadina; Bertolaccini, Pietro; Bonini, Rita

    2011-01-01

    In clinical myocardial single photon emission computed tomography (SPECT), attenuation artefacts may cause a loss of specificity in the identification of diseased vessels that can be corrected by means of gated SPECT (GSPECT) acquisition or CT attenuation correction (AC). The purpose of this multicentre study was to assess the impact of GSPECT and AC on the diagnostic performance of myocardial scintigraphy, according to patient's sex, body mass index (BMI) and site of coronary artery disease (CAD). We studied a group of 104 patients who underwent coronary angiography within 1 month before or after the SPECT study. Patients with a BMI > 27 were considered ''overweight''. Attenuation-corrected and standard GSPECT early images were randomly interpreted by three readers blinded to the clinical data. In the whole group, GSPECT and AC showed a diagnostic accuracy of 86.5% (sensitivity 82%, specificity 93%) and 77% (sensitivity 75.4%, specificity 81.4%), respectively (p < 0.05). In women, when anterior ischaemia was matched with CAD, AC failed to show any increase in specificity (AC 63.6% vs GSPECT 63.6%) with evident loss of sensitivity (AC 72.7% vs GSPECT 90.9%). AC significantly improved SPECT specificity in the identification of right CAD in overweight men (AC 100% vs GSPECT 66.7%, p <0.05). AC improved specificity in the evaluation of right CAD in overweight men. In the other evaluable subgroups specificity was not significantly affected while sensitivity was frequently reduced. (orig.)

  13. Impact of attenuation correction and gated acquisition in SPECT myocardial perfusion imaging: results of the multicentre SPAG (SPECT Attenuation Correction vs Gated) study

    Energy Technology Data Exchange (ETDEWEB)

    Genovesi, Dario; Giorgetti, Assuero; Gimelli, Alessia; Kusch, Annette; D' Aragona Tagliavia, Irene; Casagranda, Mirta; Marzullo, Paolo [Fondazione CNR-Regione Toscana ' ' G. Monasterio' ' , Nuclear Medicine, Pisa (Italy); Cannizzaro, Giorgio [A.O.V. Cervello, Nuclear Medicine, Palermo (Italy); Giubbini, Raffaele; Bertagna, Francesco [Spedali Civili, Nuclear Medicine, Brescia (Italy); Fagioli, Giorgio; Rossi, Massimiliano; Romeo, Annadina [Ospedale Maggiore, Nuclear Medicine, Bologna (Italy); Bertolaccini, Pietro; Bonini, Rita [Ospedale SS Giacomo e Cristoforo, Nuclear Medicine, Massa (Italy)

    2011-10-15

    In clinical myocardial single photon emission computed tomography (SPECT), attenuation artefacts may cause a loss of specificity in the identification of diseased vessels that can be corrected by means of gated SPECT (GSPECT) acquisition or CT attenuation correction (AC). The purpose of this multicentre study was to assess the impact of GSPECT and AC on the diagnostic performance of myocardial scintigraphy, according to patient's sex, body mass index (BMI) and site of coronary artery disease (CAD). We studied a group of 104 patients who underwent coronary angiography within 1 month before or after the SPECT study. Patients with a BMI > 27 were considered ''overweight''. Attenuation-corrected and standard GSPECT early images were randomly interpreted by three readers blinded to the clinical data. In the whole group, GSPECT and AC showed a diagnostic accuracy of 86.5% (sensitivity 82%, specificity 93%) and 77% (sensitivity 75.4%, specificity 81.4%), respectively (p < 0.05). In women, when anterior ischaemia was matched with CAD, AC failed to show any increase in specificity (AC 63.6% vs GSPECT 63.6%) with evident loss of sensitivity (AC 72.7% vs GSPECT 90.9%). AC significantly improved SPECT specificity in the identification of right CAD in overweight men (AC 100% vs GSPECT 66.7%, p <0.05). AC improved specificity in the evaluation of right CAD in overweight men. In the other evaluable subgroups specificity was not significantly affected while sensitivity was frequently reduced. (orig.)

  14. Histone deacetylase inhibitor, CG200745, attenuates cardiac hypertrophy and fibrosis in DOCA-induced hypertensive rats

    OpenAIRE

    Lee, Eunjo; Song, Min-ji; Lee, Hae-Ahm; Kang, Seol-Hee; Kim, Mina; Yang, Eun Kyoung; Lee, Do Young; Ro, Seonggu; Cho, Joong Myung; Kim, Inkyeom

    2016-01-01

    CG200745 is a novel inhibitor of histone deacetylases (HDACs), initially developed for treatment of various hematological and solid cancers. Because it is water-soluble, it can be administered orally. We hypothesized that the HDAC inhibitor, CG200745, attenuates cardiac hypertrophy and fibrosis in deoxycorticosterone acetate (DOCA)-induced hypertensive rats. For establishment of hypertension, 40 mg/kg of DOCA was subcutaneously injected four times weekly into Sprague-Dawley rats. All the rats...

  15. Vitamin D attenuates pressure overload-induced cardiac remodeling and dysfunction in mice.

    Science.gov (United States)

    Zhang, Liang; Yan, Xiao; Zhang, Yun-Long; Bai, Jie; Hidru, Tesfaldet Habtemariam; Wang, Qing-Shan; Li, Hui-Hua

    2018-04-01

    Vitamin D (VD) and its analogues play critical roles in metabolic and cardiovascular diseases. Recent studies have demonstrated that VD exerts a protective role in cardiovascular diseases. However, the beneficial effect of VD on pressure overload-induced cardiac remodeling and dysfunction and its underlying mechanisms are not fully elucidated. In this study, cardiac dysfunction and hypertrophic remodeling in mice were induced by pressure overload. Cardiac function was evaluated by echocardiography, and myocardial histology was detected by H&E and Masson's trichrome staining. Cardiomyocyte size was detected by wheat germ agglutinin staining. The protein levels of signaling mediators were examined by western blotting while mRNA expression of hypertrophic and fibrotic markers was examined by qPCR analysis. Oxidative stress was detected by dihydroethidine staining. Our results showed that administration of VD3 significantly ameliorates pressure overload-induced contractile dysfunction, cardiac hypertrophy, fibrosis and inflammation in mice. In addition, VD3 treatment also markedly inhibited cardiac oxidative stress and apoptosis. Moreover, protein levels of calcineurin A, ERK1/2, AKT, TGF-β, GRP78, cATF6, and CHOP were significantly reduced whereas SERCA2 level was upregulated in the VD3-treated hearts compared with control. These results suggest that VD3 attenuates cardiac remodeling and dysfunction induced by pressure overload, and this protective effect is associated with inhibition of multiple signaling pathways. Copyright © 2018 Elsevier Ltd. All rights reserved.

  16. Direct Reconstruction of CT-based Attenuation Correction Images for PET with Cluster-Based Penalties

    Science.gov (United States)

    Kim, Soo Mee; Alessio, Adam M.; De Man, Bruno; Asma, Evren; Kinahan, Paul E.

    2015-01-01

    Extremely low-dose CT acquisitions for the purpose of PET attenuation correction will have a high level of noise and biasing artifacts due to factors such as photon starvation. This work explores a priori knowledge appropriate for CT iterative image reconstruction for PET attenuation correction. We investigate the maximum a posteriori (MAP) framework with cluster-based, multinomial priors for the direct reconstruction of the PET attenuation map. The objective function for direct iterative attenuation map reconstruction was modeled as a Poisson log-likelihood with prior terms consisting of quadratic (Q) and mixture (M) distributions. The attenuation map is assumed to have values in 4 clusters: air+background, lung, soft tissue, and bone. Under this assumption, the MP was a mixture probability density function consisting of one exponential and three Gaussian distributions. The relative proportion of each cluster was jointly estimated during each voxel update of direct iterative coordinate decent (dICD) method. Noise-free data were generated from NCAT phantom and Poisson noise was added. Reconstruction with FBP (ramp filter) was performed on the noise-free (ground truth) and noisy data. For the noisy data, dICD reconstruction was performed with the combination of different prior strength parameters (β and γ) of Q- and M-penalties. The combined quadratic and mixture penalties reduces the RMSE by 18.7% compared to post-smoothed iterative reconstruction and only 0.7% compared to quadratic alone. For direct PET attenuation map reconstruction from ultra-low dose CT acquisitions, the combination of quadratic and mixture priors offers regularization of both variance and bias and is a potential method to derive attenuation maps with negligible patient dose. However, the small improvement in quantitative accuracy relative to the substantial increase in algorithm complexity does not currently justify the use of mixture-based PET attenuation priors for reconstruction of CT

  17. X-ray-based attenuation correction for positron emission tomography/computed tomography scanners.

    Science.gov (United States)

    Kinahan, Paul E; Hasegawa, Bruce H; Beyer, Thomas

    2003-07-01

    A synergy of positron emission tomography (PET)/computed tomography (CT) scanners is the use of the CT data for x-ray-based attenuation correction of the PET emission data. Current methods of measuring transmission use positron sources, gamma-ray sources, or x-ray sources. Each of the types of transmission scans involves different trade-offs of noise versus bias, with positron transmission scans having the highest noise but lowest bias, whereas x-ray scans have negligible noise but the potential for increased quantitative errors. The use of x-ray-based attenuation correction, however, has other advantages, including a lack of bias introduced from post-injection transmission scanning, which is an important practical consideration for clinical scanners, as well as reduced scan times. The sensitivity of x-ray-based attenuation correction to artifacts and quantitative errors depends on the method of translating the CT image from the effective x-ray energy of approximately 70 keV to attenuation coefficients at the PET energy of 511 keV. These translation methods are usually based on segmentation and/or scaling techniques. Errors in the PET emission image arise from positional mismatches caused by patient motion or respiration differences between the PET and CT scans; incorrect calculation of attenuation coefficients for CT contrast agents or metallic implants; or keeping the patient's arms in the field of view, which leads to truncation and/or beam-hardening (or x-ray scatter) artifacts. Proper interpretation of PET emission images corrected for attenuation by using the CT image relies on an understanding of the potential artifacts. In cases where an artifact or bias is suspected, careful inspection of all three available images (CT and PET emission with and without attenuation correction) is recommended. Copyright 2003 Elsevier Inc. All rights reserved.

  18. A comparative study of attenuation correction algorithms in single photon emission computed tomography (SPECT)

    International Nuclear Information System (INIS)

    Murase, Kenya; Itoh, Hisao; Mogami, Hiroshi; Ishine, Masashiro; Kawamura, Masashi; Iio, Atsushi; Hamamoto, Ken

    1987-01-01

    A computer based simulation method was developed to assess the relative effectiveness and availability of various attenuation compensation algorithms in single photon emission computed tomography (SPECT). The effect of the nonuniformity of attenuation coefficient distribution in the body, the errors in determining a body contour and the statistical noise on reconstruction accuracy and the computation time in using the algorithms were studied. The algorithms were classified into three groups: precorrection, post correction and iterative correction methods. Furthermore, a hybrid method was devised by combining several methods. This study will be useful for understanding the characteristics limitations and strengths of the algorithms and searching for a practical correction method for photon attenuation in SPECT. (orig.)

  19. Accelerated acquisition of tagged MRI for cardiac motion correction in simultaneous PET-MR: Phantom and patient studies

    International Nuclear Information System (INIS)

    Huang, Chuan; Petibon, Yoann; Ouyang, Jinsong; El Fakhri, Georges; Reese, Timothy G.; Ahlman, Mark A.; Bluemke, David A.

    2015-01-01

    Purpose: Degradation of image quality caused by cardiac and respiratory motions hampers the diagnostic quality of cardiac PET. It has been shown that improved diagnostic accuracy of myocardial defect can be achieved by tagged MR (tMR) based PET motion correction using simultaneous PET-MR. However, one major hurdle for the adoption of tMR-based PET motion correction in the PET-MR routine is the long acquisition time needed for the collection of fully sampled tMR data. In this work, the authors propose an accelerated tMR acquisition strategy using parallel imaging and/or compressed sensing and assess the impact on the tMR-based motion corrected PET using phantom and patient data. Methods: Fully sampled tMR data were acquired simultaneously with PET list-mode data on two simultaneous PET-MR scanners for a cardiac phantom and a patient. Parallel imaging and compressed sensing were retrospectively performed by GRAPPA and kt-FOCUSS algorithms with various acceleration factors. Motion fields were estimated using nonrigid B-spline image registration from both the accelerated and fully sampled tMR images. The motion fields were incorporated into a motion corrected ordered subset expectation maximization reconstruction algorithm with motion-dependent attenuation correction. Results: Although tMR acceleration introduced image artifacts into the tMR images for both phantom and patient data, motion corrected PET images yielded similar image quality as those obtained using the fully sampled tMR images for low to moderate acceleration factors (<4). Quantitative analysis of myocardial defect contrast over ten independent noise realizations showed similar results. It was further observed that although the image quality of the motion corrected PET images deteriorates for high acceleration factors, the images were still superior to the images reconstructed without motion correction. Conclusions: Accelerated tMR images obtained with more than 4 times acceleration can still provide

  20. Accelerated acquisition of tagged MRI for cardiac motion correction in simultaneous PET-MR: Phantom and patient studies

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Chuan, E-mail: chuan.huang@stonybrookmedicine.edu [Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114 (United States); Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115 (United States); Departments of Radiology, Psychiatry, Stony Brook Medicine, Stony Brook, New York 11794 (United States); Petibon, Yoann [Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114 (United States); Ouyang, Jinsong; El Fakhri, Georges [Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114 and Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115 (United States); Reese, Timothy G. [Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115 and Martinos Center for Biomedical Imaging, Charlestown, Massachusetts 02129 (United States); Ahlman, Mark A.; Bluemke, David A. [Radiology and Imaging Sciences, National Institutes of Health Clinical Center, Bethesda, Maryland 20892 (United States)

    2015-02-15

    Purpose: Degradation of image quality caused by cardiac and respiratory motions hampers the diagnostic quality of cardiac PET. It has been shown that improved diagnostic accuracy of myocardial defect can be achieved by tagged MR (tMR) based PET motion correction using simultaneous PET-MR. However, one major hurdle for the adoption of tMR-based PET motion correction in the PET-MR routine is the long acquisition time needed for the collection of fully sampled tMR data. In this work, the authors propose an accelerated tMR acquisition strategy using parallel imaging and/or compressed sensing and assess the impact on the tMR-based motion corrected PET using phantom and patient data. Methods: Fully sampled tMR data were acquired simultaneously with PET list-mode data on two simultaneous PET-MR scanners for a cardiac phantom and a patient. Parallel imaging and compressed sensing were retrospectively performed by GRAPPA and kt-FOCUSS algorithms with various acceleration factors. Motion fields were estimated using nonrigid B-spline image registration from both the accelerated and fully sampled tMR images. The motion fields were incorporated into a motion corrected ordered subset expectation maximization reconstruction algorithm with motion-dependent attenuation correction. Results: Although tMR acceleration introduced image artifacts into the tMR images for both phantom and patient data, motion corrected PET images yielded similar image quality as those obtained using the fully sampled tMR images for low to moderate acceleration factors (<4). Quantitative analysis of myocardial defect contrast over ten independent noise realizations showed similar results. It was further observed that although the image quality of the motion corrected PET images deteriorates for high acceleration factors, the images were still superior to the images reconstructed without motion correction. Conclusions: Accelerated tMR images obtained with more than 4 times acceleration can still provide

  1. Histone deacetylase inhibitor, CG200745, attenuates cardiac hypertrophy and fibrosis in DOCA-induced hypertensive rats.

    Science.gov (United States)

    Lee, Eunjo; Song, Min-Ji; Lee, Hae-Ahm; Kang, Seol-Hee; Kim, Mina; Yang, Eun Kyoung; Lee, Do Young; Ro, Seonggu; Cho, Joong Myung; Kim, Inkyeom

    2016-09-01

    CG200745 is a novel inhibitor of histone deacetylases (HDACs), initially developed for treatment of various hematological and solid cancers. Because it is water-soluble, it can be administered orally. We hypothesized that the HDAC inhibitor, CG200745, attenuates cardiac hypertrophy and fibrosis in deoxycorticosterone acetate (DOCA)-induced hypertensive rats. For establishment of hypertension, 40 mg/kg of DOCA was subcutaneously injected four times weekly into Sprague-Dawley rats. All the rats used in this study including those in the sham group had been unilaterally nephrectomized and allowed free access to drinking water containing 1% NaCl. Systolic blood pressure was measured by the tail-cuff method. Blood chemistry including sodium, potassium, glucose, triglyceride, and cholesterol levels was analyzed. Sections of the heart were visualized after trichrome and hematoxylin and eosin stain. The expression of hypertrophic genes such as atrial natriuretic peptide A (Nppa) and atrial natriuretic peptide B (Nppb) in addition to fibrotic genes such as Collagen-1, Collagen-3, connective tissue growth factor (Ctgf), and Fibronectin were measured by quantitative real-time PCR (qRT-PCR). Injection of DOCA increased systolic blood pressure, heart weight, and cardiac fibrosis, which was attenuated by CG200745. Neither DOCA nor CG200745 affected body weight, vascular contraction and relaxation responses, and blood chemistry. Injection of DOCA increased expression of both hypertrophic and fibrotic genes, which was abrogated by CG200745. These results indicate that CG200745 attenuates cardiac hypertrophy and fibrosis in DOCA-induced hypertensive rats.

  2. Intercomparison of attenuation correction algorithms for single-polarized X-band radars

    Science.gov (United States)

    Lengfeld, K.; Berenguer, M.; Sempere Torres, D.

    2018-03-01

    Attenuation due to liquid water is one of the largest uncertainties in radar observations. The effects of attenuation are generally inversely proportional to the wavelength, i.e. observations from X-band radars are more affected by attenuation than those from C- or S-band systems. On the other hand, X-band radars can measure precipitation fields in higher temporal and spatial resolution and are more mobile and easier to install due to smaller antennas. A first algorithm for attenuation correction in single-polarized systems was proposed by Hitschfeld and Bordan (1954) (HB), but it gets unstable in case of small errors (e.g. in the radar calibration) and strong attenuation. Therefore, methods have been developed that restrict attenuation correction to keep the algorithm stable, using e.g. surface echoes (for space-borne radars) and mountain returns (for ground radars) as a final value (FV), or adjustment of the radar constant (C) or the coefficient α. In the absence of mountain returns, measurements from C- or S-band radars can be used to constrain the correction. All these methods are based on the statistical relation between reflectivity and specific attenuation. Another way to correct for attenuation in X-band radar observations is to use additional information from less attenuated radar systems, e.g. the ratio between X-band and C- or S-band radar measurements. Lengfeld et al. (2016) proposed such a method based isotonic regression of the ratio between X- and C-band radar observations along the radar beam. This study presents a comparison of the original HB algorithm and three algorithms based on the statistical relation between reflectivity and specific attenuation as well as two methods implementing additional information of C-band radar measurements. Their performance in two precipitation events (one mainly convective and the other one stratiform) shows that a restriction of the HB is necessary to avoid instabilities. A comparison with vertically pointing

  3. Correction of oral contrast artifacts in CT-based attenuation correction of PET images using an automated segmentation algorithm

    International Nuclear Information System (INIS)

    Ahmadian, Alireza; Ay, Mohammad R.; Sarkar, Saeed; Bidgoli, Javad H.; Zaidi, Habib

    2008-01-01

    Oral contrast is usually administered in most X-ray computed tomography (CT) examinations of the abdomen and the pelvis as it allows more accurate identification of the bowel and facilitates the interpretation of abdominal and pelvic CT studies. However, the misclassification of contrast medium with high-density bone in CT-based attenuation correction (CTAC) is known to generate artifacts in the attenuation map (μmap), thus resulting in overcorrection for attenuation of positron emission tomography (PET) images. In this study, we developed an automated algorithm for segmentation and classification of regions containing oral contrast medium to correct for artifacts in CT-attenuation-corrected PET images using the segmented contrast correction (SCC) algorithm. The proposed algorithm consists of two steps: first, high CT number object segmentation using combined region- and boundary-based segmentation and second, object classification to bone and contrast agent using a knowledge-based nonlinear fuzzy classifier. Thereafter, the CT numbers of pixels belonging to the region classified as contrast medium are substituted with their equivalent effective bone CT numbers using the SCC algorithm. The generated CT images are then down-sampled followed by Gaussian smoothing to match the resolution of PET images. A piecewise calibration curve was then used to convert CT pixel values to linear attenuation coefficients at 511 keV. The visual assessment of segmented regions performed by an experienced radiologist confirmed the accuracy of the segmentation and classification algorithms for delineation of contrast-enhanced regions in clinical CT images. The quantitative analysis of generated μmaps of 21 clinical CT colonoscopy datasets showed an overestimation ranging between 24.4% and 37.3% in the 3D-classified regions depending on their volume and the concentration of contrast medium. Two PET/CT studies known to be problematic demonstrated the applicability of the technique in

  4. Transplantation of mesenchymal stem cells overexpressing IL10 attenuates cardiac impairments in rats with myocardial infarction.

    Science.gov (United States)

    Meng, Xin; Li, Jianping; Yu, Ming; Yang, Jian; Zheng, Minjuan; Zhang, Jinzhou; Sun, Chao; Liang, Hongliang; Liu, Liwen

    2018-01-01

    Mesenchymal stem cell (MSC) has been well known to exert therapeutic potential for patients with myocardial infarction (MI). In addition, interleukin-10 (IL10) could attenuate MI through suppressing inflammation. Thus, the combination of MSC implantation with IL10 delivery may extend health benefits to ameliorate cardiac injury after MI. Here we established overexpression of IL10 in bone marrow-derived MSC through adenoviral transduction. Cell viability, apoptosis, and IL10 secretion under ischemic challenge in vitro were examined. In addition, MSC was transplanted into the injured hearts in a rat model of MI. Four weeks after the MI induction, MI, cardiac functions, apoptotic cells, and inflammation cytokines were assessed. In response to in vitro oxygen-glucose deprivation (OGD), IL10 overexpression in MSC (Ad.IL10-MSC) enhanced cell viability, decreased apoptosis, and increased IL10 secretion. Consistently, the implantation of Ad.IL10-MSCs into MI animals resulted in more reductions in myocardial infarct size, cardiac impairment, and cell apoptosis, compared to the individual treatments of either MSC or IL10 administration. Moreover, the attenuation of both systemic and local inflammations was most prominent for Ad.IL10-MSC treatment. IL10 overexpression and MSC may exert a synergistic anti-inflammatory effect to alleviate cardiac injury after MI. © 2017 Wiley Periodicals, Inc.

  5. Scintigraphic measurements of gastric emptying corrected for differences in tissue attenuation

    Energy Technology Data Exchange (ETDEWEB)

    Lauritzen, J.B.; Hoejgaard, L.; Uhrenholdt, A. (Copenhagen Univ. (Denmark). Hvidovre Hospital)

    1983-10-01

    In order to evaluate the importance of variations in tissue attenuation in scintigraphic measurements of gastric emptying, both in vivo and in vitro measurements of count rates from an encapsulated sup(99m)Tc dose were performed in different parts of the stomach. The obtained individual tissue correction factors were applied in the calculation of gastric emptying rates by gamma camera in healthy volunteers. The results showed that the anterior gamma camera scan without correction for differences in tissue attenuation underestimated the gastric emptying rate by 11% if the results were expressed as percentage meal emptied over 60 minutes.

  6. Influence of density and mean atomic number on CT attenuation corrected PET: Phantom studies

    International Nuclear Information System (INIS)

    Maintas, D.; Houzard, C.; Galy, G.; Maintas, C.; Itti, R.; Cachin, F.; Mognetti, Th.; Slosman

    2007-01-01

    Aim: the aim of this work is to study the influence of medium density on the CT or external source attenuation corrected images, by simulation on a phantom, with various positron emission tomographs. Material and method: a series of experiments on a cylindrical phantom filled with water marked with [18 F]-FDG, containing six vials filled per pair with mediums of different densities or solutions of KI, CaCl 2 and saccharose with various densities, was carried out under comparable conditions on three different tomographs. In only one of the vials of each pair, an identical radioactivity of [18 F]-FDG was added, three to five fold the surrounding activity. The reconstructions and attenuation corrections suggested by the manufacturers, were carried out under the usual conditions of each site. The activity of each structure was estimated by the methods of profiles and regions of interest, on the non attenuation corrected images (N.A.C.), the images corrected by CT (C.T.A.C.), and/or external source (G.P.A.C.). Results: with all three tomographs, the activities estimated on the N.A.C. images present an inverse correlation to the medium density (important absorption by dense material). On C.T.A.C. images, we observed with only two of the three tomographs, an overestimation of the activity in the 'radioactive' vials, depending on the medium mean Z number and density (over correction), and a artifactual 'activity' in the denser 'cold' vial (incorrect attenuation correction. The dense saccharose solutions, with non elevated Z number, do not affect the CT attenuation correction. (authors)

  7. Towards quantitative PET/MRI: a review of MR-based attenuation correction techniques.

    Science.gov (United States)

    Hofmann, Matthias; Pichler, Bernd; Schölkopf, Bernhard; Beyer, Thomas

    2009-03-01

    Positron emission tomography (PET) is a fully quantitative technology for imaging metabolic pathways and dynamic processes in vivo. Attenuation correction of raw PET data is a prerequisite for quantification and is typically based on separate transmission measurements. In PET/CT attenuation correction, however, is performed routinely based on the available CT transmission data. Recently, combined PET/magnetic resonance (MR) has been proposed as a viable alternative to PET/CT. Current concepts of PET/MRI do not include CT-like transmission sources and, therefore, alternative methods of PET attenuation correction must be found. This article reviews existing approaches to MR-based attenuation correction (MR-AC). Most groups have proposed MR-AC algorithms for brain PET studies and more recently also for torso PET/MR imaging. Most MR-AC strategies require the use of complementary MR and transmission images, or morphology templates generated from transmission images. We review and discuss these algorithms and point out challenges for using MR-AC in clinical routine. MR-AC is work-in-progress with potentially promising results from a template-based approach applicable to both brain and torso imaging. While efforts are ongoing in making clinically viable MR-AC fully automatic, further studies are required to realize the potential benefits of MR-based motion compensation and partial volume correction of the PET data.

  8. Towards quantitative PET/MRI: a review of MR-based attenuation correction techniques

    International Nuclear Information System (INIS)

    Hofmann, Matthias; Pichler, Bernd; Schoelkopf, Bernhard; Beyer, Thomas

    2009-01-01

    Positron emission tomography (PET) is a fully quantitative technology for imaging metabolic pathways and dynamic processes in vivo. Attenuation correction of raw PET data is a prerequisite for quantification and is typically based on separate transmission measurements. In PET/CT attenuation correction, however, is performed routinely based on the available CT transmission data. Recently, combined PET/magnetic resonance (MR) has been proposed as a viable alternative to PET/CT. Current concepts of PET/MRI do not include CT-like transmission sources and, therefore, alternative methods of PET attenuation correction must be found. This article reviews existing approaches to MR-based attenuation correction (MR-AC). Most groups have proposed MR-AC algorithms for brain PET studies and more recently also for torso PET/MR imaging. Most MR-AC strategies require the use of complementary MR and transmission images, or morphology templates generated from transmission images. We review and discuss these algorithms and point out challenges for using MR-AC in clinical routine. MR-AC is work-in-progress with potentially promising results from a template-based approach applicable to both brain and torso imaging. While efforts are ongoing in making clinically viable MR-AC fully automatic, further studies are required to realize the potential benefits of MR-based motion compensation and partial volume correction of the PET data. (orig.)

  9. Towards quantitative PET/MRI: a review of MR-based attenuation correction techniques

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, Matthias [Max Planck Institute for Biological Cybernetics, Tuebingen (Germany); University of Tuebingen, Laboratory for Preclinical Imaging and Imaging Technology of the Werner Siemens-Foundation, Department of Radiology, Tuebingen (Germany); University of Oxford, Wolfson Medical Vision Laboratory, Department of Engineering Science, Oxford (United Kingdom); Pichler, Bernd [University of Tuebingen, Laboratory for Preclinical Imaging and Imaging Technology of the Werner Siemens-Foundation, Department of Radiology, Tuebingen (Germany); Schoelkopf, Bernhard [Max Planck Institute for Biological Cybernetics, Tuebingen (Germany); Beyer, Thomas [University Hospital Duisburg-Essen, Department of Nuclear Medicine, Essen (Germany); Cmi-Experts GmbH, Zurich (Switzerland)

    2009-03-15

    Positron emission tomography (PET) is a fully quantitative technology for imaging metabolic pathways and dynamic processes in vivo. Attenuation correction of raw PET data is a prerequisite for quantification and is typically based on separate transmission measurements. In PET/CT attenuation correction, however, is performed routinely based on the available CT transmission data. Recently, combined PET/magnetic resonance (MR) has been proposed as a viable alternative to PET/CT. Current concepts of PET/MRI do not include CT-like transmission sources and, therefore, alternative methods of PET attenuation correction must be found. This article reviews existing approaches to MR-based attenuation correction (MR-AC). Most groups have proposed MR-AC algorithms for brain PET studies and more recently also for torso PET/MR imaging. Most MR-AC strategies require the use of complementary MR and transmission images, or morphology templates generated from transmission images. We review and discuss these algorithms and point out challenges for using MR-AC in clinical routine. MR-AC is work-in-progress with potentially promising results from a template-based approach applicable to both brain and torso imaging. While efforts are ongoing in making clinically viable MR-AC fully automatic, further studies are required to realize the potential benefits of MR-based motion compensation and partial volume correction of the PET data. (orig.)

  10. PET attenuation correction for rigid MR Tx/Rx coils from 176Lu background activity

    Science.gov (United States)

    Lerche, Christoph W.; Kaltsas, Theodoris; Caldeira, Liliana; Scheins, Jürgen; Rota Kops, Elena; Tellmann, Lutz; Pietrzyk, Uwe; Herzog, Hans; Shah, N. Jon

    2018-02-01

    One challenge for PET-MR hybrid imaging is the correction for attenuation of the 511 keV annihilation radiation by the required RF transmit and/or RF receive coils. Although there are strategies for building PET transparent Tx/Rx coils, such optimised coils still cause significant attenuation of the annihilation radiation leading to artefacts and biases in the reconstructed activity concentrations. We present a straightforward method to measure the attenuation of Tx/Rx coils in simultaneous MR-PET imaging based on the natural 176Lu background contained in the scintillator of the PET detector without the requirement of an external CT scanner or PET scanner with transmission source. The method was evaluated on a prototype 3T MR-BrainPET produced by Siemens Healthcare GmbH, both with phantom studies and with true emission images from patient/volunteer examinations. Furthermore, the count rate stability of the PET scanner and the x-ray properties of the Tx/Rx head coil were investigated. Even without energy extrapolation from the two dominant γ energies of 176Lu to 511 keV, the presented method for attenuation correction, based on the measurement of 176Lu background attenuation, shows slightly better performance than the coil attenuation correction currently used. The coil attenuation correction currently used is based on an external transmission scan with rotating 68Ge sources acquired on a Siemens ECAT HR  +  PET scanner. However, the main advantage of the presented approach is its straightforwardness and ready availability without the need for additional accessories.

  11. SU-F-I-59: Quality Assurance Phantom for PET/CT Alignment and Attenuation Correction

    International Nuclear Information System (INIS)

    Lin, T; Hamacher, K

    2016-01-01

    Purpose: This study utilizes a commercial PET/CT phantom to investigate two specific properties of a PET/CT system: the alignment accuracy of PET images with those from CT used for attenuation correction and the accuracy of this correction in PET images. Methods: A commercial PET/CT phantom consisting of three aluminum rods, two long central cylinders containing uniform activity, and attenuating materials such as air, water, bone and iodine contrast was scanned using a standard PET/CT protocol. Images reconstructed with 2 mm slice thickness and a 512 by 512 matrix were obtained. The center of each aluminum rod in the PET and CT images was compared to evaluate alignment accuracy. ROIs were drawn on transaxial images of the central rods at each section of attenuating material to determine the corrected activity (in BQML). BQML values were graphed as a function of slice number to provide a visual representation of the attenuation-correction throughout the whole phantom. Results: Alignment accuracy is high between the PET and CT images. The maximum deviation between the two in the axial plane is less than 1.5 mm, which is less than the width of a single pixel. BQML values measured along different sections of the large central rods are similar among the different attenuating materials except iodine contrast. Deviation of BQML values in the air and bone sections from the water section is less than 1%. Conclusion: Accurate alignment of PET and CT images is critical to ensure proper calculation and application of CT-based attenuation correction. This study presents a simple and quick method to evaluate the two with a single acquisition. As the phantom also includes spheres of increasing diameter, this could serve as a straightforward means to annually evaluate the status of a modern PET/CT system.

  12. SU-F-I-59: Quality Assurance Phantom for PET/CT Alignment and Attenuation Correction

    Energy Technology Data Exchange (ETDEWEB)

    Lin, T; Hamacher, K [Columbia University Medical Center, New York, NY (United States)

    2016-06-15

    Purpose: This study utilizes a commercial PET/CT phantom to investigate two specific properties of a PET/CT system: the alignment accuracy of PET images with those from CT used for attenuation correction and the accuracy of this correction in PET images. Methods: A commercial PET/CT phantom consisting of three aluminum rods, two long central cylinders containing uniform activity, and attenuating materials such as air, water, bone and iodine contrast was scanned using a standard PET/CT protocol. Images reconstructed with 2 mm slice thickness and a 512 by 512 matrix were obtained. The center of each aluminum rod in the PET and CT images was compared to evaluate alignment accuracy. ROIs were drawn on transaxial images of the central rods at each section of attenuating material to determine the corrected activity (in BQML). BQML values were graphed as a function of slice number to provide a visual representation of the attenuation-correction throughout the whole phantom. Results: Alignment accuracy is high between the PET and CT images. The maximum deviation between the two in the axial plane is less than 1.5 mm, which is less than the width of a single pixel. BQML values measured along different sections of the large central rods are similar among the different attenuating materials except iodine contrast. Deviation of BQML values in the air and bone sections from the water section is less than 1%. Conclusion: Accurate alignment of PET and CT images is critical to ensure proper calculation and application of CT-based attenuation correction. This study presents a simple and quick method to evaluate the two with a single acquisition. As the phantom also includes spheres of increasing diameter, this could serve as a straightforward means to annually evaluate the status of a modern PET/CT system.

  13. Novel Toll-like receptor-4 deficiency attenuates trastuzumab (Herceptin induced cardiac injury in mice

    Directory of Open Access Journals (Sweden)

    Yousif Nasser

    2011-10-01

    Full Text Available Abstract Background Cardiac inflammation and generation of oxidative stress are known to contribute to trastuzumab (herceptin induced cardiac toxicity. Toll-like receptors (TLRs are a part of the innate immune system and are involved in cardiac stress reactions. Since TLR4 might play a relevant role in cardiac inflammatory signaling, we investigated whether or not TLR4 is involved in trastuzumab induced cardiotoxicity. Methods Seven days after a single injection of herceptin (2 mg/kg; i.p., left ventricular pressure volume loops were measured in HeN compotent (TLR4+/+ and HeJ mutant (TLR4-/- treated with trastuzumab and control mice. Immunofluorescent staining for monocyte infiltration and analyses of plasma by (ELISAs for different chemokines including: MCP-1and tumor necrosis factor-α (TNF-α, Western immunoblotting assay for ICAM-1, and used troponin I for cardiac injury marker. Results Trastuzumab injection resulted in an impairment of left ventricular function in TLR-4 competent (HeN, in contrast TLR4-/- trastuzumab mice showed improved left ventricular function EF%, CO; p -/-; p -/-, marked reduction of myocardial troponin-I levels in TLR4-deficient mice. Data are presented as means ± SE; n = 8 in each group p Conclusions Treatment with trastuzumab induces an inflammatory response that contributes to myocardial tissue TLR4 mediates chemokine expression (TNF-α, MCP-1and ICAM-1, so in experimental animals TLR4 deficiency improves left ventricular function and attenuates pathophysiological key mechanisms in trastuzumab induced cardiomyopathy.

  14. Calorie restriction attenuates cardiac remodeling and diastolic dysfunction in a rat model of metabolic syndrome.

    Science.gov (United States)

    Takatsu, Miwa; Nakashima, Chieko; Takahashi, Keiji; Murase, Tamayo; Hattori, Takuya; Ito, Hiromi; Murohara, Toyoaki; Nagata, Kohzo

    2013-11-01

    Calorie restriction (CR) can modulate the features of obesity-related metabolic and cardiovascular diseases. We have recently characterized DahlS.Z-Lepr(fa)/Lepr(fa) (DS/obese) rats, derived from a cross between Dahl salt-sensitive and Zucker rats, as a new animal model of metabolic syndrome. DS/obese rats develop hypertension and manifest left ventricular remodeling and diastolic dysfunction, as well as increased cardiac oxidative stress and inflammation. We have now investigated the effects of CR on cardiac pathophysiology in DS/obese rats. DS/obese rats were fed either normal laboratory chow ad libitum or a calorie-restricted diet (65% of the average food intake for ad libitum) from 9 to 13 weeks. Age-matched homozygous lean (DahlS.Z-Lepr(+)/Lepr(+) or DS/lean) littermates served as controls. CR reduced body weight in both DS/obese and DS/lean rats, as well as attenuated the development of hypertension in DS/obese rats without affecting blood pressure in DS/lean rats. CR also reduced body fat content, ameliorated left ventricular hypertrophy, fibrosis, and diastolic dysfunction, and attenuated cardiac oxidative stress and inflammation in DS/obese rats. In addition, it increased serum adiponectin concentration, as well as downregulated the expression of angiotensin-converting enzyme and angiotensin II type 1A receptor genes in the heart of DS/obese rats. Our results thus show that CR attenuated obesity and hypertension, as well as left ventricular remodeling and diastolic dysfunction in DS/obese rats, with these latter effects being associated with reduced cardiac oxidative stress and inflammation.

  15. Attenuation correction in pulmonary and myocardial single photon emission computed tomography

    International Nuclear Information System (INIS)

    Almquist, H.

    2000-01-01

    The objective was to develop and validate methods for single photon emission computed tomography, SPECT, allowing quantitative physiologic and diagnostic studies of lung and heart. A method for correction of variable attenuation in SPECT, based on transmission measurements before administration of an isotope to the subject, was developed and evaluated. A protocol based upon geometrically well defined phantoms was developed. In a mosaic pattern phantom count rates were corrected from 39-43% to 101-110% of reference. In healthy subjects non-gravitational pulmonary perfusion gradients observed without attenuation correction were artefacts caused by attenuation. Pulmonary density in centre of right lung, obtained from the transmission measurement, was 0.28 ± 0.03 g/ml in normal subjects. Mean density was lower in large lungs compared to smaller ones. We also showed that regional ventilation/perfusion ratios could be measured with SPECT, using the readily available tracer 133 Xe. Because of the low energy of 133 Xe this relies heavily upon attenuation correction. A commercially available system for attenuation correction with simultaneous emission and transmission, considered to improve myocardial SPECT, performed erroneously. This could lead to clinical misjudgement. We considered that manufacturer-independent pre-clinical tests are required. In a test of two other commercial systems, based on different principles, an adapted variant of our initial protocol was proven useful. Only one of the systems provided correct emission count rates independently on phantom configuration. Errors in the other system were related to inadequate compensation of the influence of emission activity on the transmission study

  16. PET/CT with intravenous contrast can be used for PET attenuation correction in cancer patients

    DEFF Research Database (Denmark)

    Berthelsen, A K; Holm, S; Loft, A

    2005-01-01

    PURPOSE: If the CT scan of a combined PET/CT study is performed as a full diagnostic quality CT scan including intravenous (IV) contrast agent, the quality of the joint PET/CT procedure is improved and a separate diagnostic CT scan can be avoided. CT with IV contrast can be used for PET attenuation...... correction, but this may result in a bias in the attenuation factors. The clinical significance of this bias has not been established. Our aim was to perform a prospective clinical study where each patient had CT performed with and without IV contrast agent to establish whether PET/CT with IV contrast can...... scans without, and then with contrast agent, followed by an 18F-fluorodeoxyglucose whole-body PET scan. The CT examinations were performed with identical parameters on a GE Discovery LS scanner. The PET data were reconstructed with attenuation correction based on the two CT data sets. A global...

  17. Determination of the self-attenuation correction factor for environmental samples analysis in gamma spectrometry

    International Nuclear Information System (INIS)

    Santos, Talita O.; Rocha, Zildete; Knupp, Eliana A.N.; Kastner, Geraldo F.; Oliveira, Arno H. de; Oliveira, Arno H. de

    2015-01-01

    Gamma spectrometry technique has been used in order to obtain the activity concentrations of natural and artificial radionuclides in environmental samples of different origins, compositions and densities. These samples characteristics may influence the calibration condition by the self-attenuation effect. The sample density has been considered the most important factor. For reliable results, it is necessary to determine self-attenuation correction factor which has been subject of great interest due to its effect on activity concentration. In this context, the aim of this work is to show the calibration process considering the correction by self-attenuation in the evaluation of the concentration of each radionuclide to a gamma HPGEe detector spectrometry system. (author)

  18. Correction for gamma-ray self-attenuation in regular heterogeneous materials

    International Nuclear Information System (INIS)

    Parker, J.L.

    1981-09-01

    A procedure for determining the total correction factor for gamma-ray self-attenuation in regular heterogeneous materials is derived and discussed. The result of a practical application of the procedure to the passive gamma-ray assay of the 235 U content of high-temperature gas reactor fuel is presented

  19. Estimation of the self-attenuation correction factor for gamma rays emission from nuclear materials

    International Nuclear Information System (INIS)

    Badawy, A.; El-Gammal, W.A.

    2001-01-01

    This work presents an investigation of the self-attenuation of gamma-rays emission from nuclear materials (NMs) for measuring the U-235 enrichment, U-235 mass content and isotopic composition of NMs by non-destructive assay technique [NDA]. The measurements then would not need the use of suitable NM Standards which may not be available in many situations. The self-attenuation correction factor (F) may be estimated by the use of the linear attenuation factor of the assayed sample, the geometrical configuration of the assay set-up and the position of the assayed sample relative to the detector. A developed mathematical analysis makes use of specific parameters which affect the estimation of the self-attenuation of the source-detector system which emits passive gamma-rays at certain prominent signatures

  20. Qualitative evaluation of Chang method of attenuation correction on heart SPECT by using custom made heart phantom

    International Nuclear Information System (INIS)

    Takavar, A.; Eftekhari, M.; Beiki, D.; Saghari, M.; Mostaghim, N.; Sohrabi, M.

    2003-01-01

    SPECT detects γ- rays from administrated radiopharmaceutical within the patient body. γ-rays pass through different tissues before reaching detectors and are attenuated. Attenuation can cause artifacts; therefore different and used to minimize attenuation effects. In our study efficacy of Chang method was evaluated for attenuation purpose, using a custom made heart phantom. Due to different tissues surrounding heart, evaluation is not uniform more over activity distribution around heart is also non- uniform. In Chang method distribution of radioactivity and attenuation due to the surrounding tissue is considered uniform. Our phantom is a piece of plastic producing similar SPECT image as left ventricle. A dual head, ADAC system was used in our study. Images were taken by 180 d ig C (limited angle) and 360 d ig C (total rotation). Images are compared with and without attenuation correction. Our results indicate that Chang attenuation correction method is not capable of eliminating attenuation artifact completely in particular attenuation effects caused by breast

  1. Evaluation of Sinus/Edge-Corrected Zero-Echo-Time-Based Attenuation Correction in Brain PET/MRI.

    Science.gov (United States)

    Yang, Jaewon; Wiesinger, Florian; Kaushik, Sandeep; Shanbhag, Dattesh; Hope, Thomas A; Larson, Peder E Z; Seo, Youngho

    2017-11-01

    In brain PET/MRI, the major challenge of zero-echo-time (ZTE)-based attenuation correction (ZTAC) is the misclassification of air/tissue/bone mixtures or their boundaries. Our study aimed to evaluate a sinus/edge-corrected (SEC) ZTAC (ZTAC SEC ), relative to an uncorrected (UC) ZTAC (ZTAC UC ) and a CT atlas-based attenuation correction (ATAC). Methods: Whole-body 18 F-FDG PET/MRI scans were obtained for 12 patients after PET/CT scans. Only data acquired at a bed station that included the head were used for this study. Using PET data from PET/MRI, we applied ZTAC UC , ZTAC SEC , ATAC, and reference CT-based attenuation correction (CTAC) to PET attenuation correction. For ZTAC UC , the bias-corrected and normalized ZTE was converted to pseudo-CT with air (-1,000 HU for ZTE 0.75), and bone (-2,000 × [ZTE - 1] + 42 HU for 0.2 ≤ ZTE ≤ 0.75). Afterward, in the pseudo-CT, sinus/edges were automatically estimated as a binary mask through morphologic processing and edge detection. In the binary mask, the overestimated values were rescaled below 42 HU for ZTAC SEC For ATAC, the atlas deformed to MR in-phase was segmented to air, inner air, soft tissue, and continuous bone. For the quantitative evaluation, PET mean uptake values were measured in twenty 1-mL volumes of interest distributed throughout brain tissues. The PET uptake was compared using a paired t test. An error histogram was used to show the distribution of voxel-based PET uptake differences. Results: Compared with CTAC, ZTAC SEC achieved the overall PET quantification accuracy (0.2% ± 2.4%, P = 0.23) similar to CTAC, in comparison with ZTAC UC (5.6% ± 3.5%, P PET quantification in brain PET/MRI, comparable to the accuracy achieved by CTAC, particularly in the cerebellum. © 2017 by the Society of Nuclear Medicine and Molecular Imaging.

  2. Development of a new technic for breast attenuation correction in myocardial perfusion scintigraphy using computational methods

    International Nuclear Information System (INIS)

    Oliveira, Anderson de

    2015-01-01

    Introduction: One of the limitations of nuclear medicine studies are false-positive results that lead to unnecessary exams and procedures associated to morbidity and costs to the individual and society. One of the most frequent causes for reducing the specificity of myocardial perfusion imaging (MPI) is photon attenuation, especially by breast in women. Objective: To develop a new technique to compensate the photon attenuation by women breasts in myocardial perfusion imaging with 99m Tc-sestamibi, using computational methods. Materials and methods: A procedure was proposed which integrates Monte Carlo simulation, computational methods and experimental techniques. Initially, were obtained the chest attenuation correction percentages using a phantom Jaszczak and breast attenuation percentages by Monte Carlo simulation method, using the EGS4 program. The percentages of attenuation correction were linked to individual patients' characteristics by an artificial neural network and a multivariate analysis. A preliminary technical validation was done by comparing the results of the MPI and catheterism (CAT), before and after applying the technique to 4 patients. The t test for parametric data, Wilcoxon, Mann-Whitney and X 2 for the others were used. Probability values less than 0.05 were considered statistically significant. Results: Each increment of 1 cm in the thickness of breast was associated to an average increment of 6% on photon attenuation, while the maximum increase related to breast composition was about 2%. The average chest attenuation percentage per unit was 2.9%. Both, the artificial neural network and linear regression, showed an error less than 3% as predictive models for percentage of female attenuation. The anatomical-functional correlation between MPI and CAT was maintained after the use of the technique. Conclusion: Results suggest that the proposed technique is promising and could be a possible alternative to other conventional methods employed

  3. Inhibition of Uncoupling Protein 2 Attenuates Cardiac Hypertrophy Induced by Transverse Aortic Constriction in Mice

    Directory of Open Access Journals (Sweden)

    Xiao-Bing Ji

    2015-07-01

    Full Text Available Background: Uncoupling protein 2 (UCP2 is critical in regulating energy metabolism. Due to the significant change in energy metabolism of myocardium upon pressure overload, we hypothesize that UCP2 could contribute to the etiology of cardiac hypertrophy. Methods: Adult male C57BL/6J mice were subjected to pressure overload by using transverse aortic constriction (TAC, and then received genipin (a UCP2 selective inhibitor; 25 mg/kg/d, ip or vehicle for three weeks prior to histologic assessment of myocardial hypertrophy. ATP concentration, ROS level, and myocardial apoptosis were also examined. A parallel set of experiments was also conducted in UCP2-/- mice. Results: TAC induced left ventricular hypertrophy, as reflected by increased ventricular weight/thickness and increased size of myocardial cell (vs. sham controls. ATP concentration was decreased; ROS level was increased. Apoptosis and fibrosis markers were increased. TAC increased mitochondrial UCP2 expression in the myocardium at both mRNA and protein levels. Genipin treatment attenuated cardiac hypertrophy and the histologic/biochemical changes described above. Hypertrophy and associated changes induced by TAC in UCP2-/- mice were much less pronounced than in WT mice. Conclusions: Blocking UCP2 expression attenuates cardiac hypertrophy induced by pressure overload.

  4. Attenuation correction in pulmonary and myocardial single photon emission computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Almquist, H

    2000-01-01

    The objective was to develop and validate methods for single photon emission computed tomography, SPECT, allowing quantitative physiologic and diagnostic studies of lung and heart. A method for correction of variable attenuation in SPECT, based on transmission measurements before administration of an isotope to the subject, was developed and evaluated. A protocol based upon geometrically well defined phantoms was developed. In a mosaic pattern phantom count rates were corrected from 39-43% to 101-110% of reference. In healthy subjects non-gravitational pulmonary perfusion gradients observed without attenuation correctionwere artefacts caused by attenuation. Pulmonary density in centre of right lung, obtained from the transmission measurement, was 0.28 {+-} 0.03 g/ml in normal subjects. Mean density was lower in large lungs compared to smaller ones. We also showed that regional ventilation/perfusion ratios could be measured with SPECT, using the readily available tracer {sup 133}Xe. Because of the low energy of {sup 133}Xe this relies heavily upon attenuation correction. A commercially available system for attenuation correction with simultaneous emission and transmission, considered to improve myocardial SPECT, performed erroneously. This could lead to clinical misjudgement. We considered that manufacturer-independent pre-clinical tests are required. In a test of two other commercial systems, based on different principles, an adapted variant of our initial protocol was proven useful. Only one of the systems provided correct emission count rates independently on phantom configuration. Errors in the other system were related to inadequate compensation of the influence of emission activity on the transmission study.

  5. The evaluation of the effect of attenuation correction on lesion detectability in whole-body FDG-PET

    International Nuclear Information System (INIS)

    Tomemori, Takashi; Uno, Kimiichi; Oka, Takashi; Suzuki, Takayuki; Tomiyoshi, Katsumi; Jin Wu

    2004-01-01

    The aim of this study was to compare the attenuation corrected and non-corrected FDG-PET images in patients with malignant lesions and to evaluate the effect of attenuation correction on lesion detectability. A total of 71 persons with 112 malignant lesions was examined. All subjects fasted for at least 4 hours before PET study and whole-body PET imaging was performed 45 min after the intravenous administration of FDG (mean dose: 273.8 MBq). Emission scans of 6 min and post-injection transmission scans of 6 min per bed position were used. The intensity of lesion uptake in FDG-PET image was visually classified into 3 grades; grade 2=the lesion was clearly identified in the maximum intensity projection (MIP) image of FDG-PET, grade 1=the lesion was not identified in MIP image but it can be identified in coronal image, grade 0=there was no contrast between lesion and background in both MIP and coronal image. Ninety-eight lesions (87.5%) were classified into same grade in both attenuation corrected and non-corrected image, but in 11 lesions (9.8%) attenuation corrected image was better lesion visualization than non-corrected image. All lesions divided between the primary lesions and the metastatic lesions. In 50 primary lesions, 43 lesions were depicted in both attenuation corrected and non-corrected image and other 7 lesions were not in both image. In 62 metastatic lesions, 50 lesions (80.7%) were classified into same grade in both attenuation corrected and non-corrected image, but in 10 lesions (16.1%) attenuation corrected image were better lesion visualization than non-corrected image. In the most cases, the lesions were depicted in both attenuation corrected and non-corrected image. In the primary lesions, the lesion detectability between attenuation corrected and non-corrected image was similar. But in some cases with the metastatic lesions, attenuation corrected image were better lesion visualization than non-corrected image. For asymptomatic patients, non-corrected

  6. A virtual sinogram method to reduce dental metallic implant artefacts in computed tomography-based attenuation correction for PET

    NARCIS (Netherlands)

    Abdoli, Mehrsima; Ay, Mohammad Reza; Ahmadian, Alireza; Zaidi, Habib

    Objective Attenuation correction of PET data requires accurate determination of the attenuation map (mu map), which represents the spatial distribution of linear attenuation coefficients of different tissues at 511 keV. The presence of high-density metallic dental filling material in head and neck

  7. Non-uniform versus uniform attenuation correction in brain perfusion SPET of healthy volunteers

    International Nuclear Information System (INIS)

    Van Laere, K.; Versijpt, J.; Dierckx, R.; Koole, M.

    2001-01-01

    Although non-uniform attenuation correction (NUAC) can supply more accurate absolute quantification, it is not entirely clear whether NUAC provides clear-cut benefits in the routine clinical practice of brain SPET imaging. The aim of this study was to compare the effect of NUAC versus uniform attenuation correction (UAC) on volume of interest (VOI)-based semi-quantification of a large age- and gender-stratified brain perfusion normal database. Eighty-nine healthy volunteers (46 females and 43 males, aged 20-81 years) underwent standardised high-resolution single-photon emission tomography (SPET) with 925 MBq 99m Tc-ethyl cysteinate dimer (ECD) on a Toshiba GCA-9300A camera with 153 Gd or 99m Tc transmission CT scanning. Emission images were reconstructed by filtered back-projection and scatter corrected using the triple-energy window correction method. Both non-uniform Chang attenuation correction (one iteration) and uniform Sorenson correction (attenuation coefficient 0.09 cm -1 ) were applied. Images were automatically re-oriented to a stereotactic template on which 35 predefined VOIs were defined for semi-quantification (normalisation on total VOI counts). Small but significant differences between relative VOI uptake values for NUAC versus UAC in the infratentorial region were found. VOI standard deviations were significantly smaller for UAC, 4.5% (range 2.6-7.5), than for NUAC, 5.0% (2.3-9.0) (P 99m Tc-ECD uptake values in healthy volunteers to those obtained with NUAC, although values for the infratentorial region are slightly lower. NUAC produces a slight increase in inter-subject variability. Further study is necessary in various patient populations to establish the full clinical impact of NUAC in brain perfusion SPET. (orig.)

  8. Kaempferol Attenuates Cardiac Hypertrophy via Regulation of ASK1/MAPK Signaling Pathway and Oxidative Stress.

    Science.gov (United States)

    Feng, Hong; Cao, Jianlei; Zhang, Guangyu; Wang, Yanggan

    2017-07-01

    Kaempferol has been demonstrated to provide benefits for the treatment of atherosclerosis, coronary heart disease, hyperlipidemia, and diabetes through its antioxidant and anti-inflammatory properties. However, its role in cardiac hypertrophy remains to be elucidated. The aim of our study was to investigate the effects of kaempferol on cardiac hypertrophy and the underlying mechanism. Mice subjected to aorta banding were treated with or without kaempferol (100 mg/kg/d, p. o.) for 6 weeks. Echocardiography was performed to evaluate cardiac function. Mice hearts were collected for pathological observation and molecular mechanism investigation. H9c2 cardiomyocytes were stimulated with or without phenylephrine for in vitro study. Kaempferol significantly attenuated cardiac hypertrophy induced by aorta banding as evidenced by decreased cardiomyocyte areas and interstitial fibrosis, accompanied with improved cardiac functions and decreased apoptosis. The ASK1/MAPK signaling pathways (JNK1/2 and p38) were markedly activated in the aorta banding mouse heart but inhibited by kaempferol treatment. In in vitro experiments, kaempferol also inhibited the activity of ASK1/JNK1/2/p38 signaling pathway and the enlargement of H9c2 cardiomyocytes. Furthermore, our study revealed that kaempferol could protect the mouse heart and H9c2 cells from pathological oxidative stress. Our investigation indicated that treatment with kaempferol protects against cardiac hypertrophy, and its cardioprotection may be partially explained by the inhibition of the ASK1/MAPK signaling pathway and the regulation of oxidative stress. Georg Thieme Verlag KG Stuttgart · New York.

  9. Evaluation of transmission methodology and attenuation correction for the microPET Focus 220 animal scanner

    International Nuclear Information System (INIS)

    Lehnert, Wencke; Meikle, Steven R; Siegel, Stefan; Newport, Danny; Banati, Richard B; Rosenfeld, Anatoly B

    2006-01-01

    An accurate, low noise estimate of photon attenuation in the subject is required for quantitative microPET studies of molecular tracer distributions in vivo. In this work, several transmission-based measurement techniques were compared, including coincidence mode with and without rod windowing, singles mode with two different energy sources ( 68 Ge and 57 Co), and postinjection transmission scanning. In addition, the effectiveness of transmission segmentation and the propagation of transmission bias and noise into the emission images were examined. The 57 Co singles measurements provided the most accurate attenuation coefficients and superior signal-to-noise ratio, while 68 Ge singles measurements were degraded due to scattering from the object. Scatter correction of 68 Ge transmission data improved the accuracy for a 10 cm phantom but over-corrected for a mouse phantom. 57 Co scanning also resulted in low bias and noise in postinjection transmission scans for emission activities up to 20 MBq. Segmentation worked most reliably for transmission data acquired with 57 Co but the minor improvement in accuracy of attenuation coefficients and signal-to-noise may not justify its use, particularly for small subjects. We conclude that 57 Co singles transmission scanning is the most suitable method for measured attenuation correction on the microPET Focus 220 animal scanner

  10. Field of view extension and truncation correction for MR-based human attenuation correction in simultaneous MR/PET imaging

    International Nuclear Information System (INIS)

    Blumhagen, Jan O.; Ladebeck, Ralf; Fenchel, Matthias; Braun, Harald; Quick, Harald H.; Faul, David; Scheffler, Klaus

    2014-01-01

    Purpose: In quantitative PET imaging, it is critical to accurately measure and compensate for the attenuation of the photons absorbed in the tissue. While in PET/CT the linear attenuation coefficients can be easily determined from a low-dose CT-based transmission scan, in whole-body MR/PET the computation of the linear attenuation coefficients is based on the MR data. However, a constraint of the MR-based attenuation correction (AC) is the MR-inherent field-of-view (FoV) limitation due to static magnetic field (B 0 ) inhomogeneities and gradient nonlinearities. Therefore, the MR-based human AC map may be truncated or geometrically distorted toward the edges of the FoV and, consequently, the PET reconstruction with MR-based AC may be biased. This is especially of impact laterally where the patient arms rest beside the body and are not fully considered. Methods: A method is proposed to extend the MR FoV by determining an optimal readout gradient field which locally compensates B 0 inhomogeneities and gradient nonlinearities. This technique was used to reduce truncation in AC maps of 12 patients, and the impact on the PET quantification was analyzed and compared to truncated data without applying the FoV extension and additionally to an established approach of PET-based FoV extension. Results: The truncation artifacts in the MR-based AC maps were successfully reduced in all patients, and the mean body volume was thereby increased by 5.4%. In some cases large patient-dependent changes in SUV of up to 30% were observed in individual lesions when compared to the standard truncated attenuation map. Conclusions: The proposed technique successfully extends the MR FoV in MR-based attenuation correction and shows an improvement of PET quantification in whole-body MR/PET hybrid imaging. In comparison to the PET-based completion of the truncated body contour, the proposed method is also applicable to specialized PET tracers with little uptake in the arms and might reduce the

  11. Inhibition of NF-κB activity in the hypothalamic paraventricular nucleus attenuates hypertension and cardiac hypertrophy by modulating cytokines and attenuating oxidative stress

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Xiao-Jing [Department of Physiology and Pathophysiology, Xi' an Jiaotong University School of Basic Medical Sciences, Xi' an Jiaotong University Cardiovascular Research Center, Xi' an Jiaotong University Health Science Center, Xi' an 710061 (China); Zhang, Dong-Mei [Department of Physiology, Dalian Medical University, Dalian 116044 (China); Jia, Lin-Lin; Qi, Jie; Song, Xin-Ai; Tan, Hong [Department of Physiology and Pathophysiology, Xi' an Jiaotong University School of Basic Medical Sciences, Xi' an Jiaotong University Cardiovascular Research Center, Xi' an Jiaotong University Health Science Center, Xi' an 710061 (China); Cui, Wei [Department of Endocrinology and Metabolism, First Affiliated Hospital of Xi' an Jiaotong University, Xi' an Jiaotong University Health Science Center, Xi' an 710061 (China); Chen, Wensheng [Department of Cardiovascular Surgery, Xijing Hospital, Fourth Military Medical University, Xi' an 710032 (China); Zhu, Guo-Qing [Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing 210029 (China); Qin, Da-Nian, E-mail: dnqin@stu.edu.cn [Department of Physiology, Shantou University Medical College, Shantou 515041 (China); Kang, Yu-Ming, E-mail: ykang@mail.xjtu.edu.cn [Department of Physiology and Pathophysiology, Xi' an Jiaotong University School of Basic Medical Sciences, Xi' an Jiaotong University Cardiovascular Research Center, Xi' an Jiaotong University Health Science Center, Xi' an 710061 (China)

    2015-05-01

    We hypothesized that chronic inhibition of NF-κB activity in the hypothalamic paraventricular nucleus (PVN) delays the progression of hypertension and attenuates cardiac hypertrophy by up-regulating anti-inflammatory cytokines, reducing pro-inflammatory cytokines (PICs), attenuating nuclear factor-κB (NF-κB) p65 and NAD(P)H oxidase in the PVN of young spontaneously hypertensive rats (SHR). Young normotensive Wistar–Kyoto (WKY) and SHR rats received bilateral PVN infusions with NF–κB inhibitor pyrrolidine dithiocarbamate (PDTC) or vehicle for 4 weeks. SHR rats had higher mean arterial pressure and cardiac hypertrophy as indicated by increased whole heart weight/body weight ratio, whole heart weight/tibia length ratio, left ventricular weight/tibia length ratio, cardiomyocyte diameters of the left cardiac ventricle, and mRNA expressions of cardiac atrial natriuretic peptide (ANP) and beta-myosin heavy chain (β-MHC). These SHR rats had higher PVN levels of proinflammatory cytokines (PICs), reactive oxygen species (ROS), the chemokine monocyte chemoattractant protein-1 (MCP-1), NAD(P)H oxidase activity, mRNA expression of NOX-2 and NOX-4, and lower PVN IL-10, and higher plasma levels of PICs and NE, and lower plasma IL-10. PVN infusion of NF-κB inhibitor PDTC attenuated all these changes. These findings suggest that NF-κB activation in the PVN increases sympathoexcitation and hypertensive response, which are associated with the increases of PICs and oxidative stress in the PVN; PVN inhibition of NF-κB activity attenuates PICs and oxidative stress in the PVN, thereby attenuates hypertension and cardiac hypertrophy. - Highlights: • Spontaneously hypertensive rats exhibit neurohormonal excitation in the PVN. • PVN inhibition of NF-κB attenuates hypertension-induced cardiac hypertrophy. • PVN inhibition of NF-κB attenuates hypertension-induced neurohormonal excitation. • PVN inhibition of NF-κB attenuates hypertension-induced imbalance of cytokines

  12. Magnetic resonance imaging-guided attenuation correction of positron emission tomography data in PET/MRI

    OpenAIRE

    Izquierdo-Garcia, David; Catana, Ciprian

    2016-01-01

    Attenuation correction (AC) is one of the most important challenges in the recently introduced combined positron emission tomography/magnetic resonance imaging (PET/MR) scanners. PET/MR AC (MR-AC) approaches aim to develop methods that allow accurate estimation of the linear attenuation coefficients (LACs) of the tissues and other components located in the PET field of view (FoV). MR-AC methods can be divided into three main categories: segmentation-, atlas- and PET-based. This review aims to...

  13. Errors in MR-based attenuation correction for brain imaging with PET/MR scanners

    International Nuclear Information System (INIS)

    Rota Kops, Elena; Herzog, Hans

    2013-01-01

    Aim: Attenuation correction of PET data acquired by hybrid MR/PET scanners remains a challenge, even if several methods for brain and whole-body measurements have been developed recently. A template-based attenuation correction for brain imaging proposed by our group is easy to handle and delivers reliable attenuation maps in a short time. However, some potential error sources are analyzed in this study. We investigated the choice of template reference head among all the available data (error A), and possible skull anomalies of the specific patient, such as discontinuities due to surgery (error B). Materials and methods: An anatomical MR measurement and a 2-bed-position transmission scan covering the whole head and neck region were performed in eight normal subjects (4 females, 4 males). Error A: Taking alternatively one of the eight heads as reference, eight different templates were created by nonlinearly registering the images to the reference and calculating the average. Eight patients (4 females, 4 males; 4 with brain lesions, 4 w/o brain lesions) were measured in the Siemens BrainPET/MR scanner. The eight templates were used to generate the patients' attenuation maps required for reconstruction. ROI and VOI atlas-based comparisons were performed employing all the reconstructed images. Error B: CT-based attenuation maps of two volunteers were manipulated by manually inserting several skull lesions and filling a nasal cavity. The corresponding attenuation coefficients were substituted with the water's coefficient (0.096/cm). Results: Error A: The mean SUVs over the eight templates pairs for all eight patients and all VOIs did not differ significantly one from each other. Standard deviations up to 1.24% were found. Error B: After reconstruction of the volunteers' BrainPET data with the CT-based attenuation maps without and with skull anomalies, a VOI-atlas analysis was performed revealing very little influence of the skull lesions (less than 3%), while the filled

  14. Errors in MR-based attenuation correction for brain imaging with PET/MR scanners

    Science.gov (United States)

    Rota Kops, Elena; Herzog, Hans

    2013-02-01

    AimAttenuation correction of PET data acquired by hybrid MR/PET scanners remains a challenge, even if several methods for brain and whole-body measurements have been developed recently. A template-based attenuation correction for brain imaging proposed by our group is easy to handle and delivers reliable attenuation maps in a short time. However, some potential error sources are analyzed in this study. We investigated the choice of template reference head among all the available data (error A), and possible skull anomalies of the specific patient, such as discontinuities due to surgery (error B). Materials and methodsAn anatomical MR measurement and a 2-bed-position transmission scan covering the whole head and neck region were performed in eight normal subjects (4 females, 4 males). Error A: Taking alternatively one of the eight heads as reference, eight different templates were created by nonlinearly registering the images to the reference and calculating the average. Eight patients (4 females, 4 males; 4 with brain lesions, 4 w/o brain lesions) were measured in the Siemens BrainPET/MR scanner. The eight templates were used to generate the patients' attenuation maps required for reconstruction. ROI and VOI atlas-based comparisons were performed employing all the reconstructed images. Error B: CT-based attenuation maps of two volunteers were manipulated by manually inserting several skull lesions and filling a nasal cavity. The corresponding attenuation coefficients were substituted with the water's coefficient (0.096/cm). ResultsError A: The mean SUVs over the eight templates pairs for all eight patients and all VOIs did not differ significantly one from each other. Standard deviations up to 1.24% were found. Error B: After reconstruction of the volunteers' BrainPET data with the CT-based attenuation maps without and with skull anomalies, a VOI-atlas analysis was performed revealing very little influence of the skull lesions (less than 3%), while the filled nasal

  15. Coincidence detection FDG-PET (Co-PET) in the management of oncological patients: attenuation correction versus non-attenuation correction

    International Nuclear Information System (INIS)

    Chan, W.L.; Freund, J.; Pocock, N.; Szeto, E.; Chan, F.; Sorensen, B.; McBride, B.

    2000-01-01

    Full text: This study was to determine if attenuation correction (AC) in FDG Co-PET improved image quality, lesion detection, patient staging and management of various malignant neoplasms, compared to non-attenuation-corrected (NAC) images. Thirty patients (25 men, 5 women, mean age 58 years) with known or suspected malignant neoplasms, including non-small-cell lung cancer, non Hodgkin's and Hodgkin's lymphoma, carcinoma of the breast, head and neck cancer and melanoma, underwent FDG Co-PET, which was correlated with histopathology, CT and other conventional imaging modalities and clinical follow-up. Whole body tomography was performed (ADAC Vertex MCD) 60 min after 200 MBq of 18 F-FDG (>6h fasting). The number and location of FDG avid lesions detected on the AC images and NAC Co-PET images were blindly assessed by two independent observers. Semi-quantitative grading of image clarity and lesion-to-background quality was performed. This revealed markedly improved image clarity and lesion-to-background quality, in the AC versus NAC images. AC and NAC Co-PET were statistically different in relation to lesion detection (p<0.01) and tumour staging (p<0.0 1). NAC Co-PET demonstrated 51 of the 65 lesions (78%) detected by AC Co-PET. AC Co-PET staging was correct in 27 patients (90%), compared with NAC Co-PET in 22 patients (73%). AC Co-PET altered tumour staging in five of 30 patients (16%) and NAC Co-PET did not alter tumour staging in any of the patients- management was altered in only two of these five patients (7%). In conclusion, AC Co-PET resulted in better image quality with significantly improved lesion detectability and tumour staging compared to NAC Co-PET. Its additional impact on patient management in this relatively small sample was minor. Copyright (2000) The Australian and New Zealand Society of Nuclear Medicine Inc

  16. Exercise training prior to myocardial infarction attenuates cardiac deterioration and cardiomyocyte dysfunction in rats

    Directory of Open Access Journals (Sweden)

    Luiz Henrique Marchesi Bozi

    2013-04-01

    Full Text Available OBJECTIVES: The present study was performed to investigate 1 whether aerobic exercise training prior to myocardial infarction would prevent cardiac dysfunction and structural deterioration and 2 whether the potential cardiac benefits of aerobic exercise training would be associated with preserved morphological and contractile properties of cardiomyocytes in post-infarct remodeled myocardium. METHODS: Male Wistar rats underwent an aerobic exercise training protocol for eight weeks. The rats were then assigned to sham surgery (SHAM, sedentary lifestyle and myocardial infarction or exercise training and myocardial infarction groups and were evaluated 15 days after the surgery. Left ventricular tissue was analyzed histologically, and the contractile function of isolated myocytes was measured. Student's t-test was used to analyze infarct size and ventricular wall thickness, and the other parameters were analyzed by the Kruskal-Wallis test followed by Dunn's test or a one-way analysis of variance followed by Tukey's test (p<0.05. RESULTS: Myocardial infarctions in exercise-trained animals resulted in a smaller myocardial infarction extension, a thicker infarcted wall and less collagen accumulation as compared to myocardial infarctions in sedentary animals. Myocardial infarction-induced left ventricular dilation and cardiac dysfunction, as evaluated by +dP/dt and -dP/dt, were both prevented by previous aerobic exercise training. Moreover, aerobic exercise training preserved cardiac myocyte shortening, improved the maximum shortening and relengthening velocities in infarcted hearts and enhanced responsiveness to calcium. CONCLUSION: Previous aerobic exercise training attenuated the cardiac dysfunction and structural deterioration promoted by myocardial infarction, and such benefits were associated with preserved cardiomyocyte morphological and contractile properties.

  17. Cardiac-specific overexpression of catalase attenuates lipopolysaccharide-induced myocardial contractile dysfunction: role of autophagy.

    Science.gov (United States)

    Turdi, Subat; Han, Xuefeng; Huff, Anna F; Roe, Nathan D; Hu, Nan; Gao, Feng; Ren, Jun

    2012-09-15

    Lipopolysaccharide (LPS) from gram-negative bacteria is a major initiator of sepsis, leading to cardiovascular collapse. Accumulating evidence has indicated a role of reactive oxygen species (ROS) in cardiovascular complications in sepsis. This study was designed to examine the effect of cardiac-specific overexpression of catalase in LPS-induced cardiac contractile dysfunction and the underlying mechanism(s) with a focus on autophagy. Catalase transgenic and wild-type FVB mice were challenged with LPS (6 mg/kg) and cardiac function was evaluated. Levels of oxidative stress, autophagy, apoptosis, and protein damage were examined using fluorescence microscopy, Western blot, TUNEL assay, caspase-3 activity, and carbonyl formation. A Kaplan-Meier curve was constructed for survival after LPS treatment. Our results revealed a lower mortality in catalase mice compared with FVB mice after LPS challenge. LPS injection led to depressed cardiac contractile capacity as evidenced by echocardiography and cardiomyocyte contractile function, the effect of which was ablated by catalase overexpression. LPS treatment induced elevated TNF-α level, autophagy, apoptosis (TUNEL, caspase-3 activation, cleaved caspase-3), production of ROS and O(2)(-), and protein carbonyl formation, the effects of which were significantly attenuated by catalase overexpression. Electron microscopy revealed focal myocardial damage characterized by mitochondrial injury after LPS treatment, which was less severe in catalase mice. Interestingly, LPS-induced cardiomyocyte contractile dysfunction was prevented by the antioxidant N-acetylcysteine and the autophagy inhibitor 3-methyladenine. Taken together, our data revealed that catalase protects against LPS-induced cardiac dysfunction and mortality, which may be associated with inhibition of oxidative stress and autophagy. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. Cardiac-Specific Overexpression of Catalase Attenuates Lipopolysaccharide-Induced Myocardial Contractile Dysfunction: Role of Autophagy

    Science.gov (United States)

    Turdi, Subat; Han, Xuefeng; Huff, Anna F.; Roe, Nathan D.; Hu, Nan; Gao, Feng; Ren, Jun

    2012-01-01

    Lipopolysaccharide (LPS) from Gram-negative bacteria is a major initiator of sepsis, leading to cardiovascular collapse. Accumulating evidence has indicated a role of reactive oxygen species (ROS) in cardiovascular complication in sepsis. This study was designed to examine the effect of cardiac-specific overexpression of catalase in LPS-induced cardiac contractile dysfunction and the underlying mechanism(s) with a focus on autophagy. Catalase transgenic and wild-type FVB mice were challenged with LPS (6 mg/kg) and cardiac function was evaluated. Levels of oxidative stress, autophagy, apoptosis and protein damage were examined using fluorescence microscopy, Western blot, TUNEL assay, caspase-3 activity and carbonyl formation. Kaplan-Meier curve was constructed for survival following LPS treatment. Our results revealed a lower mortality in catalase mice compared with FVB mice following LPS challenge. LPS injection led to depressed cardiac contractile capacity as evidenced by echocardiography and cardiomyocyte contractile function, the effect of which was ablated by catalase overexpression. LPS treatment induced elevated TNF-α level, autophagy, apoptosis (TUNEL, caspase-3 activation, cleaved caspase-3), production of ROS and O2−, and protein carbonyl formation, the effects of which were significantly attenuated by catalase overexpression. Electron microscopy revealed focal myocardial damage characterized by mitochondrial injury following LPS treatment, which was less severe in catalase mice. Interestingly, LPS-induced cardiomyocyte contractile dysfunction was prevented by antioxidant NAC and the autophagy inhibitor 3-methyladenine. Taken together, our data revealed that catalase protects against LPS-induced cardiac dysfunction and mortality, which may be associated with inhibition of oxidative stress and autophagy. PMID:22902401

  19. Magnetic resonance imaging-guided attenuation correction of positron emission tomography data in PET/MRI

    Science.gov (United States)

    Izquierdo-Garcia, David; Catana, Ciprian

    2018-01-01

    Synopsis Attenuation correction (AC) is one of the most important challenges in the recently introduced combined positron emission tomography/magnetic resonance imaging (PET/MR) scanners. PET/MR AC (MR-AC) approaches aim to develop methods that allow accurate estimation of the linear attenuation coefficients (LACs) of the tissues and other components located in the PET field of view (FoV). MR-AC methods can be divided into three main categories: segmentation-, atlas- and PET-based. This review aims to provide a comprehensive list of the state of the art MR-AC approaches as well as their pros and cons. The main sources of artifacts such as body-truncation, metallic implants and hardware correction will be presented. Finally, this review will discuss the current status of MR-AC approaches for clinical applications. PMID:26952727

  20. Determination of the air attenuation correction factor for a free air ionization chamber

    International Nuclear Information System (INIS)

    Silva, Natalia F.; Cintra, Felipe B.; Castro, Maysa C. de; Caldas, Linda V.E.

    2016-01-01

    The objective of this work is to present the experimental and simulation results for the air attenuation correction factor for a free air ionization chamber with concentric cylinders of Victoreen, model 481-5. This correction factor was obtained for the standard mammography qualities established in the Instrument Calibration Laboratory (LCI) of IPEN. The values were compared with the results from the German primary standard laboratory Physikalisch- Technische Bundesanstalt (PTB), and maximum differences of 0.40% in relation to the experimental value and 0.31% in relation to the simulated value were obtained. (author)

  1. Multiple scattering and attenuation corrections in Deep Inelastic Neutron Scattering experiments

    International Nuclear Information System (INIS)

    Dawidowski, J; Blostein, J J; Granada, J R

    2006-01-01

    Multiple scattering and attenuation corrections in Deep Inelastic Neutron Scattering experiments are analyzed. The theoretical basis of the method is stated, and a Monte Carlo procedure to perform the calculation is presented. The results are compared with experimental data. The importance of the accuracy in the description of the experimental parameters is tested, and the implications of the present results on the data analysis procedures is examined

  2. Gamma ray self-attenuation correction: a simple numerical approach and its validation

    International Nuclear Information System (INIS)

    Agarwal, Chhavi; Poi, Sanhita; Mhatre, Amol; Goswami, A.

    2009-03-01

    A hybrid Monte Carlo method for gamma ray attenuation correction has been developed. The method has been applied to some common counting geometries like cylinder, box, sphere and disc. The method has been validated theoretically and experimentally over a wide range of transmittance and sample-to-detector distances. The advantage of the approach is that it is common to all sample geometries and can be used at all sample-to detector distances. (author)

  3. Effective radiation attenuation calibration for breast density: compression thickness influences and correction

    Directory of Open Access Journals (Sweden)

    Thomas Jerry A

    2010-11-01

    Full Text Available Abstract Background Calibrating mammograms to produce a standardized breast density measurement for breast cancer risk analysis requires an accurate spatial measure of the compressed breast thickness. Thickness inaccuracies due to the nominal system readout value and compression paddle orientation induce unacceptable errors in the calibration. Method A thickness correction was developed and evaluated using a fully specified two-component surrogate breast model. A previously developed calibration approach based on effective radiation attenuation coefficient measurements was used in the analysis. Water and oil were used to construct phantoms to replicate the deformable properties of the breast. Phantoms consisting of measured proportions of water and oil were used to estimate calibration errors without correction, evaluate the thickness correction, and investigate the reproducibility of the various calibration representations under compression thickness variations. Results The average thickness uncertainty due to compression paddle warp was characterized to within 0.5 mm. The relative calibration error was reduced to 7% from 48-68% with the correction. The normalized effective radiation attenuation coefficient (planar representation was reproducible under intra-sample compression thickness variations compared with calibrated volume measures. Conclusion Incorporating this thickness correction into the rigid breast tissue equivalent calibration method should improve the calibration accuracy of mammograms for risk assessments using the reproducible planar calibration measure.

  4. Minimal residual cone-beam reconstruction with attenuation correction in SPECT

    International Nuclear Information System (INIS)

    La, Valerie; Grangeat, Pierre

    1998-01-01

    This paper presents an iterative method based on the minimal residual algorithm for tomographic attenuation compensated reconstruction from attenuated cone-beam projections given the attenuation distribution. Unlike conjugate-gradient based reconstruction techniques, the proposed minimal residual based algorithm solves directly a quasisymmetric linear system, which is a preconditioned system. Thus it avoids the use of normal equations, which improves the convergence rate. Two main contributions are introduced. First, a regularization method is derived for quasisymmetric problems, based on a Tikhonov-Phillips regularization applied to the factorization of the symmetric part of the system matrix. This regularization is made spatially adaptive to avoid smoothing the region of interest. Second, our existing reconstruction algorithm for attenuation correction in parallel-beam geometry is extended to cone-beam geometry. A circular orbit is considered. Two preconditioning operators are proposed: the first one is Grangeat's inversion formula and the second one is Feldkamp's inversion formula. Experimental results obtained on simulated data are presented and the shadow zone effect on attenuated data is illustrated. (author)

  5. Single photon emission computed tomography using a regularizing iterative method for attenuation correction

    International Nuclear Information System (INIS)

    Soussaline, Francoise; Cao, A.; Lecoq, G.

    1981-06-01

    An analytically exact solution to the attenuated tomographic operator is proposed. Such a technique called Regularizing Iterative Method (RIM) belongs to the iterative class of procedures where a priori knowledge can be introduced on the evaluation of the size and shape of the activity domain to be reconstructed, and on the exact attenuation distribution. The relaxation factor used is so named because it leads to fast convergence and provides noise filtering for a small number of iteractions. The effectiveness of such a method was tested in the Single Photon Emission Computed Tomography (SPECT) reconstruction problem, with the goal of precise correction for attenuation before quantitative study. Its implementation involves the use of a rotating scintillation camera based SPECT detector connected to a mini computer system. Mathematical simulations of cylindical uniformly attenuated phantoms indicate that in the range of a priori calculated relaxation factor a fast converging solution can always be found with a (contrast) accuracy of the order of 0.2 to 4% given that numerical errors and noise are or not, taken into account. The sensitivity of the (RIM) algorithm to errors in the size of the reconstructed object and in the value of the attenuation coefficient μ was studied, using the same simulation data. Extreme variations of +- 15% in these parameters will lead to errors of the order of +- 20% in the quantitative results. Physical phantoms representing a variety of geometrical situations were also studied

  6. Receiver calibration and the nonlinearity parameter measurement of thick solid samples with diffraction and attenuation corrections.

    Science.gov (United States)

    Jeong, Hyunjo; Barnard, Daniel; Cho, Sungjong; Zhang, Shuzeng; Li, Xiongbing

    2017-11-01

    This paper presents analytical and experimental techniques for accurate determination of the nonlinearity parameter (β) in thick solid samples. When piezoelectric transducers are used for β measurements, the receiver calibration is required to determine the transfer function from which the absolute displacement can be calculated. The measured fundamental and second harmonic displacement amplitudes should be modified to account for beam diffraction and material absorption. All these issues are addressed in this study and the proposed technique is validated through the β measurements of thick solid samples. A simplified self-reciprocity calibration procedure for a broadband receiver is described. The diffraction and attenuation corrections for the fundamental and second harmonics are explicitly derived. Aluminum alloy samples in five different thicknesses (4, 6, 8, 10, 12cm) are prepared and β measurements are made using the finite amplitude, through-transmission method. The effects of diffraction and attenuation corrections on β measurements are systematically investigated. When diffraction and attenuation corrections are all properly made, the variation of β between different thickness samples is found to be less than 3.2%. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Attenuation correction with region growing method used in the positron emission mammography imaging system

    Science.gov (United States)

    Gu, Xiao-Yue; Li, Lin; Yin, Peng-Fei; Yun, Ming-Kai; Chai, Pei; Huang, Xian-Chao; Sun, Xiao-Li; Wei, Long

    2015-10-01

    The Positron Emission Mammography imaging system (PEMi) provides a novel nuclear diagnosis method dedicated for breast imaging. With a better resolution than whole body PET, PEMi can detect millimeter-sized breast tumors. To address the requirement of semi-quantitative analysis with a radiotracer concentration map of the breast, a new attenuation correction method based on a three-dimensional seeded region growing image segmentation (3DSRG-AC) method has been developed. The method gives a 3D connected region as the segmentation result instead of image slices. The continuity property of the segmentation result makes this new method free of activity variation of breast tissues. The threshold value chosen is the key process for the segmentation method. The first valley in the grey level histogram of the reconstruction image is set as the lower threshold, which works well in clinical application. Results show that attenuation correction for PEMi improves the image quality and the quantitative accuracy of radioactivity distribution determination. Attenuation correction also improves the probability of detecting small and early breast tumors. Supported by Knowledge Innovation Project of The Chinese Academy of Sciences (KJCX2-EW-N06)

  8. Improving the quantitative accuracy of optical-emission computed tomography by incorporating an attenuation correction: application to HIF1 imaging

    Science.gov (United States)

    Kim, E.; Bowsher, J.; Thomas, A. S.; Sakhalkar, H.; Dewhirst, M.; Oldham, M.

    2008-10-01

    Optical computed tomography (optical-CT) and optical-emission computed tomography (optical-ECT) are new techniques for imaging the 3D structure and function (including gene expression) of whole unsectioned tissue samples. This work presents a method of improving the quantitative accuracy of optical-ECT by correcting for the 'self'-attenuation of photons emitted within the sample. The correction is analogous to a method commonly applied in single-photon-emission computed tomography reconstruction. The performance of the correction method was investigated by application to a transparent cylindrical gelatin phantom, containing a known distribution of attenuation (a central ink-doped gelatine core) and a known distribution of fluorescing fibres. Attenuation corrected and uncorrected optical-ECT images were reconstructed on the phantom to enable an evaluation of the effectiveness of the correction. Significant attenuation artefacts were observed in the uncorrected images where the central fibre appeared ~24% less intense due to greater attenuation from the surrounding ink-doped gelatin. This artefact was almost completely removed in the attenuation-corrected image, where the central fibre was within ~4% of the others. The successful phantom test enabled application of attenuation correction to optical-ECT images of an unsectioned human breast xenograft tumour grown subcutaneously on the hind leg of a nude mouse. This tumour cell line had been genetically labelled (pre-implantation) with fluorescent reporter genes such that all viable tumour cells expressed constitutive red fluorescent protein and hypoxia-inducible factor 1 transcription-produced green fluorescent protein. In addition to the fluorescent reporter labelling of gene expression, the tumour microvasculature was labelled by a light-absorbing vasculature contrast agent delivered in vivo by tail-vein injection. Optical-CT transmission images yielded high-resolution 3D images of the absorbing contrast agent, and

  9. Improving the quantitative accuracy of optical-emission computed tomography by incorporating an attenuation correction: application to HIF1 imaging

    International Nuclear Information System (INIS)

    Kim, E; Bowsher, J; Thomas, A S; Sakhalkar, H; Dewhirst, M; Oldham, M

    2008-01-01

    Optical computed tomography (optical-CT) and optical-emission computed tomography (optical-ECT) are new techniques for imaging the 3D structure and function (including gene expression) of whole unsectioned tissue samples. This work presents a method of improving the quantitative accuracy of optical-ECT by correcting for the 'self'-attenuation of photons emitted within the sample. The correction is analogous to a method commonly applied in single-photon-emission computed tomography reconstruction. The performance of the correction method was investigated by application to a transparent cylindrical gelatin phantom, containing a known distribution of attenuation (a central ink-doped gelatine core) and a known distribution of fluorescing fibres. Attenuation corrected and uncorrected optical-ECT images were reconstructed on the phantom to enable an evaluation of the effectiveness of the correction. Significant attenuation artefacts were observed in the uncorrected images where the central fibre appeared ∼24% less intense due to greater attenuation from the surrounding ink-doped gelatin. This artefact was almost completely removed in the attenuation-corrected image, where the central fibre was within ∼4% of the others. The successful phantom test enabled application of attenuation correction to optical-ECT images of an unsectioned human breast xenograft tumour grown subcutaneously on the hind leg of a nude mouse. This tumour cell line had been genetically labelled (pre-implantation) with fluorescent reporter genes such that all viable tumour cells expressed constitutive red fluorescent protein and hypoxia-inducible factor 1 transcription-produced green fluorescent protein. In addition to the fluorescent reporter labelling of gene expression, the tumour microvasculature was labelled by a light-absorbing vasculature contrast agent delivered in vivo by tail-vein injection. Optical-CT transmission images yielded high-resolution 3D images of the absorbing contrast agent

  10. Development and evaluation of attenuation and scatter correction techniques for SPECT using the Monte Carlo method

    International Nuclear Information System (INIS)

    Ljungberg, M.

    1990-05-01

    Quantitative scintigrafic images, obtained by NaI(Tl) scintillation cameras, are limited by photon attenuation and contribution from scattered photons. A Monte Carlo program was developed in order to evaluate these effects. Simple source-phantom geometries and more complex nonhomogeneous cases can be simulated. Comparisons with experimental data for both homogeneous and nonhomogeneous regions and with published results have shown good agreement. The usefulness for simulation of parameters in scintillation camera systems, stationary as well as in SPECT systems, has also been demonstrated. An attenuation correction method based on density maps and build-up functions has been developed. The maps were obtained from a transmission measurement using an external 57 Co flood source and the build-up was simulated by the Monte Carlo code. Two scatter correction methods, the dual-window method and the convolution-subtraction method, have been compared using the Monte Carlo method. The aim was to compare the estimated scatter with the true scatter in the photo-peak window. It was concluded that accurate depth-dependent scatter functions are essential for a proper scatter correction. A new scatter and attenuation correction method has been developed based on scatter line-spread functions (SLSF) obtained for different depths and lateral positions in the phantom. An emission image is used to determine the source location in order to estimate the scatter in the photo-peak window. Simulation studies of a clinically realistic source in different positions in cylindrical water phantoms were made for three photon energies. The SLSF-correction method was also evaluated by simulation studies for 1. a myocardial source, 2. uniform source in the lungs and 3. a tumour located in the lungs in a realistic, nonhomogeneous computer phantom. The results showed that quantitative images could be obtained in nonhomogeneous regions. (67 refs.)

  11. Improvement of brain perfusion SPET using iterative reconstruction with scatter and non-uniform attenuation correction

    Energy Technology Data Exchange (ETDEWEB)

    Kauppinen, T.; Vanninen, E.; Kuikka, J.T. [Kuopio Central Hospital (Finland). Dept. of Clinical Physiology; Koskinen, M.O. [Dept. of Clinical Physiology and Nuclear Medicine, Tampere Univ. Hospital, Tampere (Finland); Alenius, S. [Signal Processing Lab., Tampere Univ. of Technology, Tampere (Finland)

    2000-09-01

    Filtered back-projection (FBP) is generally used as the reconstruction method for single-photon emission tomography although it produces noisy images with apparent streak artefacts. It is possible to improve the image quality by using an algorithm with iterative correction steps. The iterative reconstruction technique also has an additional benefit in that computation of attenuation correction can be included in the process. A commonly used iterative method, maximum-likelihood expectation maximisation (ML-EM), can be accelerated using ordered subsets (OS-EM). We have applied to the OS-EM algorithm a Bayesian one-step late correction method utilising median root prior (MRP). Methodological comparison was performed by means of measurements obtained with a brain perfusion phantom and using patient data. The aim of this work was to quantitate the accuracy of iterative reconstruction with scatter and non-uniform attenuation corrections and post-filtering in SPET brain perfusion imaging. SPET imaging was performed using a triple-head gamma camera with fan-beam collimators. Transmission and emission scans were acquired simultaneously. The brain phantom used was a high-resolution three-dimensional anthropomorphic JB003 phantom. Patient studies were performed in ten chronic pain syndrome patients. The images were reconstructed using conventional FBP and iterative OS-EM and MRP techniques including scatter and nonuniform attenuation corrections. Iterative reconstructions were individually post-filtered. The quantitative results obtained with the brain perfusion phantom were compared with the known actual contrast ratios. The calculated difference from the true values was largest with the FBP method; iteratively reconstructed images proved closer to the reality. Similar findings were obtained in the patient studies. The plain OS-EM method improved the contrast whereas in the case of the MRP technique the improvement in contrast was not so evident with post-filtering. (orig.)

  12. Improvement of brain perfusion SPET using iterative reconstruction with scatter and non-uniform attenuation correction

    International Nuclear Information System (INIS)

    Kauppinen, T.; Vanninen, E.; Kuikka, J.T.; Alenius, S.

    2000-01-01

    Filtered back-projection (FBP) is generally used as the reconstruction method for single-photon emission tomography although it produces noisy images with apparent streak artefacts. It is possible to improve the image quality by using an algorithm with iterative correction steps. The iterative reconstruction technique also has an additional benefit in that computation of attenuation correction can be included in the process. A commonly used iterative method, maximum-likelihood expectation maximisation (ML-EM), can be accelerated using ordered subsets (OS-EM). We have applied to the OS-EM algorithm a Bayesian one-step late correction method utilising median root prior (MRP). Methodological comparison was performed by means of measurements obtained with a brain perfusion phantom and using patient data. The aim of this work was to quantitate the accuracy of iterative reconstruction with scatter and non-uniform attenuation corrections and post-filtering in SPET brain perfusion imaging. SPET imaging was performed using a triple-head gamma camera with fan-beam collimators. Transmission and emission scans were acquired simultaneously. The brain phantom used was a high-resolution three-dimensional anthropomorphic JB003 phantom. Patient studies were performed in ten chronic pain syndrome patients. The images were reconstructed using conventional FBP and iterative OS-EM and MRP techniques including scatter and nonuniform attenuation corrections. Iterative reconstructions were individually post-filtered. The quantitative results obtained with the brain perfusion phantom were compared with the known actual contrast ratios. The calculated difference from the true values was largest with the FBP method; iteratively reconstructed images proved closer to the reality. Similar findings were obtained in the patient studies. The plain OS-EM method improved the contrast whereas in the case of the MRP technique the improvement in contrast was not so evident with post-filtering. (orig.)

  13. A knowledge-based method for reducing attenuation artefacts caused by cardiac appliances in myocardial PET/CT

    Energy Technology Data Exchange (ETDEWEB)

    Hamill, James J [Siemens Medical Solutions, Molecular Imaging, 810 Innovation Dr., Knoxville, TN (United States); Brunken, Richard C [Department of Molecular and Functional Imaging, Cleveland Clinic Foundation, 9500 Euclid Ave., Cleveland, OH (United States); Bybel, Bohdan [Department of Molecular and Functional Imaging, Cleveland Clinic Foundation, 9500 Euclid Ave., Cleveland, OH (United States); DiFilippo, Frank P [Department of Molecular and Functional Imaging, Cleveland Clinic Foundation, 9500 Euclid Ave., Cleveland, OH (United States); Faul, David D [Siemens Medical Solutions, Molecular Imaging, 810 Innovation Dr., Knoxville, TN (United States)

    2006-06-07

    Attenuation artefacts due to implanted cardiac defibrillator leads have previously been shown to adversely impact cardiac PET/CT imaging. In this study, the severity of the problem is characterized, and an image-based method is described which reduces the resulting artefact in PET. Automatic implantable cardioverter defibrillator (AICD) leads cause a moving-metal artefact in the CT sections from which the PET attenuation correction factors (ACFs) are derived. Fluoroscopic cine images were measured to demonstrate that the defibrillator's highly attenuating distal shocking coil moves rhythmically across distances on the order of 1 cm. Rhythmic motion of this magnitude was created in a phantom with a moving defibrillator lead. A CT study of the phantom showed that the artefact contained regions of incorrect, very high CT values and adjacent regions of incorrect, very low CT values. The study also showed that motion made the artefact more severe. A knowledge-based metal artefact reduction method (MAR) is described that reduces the magnitude of the error in the CT images, without use of the corrupted sinograms. The method modifies the corrupted image through a sequence of artefact detection procedures, morphological operations, adjustments of CT values and three-dimensional filtering. The method treats bone the same as metal. The artefact reduction method is shown to run in a few seconds, and is validated by applying it to a series of phantom studies in which reconstructed PET tracer distribution values are wrong by as much as 60% in regions near the CT artefact when MAR is not applied, but the errors are reduced to about 10% of expected values when MAR is applied. MAR changes PET image values by a few per cent in regions not close to the artefact. The changes can be larger in the vicinity of bone. In patient studies, the PET reconstruction without MAR sometimes results in anomalously high values in the infero-septal wall. Clinical performance of MAR is assessed by

  14. A knowledge-based method for reducing attenuation artefacts caused by cardiac appliances in myocardial PET/CT

    International Nuclear Information System (INIS)

    Hamill, James J; Brunken, Richard C; Bybel, Bohdan; DiFilippo, Frank P; Faul, David D

    2006-01-01

    Attenuation artefacts due to implanted cardiac defibrillator leads have previously been shown to adversely impact cardiac PET/CT imaging. In this study, the severity of the problem is characterized, and an image-based method is described which reduces the resulting artefact in PET. Automatic implantable cardioverter defibrillator (AICD) leads cause a moving-metal artefact in the CT sections from which the PET attenuation correction factors (ACFs) are derived. Fluoroscopic cine images were measured to demonstrate that the defibrillator's highly attenuating distal shocking coil moves rhythmically across distances on the order of 1 cm. Rhythmic motion of this magnitude was created in a phantom with a moving defibrillator lead. A CT study of the phantom showed that the artefact contained regions of incorrect, very high CT values and adjacent regions of incorrect, very low CT values. The study also showed that motion made the artefact more severe. A knowledge-based metal artefact reduction method (MAR) is described that reduces the magnitude of the error in the CT images, without use of the corrupted sinograms. The method modifies the corrupted image through a sequence of artefact detection procedures, morphological operations, adjustments of CT values and three-dimensional filtering. The method treats bone the same as metal. The artefact reduction method is shown to run in a few seconds, and is validated by applying it to a series of phantom studies in which reconstructed PET tracer distribution values are wrong by as much as 60% in regions near the CT artefact when MAR is not applied, but the errors are reduced to about 10% of expected values when MAR is applied. MAR changes PET image values by a few per cent in regions not close to the artefact. The changes can be larger in the vicinity of bone. In patient studies, the PET reconstruction without MAR sometimes results in anomalously high values in the infero-septal wall. Clinical performance of MAR is assessed by two

  15. Impact of attenuation correction strategies on the quantification of High Resolution Research Tomograph PET studies

    International Nuclear Information System (INIS)

    Velden, Floris H P van; Kloet, Reina W; Berckel, Bart N M van; Molthoff, Carla F M; Jong, Hugo W A M de; Lammertsma, Adriaan A; Boellaard, Ronald

    2008-01-01

    In this study, the quantitative accuracy of different attenuation correction strategies presently available for the High Resolution Research Tomograph (HRRT) was investigated. These attenuation correction methods differ in reconstruction and processing (segmentation) algorithms used for generating a μ-image from measured 2D transmission scans, an intermediate step in the generation of 3D attenuation correction factors. Available methods are maximum-a-posteriori reconstruction (MAP-TR), unweighted OSEM (UW-OSEM) and NEC-TR, which transforms sinogram values back to their noise equivalent counts (NEC) to restore Poisson distribution. All methods can be applied with or without μ-image segmentation. However, for MAP-TR a μ-histogram is a prior during reconstruction. All possible strategies were evaluated using phantoms of various sizes, simulating preclinical and clinical situations. Furthermore, effects of emission contamination of the transmission scan on the accuracy of various attenuation correction strategies were studied. Finally, the accuracy of various attenuation corrections strategies and its relative impact on the reconstructed activity concentration (AC) were evaluated using small animal and human brain studies. For small structures, MAP-TR with human brain priors showed smaller differences in μ-values for transmission scans with and without emission contamination (<8%) than the other methods (<26%). In addition, it showed best agreement with true AC (deviation <4.5%). A specific prior designed to take into account the presence of small animal fixation devices only very slightly improved AC precision to 4.3%. All methods scaled μ-values of a large homogeneous phantom to within 4% of the water peak, but MAP-TR provided most accurate AC after reconstruction. However, for clinical data MAP-TR using the default prior settings overestimated the thickness of the skull, resulting in overestimations of μ-values in regions near the skull and thus in incorrect

  16. Whole-body PET/MRI: The effect of bone attenuation during MR-based attenuation correction in oncology imaging

    Energy Technology Data Exchange (ETDEWEB)

    Aznar, M.C., E-mail: marianne.aznar@regionh.dk [Department of Oncology, Section of Radiotherapy 3994, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen (Denmark); Sersar, R., E-mail: rachidadk@hotmail.com [DTU Informatics, Technical University of Denmark, Kongens Lyngby (Denmark); Saabye, J., E-mail: julie_saa@hotmail.com [DTU Informatics, Technical University of Denmark, Kongens Lyngby (Denmark); Ladefoged, C.N., E-mail: claesnl@gmail.com [Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen (Denmark); Andersen, F.L., E-mail: Flemming.Andersen@regionh.dk [Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen (Denmark); Rasmussen, J.H., E-mail: jacobrasmu@gmail.com [Department of Oncology, Section of Radiotherapy 3994, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen (Denmark); Löfgren, J., E-mail: Johan.Loefgren@regionh.dk [Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen (Denmark); Beyer, T., E-mail: thomas.beyer@meduniwien.ac.at [Centre for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna (Austria)

    2014-07-15

    Purpose: In combined PET/MRI standard PET attenuation correction (AC) is based on tissue segmentation following dedicated MR sequencing and, typically, bone tissue is not represented. We evaluate PET quantification in whole-body (WB)-PET/MRI following MR-AC without considering bone attenuation and then investigate different strategies to account for bone tissue in clinical PET/MR imaging. To this purpose, bone tissue representation was extracted from separate CT images, and different bone representations were simulated from hypothetically derived MR-based bone classifications. Methods: Twenty oncology patients referred for a PET/CT were injected with either [18F]-FDG or [18F]-NaF and imaged on PET/CT (Biograph TruePoint/mCT, Siemens) and PET/MRI (mMR, Siemens) following a standard single-injection, dual-imaging clinical WB-protocol. Routine MR-AC was based on in-/opposed-phase MR imaging (orgMR-AC). PET(/MRI) images were reconstructed (AW-OSEM, 3 iterations, 21 subsets, 4 mm Gaussian) following routine MR-AC and MR-AC based on four modified attenuation maps. These modified attenuation maps were created for each patient by non-linear co-registration of the CT images to the orgMR-AC images, and adding CT bone mask values representing cortical bone: 1200 HU (cortCT), spongiosa bone: 350 HU (spongCT), average CT value (meanCT) and original CT values (orgCT). Relative difference images of the PET following AC using the modified attenuation maps were compared. SUVmean was calculated in anatomical reference regions and for PET-positive lesions. Results: The relative differences in SUVmean across patients following orgMR-AC and orgCT in soft tissue lesions and in bone lesions were similar (range: 0.0% to −22.5%), with an average underestimation of SUVmean of 7.2% and 10.0%, respectively when using orgMR-AC. In bone lesions, spongCT values were closest to orgCT (median bias of 1.3%, range: –9.0% to 13.5%) while the overestimation of SUVmean with respect to orgCT was

  17. Rosemary supplementation (Rosmarinus oficinallis L. attenuates cardiac remodeling after myocardial infarction in rats.

    Directory of Open Access Journals (Sweden)

    Bruna Paola Murino Rafacho

    Full Text Available Myocardial infarction (MI is one of the leading causes of morbidity and mortality worldwide. Dietary intervention on adverse cardiac remodeling after MI has significant clinical relevance. Rosemary leaves are a natural product with antioxidant/anti-inflammatory properties, but its effect on morphology and ventricular function after MI is unknown.To determine the effect of the dietary supplementation of rosemary leaves on cardiac remodeling after MI, male Wistar rats were divided into 6 groups after sham procedure or experimental induced MI: 1 Sham group fed standard chow (SR0, n = 23; 2 Sham group fed standard chow supplemented with 0.02% rosemary (R002 (SR002, n = 23; 3 Sham group fed standard chow supplemented with 0.2% rosemary (R02 (SR02, n = 22; 4 group submitted to MI and fed standard chow (IR0, n = 13; 5 group submitted to MI and fed standard chow supplemented with R002 (IR002, n = 8; and 6 group submitted to MI and fed standard chow supplemented with R02 (IR02, n = 9. After 3 months of the treatment, systolic pressure evaluation, echocardiography and euthanasia were performed. Left ventricular samples were evaluated for: fibrosis, cytokine levels, apoptosis, energy metabolism enzymes, and oxidative stress. Rosemary dietary supplementation attenuated cardiac remodeling by improving energy metabolism and decreasing oxidative stress. Rosemary supplementation of 0.02% improved diastolic function and reduced hypertrophy after MI. Regarding rosemary dose, 0.02% and 0.2% for rats are equivalent to 11 mg and 110 mg for humans, respectively.Our findings support further investigations of the rosemary use as adjuvant therapy in adverse cardiac remodeling.

  18. Planar imaging quantification using 3D attenuation correction data and Monte Carlo simulated buildup factors

    International Nuclear Information System (INIS)

    Miller, C.; Filipow, L.; Jackson, S.; Riauka, T.

    1996-01-01

    A new method to correct for attenuation and the buildup of scatter in planar imaging quantification is presented. The method is based on the combined use of 3D density information provided by computed tomography to correct for attenuation and the application of Monte Carlo simulated buildup factors to correct for buildup in the projection pixels. CT and nuclear medicine images were obtained for a purpose-built nonhomogeneous phantom that models the human anatomy in the thoracic and abdominal regions. The CT transverse slices of the phantom were converted to a set of consecutive density maps. An algorithm was developed that projects the 3D information contained in the set of density maps to create opposing pairs of accurate 2D correction maps that were subsequently applied to planar images acquired from a dual-head gamma camera. A comparison of results obtained by the new method and the geometric mean approach based on published techniques is presented for some of the source arrangements used. Excellent results were obtained for various source - phantom configurations used to evaluate the method. Activity quantification of a line source at most locations in the nonhomogeneous phantom produced errors of less than 2%. Additionally, knowledge of the actual source depth is not required for accurate activity quantification. Quantification of volume sources placed in foam, Perspex and aluminium produced errors of less than 7% for the abdominal and thoracic configurations of the phantom. (author)

  19. Wall attenuation and scatter corrections for ion chambers: measurements versus calculations

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, D W.O.; Bielajew, A F [National Research Council of Canada, Ottawa, ON (Canada). Div. of Physics

    1990-08-01

    In precision ion chamber dosimetry in air, wall attenuation and scatter are corrected for A{sub wall} (K{sub att} in IAEA terminology, K{sub w}{sup -1} in standards laboratory terminology). Using the EGS4 system the authors show that Monte Carlo calculated A{sub wall} factors predict relative variations in detector response with wall thickness which agree with all available experimental data within a statistical uncertainty of less than 0.1%. They calculated correction factors for use in exposure and air kerma standards are different by up to 1% from those obtained by extrapolating these same measurements. Using calculated correction factors would imply increases of 0.7-1.0% in the exposure and air kerma standards based on spherical and large diameter, large length cylindrical chambers and decreases of 0.3-0.5% for standards based on large diameter pancake chambers. (author).

  20. Assessment of endothelial function and myocardial flow reserve using {sup 15}O-water PET without attenuation correction

    Energy Technology Data Exchange (ETDEWEB)

    Tuffier, Stephane; Joubert, Michael; Bailliez, Alban [EA 4650, Normandie Universite, Caen (France); Legallois, Damien [EA 4650, Normandie Universite, Caen (France); Caen University Hospital, Department of Cardiology, Caen (France); Belin, Annette [Caen University Hospital, Department of Cardiac Surgery, Caen (France); Redonnet, Michel [Rouen University Hospital, Department of Cardiac Surgery, Rouen (France); Agostini, Denis [EA 4650, Normandie Universite, Caen (France); Caen University Hospital, Department of Nuclear Medicine, Caen (France); Manrique, Alain [EA 4650, Normandie Universite, Caen (France); Caen University Hospital, Department of Nuclear Medicine, Caen (France); Cyceron PET Centre, Caen (France)

    2016-02-15

    Myocardial blood flow (MBF) measurement using positron emission tomography (PET) from the washout rate of {sup 15}O-water is theoretically independent of tissue attenuation. The aim of this study was to evaluate the impact of not using attenuation correction in the assessment of coronary endothelial function and myocardial flow reserve (MFR) using {sup 15}O-water PET. We retrospectively processed 70 consecutive {sup 15}O-water PET examinations obtained at rest and during cold pressor testing (CPT) in patients with dilated cardiomyopathy (n = 58), or at rest and during adenosine infusion in heart transplant recipients (n = 12). Data were reconstructed with attenuation correction (AC) and without attenuation correction (NAC) using filtered backprojection, and MBF was quantified using a single compartmental model. The agreement between AC and NAC data was assessed using Lin's concordance correlation coefficient followed by Bland-Altman plot analysis. Regarding endothelial function, NAC PET showed poor reproducibility and poor agreement with AC PET data. Conversely, NAC PET demonstrated high reproducibility and a strong agreement with AC PET for the assessment of MFR. Non-attenuation-corrected {sup 15}O-water PET provided an accurate measurement of MFR compared to attenuation-corrected PET. However, non-attenuation-corrected PET data were less effective for the assessment of endothelial function using CPT in this population. (orig.)

  1. Assessment of endothelial function and myocardial flow reserve using 15O-water PET without attenuation correction

    International Nuclear Information System (INIS)

    Tuffier, Stephane; Joubert, Michael; Bailliez, Alban; Legallois, Damien; Belin, Annette; Redonnet, Michel; Agostini, Denis; Manrique, Alain

    2016-01-01

    Myocardial blood flow (MBF) measurement using positron emission tomography (PET) from the washout rate of 15 O-water is theoretically independent of tissue attenuation. The aim of this study was to evaluate the impact of not using attenuation correction in the assessment of coronary endothelial function and myocardial flow reserve (MFR) using 15 O-water PET. We retrospectively processed 70 consecutive 15 O-water PET examinations obtained at rest and during cold pressor testing (CPT) in patients with dilated cardiomyopathy (n = 58), or at rest and during adenosine infusion in heart transplant recipients (n = 12). Data were reconstructed with attenuation correction (AC) and without attenuation correction (NAC) using filtered backprojection, and MBF was quantified using a single compartmental model. The agreement between AC and NAC data was assessed using Lin's concordance correlation coefficient followed by Bland-Altman plot analysis. Regarding endothelial function, NAC PET showed poor reproducibility and poor agreement with AC PET data. Conversely, NAC PET demonstrated high reproducibility and a strong agreement with AC PET for the assessment of MFR. Non-attenuation-corrected 15 O-water PET provided an accurate measurement of MFR compared to attenuation-corrected PET. However, non-attenuation-corrected PET data were less effective for the assessment of endothelial function using CPT in this population. (orig.)

  2. The relative contributions of scatter and attenuation corrections toward improved brain SPECT quantification

    International Nuclear Information System (INIS)

    Stodilka, Robert Z.; Msaki, Peter; Prato, Frank S.; Nicholson, Richard L.; Kemp, B.J.

    1998-01-01

    Mounting evidence indicates that scatter and attenuation are major confounds to objective diagnosis of brain disease by quantitative SPECT. There is considerable debate, however, as to the relative importance of scatter correction (SC) and attenuation correction (AC), and how they should be implemented. The efficacy of SC and AC for 99m Tc brain SPECT was evaluated using a two-compartment fully tissue-equivalent anthropomorphic head phantom. Four correction schemes were implemented: uniform broad-beam AC, non-uniform broad-beam AC, uniform SC+AC, and non-uniform SC+AC. SC was based on non-stationary deconvolution scatter subtraction, modified to incorporate a priori knowledge of either the head contour (uniform SC) or transmission map (non-uniform SC). The quantitative accuracy of the correction schemes was evaluated in terms of contrast recovery, relative quantification (cortical:cerebellar activity), uniformity ((coefficient of variation of 230 macro-voxels) x100%), and bias (relative to a calibration scan). Our results were: uniform broad-beam (μ=0.12cm -1 ) AC (the most popular correction): 71% contrast recovery, 112% relative quantification, 7.0% uniformity, +23% bias. Non-uniform broad-beam (soft tissue μ=0.12cm -1 ) AC: 73%, 114%, 6.0%, +21%, respectively. Uniform SC+AC: 90%, 99%, 4.9%, +12%, respectively. Non-uniform SC+AC: 93%, 101%, 4.0%, +10%, respectively. SC and AC achieved the best quantification; however, non-uniform corrections produce only small improvements over their uniform counterparts. SC+AC was found to be superior to AC; this advantage is distinct and consistent across all four quantification indices. (author)

  3. Count-based left ventricular volume determination utilizing a left posterior oblique view for attenuation correction

    International Nuclear Information System (INIS)

    Rabinovitch, M.A.; Kalff, V.; Koral, K.

    1984-01-01

    This study aimed to determine the inherent error of the left ventricular volume measurement from the gated equilibrium blood pool scintigram utilizing the count-based technique. The study population consisted of 26 patients who had undergone biplane contrast ventriculography. The patients were imaged with a parallel-hole collimator in the left anterior oblique position showing the septum to best advantage. A reference blood sample was counted and radionuclide volumes calculated without correction for attenuation. Attenuation corrected volumes were derived with the factor 1/e/sup -/+d/, where d = distance from skin marker to center of the left ventricle in the orthogonal left posterior oblique view and μ = linear attenuation coefficient. A series of μ values from 0.08 to 0.15 cm -1 was evaluated. The tightest 95% confidence limits achieved for an end-diastolic 150-ml ventricle were +/- 44ml, and for an end-systolic 75-ml ventricle +/- 32 ml. In view of the magnitude of inherent error, the count-based volume measurement may be more suitable for group analyses and in cases in which an individual patient serves as his own control

  4. Application of transmission scan-based attenuation compensation to scatter-corrected thallium-201 myocardial single-photon emission tomographic images

    International Nuclear Information System (INIS)

    Hashimoto, Jun; Kubo, Atsushi; Ogawa, Koichi; Ichihara, Takashi; Motomura, Nobutoku; Takayama, Takuzo; Iwanaga, Shiro; Mitamura, Hideo; Ogawa, Satoshi

    1998-01-01

    A practical method for scatter and attenuation compensation was employed in thallium-201 myocardial single-photon emission tomography (SPET or ECT) with the triple-energy-window (TEW) technique and an iterative attenuation correction method by using a measured attenuation map. The map was reconstructed from technetium-99m transmission CT (TCT) data. A dual-headed SPET gamma camera system equipped with parallel-hole collimators was used for ECT/TCT data acquisition and a new type of external source named ''sheet line source'' was designed for TCT data acquisition. This sheet line source was composed of a narrow long fluoroplastic tube embedded in a rectangular acrylic board. After injection of 99m Tc solution into the tube by an automatic injector, the board was attached in front of the collimator surface of one of the two detectors. After acquiring emission and transmission data separately or simultaneously, we eliminated scattered photons in the transmission and emission data with the TEW method, and reconstructed both images. Then, the effect of attenuation in the scatter-corrected ECT images was compensated with Chang's iterative method by using measured attenuation maps. Our method was validated by several phantom studies and clinical cardiac studies. The method offered improved homogeneity in distribution of myocardial activity and accurate measurements of myocardial tracer uptake. We conclude that the above correction method is feasible because a new type of 99m Tc external source may not produce truncation in TCT images and is cost-effective and easy to prepare in clinical situations. (orig.)

  5. Attenuation correction in positron emission tomography: Quality control and performance evaluation

    International Nuclear Information System (INIS)

    Nalis, J.; Courbon, F.; Brillouet, S.; Marre, D.; Serre, D.; Colin, V.; Caselles, O.; Flouzat, G.

    2007-01-01

    Objective: The aim of this study is to evaluate the performance of the Computed Tomography based Attenuation Correction (CTAC) for Positron Emission Tomography (PET) data. Attenuation maps containing linear attenuation coefficients at 511 keV (LAC 511 keV ) are calculated by trilinear conversion of Hounsfield Units (HU) obtained from CT slices after matrix size-reduction and Gaussian filtering. Our work focusses on this trilinear conversion. Materials and methods: CT slices of an electron density phantom. composed of 17 cylindrical inserts made of different tissue-equivalent materials, were acquired using a Discovery ST4 PET-CT. Data were processed with a customized version of CT quality control software, giving automatically the experimental conversion function: LAC 511 keV =f(HU). Furthermore, data from patient datasets were assessed using both smoothed CT slices and attenuation maps. Results: LAC 511 keV extracted from phantom data are in good correlation with the expected theoretical values, except for the standard 10 mm diameter dense bone insert, where the obtained CTAC values are underestimated, Assuming a sample size issue, similar acquisitions were performed with a special 30 mm-diameter dense bone insert, confirming the underestimation as a consequence of the sample size. (authors)

  6. Megavoltage photon beam attenuation by carbon fiber couch tops and its prediction using correction factors

    International Nuclear Information System (INIS)

    Hayashi, Naoki; Shibamoto, Yuta; Obata, Yasunori; Kimura, Takashi; Nakazawa, Hisato; Hagiwara, Masahiro; Hashizume, Chisa I.; Mori, Yoshimasa; Kobayashi, Tatsuya

    2010-01-01

    The purpose of this study was to evaluate the effect of megavoltage photon beam attenuation (PBA) by couch tops and to propose a method for correction of PBA. Four series of phantom measurements were carried out. First, PBA by the exact couch top (ECT, Varian) and Imaging Couch Top (ICT, BrainLAB) was evaluated using a water-equivalent phantom. Second, PBA by Type-S system (Med-Tec), ECT and ICT was compared with a spherical phantom. Third, percentage depth dose (PDD) after passing through ICT was measured to compare with control data of PDD. Forth, the gantry angle dependency of PBA by ICT was evaluated. Then, an equation for PBA correction was elaborated and correction factors for PBA at isocenter were obtained. Finally, this method was applied to a patient with hepatoma. PBA of perpendicular beams by ICT was 4.7% on average. With the increase in field size, the measured values became higher. PBA by ICT was greater than that by Type-S system and ECT. PBA increased significantly as the angle of incidence increased, ranging from 4.3% at 180 deg to 11.2% at 120 deg. Calculated doses obtained by the equation and correction factors agreed quite well with the measured doses between 120 deg and 180 deg of angles of incidence. Also in the patient, PBA by ICT was corrected quite well by the equation and correction factors. In conclusion, PBA and its gantry angle dependency by ICT were observed. This simple method using the equation and correction factors appeared useful to correct the isocenter dose when the PBA effect cannot be corrected by a treatment planning system. (author)

  7. Improved cardiac function and exercise capacity following correction of pectus excavatum: a review of current literature.

    Science.gov (United States)

    Maagaard, Marie; Heiberg, Johan

    2016-09-01

    Patients with pectus excavatum (PE) often describe improvements in exercise stamina following corrective surgery. Studies have investigated the surgical effect on physiological parameters; still, no consensus has yet been reached. Therefore, the aim of this literature review was to describe the cardiac outcome after surgical correction, both at rest and during exercise. In February 2016, a detailed search of the databases PubMed, Medline, and EMBASE was performed. We assessed clinical studies that described cardiac outcomes both before and after surgical correction of PE. We only included studies reporting either pre-defined echocardiographic or exercise test parameters. No exclusion criteria or statistical analyses were applied. Twenty-one full-text articles, published between 1972 and 2016, were selected, with cohort-ranges of 3-168 patients, mean age-ranges of 5-33 years, and mean follow-up-ranges from immediately to 4 years after surgery. Twelve studies described resting cardiac parameters. Four studies measured cardiac output, where one described 36% immediate increase after surgery, one reported 15% increase after Nuss-bar removal and two found no difference. Three studies demonstrated improvement in mean stroke volume ranges of 22-34% and two studies found no difference. Fifteen studies investigated exercise capacity, with 11 considering peak O 2 pr. kg, where five studies demonstrated improvements with the mean ranging from 8% to 15% after surgery, five studies demonstrated no difference, and one saw a decrease of 19% 3 months after Nuss-bar implantation. A measurable increase in exercise capacity exists following surgery, which may be caused by multiple factors. This may be owed to the relief of compressed cardiac chambers with the increased anterior-posterior thoracic dimensions, which could facilitate an improved filling of the heart. With these results, the positive physiological impact of the surgery is emphasized and the potential gain in cardiac

  8. Vision 20/20: Magnetic resonance imaging-guided attenuation correction in PET/MRI: Challenges, solutions, and opportunities

    Energy Technology Data Exchange (ETDEWEB)

    Mehranian, Abolfazl; Arabi, Hossein [Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva CH-1211 (Switzerland); Zaidi, Habib, E-mail: habib.zaidi@hcuge.ch [Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva CH-1211 (Switzerland); Geneva Neuroscience Centre, University of Geneva, Geneva CH-1205 (Switzerland); Department of Nuclear Medicine and Molecular Imaging, University of Groningen, Groningen 9700 RB (Netherlands)

    2016-03-15

    Attenuation correction is an essential component of the long chain of data correction techniques required to achieve the full potential of quantitative positron emission tomography (PET) imaging. The development of combined PET/magnetic resonance imaging (MRI) systems mandated the widespread interest in developing novel strategies for deriving accurate attenuation maps with the aim to improve the quantitative accuracy of these emerging hybrid imaging systems. The attenuation map in PET/MRI should ideally be derived from anatomical MR images; however, MRI intensities reflect proton density and relaxation time properties of biological tissues rather than their electron density and photon attenuation properties. Therefore, in contrast to PET/computed tomography, there is a lack of standardized global mapping between the intensities of MRI signal and linear attenuation coefficients at 511 keV. Moreover, in standard MRI sequences, bones and lung tissues do not produce measurable signals owing to their low proton density and short transverse relaxation times. MR images are also inevitably subject to artifacts that degrade their quality, thus compromising their applicability for the task of attenuation correction in PET/MRI. MRI-guided attenuation correction strategies can be classified in three broad categories: (i) segmentation-based approaches, (ii) atlas-registration and machine learning methods, and (iii) emission/transmission-based approaches. This paper summarizes past and current state-of-the-art developments and latest advances in PET/MRI attenuation correction. The advantages and drawbacks of each approach for addressing the challenges of MR-based attenuation correction are comprehensively described. The opportunities brought by both MRI and PET imaging modalities for deriving accurate attenuation maps and improving PET quantification will be elaborated. Future prospects and potential clinical applications of these techniques and their integration in commercial

  9. MR Imaging-Guided Attenuation Correction of PET Data in PET/MR Imaging.

    Science.gov (United States)

    Izquierdo-Garcia, David; Catana, Ciprian

    2016-04-01

    Attenuation correction (AC) is one of the most important challenges in the recently introduced combined PET/magnetic resonance (MR) scanners. PET/MR AC (MR-AC) approaches aim to develop methods that allow accurate estimation of the linear attenuation coefficients of the tissues and other components located in the PET field of view. MR-AC methods can be divided into 3 categories: segmentation, atlas, and PET based. This review provides a comprehensive list of the state-of-the-art MR-AC approaches and their pros and cons. The main sources of artifacts are presented. Finally, this review discusses the current status of MR-AC approaches for clinical applications. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Viscoacoustic wave-equation traveltime inversion with correct and incorrect attenuation profiles

    KAUST Repository

    Yu, Han

    2017-08-17

    A visco-acoustic wave-equation traveltime inversion method is presented that inverts for a shallow subsurface velocity distribution with correct and incorrect attenuation profiles. Similar to the classical wave equation traveltime inversion, this method applies the misfit functional that minimizes the first break differences between the observed and predicted data. Although, WT can partly avoid the cycle skipping problem, an initial velocity model approaches to the right or wrong velocity models under different setups of the attenuation profiles. However, with a Q model far away from the real model, the inverted tomogram is obviously different from the true velocity model while a small change of the Q model does not improve the inversion quality in a strong manner if low frequency information is not lost.

  11. Induced Pluripotent Stem Cells-Derived Mesenchymal Stem Cells Attenuate Cigarette Smoke-Induced Cardiac Remodeling and Dysfunction

    Directory of Open Access Journals (Sweden)

    Yingmin Liang

    2017-07-01

    Full Text Available The strong relationship between cigarette smoking and cardiovascular disease (CVD has been well-documented, but the mechanisms by which smoking increases CVD risk appear to be multifactorial and incompletely understood. Mesenchymal stem cells (MSCs are regarded as an important candidate for cell-based therapy in CVD. We hypothesized that MSCs derived from induced pluripotent stem cell (iPSC-MSCs or bone marrow (BM-MSCs might alleviate cigarette smoke (CS-induced cardiac injury. This study aimed to investigate the effects of BM-MSCs or iPSC-MSCs on CS-induced changes in serum and cardiac lipid profiles, oxidative stress and inflammation as well as cardiac function in a rat model of passive smoking. Male Sprague-Dawley rats were randomly selected for exposure to either sham air (SA as control or 4% CS for 1 h per day for 56 days. On day 29 and 43, human adult BM-MSCs, iPSC-MSCs or PBS were administered intravenously to CS-exposed rats. Results from echocardiography, serum and cardiac lipid profiles, cardiac antioxidant capacity, cardiac pro- and anti-inflammatory cytokines and cardiac morphological changes were evaluated at the end of treatment. iPSC-MSC-treated group showed a greater effect in the improvement of CS-induced cardiac dysfunction over BM-MSCs-treated group as shown by increased percentage left ventricular ejection fraction and percentage fractional shortening, in line with the greater reversal of cardiac lipid abnormality. In addition, iPSC-MSCs administration attenuated CS-induced elevation of cardiac pro-inflammatory cytokines as well as restoration of anti-inflammatory cytokines and anti-oxidative markers, leading to ameliorate cardiac morphological abnormalities. These data suggest that iPSC-MSCs on one hand may restore CS-induced cardiac lipid abnormality and on the other hand may attenuate cardiac oxidative stress and inflammation via inhibition of CS-induced NF-κB activation, leading to improvement of cardiac remodeling and

  12. Filter Paper: Solution to High Self-Attenuation Corrections in HEPA Filter Measurements

    International Nuclear Information System (INIS)

    Oberer, R.B.; Harold, N.B.; Gunn, C.A.; Brummett, M.; Chaing, L.G.

    2005-01-01

    An 8 by 8 by 6 inch High Efficiency Particulate Air (HEPA) filter was measured as part of a uranium holdup survey in June of 2005 as it has been routinely measured every two months since 1998. Although the survey relies on gross gamma count measurements, this was one of a few measurements that had been converted to a quantitative measurement in 1998. The measurement was analyzed using the traditional Generalized Geometry Holdup (GGH) approach, using HMS3 software, with an area calibration and self-attenuation corrected with an empirical correction factor of 1.06. A result of 172 grams of 235 U was reported. The actual quantity of 235 U in the filter was approximately 1700g. Because of this unusually large discrepancy, the measurement of HEPA filters will be discussed. Various techniques for measuring HEPA filters will be described using the measurement of a 24 by 24 by 12 inch HEPA filter as an example. A new method to correct for self attenuation will be proposed for this measurement Following the discussion of the 24 by 24 by 12 inch HEPA filter, the measurement of the 8 by 8 by 6 inch will be discussed in detail

  13. Attenuation correction in emission tomography using the emission data—A review

    Energy Technology Data Exchange (ETDEWEB)

    Berker, Yannick, E-mail: berker@mail.med.upenn.edu; Li, Yusheng [Department of Radiology, University of Pennsylvania, 3620 Hamilton Walk, Philadelphia, Pennsylvania 19104 (United States)

    2016-02-15

    The problem of attenuation correction (AC) for quantitative positron emission tomography (PET) had been considered solved to a large extent after the commercial availability of devices combining PET with computed tomography (CT) in 2001; single photon emission computed tomography (SPECT) has seen a similar development. However, stimulated in particular by technical advances toward clinical systems combining PET and magnetic resonance imaging (MRI), research interest in alternative approaches for PET AC has grown substantially in the last years. In this comprehensive literature review, the authors first present theoretical results with relevance to simultaneous reconstruction of attenuation and activity. The authors then look back at the early history of this research area especially in PET; since this history is closely interwoven with that of similar approaches in SPECT, these will also be covered. We then review algorithmic advances in PET, including analytic and iterative algorithms. The analytic approaches are either based on the Helgason–Ludwig data consistency conditions of the Radon transform, or generalizations of John’s partial differential equation; with respect to iterative methods, we discuss maximum likelihood reconstruction of attenuation and activity (MLAA), the maximum likelihood attenuation correction factors (MLACF) algorithm, and their offspring. The description of methods is followed by a structured account of applications for simultaneous reconstruction techniques: this discussion covers organ-specific applications, applications specific to PET/MRI, applications using supplemental transmission information, and motion-aware applications. After briefly summarizing SPECT applications, we consider recent developments using emission data other than unscattered photons. In summary, developments using time-of-flight (TOF) PET emission data for AC have shown promising advances and open a wide range of applications. These techniques may both remedy

  14. PET/CT with intravenous contrast can be used for PET attenuation correction in cancer patients

    International Nuclear Information System (INIS)

    Berthelsen, A.K.; Holm, S.; Loft, A.; Klausen, T.L.; Andersen, F.; Hoejgaard, L.

    2005-01-01

    If the CT scan of a combined PET/CT study is performed as a full diagnostic quality CT scan including intravenous (IV) contrast agent, the quality of the joint PET/CT procedure is improved and a separate diagnostic CT scan can be avoided. CT with IV contrast can be used for PET attenuation correction, but this may result in a bias in the attenuation factors. The clinical significance of this bias has not been established. Our aim was to perform a prospective clinical study where each patient had CT performed with and without IV contrast agent to establish whether PET/CT with IV contrast can be used for PET attenuation without reducing the clinical value of the PET scan. A uniform phantom study was used to document that the PET acquisition itself is not significantly influenced by the presence of IV contrast medium. Then, 19 patients referred to PET/CT with IV contrast underwent CT scans without, and then with contrast agent, followed by an 18 F-fluorodeoxyglucose whole-body PET scan. The CT examinations were performed with identical parameters on a GE Discovery LS scanner. The PET data were reconstructed with attenuation correction based on the two CT data sets. A global comparison of standard uptake value (SUV) was performed, and SUVs in tumour, in non-tumour tissue and in the subclavian vein were calculated. Clinical evaluation of the number and location of lesions on all PET/CT scans was performed twice, blinded and in a different random order, by two independent nuclear medicine specialists. In all patients, the measured global SUV of PET images based on CT with IV contrast agent was higher than the global activity using non-contrast correction. The overall increase in the mean SUV (for two different conversion tables tested) was 4.5±2.3% and 1.6±0.5%, respectively. In 11/19 patients, focal uptake was identified corresponding to malignant tumours. Eight out of 11 tumours showed an increased SUV max (2.9±3.1%) on the PET images reconstructed using IV contrast

  15. MR-based attenuation correction in brain PET based on UTE sequences

    Energy Technology Data Exchange (ETDEWEB)

    Cabello, Jorge; Nekolla, Stephan G; Ziegler, Sibylle I [Department of Nuclear Medicine, Klinikum rechts der Isar, Technische Universität München (Germany)

    2014-07-29

    Attenuation correction (AC) in brain PET/MR has recently emerged as one of the challenging tasks in the PET/MR field. It has been shown that to ignore the attenuation produced by bone can lead to errors ranging from 5-30% in regions close to bone structures. Since the information provided by the MR signal is not directly related to tissue attenuation, alternative methods have to be developed. Signal from bone tissue is difficult to measure given its short transverse relaxation time (T2). Ultrashort-echo time (UTE) pulse sequences were developed to measure signal from tissues with short T2. A combination of two consecutive UTE echoes has been used in several works to measure signal from bone tissue. The first echo is able to measure signal from bone tissue in addition to soft tissue, while the second echo contains most of the soft tissue contained in the first echo but not bone. In this work we extract the attenuation information from the difference between the logarithm of two images obtained after applying two consecutive UTE pulse sequences using the mMR scanner (Siemens Healthcare). Subsequently, image processing techniques are applied to reduce the noise and extract air cavities within the head. The resulting image is converted to linear attenuation coefficients, generating what is known as µ-map, to be used during reconstruction. For comparison purposes PET/CT scans of the same patients were acquired prior to the PET/MR scan. Additional µ-maps obtained for comparison were extracted from a Dixon sequence (used in clinical routine) and an additional µ-map calculated by the scanner based on UTE pulse sequences. Preliminary quantitative results measured in the cerebellum, using the value obtained with CT-based AC as reference, show differences of 34% without AC, 13% using the Dixon-based and UTE-based provided by the scanner, and 0.8% with the AC strategy presented here.

  16. Stochastic simulation experiment to assess radar rainfall retrieval uncertainties associated with attenuation and its correction

    Directory of Open Access Journals (Sweden)

    R. Uijlenhoet

    2008-03-01

    Full Text Available As rainfall constitutes the main source of water for the terrestrial hydrological processes, accurate and reliable measurement and prediction of its spatial and temporal distribution over a wide range of scales is an important goal for hydrology. We investigate the potential of ground-based weather radar to provide such measurements through a theoretical analysis of some of the associated observation uncertainties. A stochastic model of range profiles of raindrop size distributions is employed in a Monte Carlo simulation experiment to investigate the rainfall retrieval uncertainties associated with weather radars operating at X-, C-, and S-band. We focus in particular on the errors and uncertainties associated with rain-induced signal attenuation and its correction for incoherent, non-polarimetric, single-frequency, operational weather radars. The performance of two attenuation correction schemes, the (forward Hitschfeld-Bordan algorithm and the (backward Marzoug-Amayenc algorithm, is analyzed for both moderate (assuming a 50 km path length and intense Mediterranean rainfall (for a 30 km path. A comparison shows that the backward correction algorithm is more stable and accurate than the forward algorithm (with a bias in the order of a few percent for the former, compared to tens of percent for the latter, provided reliable estimates of the total path-integrated attenuation are available. Moreover, the bias and root mean square error associated with each algorithm are quantified as a function of path-averaged rain rate and distance from the radar in order to provide a plausible order of magnitude for the uncertainty in radar-retrieved rain rates for hydrological applications.

  17. Exercise through a cardiac rehabilitation program attenuates oxidative stress in patients submitted to coronary artery bypass grafting.

    Science.gov (United States)

    Taty Zau, José Francisco; Costa Zeferino, Rodrigo; Sandrine Mota, Nádia; Fernandes Martins, Gerez; Manoel Serra, Salvador; Bonates da Cunha, Therezil; Medeiros Lima, Daniel; Bragança Pereira, Basilio de; Matos do Nascimento, Emília; Filho, Danilo Wilhelm; Curi Pedrosa, Rozangela; Pedrosa, Roberto Coury

    2018-12-01

    Cardiovascular disease is the main cause of morbidity and mortality in the world and oxidative stress has been implicated in the pathogenesis. Cardiac rehabilitation in patients with coronary artery disease submitted to coronary artery bypass grafting may prevent cardiovascular events probably through the attenuation of oxidative stress. The aim of this study was to evaluate the benefits of a cardiac rehabilitation program in the control of the systemic oxidative stress. The studied population consisted of 40 patients, with chronic stable coronary artery disease submitted to coronary artery bypass grafting, who attended a cardiac rehabilitation program. Biomarkers of oxidative stress were evaluated in the blood of these patients at different moments. After the onset of cardiac rehabilitation, there was a significant and progressive decrease in thiobarbituric acid reactive substances levels and protein carbonyls, an initial increase and subsequent decrease in superoxide dismutase, catalase and glutathione peroxidase activities. Also, a progressive increase of uric acid, while ferric reducing antioxidant power levels increased only at the end of the cardiac rehabilitation and a tendency to increase of glutathione contents. The results suggest that regular exercise through a cardiac rehabilitation program can attenuate oxidative stress in chronic coronary artery disease patients submitted to coronary artery bypass grafting.

  18. MicroRNA-155 attenuates late sepsis-induced cardiac dysfunction through JNK and β-arrestin 2.

    Science.gov (United States)

    Zhou, Yu; Song, Yan; Shaikh, Zahir; Li, Hui; Zhang, Haiju; Caudle, Yi; Zheng, Shouhua; Yan, Hui; Hu, Dan; Stuart, Charles; Yin, Deling

    2017-07-18

    Cardiac dysfunction is correlated with detrimental prognosis of sepsis and contributes to a high risk of mortality. After an initial hyperinflammatory reaction, most patients enter a protracted state of immunosuppression (late sepsis) that alters both innate and adaptive immunity. The changes of cardiac function in late sepsis are not yet known. MicroRNA-155 (miR-155) is previously found to play important roles in both regulations of immune activation and cardiac function. In this study, C57BL/6 mice were operated to develop into early and late sepsis phases, and miR-155 mimic was injected through the tail vein 48 h after cecal ligation and puncture (CLP). The effect of miR-155 on CLP-induced cardiac dysfunction was explored in late sepsis. We found that increased expression of miR-155 in the myocardium protected against cardiac dysfunction in late sepsis evidenced by attenuating sepsis-reduced cardiac output and enhancing left ventricular systolic function. We also observed that miR-155 markedly reduced the infiltration of macrophages and neutrophils into the myocardium and attenuated the inflammatory response via suppression of JNK signaling pathway. Moreover, overexpression of β-arrestin 2 (Arrb2) exacerbated the mice mortality and immunosuppression in late sepsis. Furthermore, transfection of miR-155 mimic reduced Arrb2 expression, and then restored immunocompetence and improved survival in late septic mice. We conclude that increased miR-155 expression through systemic administration of miR-155 mimic attenuates cardiac dysfunction and improves late sepsis survival by targeting JNK associated inflammatory signaling and Arrb2 mediated immunosuppression.

  19. Technical Note: Correcting for signal attenuation from noisy proxy data in climate reconstructions

    KAUST Repository

    Ammann, C. M.

    2010-04-20

    Regression-based climate reconstructions scale one or more noisy proxy records against a (generally) short instrumental data series. Based on that relationship, the indirect information is then used to estimate that particular measure of climate back in time. A well-calibrated proxy record(s), if stationary in its relationship to the target, should faithfully preserve the mean amplitude of the climatic variable. However, it is well established in the statistical literature that traditional regression parameter estimation can lead to substantial amplitude attenuation if the predictors carry significant amounts of noise. This issue is known as "Measurement Error" (Fuller, 1987; Carroll et al., 2006). Climate proxies derived from tree-rings, ice cores, lake sediments, etc., are inherently noisy and thus all regression-based reconstructions could suffer from this problem. Some recent applications attempt to ward off amplitude attenuation, but implementations are often complex (Lee et al., 2008) or require additional information, e.g. from climate models (Hegerl et al., 2006, 2007). Here we explain the cause of the problem and propose an easy, generally applicable, data-driven strategy to effectively correct for attenuation (Fuller, 1987; Carroll et al., 2006), even at annual resolution. The impact is illustrated in the context of a Northern Hemisphere mean temperature reconstruction. An inescapable trade-off for achieving an unbiased reconstruction is an increase in variance, but for many climate applications the change in mean is a core interest.

  20. Technical Note: Correcting for signal attenuation from noisy proxy data in climate reconstructions

    Directory of Open Access Journals (Sweden)

    C. M. Ammann

    2010-04-01

    Full Text Available Regression-based climate reconstructions scale one or more noisy proxy records against a (generally short instrumental data series. Based on that relationship, the indirect information is then used to estimate that particular measure of climate back in time. A well-calibrated proxy record(s, if stationary in its relationship to the target, should faithfully preserve the mean amplitude of the climatic variable. However, it is well established in the statistical literature that traditional regression parameter estimation can lead to substantial amplitude attenuation if the predictors carry significant amounts of noise. This issue is known as "Measurement Error" (Fuller, 1987; Carroll et al., 2006. Climate proxies derived from tree-rings, ice cores, lake sediments, etc., are inherently noisy and thus all regression-based reconstructions could suffer from this problem. Some recent applications attempt to ward off amplitude attenuation, but implementations are often complex (Lee et al., 2008 or require additional information, e.g. from climate models (Hegerl et al., 2006, 2007. Here we explain the cause of the problem and propose an easy, generally applicable, data-driven strategy to effectively correct for attenuation (Fuller, 1987; Carroll et al., 2006, even at annual resolution. The impact is illustrated in the context of a Northern Hemisphere mean temperature reconstruction. An inescapable trade-off for achieving an unbiased reconstruction is an increase in variance, but for many climate applications the change in mean is a core interest.

  1. An examination on the correction of attenuation for calculating the renal RI accumulation

    International Nuclear Information System (INIS)

    Onoue, Koichi; Tachibana, Keizo; Maeda, Yoshihiro; Yanoo, Sanae; Morishita, Etsuko; Kawanaka, Masahiro; Kashiwagi, Toru; Fukuchi, Minoru

    1999-01-01

    An examination was made on the attenuation coefficients for calculation of true renal accumulation rate together with the precision of measurement of depth in the kidney. Kidney phantom for attenuation coefficients was a 20 x 20 cm cube where water was filled and radioactivity source of 99m Tc was placed at various depths. Radioactivity was measured by four kinds of scinti-camera with the collimator LEGP and LEHR. The phantom for radioactivity accumulation in the kidney was a 10 x 5 x 1, 3 or 5 cm box where 99m Tc solution of the standard 30 MBq was filled, and subjected to radioactivity measurement from various angles. Phantom radioactivity was found corrected by the effective attenuation coefficient, 0.131 cm, within the range of 98-114% of the standard counts. The precision of measurement of the depth was examined in sideways scintigrams obtained in clinical practice and was found to have the deviation of 1.1 cm as the mean of maximum ones and the variation coefficient of 7.1%. Measured depth was found to be well correlated with estimated ones by the method of Tonnesen or Ito which had the maximum deviation of 5.4 or 3.5 cm, respectively. (K.H.)

  2. Effect of Attenuation Correction on Regional Quantification Between PET/MR and PET/CT

    DEFF Research Database (Denmark)

    Teuho, Jarmo; Johansson, Jarkko; Linden, Jani

    2016-01-01

    UNLABELLED: A spatial bias in brain PET/MR exists compared with PET/CT, because of MR-based attenuation correction. We performed an evaluation among 4 institutions, 3 PET/MR systems, and 4 PET/CT systems using an anthropomorphic brain phantom, hypothesizing that the spatial bias would be minimized....../MR systems, CTAC was applied as the reference method for attenuation correction. RESULTS: With CTAC, visual and quantitative differences between PET/MR and PET/CT systems were minimized. Intersystem variation between institutions was +3.42% to -3.29% in all VOIs for PET/CT and +2.15% to -4.50% in all VOIs...... for PET/MR. PET/MR systems differed by +2.34% to -2.21%, +2.04% to -2.08%, and -1.77% to -5.37% when compared with a PET/CT system at each institution, and these differences were not significant (P ≥ 0.05). CONCLUSION: Visual and quantitative differences between PET/MR and PET/CT systems can be minimized...

  3. Magnetic resonance imaging-guided attenuation and scatter corrections in three-dimensional brain positron emission tomography

    CERN Document Server

    Zaidi, H; Slosman, D O

    2003-01-01

    Reliable attenuation correction represents an essential component of the long chain of modules required for the reconstruction of artifact-free, quantitative brain positron emission tomography (PET) images. In this work we demonstrate the proof of principle of segmented magnetic resonance imaging (MRI)-guided attenuation and scatter corrections in 3D brain PET. We have developed a method for attenuation correction based on registered T1-weighted MRI, eliminating the need of an additional transmission (TX) scan. The MR images were realigned to preliminary reconstructions of PET data using an automatic algorithm and then segmented by means of a fuzzy clustering technique which identifies tissues of significantly different density and composition. The voxels belonging to different regions were classified into air, skull, brain tissue and nasal sinuses. These voxels were then assigned theoretical tissue-dependent attenuation coefficients as reported in the ICRU 44 report followed by Gaussian smoothing and additio...

  4. Effect of attenuation by the cranium on quantitative SPECT measurements of cerebral blood flow and a correction method

    International Nuclear Information System (INIS)

    Iwase, Mikio; Kurono, Kenji; Iida, Akihiko.

    1998-01-01

    Attenuation correction for cerebral blood flow SPECT image reconstruction is usually performed by considering the head as a whole to be equivalent to water, and the effects of differences in attenuation between subjects produced by the cranium have not been taken into account. We determined the differences in attenuation between subjects and assessed a method of correcting quantitative cerebral blood flow values. Attenuations by head on the right and left sides were measured before intravenous injection of 123 I-IMP, and water-converted diameters of both sides (Ta) were calculated from the measurements obtained. After acquiring SPECT images, attenuation correction was conducted according to the method of Sorenson, and images were reconstructed. The diameters of the right and left sides in the same position as the Ta (Tt) were calculated from the contours determined by threshold values. Using Ts given by 2 Ts=Ta-Tt, the correction factor λ=exp(μ 1 Ts) was calculated and multiplied as the correction factor when rCBF was determined. The results revealed significant differences between Tt and Ta. Although no gender differences were observed in Tt, they were seen in both Ta and Ts. Thus, interindividual differences in attenuation by the cranium were found to have an influence that cannot be ignored. Inter-subject correlation is needed to obtain accurate quantitative values. (author)

  5. Bias atlases for segmentation-based PET attenuation correction using PET-CT and MR.

    Science.gov (United States)

    Ouyang, Jinsong; Chun, Se Young; Petibon, Yoann; Bonab, Ali A; Alpert, Nathaniel; Fakhri, Georges El

    2013-10-01

    This study was to obtain voxel-wise PET accuracy and precision using tissue-segmentation for attenuation correction. We applied multiple thresholds to the CTs of 23 patients to classify tissues. For six of the 23 patients, MR images were also acquired. The MR fat/in-phase ratio images were used for fat segmentation. Segmented tissue classes were used to create attenuation maps, which were used for attenuation correction in PET reconstruction. PET bias images were then computed using the PET reconstructed with the original CT as the reference. We registered the CTs for all the patients and transformed the corresponding bias images accordingly. We then obtained the mean and standard deviation bias atlas using all the registered bias images. Our CT-based study shows that four-class segmentation (air, lungs, fat, other tissues), which is available on most PET-MR scanners, yields 15.1%, 4.1%, 6.6%, and 12.9% RMSE bias in lungs, fat, non-fat soft-tissues, and bones, respectively. An accurate fat identification is achievable using fat/in-phase MR images. Furthermore, we have found that three-class segmentation (air, lungs, other tissues) yields less than 5% standard deviation of bias within the heart, liver, and kidneys. This implies that three-class segmentation can be sufficient to achieve small variation of bias for imaging these three organs. Finally, we have found that inter- and intra-patient lung density variations contribute almost equally to the overall standard deviation of bias within the lungs.

  6. Simultaneous correction of attenuation and geometric response in emission tomography applied to nuclear waste drums

    International Nuclear Information System (INIS)

    Thierry, Raphael

    1999-01-01

    Multi-photonic emission tomography is a non destructive technique applied to the control of radioactive waste drums. The emitted gamma rays are detected on the range [50 keV, 2 MeV] by a hyper pure germanium, of high resolution in energy, which enables to set up a detailed list of radionuclides contained within the drum. From different points of measurement located in a transaxial plane of the drum, the activity distribution is computed by a reconstruction algorithm. An algebraic modelling of the physical process has been developed in order to correct the different degrading phenomenon, in particular the attenuation and the detector geometric response. Attenuation through the materials constituting the barrel is the preponderant phenomena. Its ignorance prevents from accurate activity quantification. Its correction has been realised from an attenuation map obtained by a transmission tomograph. The detector geometric response, introducing a blurring within the detection, is compensated by an analytic model. An adequate modelling of those phenomenon is primordial: it highly contributes on a large scale the image quality and the quantification. The image reconstruction, requiring the resolution of sparse linear system, is realised by iterative algorithms. Due to the 'ill-posed' nature of tomographic reconstruction, it is necessary to use regularisation: by introducing an a priori information on the solution, the stabilisation of the methods is carried out. We chose to minimise the Maximum A Posteriori criterion. Its resolution is considered with a half-quadratic regularisation: it permits the preservation of natural discontinuities, and avoids global-over smoothing of the image. It is evaluated on real phantoms and waste drums. Efficient sampling of the data is considered. (author) [fr

  7. Clinical Evaluation of Zero-Echo-Time Attenuation Correction for Brain 18F-FDG PET/MRI: Comparison with Atlas Attenuation Correction.

    Science.gov (United States)

    Sekine, Tetsuro; Ter Voert, Edwin E G W; Warnock, Geoffrey; Buck, Alfred; Huellner, Martin; Veit-Haibach, Patrick; Delso, Gaspar

    2016-12-01

    Accurate attenuation correction (AC) on PET/MR is still challenging. The purpose of this study was to evaluate the clinical feasibility of AC based on fast zero-echo-time (ZTE) MRI by comparing it with the default atlas-based AC on a clinical PET/MR scanner. We recruited 10 patients with malignant diseases not located on the brain. In all patients, a clinically indicated whole-body 18 F-FDG PET/CT scan was acquired. In addition, a head PET/MR scan was obtained voluntarily. For each patient, 2 AC maps were generated from the MR images. One was atlas-AC, derived from T1-weighted liver acquisition with volume acceleration flex images (clinical standard). The other was ZTE-AC, derived from proton-density-weighted ZTE images by applying tissue segmentation and assigning continuous attenuation values to the bone. The AC map generated by PET/CT was used as a silver standard. On the basis of each AC map, PET images were reconstructed from identical raw data on the PET/MR scanner. All PET images were normalized to the SPM5 PET template. After that, these images were qualified visually and quantified in 67 volumes of interest (VOIs; automated anatomic labeling, atlas). Relative differences and absolute relative differences between PET images based on each AC were calculated. 18 F-FDG uptake in all 670 VOIs and generalized merged VOIs were compared using a paired t test. Qualitative analysis shows that ZTE-AC was robust to patient variability. Nevertheless, misclassification of air and bone in mastoid and nasal areas led to the overestimation of PET in the temporal lobe and cerebellum (%diff of ZTE-AC, 2.46% ± 1.19% and 3.31% ± 1.70%, respectively). The |%diff| of all 670 VOIs on ZTE was improved by approximately 25% compared with atlas-AC (ZTE-AC vs. atlas-AC, 1.77% ± 1.41% vs. 2.44% ± 1.63%, P PET in regions near the skull base. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

  8. Cell therapy attenuates cardiac dysfunction post myocardial infarction: effect of timing, routes of injection and a fibrin scaffold.

    Directory of Open Access Journals (Sweden)

    Juliana S Nakamuta

    Full Text Available BACKGROUND: Cell therapy approaches for biologic cardiac repair hold great promises, although basic fundamental issues remain poorly understood. In the present study we examined the effects of timing and routes of administration of bone marrow cells (BMC post-myocardial infarction (MI and the efficacy of an injectable biopolymer scaffold to improve cardiac cell retention and function. METHODOLOGY/PRINCIPAL FINDINGS: (99mTc-labeled BMC (6 x 10(6 cells were injected by 4 different routes in adult rats: intravenous (IV, left ventricular cavity (LV, left ventricular cavity with temporal aorta occlusion (LV(+ to mimic coronary injection, and intramyocardial (IM. The injections were performed 1, 2, 3, or 7 days post-MI and cell retention was estimated by gamma-emission counting of the organs excised 24 hs after cell injection. IM injection improved cell retention and attenuated cardiac dysfunction, whereas IV, LV or LV* routes were somewhat inefficient (<1%. Cardiac BMC retention was not influenced by timing except for the IM injection that showed greater cell retention at 7 (16% vs. 1, 2 or 3 (average of 7% days post-MI. Cardiac cell retention was further improved by an injectable fibrin scaffold at day 3 post-MI (17 vs. 7%, even though morphometric and function parameters evaluated 4 weeks later displayed similar improvements. CONCLUSIONS/SIGNIFICANCE: These results show that cells injected post-MI display comparable tissue distribution profile regardless of the route of injection and that there is no time effect for cardiac cell accumulation for injections performed 1 to 3 days post-MI. As expected the IM injection is the most efficient for cardiac cell retention, it can be further improved by co-injection with a fibrin scaffold and it significantly attenuates cardiac dysfunction evaluated 4 weeks post myocardial infarction. These pharmacokinetic data obtained under similar experimental conditions are essential for further development of these

  9. Cardiac MRI in mice at 9.4 Tesla with a transmit-receive surface coil and a cardiac-tailored intensity-correction algorithm.

    Science.gov (United States)

    Sosnovik, David E; Dai, Guangping; Nahrendorf, Matthias; Rosen, Bruce R; Seethamraju, Ravi

    2007-08-01

    To evaluate the use of a transmit-receive surface (TRS) coil and a cardiac-tailored intensity-correction algorithm for cardiac MRI in mice at 9.4 Tesla (9.4T). Fast low-angle shot (FLASH) cines, with and without delays alternating with nutations for tailored excitation (DANTE) tagging, were acquired in 13 mice. An intensity-correction algorithm was developed to compensate for the sensitivity profile of the surface coil, and was tailored to account for the unique distribution of noise and flow artifacts in cardiac MR images. Image quality was extremely high and allowed fine structures such as trabeculations, valve cusps, and coronary arteries to be clearly visualized. The tag lines created with the surface coil were also sharp and clearly visible. Application of the intensity-correction algorithm improved signal intensity, tissue contrast, and image quality even further. Importantly, the cardiac-tailored properties of the correction algorithm prevented noise and flow artifacts from being significantly amplified. The feasibility and value of cardiac MRI in mice with a TRS coil has been demonstrated. In addition, a cardiac-tailored intensity-correction algorithm has been developed and shown to improve image quality even further. The use of these techniques could produce significant potential benefits over a broad range of scanners, coil configurations, and field strengths. (c) 2007 Wiley-Liss, Inc.

  10. SPECT quantification: a review of the different correction methods with compton scatter, attenuation and spatial deterioration effects

    International Nuclear Information System (INIS)

    Groiselle, C.; Rocchisani, J.M.; Moretti, J.L.; Dreuille, O. de; Gaillard, J.F.; Bendriem, B.

    1997-01-01

    SPECT quantification: a review of the different correction methods with Compton scatter attenuation and spatial deterioration effects. The improvement of gamma-cameras, acquisition and reconstruction software opens new perspectives in term of image quantification in nuclear medicine. In order to meet the challenge, numerous works have been undertaken in recent years to correct for the different physical phenomena that prevent an exact estimation of the radioactivity distribution. The main phenomena that have to betaken into account are scatter, attenuation and resolution. In this work, authors present the physical basis of each issue, its consequences on quantification and the main methods proposed to correct them. (authors)

  11. Attenuation correction for renal scintigraphy with 99mTc - DMSA: comparison between Raynaud and the geometric mean methods

    International Nuclear Information System (INIS)

    Argenta, J.; Brambilla, C.R.; Marques da Silva, A.M.

    2009-01-01

    The evaluation of the index of renal function (IF) requires soft-tissue attenuation correction. This paper investigates the impact over the IF, when attenuation correction is applied using the Raynaud method and the geometric mean method in renal planar scintigraphy, using posterior and anterior views. The study was conducted with Monte Carlo simulated images of five GSF family voxel phantoms with different relative uptakes in each kidney from normal (50% -50%) to pathological (10% -90%). The results showed that Raynaud method corrects more efficiently the cases where the renal depth is close to the value of the standard phantom. The geometric mean method showed similar results to the Raynaud method for Baby, Child and Golem. For Helga and Donna models, the errors were above 20%, increasing with relative uptake. Further studies should be conducted to assess the influences of the standard phantom in the correcting attenuation methods. (author)

  12. Attenuation correction for renal scintigraphy with 99mTc-DMSA: analysis between Raynaud and the geometric mean methods

    International Nuclear Information System (INIS)

    Argenta, Jackson; Brambilla, Claudia R.; Silva, Ana Maria M. da

    2010-01-01

    The evaluation of the index of renal function (IF) requires soft-tissue attenuation correction. This paper investigates the impact over the IF, when attenuation correction is applied using the Raynaud method and the Geometric Mean method in renal planar scintigraphy, using posterior and anterior views. The study was conducted with Monte Carlo simulated images of five GSF family voxel phantoms with different relative uptakes in each kidney from normal (50% -50%) to pathological (10% -90%). The results showed that Raynaud method corrects more efficiently the cases where the renal depth is close to the value of the standard phantom. The geometric mean method showed similar results to the Raynaud method for Baby, Child and Golem. For Helga and Donna models, the errors were above 20%, increasing with relative uptake. Further studies should be conducted to assess the influences of the standard phantom in the correcting attenuation methods. (author)

  13. Nutritional leucine supplementation attenuates cardiac failure in tumour-bearing cachectic animals.

    Science.gov (United States)

    Toneto, Aline Tatiane; Ferreira Ramos, Luiz Alberto; Salomão, Emilianne Miguel; Tomasin, Rebeka; Aereas, Miguel Arcanjo; Gomes-Marcondes, Maria Cristina Cintra

    2016-12-01

    The condition known as cachexia presents in most patients with malignant tumours, leading to a poor quality of life and premature death. Although the cancer-cachexia state primarily affects skeletal muscle, possible damage in the cardiac muscle remains to be better characterized and elucidated. Leucine, which is a branched chain amino acid, is very useful for preserving lean body mass. Thus, this amino acid has been studied as a coadjuvant therapy in cachectic cancer patients, but whether this treatment attenuates the effects of cachexia and improves cardiac function remains poorly understood. Therefore, using an experimental cancer-cachexia model, we evaluated whether leucine supplementation ameliorates cachexia in the heart. Male Wistar rats were fed either a leucine-rich or a normoprotein diet and implanted or not with subcutaneous Walker-256 carcinoma. During the cachectic stage (approximately 21 days after tumour implantation), when the tumour mass was greater than 10% of body weight, the rats were subjected to an electrocardiogram analysis to evaluate the heart rate, QT-c, and T wave amplitude. The myocardial tissues were assayed for proteolytic enzymes (chymotrypsin, alkaline phosphatase, cathepsin, and calpain), cardiomyopathy biomarkers (myeloperoxidase, tissue inhibitor of metalloproteinases, and total plasminogen activator inhibitor 1), and caspase-8, -9, -3, and -7 activity. Both groups of tumour-bearing rats, especially the untreated group, had electrocardiography alterations that were suggestive of ischemia, dilated cardiomyopathy, and sudden death risk. Additionally, the rats in the untreated tumour-bearing group but not their leucine-supplemented littermates exhibited remarkable increases in chymotrypsin activity and all three heart failure biomarkers analysed, including an increase in caspase-3 and -7 activity. Our data suggest that a leucine-rich diet could modulate heart damage, cardiomyocyte proteolysis, and apoptosis driven by cancer

  14. Secoisolariciresinol diglucoside attenuates cardiac hypertrophy and oxidative stress in monocrotaline-induced right heart dysfunction.

    Science.gov (United States)

    Puukila, Stephanie; Fernandes, Rafael Oliveira; Türck, Patrick; Carraro, Cristina Campos; Bonetto, Jéssica Hellen Poletto; de Lima-Seolin, Bruna Gazzi; da Rosa Araujo, Alex Sander; Belló-Klein, Adriane; Boreham, Douglas; Khaper, Neelam

    2017-08-01

    Pulmonary arterial hypertension (PAH) occurs when remodeling of pulmonary vessels leads to increased pulmonary vascular resistance resulting in increased pulmonary arterial pressure. Increased pulmonary arterial pressure results in right ventricle hypertrophy and eventually heart failure. Oxidative stress has been implicated in the pathogenesis of PAH and may play a role in the regulation of cellular signaling involved in cardiac response to pressure overload. Secoisolariciresinol diglucoside (SDG), a component from flaxseed, has been shown to reduce cardiac oxidative stress in various pathophysiological conditions. We investigated the potential protective effects of SDG in a monocrotaline-induced model of PAH. Five- to six-week-old male Wistar rats were given a single intraperitoneal injection of monocrotaline (60 mg/kg) and sacrificed 21 days later where heart, lung, and plasma were collected. SDG (25 mg/kg) was given via gavage as either a 21-day co-treatment or pre-treatment of 14 days before monocrotaline administration and continued for 21 days. Monocrotaline led to right ventricle hypertrophy, increased lipid peroxidation, and elevated plasma levels of alanine transaminase (ALT) and aspartate transaminase (AST). Co-treatment with SDG did not attenuate hypertrophy or ALT and AST levels but decreased reactive oxygen species (ROS) levels and catalase and superoxide dismutase activity compared to the monocrotaline-treated group. Pre-treatment with SDG decreased right ventricle hypertrophy, ROS levels, lipid peroxidation, catalase, superoxide dismutase, and glutathione peroxidase activity and plasma levels of ALT and AST when compared to the monocrotaline group. These findings indicate that pre-treatment with SDG provided better protection than co-treatment in this model of right heart dysfunction, suggesting an important role for SDG in PAH and right ventricular remodeling.

  15. Evaluation of various energy windows at different radionuclides for scatter and attenuation correction in nuclear medicine.

    Science.gov (United States)

    Asgari, Afrouz; Ashoor, Mansour; Sohrabpour, Mostafa; Shokrani, Parvaneh; Rezaei, Ali

    2015-05-01

    Improving signal to noise ratio (SNR) and qualified images by the various methods is very important for detecting the abnormalities at the body organs. Scatter and attenuation of photons by the organs lead to errors in radiopharmaceutical estimation as well as degradation of images. The choice of suitable energy window and the radionuclide have a key role in nuclear medicine which appearing the lowest scatter fraction as well as having a nearly constant linear attenuation coefficient as a function of phantom thickness. The energy windows of symmetrical window (SW), asymmetric window (ASW), high window (WH) and low window (WL) using Tc-99m and Sm-153 radionuclide with solid water slab phantom (RW3) and Teflon bone phantoms have been compared, and Matlab software and Monte Carlo N-Particle (MCNP4C) code were modified to simulate these methods and obtaining the amounts of FWHM and full width at tenth maximum (FWTM) using line spread functions (LSFs). The experimental data were obtained from the Orbiter Scintron gamma camera. Based on the results of the simulation as well as experimental work, the performance of WH and ASW display of the results, lowest scatter fraction as well as constant linear attenuation coefficient as a function of phantom thickness. WH and ASW were optimal windows in nuclear medicine imaging for Tc-99m in RW3 phantom and Sm-153 in Teflon bone phantom. Attenuation correction was done for WH and ASW optimal windows and for these radionuclides using filtered back projection algorithm. Results of simulation and experimental show that very good agreement between the set of experimental with simulation as well as theoretical values with simulation data were obtained which was nominally less than 7.07 % for Tc-99m and less than 8.00 % for Sm-153. Corrected counts were not affected by the thickness of scattering material. The Simulated results of Line Spread Function (LSF) for Sm-153 and Tc-99m in phantom based on four windows and TEW method were

  16. Low Intensity Physical Exercise Attenuates Cardiac Remodeling and Myocardial Oxidative Stress and Dysfunction in Diabetic Rats

    Directory of Open Access Journals (Sweden)

    C. Gimenes

    2015-01-01

    Full Text Available We evaluated the effects of a low intensity aerobic exercise protocol on cardiac remodeling and myocardial function in diabetic rats. Wistar rats were assigned into four groups: sedentary control (C-Sed, exercised control (C-Ex, sedentary diabetes (DM-Sed, and exercised diabetes (DM-Ex. Diabetes was induced by intraperitoneal injection of streptozotocin. Rats exercised for 9 weeks in treadmill at 11 m/min, 18 min/day. Myocardial function was evaluated in left ventricular (LV papillary muscles and oxidative stress in LV tissue. Statistical analysis was given by ANOVA or Kruskal-Wallis. Echocardiogram showed diabetic groups with higher LV diastolic diameter-to-body weight ratio and lower posterior wall shortening velocity than controls. Left atrium diameter was lower in DM-Ex than DM-Sed (C-Sed: 5.73±0.49; C-Ex: 5.67±0.53; DM-Sed: 6.41±0.54; DM-Ex: 5.81±0.50 mm; P<0.05 DM-Sed vs C-Sed and DM-Ex. Papillary muscle function was depressed in DM-Sed compared to C-Sed. Exercise attenuated this change in DM-Ex. Lipid hydroperoxide concentration was higher in DM-Sed than C-Sed and DM-Ex. Catalase and superoxide dismutase activities were lower in diabetics than controls and higher in DM-Ex than DM-Sed. Glutathione peroxidase activity was lower in DM-Sed than C-Sed and DM-Ex. Conclusion. Low intensity exercise attenuates left atrium dilation and myocardial oxidative stress and dysfunction in type 1 diabetic rats.

  17. Influence of attenuation correction and reconstruction techniques on the detection of hypoperfused lesions in brain SPECT studies

    International Nuclear Information System (INIS)

    Ghoorun, S.; Groenewald, W.A.; Baete, K.; Nuyts, J.; Dupont, P.

    2004-01-01

    Full text: Aim: To study the influence of attenuation correction and the reconstruction technique on the detection of hypoperfused lesions in brain SPECT imaging, Material and Methods: A simulation experiment was used in which the effects of attenuation and reconstruction were decoupled, A high resolution SPECT phantom was constructed using the BrainWeb database, In this phantom, activity values were assigned to grey and white matter (ratio 4:1) and scaled to obtain counts of the same magnitude as in clinical practice, The true attenuation map was generated by assigning attenuation coefficients to each tissue class (grey and white matter, cerebral spinal fluid, skull, soft and fatty tissue and air) to create a non-uniform attenuation map, The uniform attenuation map was calculated using an attenuation coefficient of 0.15 cm-1, Hypoperfused lesions of varying intensities and sizes were added. The phantom was then projected as typical SPECT projection data, taking into account attenuation and collimator blurring with the addition of Poisson noise, The projection data was reconstructed using four different methods of reconstruction: (1) filtered backprojection (FBP) with the uniform attenuation map; (2) FBP using the true attenuation map; (3) ordered subset expectation maximization (OSEM) (equivalent to 423 iterations) with a uniform attenuation map; and (4) OSEM with a true attenuation map. Different Gaussian postsmooth kernels were applied to the reconstructed images. Results: The analysis of the reconstructed data was performed using figures of merit such as signal to noise ratio (SNR), bias and variance. The results illustrated that uniform attenuation correction offered slight deterioration (less than 2%) with regard to SNR when compared to the ideal attenuation map. which in reality is not known. The iterative techniques produced superior signal to noise ratios (increase of 5 - 20 % depending on the lesion and the postsmooth) in comparison to the FBP methods

  18. Valsartan attenuates cardiac and renal hypertrophy in rats with experimental cardiorenal syndrome possibly through down-regulating galectin-3 signaling.

    Science.gov (United States)

    Zhang, M-J; Gu, Y; Wang, H; Zhu, P-F; Liu, X-Y; Wu, J

    2016-01-01

    Aortocaval fistula (AV) induced chronic volume overload in rats with preexisting mild renal dysfunction (right kidney remove: UNX) could mimic the type 4 cardiorenal syndrome (CRS): chronic renocardiac syndrome. Galectin-3, a β-galactoside binding lectin, is an emerging biomarker in cardiovascular as well as renal diseases. We observed the impact of valsartan on cardiac and renal hypertrophy and galectin-3 changes in this model. Adult male Sprague-Dawley (SD) rats (200-250 g) were divided into S (Sham, n = 7), M (UNX+AV, n = 7) and M+V (UNX+AV+valsartan, n = 7) groups. Eight weeks later, cardiac function was measured by echocardiography. Renal outcome was measured by glomerular filtration rate, effective renal plasma flow, renal blood flow and 24 hours albuminuria. Immunohistochemistry and real-time PCR were used to evaluate the expressions of galectin-3 in heart and renal. Cardiac hypertrophy and renal hypertrophy as well as cardiac enlargement were evidenced in this AV shunt induced chronic volume overload rat model with preexisting mild renal dysfunction. Cardiac and renal hypertrophy were significantly attenuated but cardiac enlargement was unaffected by valsartan independent of its blood pressure lowering effect. 24 hours urine albumin was significantly increased, which was significantly reduced by valsartan in this model. Immunohistochemistry and real-time PCR evidenced significantly up-regulated galectin-3 expression in heart and kidney and borderline increased myocardial collagen I expression, which tended to be lower post valsartan treatment. Up-regulated galectin-3 signaling might also be involved in the pathogenesis in this CRS model. The beneficial effects of valsartan in terms of attenuating cardiac and renal hypertrophy and reducing 24 hours albumin in this model might partly be mediated through down-regulating galectin-3 signal pathway.

  19. Cardiac expression of microsomal triglyceride transfer protein is increased in obesity and serves to attenuate cardiac triglyceride accumulation

    DEFF Research Database (Denmark)

    Bartels, Emil D; Nielsen, Jan M; Hellgren, Lars I

    2009-01-01

    Obesity causes lipid accumulation in the heart and may lead to lipotoxic heart disease. Traditionally, the size of the cardiac triglyceride pool is thought to reflect the balance between uptake and beta-oxidation of fatty acids. However, triglycerides can also be exported from cardiomyocytes via...... secretion of apolipoproteinB-containing (apoB) lipoproteins. Lipoprotein formation depends on expression of microsomal triglyceride transfer protein (MTP); the mouse expresses two isoforms of MTP, A and B. Since many aspects of the link between obesity-induced cardiac disease and cardiac lipid metabolism...... remain unknown, we investigated how cardiac lipoprotein synthesis affects cardiac expression of triglyceride metabolism-controlling genes, insulin sensitivity, and function in obese mice. Heart-specific ablation of MTP-A in mice using Cre-loxP technology impaired upregulation of MTP expression...

  20. Respiration-averaged CT for attenuation correction in non-small-cell lung cancer

    International Nuclear Information System (INIS)

    Cheng, Nai-Ming; Ho, Kung-Chu; Yen, Tzu-Chen; Yu, Chih-Teng; Wu, Yi-Cheng; Liu, Yuan-Chang; Wang, Chih-Wei

    2009-01-01

    Breathing causes artefacts on PET/CT images. Cine CT has been used to reduce respiratory artefacts by acquiring multiple images during a single breathing cycle. The aim of this prospective study in non-small-cell lung cancer (NSCLC) patients was twofold. Firstly, we sought to compare the motion artefacts in PET/CT images attenuation-corrected with helical CT (HCT) and with averaged CT (ACT), which provides an average of cine CT images. Secondly, we wanted to evaluate the differences in maximum standardized uptake values (SUV max ) between HCT and ACT. Enrolled in the study were 80 patients with NSCLC. PET images attenuation-corrected with HCT (PET/HCT) and with ACT (PET/ACT) were obtained in all patients. Misregistration was evaluated by measurement of the curved photopenic area in the lower thorax of the PET images for all patients and direct measurement of misregistration for selected lesions. SUV max was measured separately at the primary tumours, regional lymph nodes, and background. A total of 80 patients with NSCLC were included. Significantly lower misregistrations were observed in PET/ACT images than in PET/HCT images (below-thoracic misregistration 0.25±0.58 cm vs. 1.17±1.17 cm, p max were noted in PET/ACT images than in PET/HCT images in the primary tumour (p max in PET/ACT images was higher by 0.35 for the main tumours and 0.34 for lymph nodes. Due to its significantly reduced misregistration, PET/ACT provided more reliable SUV max and may be useful in treatment planning and monitoring the therapeutic response in patients with NSCLC. (orig.)

  1. Andrographolide Attenuates LPS-Induced Cardiac Malfunctions Through Inhibition of IκB Phosphorylation and Apoptosis in Mice

    Directory of Open Access Journals (Sweden)

    Jinlong Zhang

    2015-11-01

    Full Text Available Background/Aims: Cardiac malfunction is a common complication in sepsis and significantly increases the mortality of patients in septic shock. However, no studies have examined whether andrographolide (And reduces LPS-induced myocardial malfunction. Methods: Left ventricular systolic and diastolic functions were examined using echocardiography. TNF-a and IL-1ß protein levels were detected by an enzyme-linked immunosorbent assay (ELISA. NO oxidation products were determined using Griess reagent. Protein expression levels of inhibitors of NF-κBa (IκB and phospho-IκB were determined via Western blot. Oxidative injury was determined by measuring myocardial lipid peroxidation and superoxide dismutase activity. Cardiac apoptosis was examined by terminal deoxynucleotidyl transferase-mediated dUTP nickend-labeling (TUNEL and cardiac caspase 3/7 activity. Results: And blunted LPS-induced myocardial malfunctions in mice. LPS induced TNF-a, IL-1ß, and NO production as well as I-κB phosphorylation. Cardiac apoptosis was attenuated via incubation with And, but the extent of oxidative injury remained unaffected. Conclusion: And prevents LPS-induced cardiac malfunctions in mice by inhibiting TNF-a, IL-1ß, and NO production, IκB phosphorylation, and cardiac apoptosis, indicating that And may be a potential agent for preventing myocardial malfunction during sepsis.

  2. Design of respiration averaged CT for attenuation correction of the PET data from PET/CT

    International Nuclear Information System (INIS)

    Chi, Pai-Chun Melinda; Mawlawi, Osama; Nehmeh, Sadek A.; Erdi, Yusuf E.; Balter, Peter A.; Luo, Dershan; Mohan, Radhe; Pan Tinsu

    2007-01-01

    Our previous patient studies have shown that the use of respiration averaged computed tomography (ACT) for attenuation correction of the positron emission tomography (PET) data from PET/CT reduces the potential misalignment in the thorax region by matching the temporal resolution of the CT to that of the PET. In the present work, we investigated other approaches of acquiring ACT in order to reduce the CT dose and to improve the ease of clinical implementation. Four-dimensional CT (4DCT) data sets for ten patients (17 lung/esophageal tumors) were acquired in the thoracic region immediately after the routine PET/CT scan. For each patient, multiple sets of ACTs were generated based on both phase image averaging (phase approach) and fixed cine duration image averaging (cine approach). In the phase approach, the ACTs were calculated from CT images corresponding to the significant phases of the respiratory cycle: ACT 050phs from end-inspiration (0%) and end-expiration (50%), ACT 2070phs from mid-inspiration (20%) and mid-expiration (70%), ACT 4phs from 0%, 20%, 50% and 70%, and ACT 10phs from all ten phases, which was the original approach. In the cine approach, which does not require 4DCT, the ACTs were calculated based on the cine images from cine durations of 1 to 6 s at 1 s increments. PET emission data for each patient were attenuation corrected with each of the above mentioned ACTs and the tumor maximum standard uptake value (SUV max ), average SUV (SUV avg ), and tumor volume measurements were compared. Percent differences were calculated between PET data corrected with various ACTs and that corrected with ACT 10phs . In the phase approach, the ACT 10phs can be approximated by the ACT 4phs to within a mean percent difference of 2% in SUV and tumor volume measurements. In cine approach, ACT 10phs can be approximated to within a mean percent difference of 3% by ACTs computed from cine durations ≥3 s. Acquiring CT images only at the four significant phases for the

  3. MR/PET quantification tools: Registration, segmentation, classification, and MR-based attenuation correction

    Science.gov (United States)

    Fei, Baowei; Yang, Xiaofeng; Nye, Jonathon A.; Aarsvold, John N.; Raghunath, Nivedita; Cervo, Morgan; Stark, Rebecca; Meltzer, Carolyn C.; Votaw, John R.

    2012-01-01

    Purpose: Combined MR/PET is a relatively new, hybrid imaging modality. A human MR/PET prototype system consisting of a Siemens 3T Trio MR and brain PET insert was installed and tested at our institution. Its present design does not offer measured attenuation correction (AC) using traditional transmission imaging. This study is the development of quantification tools including MR-based AC for quantification in combined MR/PET for brain imaging. Methods: The developed quantification tools include image registration, segmentation, classification, and MR-based AC. These components were integrated into a single scheme for processing MR/PET data. The segmentation method is multiscale and based on the Radon transform of brain MR images. It was developed to segment the skull on T1-weighted MR images. A modified fuzzy C-means classification scheme was developed to classify brain tissue into gray matter, white matter, and cerebrospinal fluid. Classified tissue is assigned an attenuation coefficient so that AC factors can be generated. PET emission data are then reconstructed using a three-dimensional ordered sets expectation maximization method with the MR-based AC map. Ten subjects had separate MR and PET scans. The PET with [11C]PIB was acquired using a high-resolution research tomography (HRRT) PET. MR-based AC was compared with transmission (TX)-based AC on the HRRT. Seventeen volumes of interest were drawn manually on each subject image to compare the PET activities between the MR-based and TX-based AC methods. Results: For skull segmentation, the overlap ratio between our segmented results and the ground truth is 85.2 ± 2.6%. Attenuation correction results from the ten subjects show that the difference between the MR and TX-based methods was <6.5%. Conclusions: MR-based AC compared favorably with conventional transmission-based AC. Quantitative tools including registration, segmentation, classification, and MR-based AC have been developed for use in combined MR

  4. MR/PET quantification tools: Registration, segmentation, classification, and MR-based attenuation correction

    Energy Technology Data Exchange (ETDEWEB)

    Fei, Baowei, E-mail: bfei@emory.edu [Department of Radiology and Imaging Sciences, Emory University School of Medicine, 1841 Clifton Road Northeast, Atlanta, Georgia 30329 (United States); Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, Georgia 30322 (United States); Department of Mathematics and Computer Sciences, Emory University, Atlanta, Georgia 30322 (United States); Yang, Xiaofeng; Nye, Jonathon A.; Raghunath, Nivedita; Votaw, John R. [Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia 30329 (United States); Aarsvold, John N. [Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia 30329 (United States); Nuclear Medicine Service, Atlanta Veterans Affairs Medical Center, Atlanta, Georgia 30033 (United States); Cervo, Morgan; Stark, Rebecca [The Medical Physics Graduate Program in the George W. Woodruff School, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Meltzer, Carolyn C. [Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia 30329 (United States); Department of Neurology and Department of Psychiatry and Behavior Sciences, Emory University School of Medicine, Atlanta, Georgia 30322 (United States)

    2012-10-15

    Purpose: Combined MR/PET is a relatively new, hybrid imaging modality. A human MR/PET prototype system consisting of a Siemens 3T Trio MR and brain PET insert was installed and tested at our institution. Its present design does not offer measured attenuation correction (AC) using traditional transmission imaging. This study is the development of quantification tools including MR-based AC for quantification in combined MR/PET for brain imaging. Methods: The developed quantification tools include image registration, segmentation, classification, and MR-based AC. These components were integrated into a single scheme for processing MR/PET data. The segmentation method is multiscale and based on the Radon transform of brain MR images. It was developed to segment the skull on T1-weighted MR images. A modified fuzzy C-means classification scheme was developed to classify brain tissue into gray matter, white matter, and cerebrospinal fluid. Classified tissue is assigned an attenuation coefficient so that AC factors can be generated. PET emission data are then reconstructed using a three-dimensional ordered sets expectation maximization method with the MR-based AC map. Ten subjects had separate MR and PET scans. The PET with [{sup 11}C]PIB was acquired using a high-resolution research tomography (HRRT) PET. MR-based AC was compared with transmission (TX)-based AC on the HRRT. Seventeen volumes of interest were drawn manually on each subject image to compare the PET activities between the MR-based and TX-based AC methods. Results: For skull segmentation, the overlap ratio between our segmented results and the ground truth is 85.2 ± 2.6%. Attenuation correction results from the ten subjects show that the difference between the MR and TX-based methods was <6.5%. Conclusions: MR-based AC compared favorably with conventional transmission-based AC. Quantitative tools including registration, segmentation, classification, and MR-based AC have been developed for use in combined MR/PET.

  5. MR/PET quantification tools: Registration, segmentation, classification, and MR-based attenuation correction

    International Nuclear Information System (INIS)

    Fei, Baowei; Yang, Xiaofeng; Nye, Jonathon A.; Raghunath, Nivedita; Votaw, John R.; Aarsvold, John N.; Cervo, Morgan; Stark, Rebecca; Meltzer, Carolyn C.

    2012-01-01

    Purpose: Combined MR/PET is a relatively new, hybrid imaging modality. A human MR/PET prototype system consisting of a Siemens 3T Trio MR and brain PET insert was installed and tested at our institution. Its present design does not offer measured attenuation correction (AC) using traditional transmission imaging. This study is the development of quantification tools including MR-based AC for quantification in combined MR/PET for brain imaging. Methods: The developed quantification tools include image registration, segmentation, classification, and MR-based AC. These components were integrated into a single scheme for processing MR/PET data. The segmentation method is multiscale and based on the Radon transform of brain MR images. It was developed to segment the skull on T1-weighted MR images. A modified fuzzy C-means classification scheme was developed to classify brain tissue into gray matter, white matter, and cerebrospinal fluid. Classified tissue is assigned an attenuation coefficient so that AC factors can be generated. PET emission data are then reconstructed using a three-dimensional ordered sets expectation maximization method with the MR-based AC map. Ten subjects had separate MR and PET scans. The PET with ["1"1C]PIB was acquired using a high-resolution research tomography (HRRT) PET. MR-based AC was compared with transmission (TX)-based AC on the HRRT. Seventeen volumes of interest were drawn manually on each subject image to compare the PET activities between the MR-based and TX-based AC methods. Results: For skull segmentation, the overlap ratio between our segmented results and the ground truth is 85.2 ± 2.6%. Attenuation correction results from the ten subjects show that the difference between the MR and TX-based methods was <6.5%. Conclusions: MR-based AC compared favorably with conventional transmission-based AC. Quantitative tools including registration, segmentation, classification, and MR-based AC have been developed for use in combined MR/PET.

  6. Whole-body bone segmentation from MRI for PET/MRI attenuation correction using shape-based averaging

    DEFF Research Database (Denmark)

    Arabi, Hossein; Zaidi, H.

    2016-01-01

    Purpose: The authors evaluate the performance of shape-based averaging (SBA) technique for whole-body bone segmentation from MRI in the context of MRI-guided attenuation correction (MRAC) in hybrid PET/MRI. To enhance the performance of the SBA scheme, the authors propose to combine it with stati......Purpose: The authors evaluate the performance of shape-based averaging (SBA) technique for whole-body bone segmentation from MRI in the context of MRI-guided attenuation correction (MRAC) in hybrid PET/MRI. To enhance the performance of the SBA scheme, the authors propose to combine...... it with statistical atlas fusion techniques. Moreover, a fast and efficient shape comparisonbased atlas selection scheme was developed and incorporated into the SBA method. Methods: Clinical studies consisting of PET/CT and MR images of 21 patients were used to assess the performance of the SBA method. In addition...... voting (MV) atlas fusion scheme was also evaluated as a conventional and commonly used method. MRI-guided attenuation maps were generated using the different segmentation methods. Thereafter, quantitative analysis of PET attenuation correction was performed using CT-based attenuation correction...

  7. Use of calibration standards and the correction for sample self-attenuation in gamma-ray nondestructive assay

    International Nuclear Information System (INIS)

    Parker, J.L.

    1984-08-01

    The efficient use of appropriate calibration standards and the correction for the attenuation of the gamma rays within an assay sample by the sample itself are two important and closely related subjects in gamma-ray nondestructive assay. Much research relating to those subjects has been done in the Nuclear Safeguards Research and Development program at the Los Alamos National Laboratory since 1970. This report brings together most of the significant results of that research. Also discussed are the nature of appropriate calibration standards and the necessary conditions on the composition, size, and shape of the samples to allow accurate assays. Procedures for determining the correction for the sample self-attenuation are described at length including both general principles and several specific useful cases. The most useful concept is that knowing the linear attenuation coefficient of the sample (which can usually be determined) and the size and shape of the sample and its position relative to the detector permits the computation of the correction factor for the self-attenuation. A major objective of the report is to explain how the procedures for determining the self-attenuation correction factor can be applied so that calibration standards can be entirely appropriate without being particularly similar, either physically or chemically, to the items to be assayed. This permits minimization of the number of standards required to assay items with a wide range of size, shape, and chemical composition. 17 references, 18 figures, 2 tables

  8. The use of calibration standards and the correction for sample self-attenuation in gamma-ray nondestructive assay

    International Nuclear Information System (INIS)

    Parker, J.L.

    1986-11-01

    The efficient use of appropriate calibration standards and the correction for the attenuation of the gamma rays within an assay sample by the sample itself are two important and closely related subjects in gamma-ray nondestructive assay. Much research relating to those subjects has been done in the Nuclear Safeguards Research and Development program at the Los Alamos National Laboratory since 1970. This report brings together most of the significant results of that research. Also discussed are the nature of appropriate calibration standards and the necessary conditions on the composition, size, and shape of the samples to allow accurate assays. Procedures for determining the correction for the sample self-attenuation are described at length including both general principles and several specific useful cases. The most useful concept is that knowing the linear attenuation coefficient of the sample (which can usually be determined) and the size and shape of the sample and its position relative to the detector permits the computation of the correction factor for the self-attenuation. A major objective of the report is to explain how the procedures for determining the self-attenuation correction factor can be applied so that calibration standards can be entirely appropriate without being particularly similar, either physically or chemically, to the items to be assayed. This permits minimization of the number of standards required to assay items with a wide range of size, shape, and chemical composition

  9. Atmospheric Attenuation Correction Based on a Constant Reference for High-Precision Infrared Radiometry

    Directory of Open Access Journals (Sweden)

    Zhiguo Huang

    2017-11-01

    Full Text Available Infrared (IR radiometry technology is an important method for characterizing the IR signature of targets, such as aircrafts or rockets. However, the received signal of targets could be reduced by a combination of atmospheric molecule absorption and aerosol scattering. Therefore, atmospheric correction is a requisite step for obtaining the real radiance of targets. Conventionally, the atmospheric transmittance and the air path radiance are calculated by an atmospheric radiative transfer calculation software. In this paper, an improved IR radiometric method based on constant reference correction of atmospheric attenuation is proposed. The basic principle and procedure of this method are introduced, and then the linear model of high-speed calibration in consideration of the integration time is employed and confirmed, which is then applicable in various complex conditions. To eliminate stochastic errors, radiometric experiments were conducted for multiple integration times. Finally, several experiments were performed on a mid-wave IR system with Φ600 mm aperture. The radiometry results indicate that the radiation inversion precision of the novel method is 4.78–4.89%, while the precision of the conventional method is 10.86–13.81%.

  10. Kinin B1 receptor blockade and ACE inhibition attenuate cardiac postinfarction remodeling and heart failure in rats

    International Nuclear Information System (INIS)

    Lin, Xinchun; Bernloehr, Christian; Hildebrandt, Tobias; Stadler, Florian J.; Doods, Henri; Wu, Dongmei

    2016-01-01

    Introduction: The aim of the present study was to evaluate the effects of the novel kinin B1 receptor antagonist BI113823 on postinfarction cardiac remodeling and heart failure, and to determine whether B1 receptor blockade alters the cardiovascular effects of an angiotensin 1 converting enzyme (ACE) inhibitor in rats. Methods and results: Sprague Dawley rats were subjected to permanent occlusion of the left coronary artery. Cardiovascular function was determined at 6 weeks postinfarction. Treatment with either B1 receptor antagonist (BI113823) or an ACE inhibitor (lisinopril) alone or in combination significantly reduced the heart weight-to-body weight and lung weight-to-body weight ratios, and improved postinfarction cardiac function as evidenced by greater cardiac output, the maximum rate of left ventricular pressure rise (± dP/dtmax), left ventricle ejection fraction, fractional shorting, better wall motion, and attenuation of elevated left ventricular end diastolic pressure (LVEDP). Furthermore, all three treatment groups exhibited significant reduction in cardiac interstitial fibrosis, collagen deposition, CD68 positive macrophages, neutrophils, and proinflammatory cytokine production (TNF-α and IL-1β), compared to vehicle controls. Conclusion: The present study shows that treatment with the novel kinin B1 receptor antagonist, BI113823, reduces postinfarction cardiac remodeling and heart failure, and does not influence the cardiovascular effects of the ACE inhibitor. - Highlights: • We examined the role of kinin B1 receptors in the development of heart failure. • Kinin B1 receptor blockade attenuates post-infarction cardiac remodeling. • Kinin B1 receptor blockade improves dysfunction, and prevented heart failure. • B1 receptor blockade does not affect the cardio-protection of an ACE inhibitor.

  11. Ultrasound-targeted microbubble destruction enhances delayed BMC delivery and attenuates post-infarction cardiac remodelling by inducing engraftment signals.

    Science.gov (United States)

    Chen, Yanmei; Zhang, Chuanxi; Shen, Shuxin; Guo, Shengcun; Zhong, Lintao; Li, Xinzhong; Chen, Guojun; Chen, Gangbin; He, Xiang; Huang, Chixiong; He, Nvqin; Liao, Wangjun; Liao, Yulin; Bin, Jianping

    2016-12-01

    Delayed administration of bone marrow cells (BMCs) at 2-4 weeks after successful reperfusion in patients with acute myocardial infarction (MI) does not improve cardiac function. The reduction in engraftment signals observed following this time interval might impair the effects of delayed BMC treatment. In the present study, we aimed to determine whether ultrasound-targeted microbubble destruction (UTMD) treatment could increase engraftment signals, enhance the delivery of delayed BMCs and subsequently attenuate post-infarction cardiac remodelling. A myocardial ischaemia/reperfusion (I/R) model was induced in Wistar rats via left coronary ligation for 45 min followed by reperfusion. Western blotting revealed that engraftment signals peaked at 7 days post-I/R and were dramatically lower at 14 days post-I/R. The lower engraftment signals at 14 days post-I/R could be triggered by UTMD treatment at a mechanical index of 1.0-1.9. The troponin I levels in the 1.9 mechanical index group were higher than in the other groups. Simultaneous haematoxylin and eosin staining and fluorescence revealed that the number of engrafted BMCs in the ischaemic zone was greater in the group treated with both UTMD and delayed BMC transplantation than in the control groups (PBMC transplantation improved cardiac function and decreased cardiac fibrosis at 4 weeks after treatment, as compared with control groups (both PBMC transplantation increased capillary density, myocardial cell proliferation and c-kit + cell proliferation. These findings indicated that UTMD treatment could induce engraftment signals and enhance homing of delayed BMCs to ischaemic myocardium, attenuating post-infarction cardiac remodelling by promoting neovascularization, cardiomyogenesis and expansion of cardiac c-kit + cells. © 2016 The Author(s). published by Portland Press Limited on behalf of the Biochemical Society.

  12. Kinin B1 receptor blockade and ACE inhibition attenuate cardiac postinfarction remodeling and heart failure in rats

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Xinchun [Department of Research, Mount Sinai Medical Center, Miami Beach, FL 33140 (United States); Bernloehr, Christian; Hildebrandt, Tobias [Boehringer Ingelheim Pharma GmbH & Co.KG, Biberach (Germany); Stadler, Florian J., E-mail: fjstadler@szu.edu.cn [Shenzhen Engineering Laboratory for Advanced Technology of Ceramics, Shenzhen 518060 (China); Doods, Henri [Boehringer Ingelheim Pharma GmbH & Co.KG, Biberach (Germany); Wu, Dongmei, E-mail: dongmeiwu@bellsouth.net [Department of Research, Mount Sinai Medical Center, Miami Beach, FL 33140 (United States); Department of BIN Convergence Technology, Chonbuk National University (Korea, Republic of)

    2016-08-15

    Introduction: The aim of the present study was to evaluate the effects of the novel kinin B1 receptor antagonist BI113823 on postinfarction cardiac remodeling and heart failure, and to determine whether B1 receptor blockade alters the cardiovascular effects of an angiotensin 1 converting enzyme (ACE) inhibitor in rats. Methods and results: Sprague Dawley rats were subjected to permanent occlusion of the left coronary artery. Cardiovascular function was determined at 6 weeks postinfarction. Treatment with either B1 receptor antagonist (BI113823) or an ACE inhibitor (lisinopril) alone or in combination significantly reduced the heart weight-to-body weight and lung weight-to-body weight ratios, and improved postinfarction cardiac function as evidenced by greater cardiac output, the maximum rate of left ventricular pressure rise (± dP/dtmax), left ventricle ejection fraction, fractional shorting, better wall motion, and attenuation of elevated left ventricular end diastolic pressure (LVEDP). Furthermore, all three treatment groups exhibited significant reduction in cardiac interstitial fibrosis, collagen deposition, CD68 positive macrophages, neutrophils, and proinflammatory cytokine production (TNF-α and IL-1β), compared to vehicle controls. Conclusion: The present study shows that treatment with the novel kinin B1 receptor antagonist, BI113823, reduces postinfarction cardiac remodeling and heart failure, and does not influence the cardiovascular effects of the ACE inhibitor. - Highlights: • We examined the role of kinin B1 receptors in the development of heart failure. • Kinin B1 receptor blockade attenuates post-infarction cardiac remodeling. • Kinin B1 receptor blockade improves dysfunction, and prevented heart failure. • B1 receptor blockade does not affect the cardio-protection of an ACE inhibitor.

  13. Quantitative Evaluation of 2 Scatter-Correction Techniques for 18F-FDG Brain PET/MRI in Regard to MR-Based Attenuation Correction.

    Science.gov (United States)

    Teuho, Jarmo; Saunavaara, Virva; Tolvanen, Tuula; Tuokkola, Terhi; Karlsson, Antti; Tuisku, Jouni; Teräs, Mika

    2017-10-01

    In PET, corrections for photon scatter and attenuation are essential for visual and quantitative consistency. MR attenuation correction (MRAC) is generally conducted by image segmentation and assignment of discrete attenuation coefficients, which offer limited accuracy compared with CT attenuation correction. Potential inaccuracies in MRAC may affect scatter correction, because the attenuation image (μ-map) is used in single scatter simulation (SSS) to calculate the scatter estimate. We assessed the impact of MRAC to scatter correction using 2 scatter-correction techniques and 3 μ-maps for MRAC. Methods: The tail-fitted SSS (TF-SSS) and a Monte Carlo-based single scatter simulation (MC-SSS) algorithm implementations on the Philips Ingenuity TF PET/MR were used with 1 CT-based and 2 MR-based μ-maps. Data from 7 subjects were used in the clinical evaluation, and a phantom study using an anatomic brain phantom was conducted. Scatter-correction sinograms were evaluated for each scatter correction method and μ-map. Absolute image quantification was investigated with the phantom data. Quantitative assessment of PET images was performed by volume-of-interest and ratio image analysis. Results: MRAC did not result in large differences in scatter algorithm performance, especially with TF-SSS. Scatter sinograms and scatter fractions did not reveal large differences regardless of the μ-map used. TF-SSS showed slightly higher absolute quantification. The differences in volume-of-interest analysis between TF-SSS and MC-SSS were 3% at maximum in the phantom and 4% in the patient study. Both algorithms showed excellent correlation with each other with no visual differences between PET images. MC-SSS showed a slight dependency on the μ-map used, with a difference of 2% on average and 4% at maximum when a μ-map without bone was used. Conclusion: The effect of different MR-based μ-maps on the performance of scatter correction was minimal in non-time-of-flight 18 F-FDG PET

  14. Improved UTE-based attenuation correction for cranial PET-MR using dynamic magnetic field monitoring

    International Nuclear Information System (INIS)

    Aitken, A. P.; Giese, D.; Tsoumpas, C.; Schleyer, P.; Kozerke, S.; Prieto, C.; Schaeffter, T.

    2014-01-01

    Purpose: Ultrashort echo time (UTE) MRI has been proposed as a way to produce segmented attenuation maps for PET, as it provides contrast between bone, air, and soft tissue. However, UTE sequences require samples to be acquired during rapidly changing gradient fields, which makes the resulting images prone to eddy current artifacts. In this work it is demonstrated that this can lead to misclassification of tissues in segmented attenuation maps (AC maps) and that these effects can be corrected for by measuring the true k-space trajectories using a magnetic field camera. Methods: The k-space trajectories during a dual echo UTE sequence were measured using a dynamic magnetic field camera. UTE images were reconstructed using nominal trajectories and again using the measured trajectories. A numerical phantom was used to demonstrate the effect of reconstructing with incorrect trajectories. Images of an ovine leg phantom were reconstructed and segmented and the resulting attenuation maps were compared to a segmented map derived from a CT scan of the same phantom, using the Dice similarity measure. The feasibility of the proposed method was demonstrated inin vivo cranial imaging in five healthy volunteers. Simulated PET data were generated for one volunteer to show the impact of misclassifications on the PET reconstruction. Results: Images of the numerical phantom exhibited blurring and edge artifacts on the bone–tissue and air–tissue interfaces when nominal k-space trajectories were used, leading to misclassification of soft tissue as bone and misclassification of bone as air. Images of the tissue phantom and thein vivo cranial images exhibited the same artifacts. The artifacts were greatly reduced when the measured trajectories were used. For the tissue phantom, the Dice coefficient for bone in MR relative to CT was 0.616 using the nominal trajectories and 0.814 using the measured trajectories. The Dice coefficients for soft tissue were 0.933 and 0.934 for the

  15. Self-attenuation correction factors for bioindicators measured by γ spectrometry for energies <100keV

    International Nuclear Information System (INIS)

    Manduci, L.; Tenailleau, L.; Trolet, J.L.; De Vismes, A.; Lopez, G.; Piccione, M.

    2010-01-01

    The mass attenuation coefficients for a number of marine and terrestrial bioindicators were measured using γ spectrometry for energies between 22 and 80 keV. These values were then used to find the correction factor k for the apparent radioactivity. The experimental results were compared with a Monte Carlo simulation performed using PENELOPE in order to evaluate the reliability of the simplified calculation and to determine the correction factors.

  16. Standardised uptake values from PET/CT images: comparison with conventional attenuation-corrected PET

    International Nuclear Information System (INIS)

    Souvatzoglou, M.; Ziegler, S.I.; Martinez, M.J.; Dzewas, G.; Schwaiger, M.; Bengel, F.; Busch, R.

    2007-01-01

    In PET/CT, CT-derived attenuation factors may influence standardised uptake values (SUVs) in tumour lesions and organs when compared with stand-alone PET. Therefore, we compared PET/CT-derived SUVs intra-individually in various organs and tumour lesions with stand-alone PET-derived SUVs. Thirty-five patients with known or suspected cancer were prospectively included. Sixteen patients underwent FDG PET using an ECAT HR+scanner, and subsequently a second scan using a Biograph Sensation 16PET/CT scanner. Nineteen patients were scanned in the reverse order. All images were reconstructed with an iterative algorithm (OSEM). Suspected lesions were grouped as paradiaphragmatic versus distant from the diaphragm. Mean and maximum SUVs were also calculated for brain, lung, liver, spleen and vertebral bone. The attenuation coefficients (μ values) used for correction of emission data (bone, soft tissue, lung) in the two data sets were determined. A body phantom containing six hot spheres and one cold cylinder was measured using the same protocol as in patients. Forty-six lesions were identified. There was a significant correlation of maximum and mean SUVs derived from PET and PET/CT for 14 paradiaphragmatic lesions (r=0.97 respectively; p<0.001 respectively) and for 32 lesions located distant from the diaphragm (r=0.87 and r=0.89 respectively; p<0.001 respectively). No significant differences were observed in the SUVs calculated with PET and PET/CT in the lesions or in the organs. In the phantom, radioactivity concentration in spheres calculated from PET and from PET/CT correlated significantly (r=0.99; p<0.001). SUVs of cancer lesions and normal organs were comparable between PET and PET/CT, supporting the usefulness of PET/CT-derived SUVs for quantification of tumour metabolism. (orig.)

  17. Examination of attenuation correction method for cerebral blood Flow SPECT Using MR imaging

    International Nuclear Information System (INIS)

    Mizuno, Takashi; Takahashi, Masaaki

    2009-01-01

    Authors developed a software for attenuation correction using MR imaging (MRAC) (Toshiba Med. System Engineer.) based on the idea that precision of AC could be improved by the head contour in MRI T2-weighted images (T2WI) obtained before 123 I-iofetamine (IMP) single photon emission computed tomography (SPECT) for cerebral blood flow (CBF) measurement. In the present study, this MRAC was retrospectively evaluated by comparison with the previous standard AC methods derived from transmission CT (TCT) and X-CT which overcoming the problem of sinogram threshold Chang method but still having cost and patient exposure issues. MRAC was essentially performed in the Toshiba GMS5500/PI processor where 3D registration was conducted with images of SPECT and MRI of the same patient. The gamma camera for 123 I-IMP SPECT and 99m TcO 4 - TCT was Toshiba 3-detector GCA9300A equipped with the above processor for MRAC and with low energy high resolution (LEHR) fan beam collimator. Machines for MRI and CT were Siemens-Asahi Meditech. MAGNETOM Symphony 1.5T and SOMATOM plus4, respectively. MRAC was examined in 8 patients with images of T1WI, TCT and SPECT, and in 18 of T2WI, CT and SPECT. Evaluation was made by comparison of attenuation coefficients (μ) by the 4 methods. As a result, the present MRAC was found to be closer to AC by TCT and CT than by the Chang method since MRAC, due to exact imaging of the head contour, was independent on radiation count, and was thought to be useful for improving the precision of CBF SPECT. (K.T.)

  18. Vitamin D treatment attenuates cardiac FGF23/FGFR4 signaling and hypertrophy in uremic rats.

    Science.gov (United States)

    Leifheit-Nestler, Maren; Grabner, Alexander; Hermann, Laura; Richter, Beatrice; Schmitz, Karin; Fischer, Dagmar-Christiane; Yanucil, Christopher; Faul, Christian; Haffner, Dieter

    2017-09-01

    Vitamin D deficiency and excess of circulating fibroblast growth factor 23 (FGF23) contribute to cardiovascular mortality in patients with chronic kidney disease (CKD). FGF23 activates FGF receptor 4 and (FGFR4) calcineurin/nuclear factor of activated T cells (NFAT) signaling in cardiac myocytes, thereby causing left ventricular hypertrophy (LVH). Here, we determined if 1,25-dihydroxyvitamin D (calcitriol) inhibits FGF23-induced cardiac signaling and LVH. 5/6 nephrectomized (5/6 Nx) rats were treated with different doses of calcitriol for 4 or 10 weeks and cardiac expression of FGF23/FGFR4 and activation of calcineurin/NFAT as well as LVH were analyzed. FGFR4 activation and hypertrophic cell growth were studied in cultured cardiac myocytes that were co-treated with FGF23 and calcitriol. In 5/6Nx rats with LVH, we detected elevated FGF23 expression in bone and myocardium, increased cardiac expression of FGFR4 and elevated cardiac activation of calcineurin/NFAT signaling. Cardiac expression levels of FGF23 and FGFR4 significantly correlated with the presence of LVH in uremic rats. Treatment with calcitriol reduced LVH as well as cardiac FGFR4 expression and calcineurin/NFAT activation. Bone and cardiac FGF23 expression were further stimulated by calcitriol in a dose-dependent manner, but levels of intact cardiac FGF23 protein were suppressed by high-dose calcitriol. In cultured cardiac myocytes, co-treatment with calcitriol blocked FGF23-induced activation of FGFR4 and hypertrophic cell growth. Our data suggest that in CKD, cardioprotective effects of calcitriol stem from its inhibitory actions on the cardiac FGF23/FGFR4 system, and based on their counterbalancing effects on cardiac myocytes, high FGF23 and low calcitriol synergistically contribute to cardiac hypertrophy. © The Author 2017. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.

  19. Novel Sulfur Metabolites of Garlic Attenuate Cardiac Hypertrophy and Remodeling through Induction of Na+/K+-ATPase Expression.

    Science.gov (United States)

    Khatua, Tarak N; Borkar, Roshan M; Mohammed, Soheb A; Dinda, Amit K; Srinivas, R; Banerjee, Sanjay K

    2017-01-01

    Epidemiologic studies show an inverse correlation between garlic consumption and progression of cardiovascular disease. However, the molecular basis for the beneficial effect of garlic on the heart is not known. Therefore, the objective of the present study was to (1) investigate the effect of raw garlic on isoproterenol (Iso) induced cardiac hypertrophy (2) find the active metabolites of garlic responsible for the beneficial effect. Cardiac hypertrophy was induced in rats by subcutaneous single injection of Iso 5 mg kg -1 day -1 for 15 days and the effect of garlic (250 mg/kg/day orally) was evaluated. Garlic metabolites in in vivo were identified by LC/MS study. The effect of garlic and its metabolites were evaluated against hypertrophy in H9C2 cells. Garlic normalized cardiac oxidative stress after Iso administration. Cardiac pathology and mitochondrial enzyme activities were improved in hypertrophy heart after garlic administration. Decreased Na + /K + -ATPase protein level that observed in hypertrophy heart was increased after garlic administration. We identified three garlic metabolites in rat serum. To confirm the role of garlic metabolites on cardiac hypertrophy, Na + /K + -ATPase expression and intracellular calcium levels were measured after treating H9C2 cells with raw garlic and two of its active metabolites, allyl methyl sulfide and allyl methyl sulfoxide. Raw garlic and both metabolites increased Na + /K + -ATPase protein level and decreased intracellular calcium levels and cell size in Iso treated H9C2 cells. This antihypertrophic effect of garlic and its sulfur metabolites were lost in H9C2 cells in presence of Na + /K + -ATPase inhibitor. In conclusion, garlic and its active metabolites increased Na + /K + -ATPase in rat heart, and attenuated cardiac hypertrophy and associated remodeling. Our data suggest that identified new garlic metabolites may be useful for therapeutic intervention against cardiac hypertrophy.

  20. Cardiomyocyte specific expression of Acyl-coA thioesterase 1 attenuates sepsis induced cardiac dysfunction and mortality

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Congying [Departments of Internal Medicine and Institute of Hypertension, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan (China); Dong, Ruolan [Department of Geriatric Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030 (China); Chen, Chen [Departments of Internal Medicine and Institute of Hypertension, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan (China); Wang, Hong, E-mail: hong.wang1988@yahoo.com [Departments of Internal Medicine and Institute of Hypertension, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan (China); Wang, Dao Wen, E-mail: dwwang@tjh.tjmu.edu.cn [Departments of Internal Medicine and Institute of Hypertension, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan (China)

    2015-12-25

    Compromised cardiac fatty acid oxidation (FAO) induced energy deprivation is a critical cause of cardiac dysfunction in sepsis. Acyl-CoA thioesterase 1 (ACOT1) is involved in regulating cardiac energy production via altering substrate metabolism. This study aims to clarify whether ACOT1 has a potency to ameliorate septic myocardial dysfunction via enhancing cardiac FAO. Transgenic mice with cardiomyocyte specific expression of ACOT1 (αMHC-ACOT1) and their wild type (WT) littermates were challenged with Escherichia coli lipopolysaccharide (LPS; 5 mg/kg i.p.) and myocardial function was assessed 6 h later using echocardiography and hemodynamics. Deteriorated cardiac function evidenced by reduction of the percentage of left ventricular ejection fraction and fractional shortening after LPS administration was significantly attenuated by cardiomyocyte specific expression of ACOT1. αMHC-ACOT1 mice exhibited a markedly increase in glucose utilization and cardiac FAO compared with LPS-treated WT mice. Suppression of cardiac peroxisome proliferator activated receptor alpha (PPARa) and PPARγ-coactivator-1α (PGC1a) signaling observed in LPS-challenged WT mice was activated by the presence of ACOT1. These results suggest that ACOT1 has potential therapeutic values to protect heart from sepsis mediated dysfunction, possibly through activating PPARa/PGC1a signaling. - Highlights: • ACOT1 has potential therapeutic values to protect heart from sepsis mediated dysfunction. • ACOT1 can regulate PPARa/PGC1a signaling pathway. • We first generate the transgenic mice with cardiomyocyte specific expression of ACOT1.

  1. Cardiomyocyte specific expression of Acyl-coA thioesterase 1 attenuates sepsis induced cardiac dysfunction and mortality

    International Nuclear Information System (INIS)

    Xia, Congying; Dong, Ruolan; Chen, Chen; Wang, Hong; Wang, Dao Wen

    2015-01-01

    Compromised cardiac fatty acid oxidation (FAO) induced energy deprivation is a critical cause of cardiac dysfunction in sepsis. Acyl-CoA thioesterase 1 (ACOT1) is involved in regulating cardiac energy production via altering substrate metabolism. This study aims to clarify whether ACOT1 has a potency to ameliorate septic myocardial dysfunction via enhancing cardiac FAO. Transgenic mice with cardiomyocyte specific expression of ACOT1 (αMHC-ACOT1) and their wild type (WT) littermates were challenged with Escherichia coli lipopolysaccharide (LPS; 5 mg/kg i.p.) and myocardial function was assessed 6 h later using echocardiography and hemodynamics. Deteriorated cardiac function evidenced by reduction of the percentage of left ventricular ejection fraction and fractional shortening after LPS administration was significantly attenuated by cardiomyocyte specific expression of ACOT1. αMHC-ACOT1 mice exhibited a markedly increase in glucose utilization and cardiac FAO compared with LPS-treated WT mice. Suppression of cardiac peroxisome proliferator activated receptor alpha (PPARa) and PPARγ-coactivator-1α (PGC1a) signaling observed in LPS-challenged WT mice was activated by the presence of ACOT1. These results suggest that ACOT1 has potential therapeutic values to protect heart from sepsis mediated dysfunction, possibly through activating PPARa/PGC1a signaling. - Highlights: • ACOT1 has potential therapeutic values to protect heart from sepsis mediated dysfunction. • ACOT1 can regulate PPARa/PGC1a signaling pathway. • We first generate the transgenic mice with cardiomyocyte specific expression of ACOT1.

  2. PET/MR brain imaging: evaluation of clinical UTE-based attenuation correction

    International Nuclear Information System (INIS)

    Aasheim, Lars Birger; Karlberg, Anna; Goa, Paal Erik; Haaberg, Asta; Soerhaug, Sveinung; Fagerli, Unn-Merete; Eikenes, Live

    2015-01-01

    One of the greatest challenges in PET/MR imaging is that of accurate MR-based attenuation correction (AC) of the acquired PET data, which must be solved if the PET/MR modality is to reach its full potential. The aim of this study was to investigate the performance of Siemens' most recent version (VB20P) of MR-based AC of head PET data, by comparing it to CT-based AC. Methods: 18 F-FDG PET data from seven lymphoma and twelve lung cancer patients examined with a Biograph mMR PET/MR system were reconstructed with both CT-based and MR-based AC, avoiding sources of error arising when comparing PET data from different systems. The resulting images were compared quantitatively by measuring changes in mean SUV in ten different brain regions in both hemispheres, as well as the brainstem. In addition, the attenuation maps (μ maps) were compared regarding volume and localization of cranial bone. The UTE μ maps clearly overestimate the amount of bone in the neck, while slightly underestimating the amount of bone in the cranium, and the localization of bone in the cranial region also differ from the CT μ maps. In air/tissue interfaces in the sinuses and ears, the MRAC method struggles to correctly classify the different tissues. The misclassification of tissue is most likely caused by a combination of artefacts and the insufficiency of the UTE method to accurately separate bone. Quantitatively, this results in a combination of overestimation (0.5-3.6 %) and underestimation (2.7-5.2 %) of PET activity throughout the brain, depending on the proximity to the inaccurate regions. Our results indicate that the performance of the UTE method as implemented in VB20P is close to the theoretical maximum of such an MRAC method in the brain, while it does not perform satisfactorily in the neck or face/nasal area. Further improvement of the UTE MRAC or other available methods for more accurate segmentation of bone should be incorporated. (orig.)

  3. Respiratory Motion Correction for Compressively Sampled Free Breathing Cardiac MRI Using Smooth l1-Norm Approximation

    Directory of Open Access Journals (Sweden)

    Muhammad Bilal

    2018-01-01

    Full Text Available Transformed domain sparsity of Magnetic Resonance Imaging (MRI has recently been used to reduce the acquisition time in conjunction with compressed sensing (CS theory. Respiratory motion during MR scan results in strong blurring and ghosting artifacts in recovered MR images. To improve the quality of the recovered images, motion needs to be estimated and corrected. In this article, a two-step approach is proposed for the recovery of cardiac MR images in the presence of free breathing motion. In the first step, compressively sampled MR images are recovered by solving an optimization problem using gradient descent algorithm. The L1-norm based regularizer, used in optimization problem, is approximated by a hyperbolic tangent function. In the second step, a block matching algorithm, known as Adaptive Rood Pattern Search (ARPS, is exploited to estimate and correct respiratory motion among the recovered images. The framework is tested for free breathing simulated and in vivo 2D cardiac cine MRI data. Simulation results show improved structural similarity index (SSIM, peak signal-to-noise ratio (PSNR, and mean square error (MSE with different acceleration factors for the proposed method. Experimental results also provide a comparison between k-t FOCUSS with MEMC and the proposed method.

  4. An experimental phantom study of the effect of gadolinium-based MR contrast agents on PET attenuation coefficients and PET quantification in PET-MR imaging: application to cardiac studies.

    Science.gov (United States)

    O' Doherty, Jim; Schleyer, Paul

    2017-12-01

    Simultaneous cardiac perfusion studies are an increasing trend in PET-MR imaging. During dynamic PET imaging, the introduction of gadolinium-based MR contrast agents (GBCA) at high concentrations during a dual injection of GBCA and PET radiotracer may cause increased attenuation effects of the PET signal, and thus errors in quantification of PET images. We thus aimed to calculate the change in linear attenuation coefficient (LAC) of a mixture of PET radiotracer and increasing concentrations of GBCA in solution and furthermore, to investigate if this change in LAC produced a measurable effect on the image-based PET activity concentration when attenuation corrected by three different AC strategies. We performed simultaneous PET-MR imaging of a phantom in a static scenario using a fixed activity of 40 MBq [18 F]-NaF, water, and an increasing GBCA concentration from 0 to 66 mM (based on an assumed maximum possible concentration of GBCA in the left ventricle in a clinical study). This simulated a range of clinical concentrations of GBCA. We investigated two methods to calculate the LAC of the solution mixture at 511 keV: (1) a mathematical mixture rule and (2) CT imaging of each concentration step and subsequent conversion to LAC at 511 keV. This comparison showed that the ranges of LAC produced by both methods are equivalent with an increase in LAC of the mixed solution of approximately 2% over the range of 0-66 mM. We then employed three different attenuation correction methods to the PET data: (1) each PET scan at a specific millimolar concentration of GBCA corrected by its corresponding CT scan, (2) each PET scan corrected by a CT scan with no GBCA present (i.e., at 0 mM GBCA), and (3) a manually generated attenuation map, whereby all CT voxels in the phantom at 0 mM were replaced by LAC = 0.1 cm -1 . All attenuation correction methods (1-3) were accurate to the true measured activity concentration within 5%, and there were no trends in image

  5. Thoracoscopic patch insulation to correct phrenic nerve stimulation secondary to cardiac resynchronization therapy.

    Science.gov (United States)

    Mediratta, Neeraj; Barker, Diane; McKevith, James; Davies, Peter; Belchambers, Sandra; Rao, Archana

    2012-07-01

    Cardiac resynchronization therapy is an established therapy for heart failure, improving quality of life and prognosis. Despite advances in technique, available leads and delivery systems, trans-venous left ventricular (LV) lead positioning remains dependent on the patient's underlying venous anatomy. The left phrenic nerve courses over the surface of the pericardium laterally and may be stimulated by the LV pacing lead, causing uncomfortable diaphragmatic twitch. This paper describes a video-assisted thoracoscopic (VATS) procedure to correct phrenic nerve stimulation secondary to cardiac resynchronization therapy. Most current ways of avoiding phrenic stimulation involve either electronic reprogramming to distance the phrenic nerve from the stimulation circuit or repositioning the lead. We describe a case where the phrenic nerve was surgically insulated from the stimulating current by insinuating a patch of bovine pericardium between the epicardium and native pericardium of the heart thus completely resolving previously intolerable and incessant diaphragmatic twitch. The procedure was performed under general anaesthesia with single-lung ventilation and minimal use of neuromuscular blocking agents. Surgical patch insulation of the phrenic nerve was performed using minimally invasive VATS surgery, as a short-stay procedure, with no complications. No diaphragmatic twitch occurred post-surgery and the patient continued to gain symptomatic benefit from cardiac synchronization therapy (New York Heart Association Class III to II), enabling return to work. In cases where the trans-venous position of a LV lead is limited by troublesome phrenic nerve stimulation, thoracoscopic surgical patch insulation of the phrenic nerve could be considered to allow beneficial cardiac resynchronization therapy.

  6. Fetal cardiac cine imaging using highly accelerated dynamic MRI with retrospective motion correction and outlier rejection.

    Science.gov (United States)

    van Amerom, Joshua F P; Lloyd, David F A; Price, Anthony N; Kuklisova Murgasova, Maria; Aljabar, Paul; Malik, Shaihan J; Lohezic, Maelene; Rutherford, Mary A; Pushparajah, Kuberan; Razavi, Reza; Hajnal, Joseph V

    2018-01-01

    Development of a MRI acquisition and reconstruction strategy to depict fetal cardiac anatomy in the presence of maternal and fetal motion. The proposed strategy involves i) acquisition and reconstruction of highly accelerated dynamic MRI, followed by image-based ii) cardiac synchronization, iii) motion correction, iv) outlier rejection, and finally v) cardiac cine reconstruction. Postprocessing entirely was automated, aside from a user-defined region of interest delineating the fetal heart. The method was evaluated in 30 mid- to late gestational age singleton pregnancies scanned without maternal breath-hold. The combination of complementary acquisition/reconstruction and correction/rejection steps in the pipeline served to improve the quality of the reconstructed 2D cine images, resulting in increased visibility of small, dynamic anatomical features. Artifact-free cine images successfully were produced in 36 of 39 acquired data sets; prolonged general fetal movements precluded processing of the remaining three data sets. The proposed method shows promise as a motion-tolerant framework to enable further detail in MRI studies of the fetal heart and great vessels. Processing data in image-space allowed for spatial and temporal operations to be applied to the fetal heart in isolation, separate from extraneous changes elsewhere in the field of view. Magn Reson Med 79:327-338, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

  7. Making of attenuation-correcting computation table for RIs and emitted gamma ray table using MS-Excel

    International Nuclear Information System (INIS)

    Miura, Shigeyuki; Takahashi, Mitsuyuki; Sato, Isamu

    1995-01-01

    In the technical workshop of National Institute for Fusion Science in the last year, report was made on the making of attenuation-correcting computation table for R/S by using the software Lotus 1-2-3 on MS-DOS. It was decided to use this table by applying Windows, and further, to partially add some functions to this table. Excel 5.0 was to be used as the software, since Excel seems to be the main of Windows. It was decided to make anew the γ-ray data table which is linked to the radioactivity data in the RI attenuation-correcting computation table. First work is to convert the RI attenuation-correcting computation table made as the file of Lotus 1-2-3 to the file of Excel 5.0 of Windows, and this is very simple. As the result of the file conversion, it was found that the data file became compact. Next work is the addition of functions to this table. The function being added this time is that for judging whether R/S are those which are stipulated in the laws or not from the values of radioactivity calculated by the attenuation correction. The concrete method of this addition of function is explained. The data table on the γ-ray for respective nuclides was made. The present state of the data base on radiation was investigated. (K.I.)

  8. Correction for patient and organ movement in SPECT: application to exercise thallium-201 cardiac imaging

    International Nuclear Information System (INIS)

    Geckle, W.J.; Frank, T.L.; Links, J.M.; Becker, L.C.

    1988-01-01

    We describe a technique for correction of artifacts in exercise 201 Tl single photon emission computed tomography (SPECT) images arising from abrupt or gradual translational movement of the heart during acquisition. The procedure involves the tracking of the center of the heart in serial projection images using an algorithm which we call diverging squares. Each projection image is then realigned in the x-y plane so that the heart center conforms to the projected position of a fixed point in space. The shifted projections are reconstructed using the normal filtered backprojection algorithm. In validation studies, the motion correction procedure successfully eliminated movement artifacts in a heart phantom. Image quality was also improved in over one-half of 36 exercise thallium patient studies. The corrected images had smoother and more continuous left ventricular walls, greater clarity of the left ventricular cavity, and reduced streak artifacts. Rest injected or redistribution images, however, were often made worse, due to reduced heart to liver activity ratios and poor tracking of the heart center. Analysis of curves of heart position versus projection angle suggests that translation of the heart is common during imaging after exercise, and results from both abrupt patient movements, and a gradual upward shift of the heart. Our motion correction technique appears to represent a promising new approach for elimination of movement artifacts and enhancement of resolution in exercise 201 Tl cardiac SPECT images

  9. Ultra-low dose CT attenuation correction for PET/CT

    International Nuclear Information System (INIS)

    Xia Ting; Kinahan, Paul E; Alessio, Adam M; De Man, Bruno; Manjeshwar, Ravindra; Asma, Evren

    2012-01-01

    A challenge for positron emission tomography/computed tomography (PET/CT) quantitation is patient respiratory motion, which can cause an underestimation of lesion activity uptake and an overestimation of lesion volume. Several respiratory motion correction methods benefit from longer duration CT scans that are phase matched with PET scans. However, even with the currently available, lowest dose CT techniques, extended duration cine CT scans impart a substantially high radiation dose. This study evaluates methods designed to reduce CT radiation dose in PET/CT scanning. We investigated selected combinations of dose reduced acquisition and noise suppression methods that take advantage of the reduced requirement of CT for PET attenuation correction (AC). These include reducing CT tube current, optimizing CT tube voltage, adding filtration, CT sinogram smoothing and clipping. We explored the impact of these methods on PET quantitation via simulations on different digital phantoms. CT tube current can be reduced much lower for AC than that in low dose CT protocols. Spectra that are higher energy and narrower are generally more dose efficient with respect to PET image quality. Sinogram smoothing could be used to compensate for the increased noise and artifacts at radiation dose reduced CT images, which allows for a further reduction of CT dose with no penalty for PET image quantitation. When CT is not used for diagnostic and anatomical localization purposes, we showed that ultra-low dose CT for PET/CT is feasible. The significant dose reduction strategies proposed here could enable respiratory motion compensation methods that require extended duration CT scans and reduce radiation exposure in general for all PET/CT imaging. (paper)

  10. Ultra-low dose CT attenuation correction for PET/CT

    Science.gov (United States)

    Xia, Ting; Alessio, Adam M.; De Man, Bruno; Manjeshwar, Ravindra; Asma, Evren; Kinahan, Paul E.

    2012-01-01

    A challenge for PET/CT quantitation is patient respiratory motion, which can cause an underestimation of lesion activity uptake and an overestimation of lesion volume. Several respiratory motion correction methods benefit from longer duration CT scans that are phase matched with PET scans. However, even with the currently-available, lowest dose CT techniques, extended duration CINE CT scans impart a substantially high radiation dose. This study evaluates methods designed to reduce CT radiation dose in PET/CT scanning. Methods We investigated selected combinations of dose reduced acquisition and noise suppression methods that take advantage of the reduced requirement of CT for PET attenuation correction (AC). These include reducing CT tube current, optimizing CT tube voltage, adding filtration, CT sinogram smoothing and clipping. We explored the impact of these methods on PET quantitation via simulations on different digital phantoms. Results CT tube current can be reduced much lower for AC than that in low dose CT protocols. Spectra that are higher energy and narrower are generally more dose efficient with respect to PET image quality. Sinogram smoothing could be used to compensate for the increased noise and artifacts at radiation dose reduced CT images, which allows for a further reduction of CT dose with no penalty for PET image quantitation. Conclusion When CT is not used for diagnostic and anatomical localization purposes, we showed that ultra-low dose CT for PET/CT is feasible. The significant dose reduction strategies proposed here could enable respiratory motion compensation methods that require extended duration CT scans and reduce radiation exposure in general for all PET/CT imaging. PMID:22156174

  11. Quantitative Evaluation of Segmentation- and Atlas-Based Attenuation Correction for PET/MR on Pediatric Patients.

    Science.gov (United States)

    Bezrukov, Ilja; Schmidt, Holger; Gatidis, Sergios; Mantlik, Frédéric; Schäfer, Jürgen F; Schwenzer, Nina; Pichler, Bernd J

    2015-07-01

    Pediatric imaging is regarded as a key application for combined PET/MR imaging systems. Because existing MR-based attenuation-correction methods were not designed specifically for pediatric patients, we assessed the impact of 2 potentially influential factors: inter- and intrapatient variability of attenuation coefficients and anatomic variability. Furthermore, we evaluated the quantification accuracy of 3 methods for MR-based attenuation correction without (SEGbase) and with bone prediction using an adult and a pediatric atlas (SEGwBONEad and SEGwBONEpe, respectively) on PET data of pediatric patients. The variability of attenuation coefficients between and within pediatric (5-17 y, n = 17) and adult (27-66 y, n = 16) patient collectives was assessed on volumes of interest (VOIs) in CT datasets for different tissue types. Anatomic variability was assessed on SEGwBONEad/pe attenuation maps by computing mean differences to CT-based attenuation maps for regions of bone tissue, lungs, and soft tissue. PET quantification was evaluated on VOIs with physiologic uptake and on 80% isocontour VOIs with elevated uptake in the thorax and abdomen/pelvis. Inter- and intrapatient variability of the bias was assessed for each VOI group and method. Statistically significant differences in mean VOI Hounsfield unit values and linear attenuation coefficients between adult and pediatric collectives were found in the lungs and femur. The prediction of attenuation maps using the pediatric atlas showed a reduced error in bone tissue and better delineation of bone structure. Evaluation of PET quantification accuracy showed statistically significant mean errors in mean standardized uptake values of -14% ± 5% and -23% ± 6% in bone marrow and femur-adjacent VOIs with physiologic uptake for SEGbase, which could be reduced to 0% ± 4% and -1% ± 5% using SEGwBONEpe attenuation maps. Bias in soft-tissue VOIs was less than 5% for all methods. Lung VOIs showed high SDs in the range of 15% for

  12. Adding attenuation corrected images in myocardial perfusion imaging reduces the need for a rest study

    International Nuclear Information System (INIS)

    Trägårdh, Elin; Valind, Sven; Edenbrandt, Lars

    2013-01-01

    The American Society of Nuclear Cardiology and the Society of Nuclear Medicine conclude that incorporation of attenuation corrected (AC) images in myocardial perfusion scintigraphy (MPS) will improve diagnostic accuracy. The aim was to investigate the value of adding AC stress-only images for the decision whether a rest study is necessary or not. 1,261 patients admitted to 99m Tc MPS were studied. The stress studies were interpreted by two physicians who judged each study as “no rest study necessary” or “rest study necessary”, by evaluating NC stress-only and NC + AC stress-only images. When there was disagreement between the two physicians, a third physician evaluated the studies. Thus, agreement between 2 out of 3 physicians was evaluated. The physicians assessed 214 more NC + AC images than NC images as “no rest study necessary” (17% of the study population). The number of no-rest-study-required was significantly higher for NC + AC studies compared to NC studies (859 vs 645 cases (p < 0.0001). In the final report according to clinical routine, ischemia or infarction was reported in 23 patients, assessed as “no rest study necessary” (22 NC + AC cases; 8 NC cases), (no statistically significant difference). In 11 of these, the final report stated “suspected/possible ischemia or infarction in a small area”. Adding AC stress-only images to NC stress-only images reduce the number of unnecessary rest studies substantially

  13. Improving best-phase image quality in cardiac CT by motion correction with MAM optimization

    Energy Technology Data Exchange (ETDEWEB)

    Rohkohl, Christopher; Bruder, Herbert; Stierstorfer, Karl [Siemens AG, Healthcare Sector, Siemensstrasse 1, 91301 Forchheim (Germany); Flohr, Thomas [Siemens AG, Healthcare Sector, Siemensstrasse 1, 91301 Forchheim (Germany); Institute of Diagnostic Radiology, Eberhard Karls University, Hoppe-Seyler-Str. 3, 72076 Tuebingen (Germany)

    2013-03-15

    Purpose: Research in image reconstruction for cardiac CT aims at using motion correction algorithms to improve the image quality of the coronary arteries. The key to those algorithms is motion estimation, which is currently based on 3-D/3-D registration to align the structures of interest in images acquired in multiple heart phases. The need for an extended scan data range covering several heart phases is critical in terms of radiation dose to the patient and limits the clinical potential of the method. Furthermore, literature reports only slight quality improvements of the motion corrected images when compared to the most quiet phase (best-phase) that was actually used for motion estimation. In this paper a motion estimation algorithm is proposed which does not require an extended scan range but works with a short scan data interval, and which markedly improves the best-phase image quality. Methods: Motion estimation is based on the definition of motion artifact metrics (MAM) to quantify motion artifacts in a 3-D reconstructed image volume. The authors use two different MAMs, entropy, and positivity. By adjusting the motion field parameters, the MAM of the resulting motion-compensated reconstruction is optimized using a gradient descent procedure. In this way motion artifacts are minimized. For a fast and practical implementation, only analytical methods are used for motion estimation and compensation. Both the MAM-optimization and a 3-D/3-D registration-based motion estimation algorithm were investigated by means of a computer-simulated vessel with a cardiac motion profile. Image quality was evaluated using normalized cross-correlation (NCC) with the ground truth template and root-mean-square deviation (RMSD). Four coronary CT angiography patient cases were reconstructed to evaluate the clinical performance of the proposed method. Results: For the MAM-approach, the best-phase image quality could be improved for all investigated heart phases, with a maximum

  14. Improving best-phase image quality in cardiac CT by motion correction with MAM optimization

    International Nuclear Information System (INIS)

    Rohkohl, Christopher; Bruder, Herbert; Stierstorfer, Karl; Flohr, Thomas

    2013-01-01

    Purpose: Research in image reconstruction for cardiac CT aims at using motion correction algorithms to improve the image quality of the coronary arteries. The key to those algorithms is motion estimation, which is currently based on 3-D/3-D registration to align the structures of interest in images acquired in multiple heart phases. The need for an extended scan data range covering several heart phases is critical in terms of radiation dose to the patient and limits the clinical potential of the method. Furthermore, literature reports only slight quality improvements of the motion corrected images when compared to the most quiet phase (best-phase) that was actually used for motion estimation. In this paper a motion estimation algorithm is proposed which does not require an extended scan range but works with a short scan data interval, and which markedly improves the best-phase image quality. Methods: Motion estimation is based on the definition of motion artifact metrics (MAM) to quantify motion artifacts in a 3-D reconstructed image volume. The authors use two different MAMs, entropy, and positivity. By adjusting the motion field parameters, the MAM of the resulting motion-compensated reconstruction is optimized using a gradient descent procedure. In this way motion artifacts are minimized. For a fast and practical implementation, only analytical methods are used for motion estimation and compensation. Both the MAM-optimization and a 3-D/3-D registration-based motion estimation algorithm were investigated by means of a computer-simulated vessel with a cardiac motion profile. Image quality was evaluated using normalized cross-correlation (NCC) with the ground truth template and root-mean-square deviation (RMSD). Four coronary CT angiography patient cases were reconstructed to evaluate the clinical performance of the proposed method. Results: For the MAM-approach, the best-phase image quality could be improved for all investigated heart phases, with a maximum

  15. Comparison between MRI-based attenuation correction methods for brain PET in dementia patients

    International Nuclear Information System (INIS)

    Cabello, Jorge; Lukas, Mathias; Pyka, Thomas; Nekolla, Stephan G.; Ziegler, Sibylle I.; Rota Kops, Elena; Shah, N. Jon; Ribeiro, Andre; Yakushev, Igor

    2016-01-01

    The combination of Positron Emission Tomography (PET) with magnetic resonance imaging (MRI) in hybrid PET/MRI scanners offers a number of advantages in investigating brain structure and function. A critical step of PET data reconstruction is attenuation correction (AC). Accounting for bone in attenuation maps (μ-map) was shown to be important in brain PET studies. While there are a number of MRI-based AC methods, no systematic comparison between them has been performed so far. The aim of this work was to study the different performance obtained by some of the recent methods presented in the literature. To perform such a comparison, we focused on [ 18 F]-Fluorodeoxyglucose-PET/MRI neurodegenerative dementing disorders, which are known to exhibit reduced levels of glucose metabolism in certain brain regions. Four novel methods were used to calculate μ-maps from MRI data of 15 patients with Alzheimer's dementia (AD). The methods cover two atlas-based methods, a segmentation method, and a hybrid template/segmentation method. Additionally, the Dixon-based and a UTE-based method, offered by a vendor, were included in the comparison. Performance was assessed at three levels: tissue identification accuracy in the μ-map, quantitative accuracy of reconstructed PET data in specific brain regions, and precision in diagnostic images at identifying hypometabolic areas. Quantitative regional errors of -20-10 % were obtained using the vendor's AC methods, whereas the novel methods produced errors in a margin of ±5 %. The obtained precision at identifying areas with abnormally low levels of glucose uptake, potentially regions affected by AD, were 62.9 and 79.5 % for the two vendor AC methods, the former ignoring bone and the latter including bone information. The precision increased to 87.5-93.3 % in average for the four new methods, exhibiting similar performances. We confirm that the AC methods based on the Dixon and UTE sequences provided by the vendor are inferior

  16. Investigation of attenuation correction in SPECT using textural features, Monte Carlo simulations, and computational anthropomorphic models.

    Science.gov (United States)

    Spirou, Spiridon V; Papadimitroulas, Panagiotis; Liakou, Paraskevi; Georgoulias, Panagiotis; Loudos, George

    2015-09-01

    To present and evaluate a new methodology to investigate the effect of attenuation correction (AC) in single-photon emission computed tomography (SPECT) using textural features analysis, Monte Carlo techniques, and a computational anthropomorphic model. The GATE Monte Carlo toolkit was used to simulate SPECT experiments using the XCAT computational anthropomorphic model, filled with a realistic biodistribution of (99m)Tc-N-DBODC. The simulated gamma camera was the Siemens ECAM Dual-Head, equipped with a parallel hole lead collimator, with an image resolution of 3.54 × 3.54 mm(2). Thirty-six equispaced camera positions, spanning a full 360° arc, were simulated. Projections were calculated after applying a ± 20% energy window or after eliminating all scattered photons. The activity of the radioisotope was reconstructed using the MLEM algorithm. Photon attenuation was accounted for by calculating the radiological pathlength in a perpendicular line from the center of each voxel to the gamma camera. Twenty-two textural features were calculated on each slice, with and without AC, using 16 and 64 gray levels. A mask was used to identify only those pixels that belonged to each organ. Twelve of the 22 features showed almost no dependence on AC, irrespective of the organ involved. In both the heart and the liver, the mean and SD were the features most affected by AC. In the liver, six features were affected by AC only on some slices. Depending on the slice, skewness decreased by 22-34% with AC, kurtosis by 35-50%, long-run emphasis mean by 71-91%, and long-run emphasis range by 62-95%. In contrast, gray-level non-uniformity mean increased by 78-218% compared with the value without AC and run percentage mean by 51-159%. These results were not affected by the number of gray levels (16 vs. 64) or the data used for reconstruction: with the energy window or without scattered photons. The mean and SD were the main features affected by AC. In the heart, no other feature was

  17. Attenuation correction for hybrid MR/PET scanners: a comparison study

    Energy Technology Data Exchange (ETDEWEB)

    Rota Kops, Elena [Forschungszentrum Jülich GmbH, Jülich (Germany); Ribeiro, Andre Santos [Imperial College London, London (United Kingdom); Caldeira, Liliana [Forschungszentrum Jülich GmbH, Jülich (Germany); Hautzel, Hubertus [Heinrich-Heine-University Düsseldorf, Düsseldorf (Germany); Lukas, Mathias [Technische Universitaet Muenchen, Munich (Germany); Antoch, Gerald [Heinrich-Heine-University Düsseldorf, Düsseldorf (Germany); Lerche, Christoph; Shah, Jon [Forschungszentrum Jülich GmbH, Jülich (Germany)

    2015-05-18

    Attenuation correction of PET data acquired in hybrid MR/PET scanners is still a challenge. Different methods have been adopted by several groups to obtain reliable attenuation maps (mu-maps). In this study we compare three methods: MGH, UCL, Neural-Network. The MGH method is based on an MR/CT template obtained with the SPM8 software. The UCL method uses a database of MR/CT pairs. Both generate mu-maps from MP-RAGE images. The feed-forward neural-network from Juelich (NN-Juelich) requires two UTE images; it generates segmented mu-maps. Data from eight subjects (S1-S8) measured in the Siemens 3T MR-BrainPET scanner were used. Corresponding CT images were acquired. The resulting mu-maps were compared against the CT-based mu-maps for each subject and method. Overlapped voxels and Dice similarity coefficients, D, for bone, soft-tissue and air regions, and relative differences images were calculated. The true positive (TP) recognized voxels for the whole head were 79.9% (NN-Juelich, S7) to 92.1% (UCL method, S1). D values of the bone were D=0.65 (NN-Juelich, S1) to D=0.87 (UCL method, S1). For S8 the MHG method failed (TP=76.4%; D=0.46 for bone). D values shared a common tendency in all subjects and methods to recognize soft-tissue as bone. The relative difference images showed a variation of -10.9% - +10.1%; for S8 and MHG method the values were -24.5% and +14.2%. A preliminary comparison of three methods for generation of mu-maps for MR/PET scanners is presented. The continuous methods (MGH, UCL) seem to generate reliable mu-maps, whilst the binary method seems to need further improvement. Future work will include more subjects, the reconstruction of corresponding PET data and their comparison.

  18. Comparison between MRI-based attenuation correction methods for brain PET in dementia patients

    Energy Technology Data Exchange (ETDEWEB)

    Cabello, Jorge; Lukas, Mathias; Pyka, Thomas; Nekolla, Stephan G.; Ziegler, Sibylle I. [Technische Universitaet Muenchen, Nuklearmedizinische Klinik und Poliklinik, Klinikum rechts der Isar, Munich (Germany); Rota Kops, Elena; Shah, N. Jon [Forschungszentrum Juelich GmbH, Institute of Neuroscience and Medicine 4, Medical Imaging Physics, Juelich (Germany); Ribeiro, Andre [Forschungszentrum Juelich GmbH, Institute of Neuroscience and Medicine 4, Medical Imaging Physics, Juelich (Germany); Institute of Biophysics and Biomedical Engineering, Lisbon (Portugal); Yakushev, Igor [Technische Universitaet Muenchen, Nuklearmedizinische Klinik und Poliklinik, Klinikum rechts der Isar, Munich (Germany); Institute TUM Neuroimaging Center (TUM-NIC), Munich (Germany)

    2016-11-15

    The combination of Positron Emission Tomography (PET) with magnetic resonance imaging (MRI) in hybrid PET/MRI scanners offers a number of advantages in investigating brain structure and function. A critical step of PET data reconstruction is attenuation correction (AC). Accounting for bone in attenuation maps (μ-map) was shown to be important in brain PET studies. While there are a number of MRI-based AC methods, no systematic comparison between them has been performed so far. The aim of this work was to study the different performance obtained by some of the recent methods presented in the literature. To perform such a comparison, we focused on [{sup 18}F]-Fluorodeoxyglucose-PET/MRI neurodegenerative dementing disorders, which are known to exhibit reduced levels of glucose metabolism in certain brain regions. Four novel methods were used to calculate μ-maps from MRI data of 15 patients with Alzheimer's dementia (AD). The methods cover two atlas-based methods, a segmentation method, and a hybrid template/segmentation method. Additionally, the Dixon-based and a UTE-based method, offered by a vendor, were included in the comparison. Performance was assessed at three levels: tissue identification accuracy in the μ-map, quantitative accuracy of reconstructed PET data in specific brain regions, and precision in diagnostic images at identifying hypometabolic areas. Quantitative regional errors of -20-10 % were obtained using the vendor's AC methods, whereas the novel methods produced errors in a margin of ±5 %. The obtained precision at identifying areas with abnormally low levels of glucose uptake, potentially regions affected by AD, were 62.9 and 79.5 % for the two vendor AC methods, the former ignoring bone and the latter including bone information. The precision increased to 87.5-93.3 % in average for the four new methods, exhibiting similar performances. We confirm that the AC methods based on the Dixon and UTE sequences provided by the vendor are

  19. Attenuation correction for hybrid MR/PET scanners: a comparison study

    International Nuclear Information System (INIS)

    Rota Kops, Elena; Ribeiro, Andre Santos; Caldeira, Liliana; Hautzel, Hubertus; Lukas, Mathias; Antoch, Gerald; Lerche, Christoph; Shah, Jon

    2015-01-01

    Attenuation correction of PET data acquired in hybrid MR/PET scanners is still a challenge. Different methods have been adopted by several groups to obtain reliable attenuation maps (mu-maps). In this study we compare three methods: MGH, UCL, Neural-Network. The MGH method is based on an MR/CT template obtained with the SPM8 software. The UCL method uses a database of MR/CT pairs. Both generate mu-maps from MP-RAGE images. The feed-forward neural-network from Juelich (NN-Juelich) requires two UTE images; it generates segmented mu-maps. Data from eight subjects (S1-S8) measured in the Siemens 3T MR-BrainPET scanner were used. Corresponding CT images were acquired. The resulting mu-maps were compared against the CT-based mu-maps for each subject and method. Overlapped voxels and Dice similarity coefficients, D, for bone, soft-tissue and air regions, and relative differences images were calculated. The true positive (TP) recognized voxels for the whole head were 79.9% (NN-Juelich, S7) to 92.1% (UCL method, S1). D values of the bone were D=0.65 (NN-Juelich, S1) to D=0.87 (UCL method, S1). For S8 the MHG method failed (TP=76.4%; D=0.46 for bone). D values shared a common tendency in all subjects and methods to recognize soft-tissue as bone. The relative difference images showed a variation of -10.9% - +10.1%; for S8 and MHG method the values were -24.5% and +14.2%. A preliminary comparison of three methods for generation of mu-maps for MR/PET scanners is presented. The continuous methods (MGH, UCL) seem to generate reliable mu-maps, whilst the binary method seems to need further improvement. Future work will include more subjects, the reconstruction of corresponding PET data and their comparison.

  20. Ventilation and cardiac related impedance changes in children undergoing corrective open heart surgery

    International Nuclear Information System (INIS)

    Schibler, Andreas; Pham, Trang M T; Moray, Amol A; Stocker, Christian

    2013-01-01

    Electrical impedance tomography (EIT) can determine ventilation and perfusion relationship. Most of the data obtained so far originates from experimental settings and in healthy subjects. The aim of this study was to demonstrate that EIT measures the perioperative changes in pulmonary blood flow after repair of a ventricular septum defect in children with haemodynamic relevant septal defects undergoing open heart surgery. In a 19 bed intensive care unit in a tertiary children's hospital ventilation and cardiac related impedance changes were measured using EIT before and after surgery in 18 spontaneously breathing patients. The EIT signals were either filtered for ventilation (ΔZV) or for cardiac (ΔZQ) related impedance changes. Impedance signals were then normalized (normΔZV, normΔZQ) for calculation of the global and regional impedance related ventilation perfusion relationship (normΔZV/normΔZQ). We observed a trend towards increased normΔZV in all lung regions, a significantly decreased normΔZQ in the global and anterior, but not the posterior lung region. The normΔZV/normΔZQ was significantly increased in the global and anterior lung region. Our study qualitatively validates our previously published modified EIT filtration technique in the clinical setting of young children with significant left-to-right shunt undergoing corrective open heart surgery, where perioperative assessment of the ventilation perfusion relation is of high clinical relevance. (paper)

  1. Ventilation and cardiac related impedance changes in children undergoing corrective open heart surgery.

    Science.gov (United States)

    Schibler, Andreas; Pham, Trang M T; Moray, Amol A; Stocker, Christian

    2013-10-01

    Electrical impedance tomography (EIT) can determine ventilation and perfusion relationship. Most of the data obtained so far originates from experimental settings and in healthy subjects. The aim of this study was to demonstrate that EIT measures the perioperative changes in pulmonary blood flow after repair of a ventricular septum defect in children with haemodynamic relevant septal defects undergoing open heart surgery. In a 19 bed intensive care unit in a tertiary children's hospital ventilation and cardiac related impedance changes were measured using EIT before and after surgery in 18 spontaneously breathing patients. The EIT signals were either filtered for ventilation (ΔZV) or for cardiac (ΔZQ) related impedance changes. Impedance signals were then normalized (normΔZV, normΔZQ) for calculation of the global and regional impedance related ventilation perfusion relationship (normΔZV/normΔZQ). We observed a trend towards increased normΔZV in all lung regions, a significantly decreased normΔZQ in the global and anterior, but not the posterior lung region. The normΔZV/normΔZQ was significantly increased in the global and anterior lung region. Our study qualitatively validates our previously published modified EIT filtration technique in the clinical setting of young children with significant left-to-right shunt undergoing corrective open heart surgery, where perioperative assessment of the ventilation perfusion relation is of high clinical relevance.

  2. A new iterative reconstruction technique for attenuation correction in high-resolution positron emission tomography

    International Nuclear Information System (INIS)

    Knesaurek, K.; Machac, J.; Vallabhajosula, S.; Buchsbaum, M.S.

    1996-01-01

    A new interative reconstruction technique (NIRT) for positron emission computed tomography (PET), which uses transmission data for nonuniform attenuation correction, is described. Utilizing the general inverse problem theory, a cost functional which includes a noise term was derived. The cost functional was minimized using a weighted-least-square maximum a posteriori conjugate gradient (CG) method. The procedure involves a change in the Hessian of the cost function by adding an additional term. Two phantoms were used in a real data acquisition. The first was a cylinder phantom filled with uniformly distributed activity of 74 MBq of fluorine-18. Two different inserts were placed in the phantom. The second was a Hoffman brain phantom filled with uniformly distributed activity of 7.4 MBq of 18 F. Resulting reconstructed images were used to test and compare a new interative reconstruction technique with a standard filtered backprojection (FBP) method. The results confirmed that NIRT, based on the conjugate gradient method, converges rapidly and provides good reconstructed images. In comaprison with standard results obtained by the FBP method, the images reconstructed by NIRT showed better noise properties. The noise was measured as rms% noise and was less, by a factor of 1.75, in images reconstructed by NIRT than in the same images reconstructed by FBP. The distance between the Hoffman brain slice created from the MRI image was 0.526, while the same distance for the Hoffman brain slice reconstructed by NIRT was 0.328. The NIRT method suppressed the propagation of the noise without visible loss of resolution in the reconstructed PET images. (orig.)

  3. Ultralow dose computed tomography attenuation correction for pediatric PET CT using adaptive statistical iterative reconstruction

    International Nuclear Information System (INIS)

    Brady, Samuel L.; Shulkin, Barry L.

    2015-01-01

    Purpose: To develop ultralow dose computed tomography (CT) attenuation correction (CTAC) acquisition protocols for pediatric positron emission tomography CT (PET CT). Methods: A GE Discovery 690 PET CT hybrid scanner was used to investigate the change to quantitative PET and CT measurements when operated at ultralow doses (10–35 mA s). CT quantitation: noise, low-contrast resolution, and CT numbers for 11 tissue substitutes were analyzed in-phantom. CT quantitation was analyzed to a reduction of 90% volume computed tomography dose index (0.39/3.64; mGy) from baseline. To minimize noise infiltration, 100% adaptive statistical iterative reconstruction (ASiR) was used for CT reconstruction. PET images were reconstructed with the lower-dose CTAC iterations and analyzed for: maximum body weight standardized uptake value (SUV bw ) of various diameter targets (range 8–37 mm), background uniformity, and spatial resolution. Radiation dose and CTAC noise magnitude were compared for 140 patient examinations (76 post-ASiR implementation) to determine relative dose reduction and noise control. Results: CT numbers were constant to within 10% from the nondose reduced CTAC image for 90% dose reduction. No change in SUV bw , background percent uniformity, or spatial resolution for PET images reconstructed with CTAC protocols was found down to 90% dose reduction. Patient population effective dose analysis demonstrated relative CTAC dose reductions between 62% and 86% (3.2/8.3–0.9/6.2). Noise magnitude in dose-reduced patient images increased but was not statistically different from predose-reduced patient images. Conclusions: Using ASiR allowed for aggressive reduction in CT dose with no change in PET reconstructed images while maintaining sufficient image quality for colocalization of hybrid CT anatomy and PET radioisotope uptake

  4. Ultralow dose computed tomography attenuation correction for pediatric PET CT using adaptive statistical iterative reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Brady, Samuel L., E-mail: samuel.brady@stjude.org [Division of Diagnostic Imaging, St. Jude Children’s Research Hospital, Memphis, Tennessee 38105 (United States); Shulkin, Barry L. [Nuclear Medicine and Department of Radiological Sciences, St. Jude Children’s Research Hospital, Memphis, Tennessee 38105 (United States)

    2015-02-15

    Purpose: To develop ultralow dose computed tomography (CT) attenuation correction (CTAC) acquisition protocols for pediatric positron emission tomography CT (PET CT). Methods: A GE Discovery 690 PET CT hybrid scanner was used to investigate the change to quantitative PET and CT measurements when operated at ultralow doses (10–35 mA s). CT quantitation: noise, low-contrast resolution, and CT numbers for 11 tissue substitutes were analyzed in-phantom. CT quantitation was analyzed to a reduction of 90% volume computed tomography dose index (0.39/3.64; mGy) from baseline. To minimize noise infiltration, 100% adaptive statistical iterative reconstruction (ASiR) was used for CT reconstruction. PET images were reconstructed with the lower-dose CTAC iterations and analyzed for: maximum body weight standardized uptake value (SUV{sub bw}) of various diameter targets (range 8–37 mm), background uniformity, and spatial resolution. Radiation dose and CTAC noise magnitude were compared for 140 patient examinations (76 post-ASiR implementation) to determine relative dose reduction and noise control. Results: CT numbers were constant to within 10% from the nondose reduced CTAC image for 90% dose reduction. No change in SUV{sub bw}, background percent uniformity, or spatial resolution for PET images reconstructed with CTAC protocols was found down to 90% dose reduction. Patient population effective dose analysis demonstrated relative CTAC dose reductions between 62% and 86% (3.2/8.3–0.9/6.2). Noise magnitude in dose-reduced patient images increased but was not statistically different from predose-reduced patient images. Conclusions: Using ASiR allowed for aggressive reduction in CT dose with no change in PET reconstructed images while maintaining sufficient image quality for colocalization of hybrid CT anatomy and PET radioisotope uptake.

  5. Integrated PET/MR breast cancer imaging: Attenuation correction and implementation of a 16-channel RF coil

    Energy Technology Data Exchange (ETDEWEB)

    Oehmigen, Mark, E-mail: mark.oehmigen@uni-due.de; Lindemann, Maike E. [High Field and Hybrid MR Imaging, University Hospital Essen, Essen 45147 (Germany); Lanz, Titus [Rapid Biomedical GmbH, Rimpar 97222 (Germany); Kinner, Sonja [Institute for Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen 45147 (Germany); Quick, Harald H. [High Field and Hybrid MR Imaging, University Hospital Essen, Essen 45147, Germany and Erwin L. Hahn Institute for MR Imaging, University Duisburg-Essen, Essen 45141 (Germany)

    2016-08-15

    Purpose: This study aims to develop, implement, and evaluate a 16-channel radiofrequency (RF) coil for integrated positron emission tomography/magnetic resonance (PET/MR) imaging of breast cancer. The RF coil is designed for optimized MR imaging performance and PET transparency and attenuation correction (AC) is applied for accurate PET quantification. Methods: A 16-channel breast array RF coil was designed for integrated PET/MR hybrid imaging of breast cancer lesions. The RF coil features a lightweight rigid design and is positioned with a spacer at a defined position on the patient table of an integrated PET/MR system. Attenuation correction is performed by generating and applying a dedicated 3D CT-based template attenuation map. Reposition accuracy of the RF coil on the system patient table while using the positioning frame was tested in repeated measurements using MR-visible markers. The MR, PET, and PET/MR imaging performances were systematically evaluated using modular breast phantoms. Attenuation correction of the RF coil was evaluated with difference measurements of the active breast phantoms filled with radiotracer in the PET detector with and without the RF coil in place, serving as a standard of reference measurement. The overall PET/MR imaging performance and PET quantification accuracy of the new 16-channel RF coil and its AC were then evaluated in first clinical examinations on ten patients with local breast cancer. Results: The RF breast array coil provides excellent signal-to-noise ratio and signal homogeneity across the volume of the breast phantoms in MR imaging and visualizes small structures in the phantoms down to 0.4 mm in plane. Difference measurements with PET revealed a global loss and thus attenuation of counts by 13% (mean value across the whole phantom volume) when the RF coil is placed in the PET detector. Local attenuation ranging from 0% in the middle of the phantoms up to 24% was detected in the peripheral regions of the phantoms at

  6. Influence of arm positioning on tomographic thallium-201 myocardial perfusion imaging and the effect of attenuation correction

    International Nuclear Information System (INIS)

    Prvulovich, E.M.; Jarritt, P.H.; Vorontsova, E.; Bomanji, J.B.; Ell, P.J.

    2000-01-01

    Lateral attenuation in single-photon emission tomography (SPET) myocardial perfusion imaging (MPI) has been attributed to the left arm if it is held by the patient's side during data acquisition. As a result MPI data are conventionally acquired with the arms held above the head. The aims of this study were to determine the effect of imaging arms down on reconstructed tomographic images depicting regional myocardial thallium-201 distribution and to assess whether attenuation-corrected (AC) myocardial perfusion images acquired arms down could replace uncorrected (NC) images acquired arms up for routine clinical service. Twenty-eight patients referred for routine MPI underwent sequential 180 emission/transmission imaging for attenuation correction using an L-shaped dual-headed gamma camera (GE Optima) fitted with two gadolinium-153 scanning line sources. Delay data were acquired twice: once supine with the arms up and then supine with the arms down. Detector radius of rotation (ROR) for arms up and arms-down studies was recorded. For each data set, count density was measured in 17 segments of a polar plot and segmental uptake expressed relative to study maximum. Oblique images were assessed qualitatively by two observers blinded to study type for tracer distribution and overall quality. Transmission maps were assessed for truncation. Mean detector ROR was 190 mm for arms-up studies and 232 mm for arms-down studies (P 201 Tl distribution, particularly anterolaterally. There is lateral undercorrection in approximately 10% of AC arms-down studies, possibly because of attenuation map truncation. Image quality is reduced in about one-third of AC arms-down studies compared with NC arms-up studies. These data suggest that this attenuation correction method is not sufficiently robust to allow routine acquisition of MPI data with the arms down. (orig.)

  7. Attenuation correction of myocardial SPECT images with X-ray CT. Effects of registration errors between X-ray CT and SPECT

    International Nuclear Information System (INIS)

    Takahashi, Yasuyuki; Murase, Kenya; Mochizuki, Teruhito; Motomura, Nobutoku

    2002-01-01

    Attenuation correction with an X-ray CT image is a new method to correct attenuation on SPECT imaging, but the effect of the registration errors between CT and SPECT images is unclear. In this study, we investigated the effects of the registration errors on myocardial SPECT, analyzing data from a phantom and a human volunteer. Registerion (fusion) of the X-ray CT and SPECT images was done with standard packaged software in three dimensional fashion, by using linked transaxial, coronal and sagittal images. In the phantom study, and X-ray CT image was shifted 1 to 3 pixels on the x, y and z axes, and rotated 6 degrees clockwise. Attenuation correction maps generated from each misaligned X-ray CT image were used to reconstruct misaligned SPECT images of the phantom filled with 201 Tl. In a human volunteer, X-ray CT was acquired in different conditions (during inspiration vs. expiration). CT values were transferred to an attenuation constant by using straight lines; an attenuation constant of 0/cm in the air (CT value=-1,000 HU) and that of 0.150/cm in water (CT value=0 HU). For comparison, attenuation correction with transmission CT (TCT) data and an external γ-ray source ( 99m Tc) was also applied to reconstruct SPECT images. Simulated breast attenuation with a breast attachment, and inferior wall attenuation were properly corrected by means of the attenuation correction map generated from X-ray CT. As pixel shift increased, deviation of the SPECT images increased in misaligned images in the phantom study. In the human study, SPECT images were affected by the scan conditions of the X-ray CT. Attenuation correction of myocardial SPECT with an X-ray CT image is a simple and potentially beneficial method for clinical use, but accurate registration of the X-ray CT to SPECT image is essential for satisfactory attenuation correction. (author)

  8. Multi-atlas attenuation correction supports full quantification of static and dynamic brain PET data in PET-MR

    Science.gov (United States)

    Mérida, Inés; Reilhac, Anthonin; Redouté, Jérôme; Heckemann, Rolf A.; Costes, Nicolas; Hammers, Alexander

    2017-04-01

    In simultaneous PET-MR, attenuation maps are not directly available. Essential for absolute radioactivity quantification, they need to be derived from MR or PET data to correct for gamma photon attenuation by the imaged object. We evaluate a multi-atlas attenuation correction method for brain imaging (MaxProb) on static [18F]FDG PET and, for the first time, on dynamic PET, using the serotoninergic tracer [18F]MPPF. A database of 40 MR/CT image pairs (atlases) was used. The MaxProb method synthesises subject-specific pseudo-CTs by registering each atlas to the target subject space. Atlas CT intensities are then fused via label propagation and majority voting. Here, we compared these pseudo-CTs with the real CTs in a leave-one-out design, contrasting the MaxProb approach with a simplified single-atlas method (SingleAtlas). We evaluated the impact of pseudo-CT accuracy on reconstructed PET images, compared to PET data reconstructed with real CT, at the regional and voxel levels for the following: radioactivity images; time-activity curves; and kinetic parameters (non-displaceable binding potential, BPND). On static [18F]FDG, the mean bias for MaxProb ranged between 0 and 1% for 73 out of 84 regions assessed, and exceptionally peaked at 2.5% for only one region. Statistical parametric map analysis of MaxProb-corrected PET data showed significant differences in less than 0.02% of the brain volume, whereas SingleAtlas-corrected data showed significant differences in 20% of the brain volume. On dynamic [18F]MPPF, most regional errors on BPND ranged from -1 to  +3% (maximum bias 5%) for the MaxProb method. With SingleAtlas, errors were larger and had higher variability in most regions. PET quantification bias increased over the duration of the dynamic scan for SingleAtlas, but not for MaxProb. We show that this effect is due to the interaction of the spatial tracer-distribution heterogeneity variation over time with the degree of accuracy of the attenuation maps. This

  9. CT-based attenuation correction and resolution compensation for I-123 IMP brain SPECT normal database: a multicenter phantom study.

    Science.gov (United States)

    Inui, Yoshitaka; Ichihara, Takashi; Uno, Masaki; Ishiguro, Masanobu; Ito, Kengo; Kato, Katsuhiko; Sakuma, Hajime; Okazawa, Hidehiko; Toyama, Hiroshi

    2018-03-19

    Statistical image analysis of brain SPECT images has improved diagnostic accuracy for brain disorders. However, the results of statistical analysis vary depending on the institution even when they use a common normal database (NDB), due to different intrinsic spatial resolutions or correction methods. The present study aimed to evaluate the correction of spatial resolution differences between equipment and examine the differences in skull bone attenuation to construct a common NDB for use in multicenter settings. The proposed acquisition and processing protocols were those routinely used at each participating center with additional triple energy window (TEW) scatter correction (SC) and computed tomography (CT) based attenuation correction (CTAC). A multicenter phantom study was conducted on six imaging systems in five centers, with either single photon emission computed tomography (SPECT) or SPECT/CT, and two brain phantoms. The gray/white matter I-123 activity ratio in the brain phantoms was 4, and they were enclosed in either an artificial adult male skull, 1300 Hounsfield units (HU), a female skull, 850 HU, or an acrylic cover. The cut-off frequency of the Butterworth filters was adjusted so that the spatial resolution was unified to a 17.9 mm full width at half maximum (FWHM), that of the lowest resolution system. The gray-to-white matter count ratios were measured from SPECT images and compared with the actual activity ratio. In addition, mean, standard deviation and coefficient of variation images were calculated after normalization and anatomical standardization to evaluate the variability of the NDB. The gray-to-white matter count ratio error without SC and attenuation correction (AC) was significantly larger for higher bone densities (p correction. The proposed protocol showed potential for constructing an appropriate common NDB from SPECT images with SC, AC and spatial resolution compensation.

  10. Attenuation-corrected radionuclide differential glomerular filtration: Using a bilateral slant hole collimator for determining depth of kidneys

    International Nuclear Information System (INIS)

    Lasher, J.C.; Kopp, D.T.; Lancaster, J.L.; Blumhardt, R.

    1986-01-01

    There has recently been considerable interest in measuring differential renal function utilizing radionuclide attenuation correction techniques. One popular method is that of estimating kidney depth from the patient's weight-to-height ratio. A recent publication showed that renal depth can also be accurately determined using measurements from lateral views of each kidney. The authors have developed a third radionculide method using a bilateral slant-hole collimator (SHC) that is capable of obtaining the depth of both kidneys without repositioning the camera. This method makes use of the fact that two unique projections of each kidney are simultaneously acquired along spatial angles. The depth of each kidney used in the attenuation correction calculation can be easily obtained trigometrically using this known angle and the distance of the collimator from the patient

  11. Cardiac-Specific Overexpression of Catalase Attenuates Lipopolysaccharide-Induced Myocardial Contractile Dysfunction: Role of Autophagy

    OpenAIRE

    Turdi, Subat; Han, Xuefeng; Huff, Anna F.; Roe, Nathan D.; Hu, Nan; Gao, Feng; Ren, Jun

    2012-01-01

    Lipopolysaccharide (LPS) from Gram-negative bacteria is a major initiator of sepsis, leading to cardiovascular collapse. Accumulating evidence has indicated a role of reactive oxygen species (ROS) in cardiovascular complication in sepsis. This study was designed to examine the effect of cardiac-specific overexpression of catalase in LPS-induced cardiac contractile dysfunction and the underlying mechanism(s) with a focus on autophagy. Catalase transgenic and wild-type FVB mice were challenged ...

  12. TVP1022 attenuates cardiac remodeling and kidney dysfunction in experimental volume overload-induced congestive heart failure.

    Science.gov (United States)

    Abassi, Zaid A; Barac, Yaron D; Kostin, Sawa; Roguin, Ariel; Ovcharenko, Elena; Awad, Hoda; Blank, Ayelet; Bar-Am, Orit; Amit, Tamar; Schaper, Jutta; Youdim, Moussa; Binah, Ofer

    2011-07-01

    Despite the availability of many pharmacological and mechanical therapies, the mortality rate among patients with congestive heart failure (CHF) remains high. We tested the hypothesis that TVP1022 (the S-isomer of rasagiline; Azilect), a neuroprotective and cytoprotective molecule, is also cardioprotective in the settings of experimental CHF in rats. In rats with volume overload-induced CHF, we investigated the therapeutic efficacy of TVP1022 (7.5 mg/kg) on cardiac function, structure, biomarkers, and kidney function. Treatment with TVP1022 for 7 days before CHF induction prevented the increase in left ventricular end-diastolic area and end-systolic area, and the decrease in fractional shortening measured 14 days after CHF induction. Additionally, TVP1022 pretreatment attenuated CHF-induced cardiomyocyte hypertrophy, fibrosis, plasma and ventricular B-type natriuretic peptide levels, and reactive oxygen species expression. Further, in CHF rats, TVP1022 decreased cytochrome c and caspase 3 expression, thereby contributing to the cardioprotective efficacy of the drug. TVP1022 also enhanced the urinary Na(+) excretion and improved the glomerular filtration rate. Similar cardioprotective effects were obtained when TVP1022 was given to rats after CHF induction. TVP1022 attenuated the adverse functional, structural, and molecular alterations in CHF, rendering this drug a promising candidate for improving cardiac and renal function in this disease state.

  13. Attenuation Correction Strategies for Positron Emission Tomography/Computed Tomography and 4-Dimensional Positron Emission Tomography/Computed Tomography

    OpenAIRE

    Pan, Tinsu; Zaidi, Habib

    2013-01-01

    This article discusses attenuation correction strategies in positron emission tomography/computed tomography (PET/CT) and 4 dimensional PET/CT imaging. Average CT scan derived from averaging the high temporal resolution CT images is effective in improving the registration of the CT and the PET images and quantification of the PET data. It underscores list mode data acquisition in 4 dimensional PET and introduces 4 dimensional CT popular in thoracic treatment planning to 4 dimensional PET/CT. ...

  14. Theoretical determination of gamma spectrometry systems efficiency based on probability functions. Application to self-attenuation correction factors

    Energy Technology Data Exchange (ETDEWEB)

    Barrera, Manuel, E-mail: manuel.barrera@uca.es [Escuela Superior de Ingeniería, University of Cadiz, Avda, Universidad de Cadiz 10, 11519 Puerto Real, Cadiz (Spain); Suarez-Llorens, Alfonso [Facultad de Ciencias, University of Cadiz, Avda, Rep. Saharaui s/n, 11510 Puerto Real, Cadiz (Spain); Casas-Ruiz, Melquiades; Alonso, José J.; Vidal, Juan [CEIMAR, University of Cadiz, Avda, Rep. Saharaui s/n, 11510 Puerto Real, Cádiz (Spain)

    2017-05-11

    A generic theoretical methodology for the calculation of the efficiency of gamma spectrometry systems is introduced in this work. The procedure is valid for any type of source and detector and can be applied to determine the full energy peak and the total efficiency of any source-detector system. The methodology is based on the idea of underlying probability of detection, which describes the physical model for the detection of the gamma radiation at the particular studied situation. This probability depends explicitly on the direction of the gamma radiation, allowing the use of this dependence the development of more realistic and complex models than the traditional models based on the point source integration. The probability function that has to be employed in practice must reproduce the relevant characteristics of the detection process occurring at the particular studied situation. Once the probability is defined, the efficiency calculations can be performed in general by using numerical methods. Monte Carlo integration procedure is especially useful to perform the calculations when complex probability functions are used. The methodology can be used for the direct determination of the efficiency and also for the calculation of corrections that require this determination of the efficiency, as it is the case of coincidence summing, geometric or self-attenuation corrections. In particular, we have applied the procedure to obtain some of the classical self-attenuation correction factors usually employed to correct for the sample attenuation of cylindrical geometry sources. The methodology clarifies the theoretical basis and approximations associated to each factor, by making explicit the probability which is generally hidden and implicit to each model. It has been shown that most of these self-attenuation correction factors can be derived by using a common underlying probability, having this probability a growing level of complexity as it reproduces more precisely

  15. Small average differences in attenuation corrected images between men and women in myocardial perfusion scintigraphy: a novel normal stress database

    International Nuclear Information System (INIS)

    Trägårdh, Elin; Sjöstrand, Karl; Jakobsson, David; Edenbrandt, Lars

    2011-01-01

    The American Society of Nuclear Cardiology and the Society of Nuclear Medicine state that incorporation of attenuation-corrected (AC) images in myocardial perfusion scintigraphy (MPS) will improve image quality, interpretive certainty, and diagnostic accuracy. However, commonly used software packages for MPS usually include normal stress databases for non-attenuation corrected (NC) images but not for attenuation-corrected (AC) images. The aim of the study was to develop and compare different normal stress databases for MPS in relation to NC vs. AC images, male vs. female gender, and presence vs. absence of obesity. The principal hypothesis was that differences in mean count values between men and women would be smaller with AC than NC images, thereby allowing for construction and use of gender-independent AC stress database. Normal stress perfusion databases were developed with data from 126 male and 205 female patients with normal MPS. The following comparisons were performed for all patients and separately for normal weight vs. obese patients: men vs. women for AC; men vs. women for NC; AC vs. NC for men; and AC vs. NC for women. When comparing AC for men vs. women, only minor differences in mean count values were observed, and there were no differences for normal weight vs. obese patients. For all other analyses major differences were found, particularly for the inferior wall. The results support the hypothesis that it is possible to use not only gender independent but also weight independent AC stress databases

  16. The effect of metal artefact reduction on CT-based attenuation correction for PET imaging in the vicinity of metallic hip implants: a phantom study.

    Science.gov (United States)

    Harnish, Roy; Prevrhal, Sven; Alavi, Abass; Zaidi, Habib; Lang, Thomas F

    2014-07-01

    To determine if metal artefact reduction (MAR) combined with a priori knowledge of prosthesis material composition can be applied to obtain CT-based attenuation maps with sufficient accuracy for quantitative assessment of (18)F-fluorodeoxyglucose uptake in lesions near metallic prostheses. A custom hip prosthesis phantom with a lesion-sized cavity filled with 0.2 ml (18)F-FDG solution having an activity of 3.367 MBq adjacent to a prosthesis bore was imaged twice with a chrome-cobalt steel hip prosthesis and a plastic replica, respectively. Scanning was performed on a clinical hybrid PET/CT system equipped with an additional external (137)Cs transmission source. PET emission images were reconstructed from both phantom configurations with CT-based attenuation correction (CTAC) and with CT-based attenuation correction using MAR (MARCTAC). To compare results with the attenuation-correction method extant prior to the advent of PET/CT, we also carried out attenuation correction with (137)Cs transmission-based attenuation correction (TXAC). CTAC and MARCTAC images were scaled to attenuation coefficients at 511 keV using a trilinear function that mapped the highest CT values to the prosthesis alloy attenuation coefficient. Accuracy and spatial distribution of the lesion activity was compared between the three reconstruction schemes. Compared to the reference activity of 3.37 MBq, the estimated activity quantified from the PET image corrected by TXAC was 3.41 MBq. The activity estimated from PET images corrected by MARCTAC was similar in accuracy at 3.32 MBq. CTAC corrected PET images resulted in nearly 40 % overestimation of lesion activity at 4.70 MBq. Comparison of PET images obtained with the plastic and metal prostheses in place showed that CTAC resulted in a marked distortion of the (18)F-FDG distribution within the lesion, whereas application of MARCTAC and TXAC resulted in lesion distributions similar to those observed with the plastic replica. MAR combined

  17. Effect of scatter and attenuation correction in ROI analysis of brain perfusion scintigraphy. Phantom experiment and clinical study in patients with unilateral cerebrovascular disease

    Energy Technology Data Exchange (ETDEWEB)

    Bai, J. [Keio Univ., Tokyo (Japan). 21st Century Center of Excellence Program; Hashimoto, J.; Kubo, A. [Keio Univ., Tokyo (Japan). Dept. of Radiology; Ogawa, K. [Hosei Univ., Tokyo (Japan). Dept. of Electronic Informatics; Fukunaga, A.; Onozuka, S. [Keio Univ., Tokyo (Japan). Dept. of Neurosurgery

    2007-07-01

    The aim of this study was to evaluate the effect of scatter and attenuation correction in region of interest (ROI) analysis of brain perfusion single-photon emission tomography (SPECT), and to assess the influence of selecting the reference area on the calculation of lesion-to-reference count ratios. Patients, methods: Data were collected from a brain phantom and ten patients with unilateral internal carotid artery stenosis. A simultaneous emission and transmission scan was performed after injecting {sup 123}I-iodoamphetamine. We reconstructed three SPECT images from common projection data: with scatter correction and nonuniform attenuation correction, with scatter correction and uniform attenuation correction, and with uniform attenuation correction applied to data without scatter correction. Regional count ratios were calculated by using four different reference areas (contralateral intact side, ipsilateral cerebellum, whole brain and hemisphere). Results: Scatter correction improved the accuracy of measuring the count ratios in the phantom experiment. It also yielded marked difference in the count ratio in the clinical study when using the cerebellum, whole brain or hemisphere as the reference. Difference between nonuniform and uniform attenuation correction was not significant in the phantom and clinical studies except when the cerebellar reference was used. Calculation of the lesion-to-normal count ratios referring the same site in the contralateral hemisphere was not dependent on the use of scatter correction or transmission scan-based attenuation correction. Conclusion: Scatter correction was indispensable for accurate measurement in most of the ROI analyses. Nonuniform attenuation correction is not necessary when using the reference area other than the cerebellum. (orig.)

  18. PET/MR imaging of bone lesions - implications for PET quantification from imperfect attenuation correction

    International Nuclear Information System (INIS)

    Samarin, Andrei; Burger, Cyrill; Crook, David W.; Burger, Irene A.; Schmid, Daniel T.; Schulthess, Gustav K. von; Kuhn, Felix P.; Wollenweber, Scott D.

    2012-01-01

    Accurate attenuation correction (AC) is essential for quantitative analysis of PET tracer distribution. In MR, the lack of cortical bone signal makes bone segmentation difficult and may require implementation of special sequences. The purpose of this study was to evaluate the need for accurate bone segmentation in MR-based AC for whole-body PET/MR imaging. In 22 patients undergoing sequential PET/CT and 3-T MR imaging, modified CT AC maps were produced by replacing pixels with values of >100 HU, representing mostly bone structures, by pixels with a constant value of 36 HU corresponding to soft tissue, thereby simulating current MR-derived AC maps. A total of 141 FDG-positive osseous lesions and 50 soft-tissue lesions adjacent to bones were evaluated. The mean standardized uptake value (SUVmean) was measured in each lesion in PET images reconstructed once using the standard AC maps and once using the modified AC maps. Subsequently, the errors in lesion tracer uptake for the modified PET images were calculated using the standard PET image as a reference. Substitution of bone by soft tissue values in AC maps resulted in an underestimation of tracer uptake in osseous and soft tissue lesions adjacent to bones of 11.2 ± 5.4 % (range 1.5-30.8 %) and 3.2 ± 1.7 % (range 0.2-4 %), respectively. Analysis of the spine and pelvic osseous lesions revealed a substantial dependence of the error on lesion composition. For predominantly sclerotic spine lesions, the mean underestimation was 15.9 ± 3.4 % (range 9.9-23.5 %) and for osteolytic spine lesions, 7.2 ± 1.7 % (range 4.9-9.3 %), respectively. CT data simulating treating bone as soft tissue as is currently done in MR maps for PET AC leads to a substantial underestimation of tracer uptake in bone lesions and depends on lesion composition, the largest error being seen in sclerotic lesions. Therefore, depiction of cortical bone and other calcified areas in MR AC maps is necessary for accurate quantification of tracer uptake

  19. Deep Learning MR Imaging-based Attenuation Correction for PET/MR Imaging.

    Science.gov (United States)

    Liu, Fang; Jang, Hyungseok; Kijowski, Richard; Bradshaw, Tyler; McMillan, Alan B

    2018-02-01

    Purpose To develop and evaluate the feasibility of deep learning approaches for magnetic resonance (MR) imaging-based attenuation correction (AC) (termed deep MRAC) in brain positron emission tomography (PET)/MR imaging. Materials and Methods A PET/MR imaging AC pipeline was built by using a deep learning approach to generate pseudo computed tomographic (CT) scans from MR images. A deep convolutional auto-encoder network was trained to identify air, bone, and soft tissue in volumetric head MR images coregistered to CT data for training. A set of 30 retrospective three-dimensional T1-weighted head images was used to train the model, which was then evaluated in 10 patients by comparing the generated pseudo CT scan to an acquired CT scan. A prospective study was carried out for utilizing simultaneous PET/MR imaging for five subjects by using the proposed approach. Analysis of covariance and paired-sample t tests were used for statistical analysis to compare PET reconstruction error with deep MRAC and two existing MR imaging-based AC approaches with CT-based AC. Results Deep MRAC provides an accurate pseudo CT scan with a mean Dice coefficient of 0.971 ± 0.005 for air, 0.936 ± 0.011 for soft tissue, and 0.803 ± 0.021 for bone. Furthermore, deep MRAC provides good PET results, with average errors of less than 1% in most brain regions. Significantly lower PET reconstruction errors were realized with deep MRAC (-0.7% ± 1.1) compared with Dixon-based soft-tissue and air segmentation (-5.8% ± 3.1) and anatomic CT-based template registration (-4.8% ± 2.2). Conclusion The authors developed an automated approach that allows generation of discrete-valued pseudo CT scans (soft tissue, bone, and air) from a single high-spatial-resolution diagnostic-quality three-dimensional MR image and evaluated it in brain PET/MR imaging. This deep learning approach for MR imaging-based AC provided reduced PET reconstruction error relative to a CT-based standard within the brain compared

  20. Technical Note: Correcting for signal attenuation from noisy proxy data in climate reconstructions

    KAUST Repository

    Ammann, C. M.; Genton, M. G.; Li, B.

    2010-01-01

    regression parameter estimation can lead to substantial amplitude attenuation if the predictors carry significant amounts of noise. This issue is known as "Measurement Error" (Fuller, 1987; Carroll et al., 2006). Climate proxies derived from tree-rings, ice

  1. The value of attenuation correction in dual-head coincidence imaging

    International Nuclear Information System (INIS)

    Shi Yiping; Huang Gang; Liu Jianjun

    2004-01-01

    Objective: To elucidate the value of attenuation correction (AC) in dual-head coincidence imaging by comparison of phantom and patients images with and without AC. Methods: We used a 20-cm-diameter cylindrical phantom, which contains four spheres of inside diameters of 1.4-2.9 cm for phantom study (1.4 cm, n=2; 2.0 cm, n=l; 2.9 cm, n=1). The axial length of the phantom was 30 cm. The wall thickness of the spheres was 1 mm. Both the phantom and spheres were filled with a solution that contained 18F-FDG. Three acquisitions were performed with the concentrations adjusted to provide a ratio of sphere-to-background activity of 3:1, 5:1 and 10:1. There were 38 patients (30 men and 8 women, age range 31 to 78 years) with suspected lung cancer included in clinical study. All patients were performed pneumonectomies and verified by histopathology. The histological tumor types were adenocarcinoma (n=11), squamous carcinoma (n=8), adenosquamous carcinoma (n=4), large cell carcinoma (n=2), neuroendocrine carcinoma (n=l), metastatic carcinoma (n=4), bronchiolo-alveolar carcinoma (n=1) and benign mass (n=7). The patients were fasted for at least 6 hours before the start of the study. Sixty minutes after intravenous administration of 111-185MBq (3-5mCi) 18F-FDG, emission scanning was performed using a dual-head gamma camera with a 128x128x16 matrix, with energy windows of 511 keV, 180 degree rotation, 32 steps and an acquisition time of 40 s per step. Subsequently, transmission scanning was performed with energy windows of 662 keV, 360 degree rotation, 96 steps and an acquisition time of 2s per step. The coincidence gamma camera imaging data were reconstructed by MCD iterative Methods with a Wiener filter (noise factor 0.75, pixel size 3.95 mm 3 ). Visual analysis and semiquantitative analysis were performed in AC and NAC images. For visual interpretation, a positive lesion was defined as any activity above local background. The count ratio of tumor to surrounded normal tissue (T

  2. Clinical usefulness of scatter and attenuation correction for brain single photon emission computed tomography (SPECT) in pediatrics

    International Nuclear Information System (INIS)

    Adachi, Itaru; Doi, Kenji; Komori, Tsuyoshi; Hou, Nobuyoshi; Tabuchi, Koujirou; Matsui, Ritsuo; Sueyoshi, Kouzou; Utsunomiya, Keita; Narabayashi, Isamu

    1998-01-01

    This investigation was undertaken to study clinical usefulness of scatter and attenuation correction (SAC) of brain SPECT in infants to compare the standard reconstruction (STD). The brain SPECT was performed in 31 patients with 19 epilepsy, 5 cerebro-vascular disease, 2 brain tumor, 3 meningitis, 1 hydrocephalus and psychosis (mean age 5.0±4.9 years old). Many patients was necessary to be injected sedatives for restraining body motion after Technetium-99m hexamethylpropylene amine oxime ( 99m Tc-HMPAO) was injected at the convulsion or rest. Brain SPECT data were acquired with triple detector gamma camera (GCA-9300 Toshiba Japan). These data were reconstructed by filtered backprojection after the raw data were corrected by triple energy windows method of scatter correction and Chang filtered method of attenuation correction. The same data was reconstructed by filtered backprojection without these corrections. Both SAC and STD SPECT images were analyzed by the visual interpretation. The uptake ratio of cerebral basal nuclei was calculated by the counts of the thalamus or lenticular nuclei divided by the cortex. All images of SAC method were excellent than that of STD method. The thalamic uptake ratio in SAC method was higher than that of STD method (1.22±0.09>0.87±0.22 p 1.02±0.16 p<0.01). Transmission scan is the most suitable method of absorption correction. But the transmission scan is not adequate for examination of children, because this scan needs a lot of time and the infants are exposed by the line source radioisotope. It was concluded that these scatter and absorption corrections were most suitable method for brain SPECT in pediatrics. (author)

  3. Clinical usefulness of scatter and attenuation correction for brain single photon emission computed tomography (SPECT) in pediatrics

    Energy Technology Data Exchange (ETDEWEB)

    Adachi, Itaru; Doi, Kenji; Komori, Tsuyoshi; Hou, Nobuyoshi; Tabuchi, Koujirou; Matsui, Ritsuo; Sueyoshi, Kouzou; Utsunomiya, Keita; Narabayashi, Isamu [Osaka Medical Coll., Takatsuki (Japan)

    1998-01-01

    This investigation was undertaken to study clinical usefulness of scatter and attenuation correction (SAC) of brain SPECT in infants to compare the standard reconstruction (STD). The brain SPECT was performed in 31 patients with 19 epilepsy, 5 cerebro-vascular disease, 2 brain tumor, 3 meningitis, 1 hydrocephalus and psychosis (mean age 5.0{+-}4.9 years old). Many patients was necessary to be injected sedatives for restraining body motion after Technetium-99m hexamethylpropylene amine oxime ({sup 99m}Tc-HMPAO) was injected at the convulsion or rest. Brain SPECT data were acquired with triple detector gamma camera (GCA-9300 Toshiba Japan). These data were reconstructed by filtered backprojection after the raw data were corrected by triple energy windows method of scatter correction and Chang filtered method of attenuation correction. The same data was reconstructed by filtered backprojection without these corrections. Both SAC and STD SPECT images were analyzed by the visual interpretation. The uptake ratio of cerebral basal nuclei was calculated by the counts of the thalamus or lenticular nuclei divided by the cortex. All images of SAC method were excellent than that of STD method. The thalamic uptake ratio in SAC method was higher than that of STD method (1.22{+-}0.09>0.87{+-}0.22 p<0.01). The lenticular nuclear uptake ratio in SAC method was higher than that of STD method (1.26{+-}0.15>1.02{+-}0.16 p<0.01). Transmission scan is the most suitable method of absorption correction. But the transmission scan is not adequate for examination of children, because this scan needs a lot of time and the infants are exposed by the line source radioisotope. It was concluded that these scatter and absorption corrections were most suitable method for brain SPECT in pediatrics. (author)

  4. Subject-specific bone attenuation correction for brain PET/MR: can ZTE-MRI substitute CT scan accurately?

    Science.gov (United States)

    Khalifé, Maya; Fernandez, Brice; Jaubert, Olivier; Soussan, Michael; Brulon, Vincent; Buvat, Irène; Comtat, Claude

    2017-10-01

    In brain PET/MR applications, accurate attenuation maps are required for accurate PET image quantification. An implemented attenuation correction (AC) method for brain imaging is the single-atlas approach that estimates an AC map from an averaged CT template. As an alternative, we propose to use a zero echo time (ZTE) pulse sequence to segment bone, air and soft tissue. A linear relationship between histogram normalized ZTE intensity and measured CT density in Hounsfield units (HU ) in bone has been established thanks to a CT-MR database of 16 patients. Continuous AC maps were computed based on the segmented ZTE by setting a fixed linear attenuation coefficient (LAC) to air and soft tissue and by using the linear relationship to generate continuous μ values for the bone. Additionally, for the purpose of comparison, four other AC maps were generated: a ZTE derived AC map with a fixed LAC for the bone, an AC map based on the single-atlas approach as provided by the PET/MR manufacturer, a soft-tissue only AC map and, finally, the CT derived attenuation map used as the gold standard (CTAC). All these AC maps were used with different levels of smoothing for PET image reconstruction with and without time-of-flight (TOF). The subject-specific AC map generated by combining ZTE-based segmentation and linear scaling of the normalized ZTE signal into HU was found to be a good substitute for the measured CTAC map in brain PET/MR when used with a Gaussian smoothing kernel of 4~mm corresponding to the PET scanner intrinsic resolution. As expected TOF reduces AC error regardless of the AC method. The continuous ZTE-AC performed better than the other alternative MR derived AC methods, reducing the quantification error between the MRAC corrected PET image and the reference CTAC corrected PET image.

  5. Ultra-low dose CT attenuation correction for PET/CT: analysis of sparse view data acquisition and reconstruction algorithms

    Science.gov (United States)

    Rui, Xue; Cheng, Lishui; Long, Yong; Fu, Lin; Alessio, Adam M.; Asma, Evren; Kinahan, Paul E.; De Man, Bruno

    2015-01-01

    For PET/CT systems, PET image reconstruction requires corresponding CT images for anatomical localization and attenuation correction. In the case of PET respiratory gating, multiple gated CT scans can offer phase-matched attenuation and motion correction, at the expense of increased radiation dose. We aim to minimize the dose of the CT scan, while preserving adequate image quality for the purpose of PET attenuation correction by introducing sparse view CT data acquisition. Methods We investigated sparse view CT acquisition protocols resulting in ultra-low dose CT scans designed for PET attenuation correction. We analyzed the tradeoffs between the number of views and the integrated tube current per view for a given dose using CT and PET simulations of a 3D NCAT phantom with lesions inserted into liver and lung. We simulated seven CT acquisition protocols with {984, 328, 123, 41, 24, 12, 8} views per rotation at a gantry speed of 0.35 seconds. One standard dose and four ultra-low dose levels, namely, 0.35 mAs, 0.175 mAs, 0.0875 mAs, and 0.04375 mAs, were investigated. Both the analytical FDK algorithm and the Model Based Iterative Reconstruction (MBIR) algorithm were used for CT image reconstruction. We also evaluated the impact of sinogram interpolation to estimate the missing projection measurements due to sparse view data acquisition. For MBIR, we used a penalized weighted least squares (PWLS) cost function with an approximate total-variation (TV) regularizing penalty function. We compared a tube pulsing mode and a continuous exposure mode for sparse view data acquisition. Global PET ensemble root-mean-squares-error (RMSE) and local ensemble lesion activity error were used as quantitative evaluation metrics for PET image quality. Results With sparse view sampling, it is possible to greatly reduce the CT scan dose when it is primarily used for PET attenuation correction with little or no measureable effect on the PET image. For the four ultra-low dose levels

  6. Eicosapentenoic Acid Attenuates Allograft Rejection in an HLA-B27/EGFP Transgenic Rat Cardiac Transplantation Model.

    Science.gov (United States)

    Liu, Zhong; Hatayama, Naoyuki; Xie, Lin; Kato, Ken; Zhu, Ping; Ochiya, Takahiro; Nagahara, Yukitoshi; Hu, Xiang; Li, Xiao-Kang

    2012-01-01

    The development of an animal model bearing definite antigens is important to facilitate the evaluation and modulation of specific allo-antigen responses after transplantation. In the present study, heterotopic cardiac transplantation was performed from F344/EGFPTg and F344/HLA-B27Tg rats to F344 rats. The F344 recipients accepted the F344/EGFPTg transplants, whereas they rejected the cardiac tissue from the F344/HLA-B27Tg rats by 39.4 ± 6.5 days, due to high production of anti-HLA-B27 IgM- and IgG-specific antibodies. In addition, immunization of F344 rats with skin grafts from F344/HLA-B27Tg rats resulted in robust production of anti- HLA-B27 IgM and IgG antibodies and accelerated the rejection of a secondary cardiac allograft (7.4 ± 1.9 days). Of interest, the F344 recipients rejected cardiac grafts from double transgenic F344/HLA-B27&EGFPTg rats within 9.0 ± 3.2 days, and this was associated with a significant increase in the infiltration of lymphocytes by day 7, suggesting a role for cellular immune rejection. Eicosapentenoic acid (EPA), one of the ω-3 polyunsaturated fatty acids in fish oil, could attenuate the production of anti-HLA IgG antibodies and B-cell proliferation, significantly prolonging double transgenic F344HLA-B27&EGFPTg to F344 rat cardiac allograft survival (36.1 ± 13.6 days). Moreover, the mRNA expression in the grafts was assessed by quantitative reverse transcription polymerase chain reaction (qRT-PCR), revealing an increase in the expression of the HO-1, IL-10, TGF-β, IDO, and Foxp3 genes in the EPA-treated group. Hence, our data indicate that HLA-B27 and/or GFP transgenic proteins are useful for establishing a unique animal transplantation model to clarify the mechanism underlying the allogeneic cellular and humoral immune response, in which the transplant antigens are specifically presented. Furthermore, we also demonstrated that EPA was effective in the treatment of rat cardiac allograft rejection and may allow the development of

  7. Determination of the mass attenuation coefficients for X-ray fluorescence measurements correction by the Rayleigh to Compton scattering ratio

    Energy Technology Data Exchange (ETDEWEB)

    Conti, C.C., E-mail: ccconti@ird.gov.br [Institute for Radioprotection and Dosimetry – IRD/CNEN, Rio de Janeiro (Brazil); Physics Institute, State University of Rio de Janeiro – UERJ, Rio de Janeiro (Brazil); Anjos, M.J. [Physics Institute, State University of Rio de Janeiro – UERJ, Rio de Janeiro (Brazil); Salgado, C.M. [Nuclear Engineering Institute – IEN/CNEN, Rio de Janeiro (Brazil)

    2014-09-15

    Highlights: •This work describes a procedure for sample self-absorption correction. •The use of Monte Carlo simulation to calculate the mass attenuation coefficients curve was effective. •No need for transmission measurement, saving time, financial resources and effort. •This article provides de curves for the 90° scattering angle. •Calculation on-line at (www.macx.net.br). -- Abstract: X-ray fluorescence technique plays an important role in nondestructive analysis nowadays. The development of equipment, including portable ones, enables a wide assortment of possibilities for analysis of stable elements, even in trace concentrations. Nevertheless, despite of the advantages, one important drawback is radiation self-attenuation in the sample being measured, which needs to be considered in the calculation for the proper determination of elemental concentration. The mass attenuation coefficient can be determined by transmission measurement, but, in this case, the sample must be in slab shape geometry and demands two different setups and measurements. The Rayleigh to Compton scattering ratio, determined from the X-ray fluorescence spectrum, provides a link to the mass attenuation coefficient by means of a polynomial type equation. This work presents a way to construct a Rayleigh to Compton scattering ratio versus mass attenuation coefficient curve by using the MCNP5 Monte Carlo computer code. The comparison between the calculated and literature values of the mass attenuation coefficient for some known samples showed to be within 15%. This calculation procedure is available on-line at (www.macx.net.br)

  8. Cardiac myocyte follistatin-like 1 functions to attenuate hypertrophy following pressure overload

    NARCIS (Netherlands)

    Shimano, Masayuki; Ouchi, Noriyuki; Nakamura, Kazuto; van Wijk, Bram; Ohashi, Koji; Asaumi, Yasuhide; Higuchi, Akiko; Pimentel, David R.; Sam, Flora; Murohara, Toyoaki; van den Hoff, Maurice J. B.; Walsh, Kenneth

    2011-01-01

    Factors secreted by the heart, referred to as "cardiokines," have diverse actions in the maintenance of cardiac homeostasis and remodeling. Follistatin-like 1 (Fstl1) is a secreted glycoprotein expressed in the adult heart and is induced in response to injurious conditions that promote myocardial

  9. Treatment with Fenofibrate plus a low dose of Benznidazole attenuates cardiac dysfunction in experimental Chagas disease

    Directory of Open Access Journals (Sweden)

    Ágata C. Cevey

    2017-12-01

    Full Text Available Trypanosoma cruzi induces serious cardiac alterations during the chronic infection. Intense inflammatory response observed from the beginning of infection, is critical for the control of parasite proliferation and evolution of Chagas disease. Peroxisome proliferator-activated receptors (PPAR-α, are known to modulate inflammation.In this study we investigated whether a PPAR-α agonist, Fenofibrate, improves cardiac function and inflammatory parameters in a murine model of T. cruzi infection. BALB/c mice were sequentially infected with two T. cruzi strains of different genetic background. Benznidazole, commonly used as trypanocidal drug, cleared parasites but did not preclude cardiac pathology, resembling what is found in human chronic chagasic cardiomyopathy. Fenofibrate treatment restored to normal values the ejection and shortening fractions, left ventricular end-diastolic, left ventricular end-systolic diameter, and isovolumic relaxation time. Moreover, it reduced cardiac inflammation and fibrosis, decreased the expression of pro-inflammatory (IL-6, TNF-α and NOS2 and heart remodeling mediators (MMP-9 and CTGF, and reduced serum creatine kinase activity. The fact that Fenofibrate partially inhibited NOS2 expression and NO release in the presence of a PPAR-α non-competitive inhibitor, suggested it also acted through PPAR-α-independent pathways. Since IκBα cytosolic degradation was inhibited by Fenofibrate, it can be concluded that the NFκB pathway has a role in its effects. Thus, we demonstrate that Fenofibrate acts through PPAR-α-dependent and -independent pathways.Our study shows that combined treatment with Fenofibrate plus Benznidazole is able both to reverse the cardiac dysfunction associated with the ongoing inflammatory response and fibrosis and to attain parasite clearance in an experimental model of Chagas disease. Keywords: Trypanosoma cruzi, Heart dysfunction, PPAR-α, Fenofibrate treatment, Inflammatory mediators

  10. Attenuation correction for brain PET imaging using deep neural network based on dixon and ZTE MR images.

    Science.gov (United States)

    Gong, Kuang; Yang, Jaewon; Kim, Kyungsang; El Fakhri, Georges; Seo, Youngho; Li, Quanzheng

    2018-05-23

    Positron Emission Tomography (PET) is a functional imaging modality widely used in neuroscience studies. To obtain meaningful quantitative results from PET images, attenuation correction is necessary during image reconstruction. For PET/MR hybrid systems, PET attenuation is challenging as Magnetic Resonance (MR) images do not reflect attenuation coefficients directly. To address this issue, we present deep neural network methods to derive the continuous attenuation coefficients for brain PET imaging from MR images. With only Dixon MR images as the network input, the existing U-net structure was adopted and analysis using forty patient data sets shows it is superior than other Dixon based methods. When both Dixon and zero echo time (ZTE) images are available, we have proposed a modified U-net structure, named GroupU-net, to efficiently make use of both Dixon and ZTE information through group convolution modules when the network goes deeper. Quantitative analysis based on fourteen real patient data sets demonstrates that both network approaches can perform better than the standard methods, and the proposed network structure can further reduce the PET quantification error compared to the U-net structure. © 2018 Institute of Physics and Engineering in Medicine.

  11. Transmission-less attenuation correction in time-of-flight PET: analysis of a discrete iterative algorithm

    International Nuclear Information System (INIS)

    Defrise, Michel; Rezaei, Ahmadreza; Nuyts, Johan

    2014-01-01

    The maximum likelihood attenuation correction factors (MLACF) algorithm has been developed to calculate the maximum-likelihood estimate of the activity image and the attenuation sinogram in time-of-flight (TOF) positron emission tomography, using only emission data without prior information on the attenuation. We consider the case of a Poisson model of the data, in the absence of scatter or random background. In this case the maximization with respect to the attenuation factors can be achieved in a closed form and the MLACF algorithm works by updating the activity. Despite promising numerical results, the convergence of this algorithm has not been analysed. In this paper we derive the algorithm and demonstrate that the MLACF algorithm monotonically increases the likelihood, is asymptotically regular, and that the limit points of the iteration are stationary points of the likelihood. Because the problem is not convex, however, the limit points might be saddle points or local maxima. To obtain some empirical insight into the latter question, we present data obtained by applying MLACF to 2D simulated TOF data, using a large number of iterations and different initializations. (paper)

  12. [Comparison of the effects of phosphodiesterase III inhibitors, milrinone and olprinone, in infant corrective cardiac surgery].

    Science.gov (United States)

    Sakimura, Shotaro; Yoshino, Jun; Izumi, Kaoru; Jimi, Nobuo; Sumiyoshi, Rieko; Mizuno, Keiichiro

    2013-05-01

    Clinical characteristics of phosphodiesterase (PDE) III inhibitors, milrinone and olprinone, is not fully understood in infants. We therefore retrospectively examined the hemodynamics, metabolism, and oxygenation of two different PDE III inhibitors in infants undergoing radical correction of ventricular septal defect with pulmonary hypertension. Twenty-six infants with pulmonary hypertension undergoing ventricular septum defect repair were retrospectively allocated to milrinone group (n= 13)and olprinone group(n=13). Hemodynamic parameters, acid-base balance, oxygenation and postoperative mechanical ventilation period were compared between the two groups at induction of anesthesia, weaning from cardiopulmonary bypass and the end of the surgery. The patients' mean age was 4.4 +/- 2.5 months. Demographic data were almost similar between the two groups. Milrinone and olprinone were administered at the rates of 0.5 and 0.3 microg x kg-1 x min-1 at the end of surgery, respectively. Hemodynamic variables, acid-base balance, Pao2 /FIo2 ratio and mechanical ventilation period were not significantly different between the two groups. No adverse side effects were observed during the study period. The effects of the PDE III inhibitors, milrinone and olprinone, on hemodynamic parameters, acid-base balance and oxygenation were similar in these infants. Both milrinone and olprinone could be used safely in infant cardiac surgery.

  13. One registration multi-atlas-based pseudo-CT generation for attenuation correction in PET/MRI

    International Nuclear Information System (INIS)

    Arabi, Hossein; Zaidi, Habib

    2016-01-01

    The outcome of a detailed assessment of various strategies for atlas-based whole-body bone segmentation from magnetic resonance imaging (MRI) was exploited to select the optimal parameters and setting, with the aim of proposing a novel one-registration multi-atlas (ORMA) pseudo-CT generation approach. The proposed approach consists of only one online registration between the target and reference images, regardless of the number of atlas images (N), while for the remaining atlas images, the pre-computed transformation matrices to the reference image are used to align them to the target image. The performance characteristics of the proposed method were evaluated and compared with conventional atlas-based attenuation map generation strategies (direct registration of the entire atlas images followed by voxel-wise weighting (VWW) and arithmetic averaging atlas fusion). To this end, four different positron emission tomography (PET) attenuation maps were generated via arithmetic averaging and VWW scheme using both direct registration and ORMA approaches as well as the 3-class attenuation map obtained from the Philips Ingenuity TF PET/MRI scanner commonly used in the clinical setting. The evaluation was performed based on the accuracy of extracted whole-body bones by the different attenuation maps and by quantitative analysis of resulting PET images compared to CT-based attenuation-corrected PET images serving as reference. The comparison of validation metrics regarding the accuracy of extracted bone using the different techniques demonstrated the superiority of the VWW atlas fusion algorithm achieving a Dice similarity measure of 0.82 ± 0.04 compared to arithmetic averaging atlas fusion (0.60 ± 0.02), which uses conventional direct registration. Application of the ORMA approach modestly compromised the accuracy, yielding a Dice similarity measure of 0.76 ± 0.05 for ORMA-VWW and 0.55 ± 0.03 for ORMA-averaging. The results of quantitative PET analysis followed the same

  14. One registration multi-atlas-based pseudo-CT generation for attenuation correction in PET/MRI

    Energy Technology Data Exchange (ETDEWEB)

    Arabi, Hossein [Geneva University Hospital, Division of Nuclear Medicine and Molecular Imaging, Geneva 4 (Switzerland); Zaidi, Habib [Geneva University Hospital, Division of Nuclear Medicine and Molecular Imaging, Geneva 4 (Switzerland); Geneva University, Geneva Neuroscience Center, Geneva (Switzerland); University of Groningen, University Medical Center Groningen, Department of Nuclear Medicine and Molecular Imaging, Groningen (Netherlands); University of Southern Denmark, Department of Nuclear Medicine, Odense (Denmark)

    2016-10-15

    The outcome of a detailed assessment of various strategies for atlas-based whole-body bone segmentation from magnetic resonance imaging (MRI) was exploited to select the optimal parameters and setting, with the aim of proposing a novel one-registration multi-atlas (ORMA) pseudo-CT generation approach. The proposed approach consists of only one online registration between the target and reference images, regardless of the number of atlas images (N), while for the remaining atlas images, the pre-computed transformation matrices to the reference image are used to align them to the target image. The performance characteristics of the proposed method were evaluated and compared with conventional atlas-based attenuation map generation strategies (direct registration of the entire atlas images followed by voxel-wise weighting (VWW) and arithmetic averaging atlas fusion). To this end, four different positron emission tomography (PET) attenuation maps were generated via arithmetic averaging and VWW scheme using both direct registration and ORMA approaches as well as the 3-class attenuation map obtained from the Philips Ingenuity TF PET/MRI scanner commonly used in the clinical setting. The evaluation was performed based on the accuracy of extracted whole-body bones by the different attenuation maps and by quantitative analysis of resulting PET images compared to CT-based attenuation-corrected PET images serving as reference. The comparison of validation metrics regarding the accuracy of extracted bone using the different techniques demonstrated the superiority of the VWW atlas fusion algorithm achieving a Dice similarity measure of 0.82 ± 0.04 compared to arithmetic averaging atlas fusion (0.60 ± 0.02), which uses conventional direct registration. Application of the ORMA approach modestly compromised the accuracy, yielding a Dice similarity measure of 0.76 ± 0.05 for ORMA-VWW and 0.55 ± 0.03 for ORMA-averaging. The results of quantitative PET analysis followed the same

  15. Image artifacts from MR-based attenuation correction in clinical, whole-body PET/MRI

    DEFF Research Database (Denmark)

    Keller, Sune H; Holm, Søren; Hansen, Adam E

    2013-01-01

    Integrated whole-body PET/MRI tomographs have become available. PET/MR imaging has the potential to supplement, or even replace combined PET/CT imaging in selected clinical indications. However, this is true only if methodological pitfalls and image artifacts arising from novel MR-based attenuation...

  16. Quantitative analysis of X-band weather radar attenuation correction accuracy

    NARCIS (Netherlands)

    Berne, A.D.; Uijlenhoet, R.

    2006-01-01

    At short wavelengths, especially C-, X-, and K-band, weather radar signals arc attenuated by the precipitation along their paths. This constitutes a major source of error for radar rainfall estimation, in particular for intense precipitation. A recently developed stochastic simulator of range

  17. Desmodium gangeticum root extract attenuates isoproterenol-induced cardiac hypertrophic growth in rats.

    OpenAIRE

    Divya Hitler; Parthasarathy Arumugam; Mathivanan Narayanasamy; Elangovan Vellaichamy

    2014-01-01

    Context: Desmodium gangeticum (L) DC (Fabaceae; DG), a medicinal plant that grows in tropical habitats, is widely used to treat various ailments including digestive and inflammatory disorders. Aims: To investigate the possible cardioprotective activity of a DG root extract against isoproterenol (ISO)-induced left ventricular cardiac hypertrophy (LVH) in adult Wistar rats. Methods: Daily intraperitoneal administration of ISO (10 mg/kg body weight, single injection) for 7 days induced LVH...

  18. Alpha-lipoic acid attenuates cardiac fibrosis in Otsuka Long-Evans Tokushima Fatty rats

    Directory of Open Access Journals (Sweden)

    Lee Jung Eun

    2012-09-01

    Full Text Available Abstract Background Hyperglycemia leads to cardiac oxidative stress and an imbalance in glucose homeostasis. Diabetic cardiomyopathy is characterised by cardiac hypertrophy and fibrosis. However, the underlying mechanisms of diabetic cardiomyopathy are not fully understood. This study aimed to investigate the effects of alpha-lipoic acid (ALA on cardiac energy metabolism, antioxidant effect, and fibrosis in the hearts of Otsuka Long-Evans Tokushima fatty (OLETF rats. Methods Animals were separated into non-diabetic Long-Evans Tokushima Otsuka (LETO rats and diabetes-prone OLETF rats with or without ALA (200 mg/kg/day administration for 16 weeks. Diabetic cardiomyopathy was assessed by staining with Sirius Red. The effect of ALA on AMPK signalling, antioxidant enzymes, and fibrosis-related genes in the heart of OLETF rats were performed by Western blot analysis or immunohistochemistry. Results Western blot analysis showed that cardiac adenosine monophosphate-activated kinase (AMPK signalling was lower in OLETF rats than in LETO rats, and that ALA treatment increased the signalling in OLETF rats. Furthermore, the low antioxidant activity in OLETF rats was increased by ALA treatment. In addition to increased Sirius red staining of collagen deposits, transforming growth factor-β1 (TGF-β1 and connective tissue growth factor (CTGF were expressed at higher levels in OLETF rat hearts than in LETO rat hearts, and the levels of these factors were decreased by ALA. Conclusions ALA enhances AMPK signalling, antioxidant, and antifibrogenic effect. Theses findings suggest that ALA may have beneficial effects in the treatment of diabetic cardiomyopathy.

  19. Triptolide Upregulates Myocardial Forkhead Helix Transcription Factor p3 Expression and Attenuates Cardiac Hypertrophy

    Science.gov (United States)

    Ding, Yuan-Yuan; Li, Jing-Mei; Guo, Feng-Jie; Liu, Ya; Tong, Yang-Fei; Pan, Xi-Chun; Lu, Xiao-Lan; Ye, Wen; Chen, Xiao-Hong; Zhang, Hai-Gang

    2016-01-01

    The forkhead/winged helix transcription factor (Fox) p3 can regulate the expression of various genes, and it has been reported that the transfer of Foxp3-positive T cells could ameliorate cardiac hypertrophy and fibrosis. Triptolide (TP) can elevate the expression of Foxp3, but its effects on cardiac hypertrophy remain unclear. In the present study, neonatal rat ventricular myocytes (NRVM) were isolated and stimulated with angiotensin II (1 μmol/L) to induce hypertrophic response. The expression of Foxp3 in NRVM was observed by using immunofluorescence assay. Fifty mice were randomly divided into five groups and received vehicle (control), isoproterenol (Iso, 5 mg/kg, s.c.), one of three doses of TP (10, 30, or 90 μg/kg, i.p.) for 14 days, respectively. The pathological morphology changes were observed after Hematoxylin and eosin, lectin and Masson’s trichrome staining. The levels of serum brain natriuretic peptide (BNP) and troponin I were determined by enzyme-linked immunosorbent assay and chemiluminescence, respectively. The mRNA and protein expressions of α- myosin heavy chain (MHC), β-MHC and Foxp3 were determined using real-time PCR and immunohistochemistry, respectively. It was shown that TP (1, 3, 10 μg/L) treatment significantly decreased cell size, mRNA and protein expression of β-MHC, and upregulated Foxp3 expression in NRVM. TP also decreased heart weight index, left ventricular weight index and, improved myocardial injury and fibrosis; and decreased the cross-scetional area of the myocardium, serum cardiac troponin and BNP. Additionally, TP markedly reduced the mRNA and protein expression of myocardial β-MHC and elevated the mRNA and protein expression of α-MHC and Foxp3 in a dose-dependent manner. In conclusion, TP can effectively ameliorate myocardial damage and inhibit cardiac hypertrophy, which is at least partly related to the elevation of Foxp3 expression in cardiomyocytes. PMID:27965581

  20. Moringa oleifera extract (Lam) attenuates Aluminium phosphide-induced acute cardiac toxicity in rats.

    Science.gov (United States)

    Gouda, Ahmed S; El-Nabarawy, Nagla A; Ibrahim, Samah F

    2018-01-01

    Moringa oleifera extract (Lam) has many antioxidant and protective properties. Objective: to investigate the antioxidant activities of Lam in counteracting the high oxidative stress caused by acute sub-lethal aluminium phosphide (AlP) intoxication in rat heart. These activities will be detected by histopathological examination and some oxidative stress biomarkers. a single sub-lethal dose of Alp (2 mg/kg body weight) was administered orally, and Lam was given orally at a dose (100 mg/kg body weight) one hour after receiving AlP to rats. aluminium phosphide caused significant cardiac histopathological changes with a significant increase in malondialdehyde (MDA); lipid peroxidation marker; and a significant depletion of antioxidant enzymes (catalase and glutathione reductase). However, treatment with Lam protected efficiently the cardiac tissue of intoxicated rats by increasing antioxidants levels with slight decreasing in MDA production compared to untreated group. This study suggested that Moringa oleifera extract could possibly restore the altered cardiac histopathology and some antioxidant power in AlP intoxicated rats, and it could even be used as adjuvant therapy against AlP-induced cardiotoxicity.

  1. Dental artifacts in the head and neck region: implications for Dixon-based attenuation correction in PET/MR

    Energy Technology Data Exchange (ETDEWEB)

    Ladefoged, Claes N; Hansen, Adam E; Keller, Sune H; Fischer, Barbara M [Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen East (Denmark); Rasmussen, Jacob H [Department of Oncology, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen East (Denmark); Law, Ian; Kjær, Andreas; Højgaard, Liselotte [Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen East (Denmark); Lauze, Francois [Department of Computer Science, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen East (Denmark); Beyer, Thomas [Centre for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, Vienna, A-1090 (Austria); Andersen, Flemming L [Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen East (Denmark)

    2015-03-11

    In the absence of CT or traditional transmission sources in combined clinical positron emission tomography/magnetic resonance (PET/MR) systems, MR images are used for MR-based attenuation correction (MR-AC). The susceptibility effects due to metal implants challenge MR-AC in the neck region of patients with dental implants. The purpose of this study was to assess the frequency and magnitude of subsequent PET image distortions following MR-AC. A total of 148 PET/MR patients with clear visual signal voids on the attenuation map in the dental region were included in this study. Patients were injected with [{sup 18}F]-FDG, [{sup 11}C]-PiB, [{sup 18}F]-FET, or [{sup 64}Cu]-DOTATATE. The PET/MR data were acquired over a single-bed position of 25.8 cm covering the head and neck. MR-AC was based on either standard MR-AC{sub DIXON} or MR-AC{sub INPAINTED} where the susceptibility-induced signal voids were substituted with soft tissue information. Our inpainting algorithm delineates the outer contour of signal voids breaching the anatomical volume using the non-attenuation-corrected PET image and classifies the inner air regions based on an aligned template of likely dental artifact areas. The reconstructed PET images were evaluated visually and quantitatively using regions of interests in reference regions. The volume of the artifacts and the computed relative differences in mean and max standardized uptake value (SUV) between the two PET images are reported. The MR-based volume of the susceptibility-induced signal voids on the MR-AC attenuation maps was between 1.6 and 520.8 mL. The corresponding/resulting bias of the reconstructed tracer distribution was localized mainly in the area of the signal void. The mean and maximum SUVs averaged across all patients increased after inpainting by 52% (± 11%) and 28% (± 11%), respectively, in the corrected region. SUV underestimation decreased with the distance to the signal void and correlated with the volume of the susceptibility

  2. The effect of metal artefact reduction on CT-based attenuation correction for PET imaging in the vicinity of metallic hip implants. A phantom study

    International Nuclear Information System (INIS)

    Harnish, R.; Lang, T.F.; Prevrhal, S.; Alavi, A.; Zaidi, H.

    2014-01-01

    To determine if metal artefact reduction (MAR) combined with a priori knowledge of prosthesis material composition can be applied to obtain CT-based attenuation maps with sufficient accuracy for quantitative assessment of 18 F-fluorodeoxyglucose uptake in lesions near metallic prostheses. A custom hip prosthesis phantom with a lesion-sized cavity filled with 0.2 ml 18 F-FDG solution having an activity of 3.367 MBq adjacent to a prosthesis bore was imaged twice with a chrome-cobalt steel hip prosthesis and a plastic replica, respectively. Scanning was performed on a clinical hybrid PET/CT system equipped with an additional external 137 Cs transmission source. PET emission images were reconstructed from both phantom configurations with CT-based attenuation correction (CTAC) and with CT-based attenuation correction using MAR (MARCTAC). To compare results with the attenuation-correction method extant prior to the advent of PET/CT, we also carried out attenuation correction with 137 Cs transmission-based attenuation correction (TXAC). CTAC and MARCTAC images were scaled to attenuation coefficients at 511 keV using a trilinear function that mapped the highest CT values to the prosthesis alloy attenuation coefficient. Accuracy and spatial distribution of the lesion activity was compared between the three reconstruction schemes. Compared to the reference activity of 3.37 MBq, the estimated activity quantified from the PET image corrected by TXAC was 3.41 MBq. The activity estimated from PET images corrected by MARCTAC was similar in accuracy at 3.32 MBq. CTAC corrected PET images resulted in nearly 40% overestimation of lesion activity at 4.70 MBq. Comparison of PET images obtained with the plastic and metal prostheses in place showed that CTAC resulted in a marked distortion of the 18 F-FDG distribution within the lesion, whereas application of MARCTAC and TXAC resulted in lesion distributions similar to those observed with the plastic replica. (author)

  3. Self-attenuation correction in the environmental sample gamma spectrometry; Correcao de auto-absorcao na espectrometria gama de amostras ambientais

    Energy Technology Data Exchange (ETDEWEB)

    Venturini, Luzia; Nisti, Marcelo B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)

    1997-10-01

    Self-attenuation corrections were calculated for gamma ray spectrometry of environmental samples with densities from 0.42 g/ml up to 1.59 g/ml, measured in Marinelli beakers and polyethylene flasks. These corrections are to be used when the counting efficiency is calculated for water measured in the same geometry. The model of Debertin for Marinelli beaker, numerical integration and experimental linear attenuation coefficients were used. (author). 3 refs., 4 figs., 6 tabs.

  4. Accuracy and Radiation Dose of CT-Based Attenuation Correction for Small Animal PET: A Monte Carlo Simulation Study

    International Nuclear Information System (INIS)

    Yang, Ching-Ching; Chan, Kai-Chieh

    2013-06-01

    -Small animal PET allows qualitative assessment and quantitative measurement of biochemical processes in vivo, but the accuracy and reproducibility of imaging results can be affected by several parameters. The first aim of this study was to investigate the performance of different CT-based attenuation correction strategies and assess the resulting impact on PET images. The absorbed dose in different tissues caused by scanning procedures was also discussed to minimize biologic damage generated by radiation exposure due to PET/CT scanning. A small animal PET/CT system was modeled based on Monte Carlo simulation to generate imaging results and dose distribution. Three energy mapping methods, including the bilinear scaling method, the dual-energy method and the hybrid method which combines the kVp conversion and the dual-energy method, were investigated comparatively through assessing the accuracy of estimating linear attenuation coefficient at 511 keV and the bias introduced into PET quantification results due to CT-based attenuation correction. Our results showed that the hybrid method outperformed the bilinear scaling method, while the dual-energy method achieved the highest accuracy among the three energy mapping methods. Overall, the accuracy of PET quantification results have similar trend as that for the estimation of linear attenuation coefficients, whereas the differences between the three methods are more obvious in the estimation of linear attenuation coefficients than in the PET quantification results. With regards to radiation exposure from CT, the absorbed dose ranged between 7.29-45.58 mGy for 50-kVp scan and between 6.61-39.28 mGy for 80-kVp scan. For 18 F radioactivity concentration of 1.86x10 5 Bq/ml, the PET absorbed dose was around 24 cGy for tumor with a target-to-background ratio of 8. The radiation levels for CT scans are not lethal to the animal, but concurrent use of PET in longitudinal study can increase the risk of biological effects. The

  5. Semi-automatic detection and correction of body organ motion, particularly cardiac motion in SPECT studies

    International Nuclear Information System (INIS)

    Quintana, J.C.; Caceres, F.; Vargas, P.

    2002-01-01

    Aim: Detect patient motion during SPECT imaging. Material and Method: SPECT study is carried out on a patient's body organ, such as the heart, and frame of image data are thereby acquired. The image data in these frames are subjected to a series of mappings and computations, from which frame containing a significant quantity of organ motion can be identified. Quantification of motion occurs by shifting some of the mapped data within a predetermined range, and selecting that data shift which minimizes the magnitude of a motion sensitive mathematical function. The sensitive mathematical function is constructed from all set of image frames using the pixel data within a region covering the body organ. Using cine display of planar image data, the operator defines the working region by marking two points, which define two horizontal lines covering the area of the body organ. This is the only operator intervention. The mathematical function integrates pixel data from all set of image frames and therefore does not use derivatives which may cause distortion in noisy data. Moreover, as a global function, this method is superior than that using frame-to-frame cross-correlation function to identify motion between adjacent frames. Using standard image processing software, the method was implemented computationally. Ten SPECT studies with movement (Sestamibi cardiac studies and 99m-ECD brain SPECT studies) were selected plus two others with no movement. The acquisition SPECT protocol for the cardiac study was as follow: Step and shoot mode, non-circular orbit, 64 stops 20s each, 64x64x16 matrix and LEHR colimator. For the brain SPECT, 128 stops over 360 0 were used. Artificial vertical displacements (±1-2 pixels) over several frames were introduced in those studies with no movement to simulate patient motion. Results: The method was successfully tested in all cases and was capable to recognize SPECT studies with no body motion as well as those with body motion (both from the

  6. Inhibition of PKR protects against H2O2-induced injury on neonatal cardiac myocytes by attenuating apoptosis and inflammation.

    Science.gov (United States)

    Wang, Yongyi; Men, Min; Xie, Bo; Shan, Jianggui; Wang, Chengxi; Liu, Jidong; Zheng, Hui; Yang, Wengang; Xue, Song; Guo, Changfa

    2016-12-08

    Reactive oxygenation species (ROS) generated from reperfusion results in cardiac injury through apoptosis and inflammation, while PKR has the ability to promote apoptosis and inflammation. The aim of the study was to investigate whether PKR is involved in hydrogen peroxide (H 2 O 2 ) induced neonatal cardiac myocytes (NCM) injury. In our study, NCM, when exposed to H 2 O 2 , resulted in persistent activation of PKR due to NCM endogenous RNA. Inhibition of PKR by 2-aminopurine (2-AP) or siRNA protected against H 2 O 2 induced apoptosis and injury. To elucidate the mechanism, we revealed that inhibition of PKR alleviated H 2 O 2 induced apoptosis companied by decreased caspase3/7 activity, BAX and caspase-3 expression. We also revealed that inhibition of PKR suppressed H 2 O 2 induced NFκB pathway and NLRP3 activation. Finally, we found ADAR1 mRNA and protein expression were both induced after H 2 O 2 treatment through STAT-2 dependent pathway. By gain and loss of ADAR1 expression, we confirmed ADAR1 modulated PKR activity. Therefore, we concluded inhibition of PKR protected against H 2 O 2 -induced injury by attenuating apoptosis and inflammation. A self-preservation mechanism existed in NCM that ADAR1 expression is induced by H 2 O 2 to limit PKR activation simultaneously. These findings identify a novel role for PKR/ADAR1 in myocardial reperfusion injury.

  7. Role of adenosine A2A receptor signaling in the nicotine-evoked attenuation of reflex cardiac sympathetic control

    International Nuclear Information System (INIS)

    El-Mas, Mahmoud M.; El-gowilly, Sahar M.; Fouda, Mohamed A.; Saad, Evan I.

    2011-01-01

    Baroreflex dysfunction contributes to increased cardiovascular risk in cigarette smokers. Given the importance of adenosinergic pathways in baroreflex control, the hypothesis was tested that defective central adenosinergic modulation of cardiac autonomic activity mediates the nicotine-baroreflex interaction. Baroreflex curves relating changes in heart rate (HR) to increases or decreases in blood pressure (BP) evoked by i.v. doses (1-16 μg/kg) of phenylephrine (PE) and sodium nitroprusside (SNP), respectively, were constructed in conscious rats; slopes of the curves were taken as measures of baroreflex sensitivity (BRS). Nicotine (25 and 100 μg/kg i.v.) dose-dependently reduced BRS SNP in contrast to no effect on BRS PE . BRS SNP was also attenuated after intracisternal (i.c.) administration of nicotine. Similar reductions in BRS SNP were observed in rats pretreated with atropine or propranolol. The combined treatment with nicotine and atropine produced additive inhibitory effects on BRS, an effect that was not demonstrated upon concurrent exposure to nicotine and propranolol. BRS SNP was reduced in preparations treated with i.c. 8-phenyltheophylline (8-PT, nonselective adenosine receptor antagonist), 8-(3-Chlorostyryl) caffeine (CSC, A 2A antagonist), or VUF5574 (A 3 antagonist). In contrast, BRS SNP was preserved after blockade of A 1 (DPCPX) or A 2B (alloxazine) receptors or inhibition of adenosine uptake by dipyridamole. CSC or 8-PT abrogated the BRS SNP depressant effect of nicotine whereas other adenosinergic antagonists were without effect. Together, nicotine preferentially impairs reflex tachycardia via disruption of adenosine A 2A receptor-mediated facilitation of reflex cardiac sympathoexcitation. Clinically, the attenuation by nicotine of compensatory sympathoexcitation may be detrimental in conditions such as hypothalamic defense response, posture changes, and ventricular rhythms. - Research highlights: → The role of central adenosinergic sites in

  8. Dasatinib Attenuates Pressure Overload Induced Cardiac Fibrosis in a Murine Transverse Aortic Constriction Model.

    Directory of Open Access Journals (Sweden)

    Sundaravadivel Balasubramanian

    Full Text Available Reactive cardiac fibrosis resulting from chronic pressure overload (PO compromises ventricular function and contributes to congestive heart failure. We explored whether nonreceptor tyrosine kinases (NTKs play a key role in fibrosis by activating cardiac fibroblasts (CFb, and could potentially serve as a target to reduce PO-induced cardiac fibrosis. Our studies were carried out in PO mouse myocardium induced by transverse aortic constriction (TAC. Administration of a tyrosine kinase inhibitor, dasatinib, via an intraperitoneally implanted mini-osmotic pump at 0.44 mg/kg/day reduced PO-induced accumulation of extracellular matrix (ECM proteins and improved left ventricular geometry and function. Furthermore, dasatinib treatment inhibited NTK activation (primarily Pyk2 and Fak and reduced the level of FSP1 positive cells in the PO myocardium. In vitro studies using cultured mouse CFb showed that dasatinib treatment at 50 nM reduced: (i extracellular accumulation of both collagen and fibronectin, (ii both basal and PDGF-stimulated activation of Pyk2, (iii nuclear accumulation of Ki67, SKP2 and histone-H2B and (iv PDGF-stimulated CFb proliferation and migration. However, dasatinib did not affect cardiomyocyte morphologies in either the ventricular tissue after in vivo administration or in isolated cells after in vitro treatment. Mass spectrometric quantification of dasatinib in cultured cells indicated that the uptake of dasatinib by CFb was greater that that taken up by cardiomyocytes. Dasatinib treatment primarily suppressed PDGF but not insulin-stimulated signaling (Erk versus Akt activation in both CFb and cardiomyocytes. These data indicate that dasatinib treatment at lower doses than that used in chemotherapy has the capacity to reduce hypertrophy-associated fibrosis and improve ventricular function.

  9. Prediction of CT Substitutes from MR Images Based on Local Diffeomorphic Mapping for Brain PET Attenuation Correction.

    Science.gov (United States)

    Wu, Yao; Yang, Wei; Lu, Lijun; Lu, Zhentai; Zhong, Liming; Huang, Meiyan; Feng, Yanqiu; Feng, Qianjin; Chen, Wufan

    2016-10-01

    Attenuation correction is important for PET reconstruction. In PET/MR, MR intensities are not directly related to attenuation coefficients that are needed in PET imaging. The attenuation coefficient map can be derived from CT images. Therefore, prediction of CT substitutes from MR images is desired for attenuation correction in PET/MR. This study presents a patch-based method for CT prediction from MR images, generating attenuation maps for PET reconstruction. Because no global relation exists between MR and CT intensities, we propose local diffeomorphic mapping (LDM) for CT prediction. In LDM, we assume that MR and CT patches are located on 2 nonlinear manifolds, and the mapping from the MR manifold to the CT manifold approximates a diffeomorphism under a local constraint. Locality is important in LDM and is constrained by the following techniques. The first is local dictionary construction, wherein, for each patch in the testing MR image, a local search window is used to extract patches from training MR/CT pairs to construct MR and CT dictionaries. The k-nearest neighbors and an outlier detection strategy are then used to constrain the locality in MR and CT dictionaries. Second is local linear representation, wherein, local anchor embedding is used to solve MR dictionary coefficients when representing the MR testing sample. Under these local constraints, dictionary coefficients are linearly transferred from the MR manifold to the CT manifold and used to combine CT training samples to generate CT predictions. Our dataset contains 13 healthy subjects, each with T1- and T2-weighted MR and CT brain images. This method provides CT predictions with a mean absolute error of 110.1 Hounsfield units, Pearson linear correlation of 0.82, peak signal-to-noise ratio of 24.81 dB, and Dice in bone regions of 0.84 as compared with real CTs. CT substitute-based PET reconstruction has a regression slope of 1.0084 and R 2 of 0.9903 compared with real CT-based PET. In this method, no

  10. Analytical fan-beam and cone-beam reconstruction algorithms with uniform attenuation correction for SPECT

    International Nuclear Information System (INIS)

    Tang Qiulin; Zeng, Gengsheng L; Gullberg, Grant T

    2005-01-01

    In this paper, we developed an analytical fan-beam reconstruction algorithm that compensates for uniform attenuation in SPECT. The new fan-beam algorithm is in the form of backprojection first, then filtering, and is mathematically exact. The algorithm is based on three components. The first one is the established generalized central-slice theorem, which relates the 1D Fourier transform of a set of arbitrary data and the 2D Fourier transform of the backprojected image. The second one is the fact that the backprojection of the fan-beam measurements is identical to the backprojection of the parallel measurements of the same object with the same attenuator. The third one is the stable analytical reconstruction algorithm for uniformly attenuated Radon data, developed by Metz and Pan. The fan-beam algorithm is then extended into a cone-beam reconstruction algorithm, where the orbit of the focal point of the cone-beam imaging geometry is a circle. This orbit geometry does not satisfy Tuy's condition and the obtained cone-beam algorithm is an approximation. In the cone-beam algorithm, the cone-beam data are first backprojected into the 3D image volume; then a slice-by-slice filtering is performed. This slice-by-slice filtering procedure is identical to that of the fan-beam algorithm. Both the fan-beam and cone-beam algorithms are efficient, and computer simulations are presented. The new cone-beam algorithm is compared with Bronnikov's cone-beam algorithm, and it is shown to have better performance with noisy projections

  11. Contribution to regularizing iterative method development for attenuation correction in gamma emission tomography

    International Nuclear Information System (INIS)

    Cao, A.

    1981-07-01

    This study is concerned with the transverse axial gamma emission tomography. The problem of self-attenuation of radiations in biologic tissues is raised. The regularizing iterative method is developed, as a reconstruction method of 3 dimensional images. The different steps from acquisition to results, necessary to its application, are described. Organigrams relative to each step are explained. Comparison notion between two reconstruction methods is introduced. Some methods used for the comparison or to bring about the characteristics of a reconstruction technique are defined. The studies realized to test the regularizing iterative method are presented and results are analyzed [fr

  12. Oral Contraceptives Attenuate Cardiac Autonomic Responses to Musical Auditory Stimulation: Pilot Study.

    Science.gov (United States)

    Milan, Réveni Carmem; Plassa, Bruna Oliveira; Guida, Heraldo Lorena; de Abreu, Luiz Carlos; Gomes, Rayana L; Garner, David M; Valenti, Vitor E

    2015-01-01

    The literature presents contradictory results regarding the effects of contraceptives on cardiac autonomic regulation. The research team aimed to evaluate the effects of musical auditory stimulation on cardiac autonomic regulation in women who use oral contraceptives. The research team designed a transversal observational pilot study. The setting was the Centro de Estudos do Sistema Nervoso Autônomo (CESNA) in the Departamento de Fonoaudiologia at the Universidade Estadual Paulista (UNESP) in Marília, SP, Brazil. Participants were 22 healthy nonathletic and nonsedentary females, all nonsmokers and aged between 18 and 27 y. Participants were divided into 2 groups: (1) 12 women who were not taking oral contraceptives, the control group; and (2) 10 women who were taking oral contraceptives, the oral contraceptive group. In the first stage, a rest control, the women sat with their earphones turned off for 20 min. After that period, the participants were exposed to 20 min of classical baroque music (ie, "Canon in D Major," Johann Pachelbel), at 63-84 dB. Measurements of the equivalent sound levels were conducted in a soundproof room, and the intervals between consecutive heartbeats (R-R intervals) were recorded, with a sampling rate of 1000 Hz. For calculation of the linear indices, the research team used software to perform an analysis of heart rate variability (HRV). Linear indices of HRV were analyzed in the time domain: (1) the standard deviation of normal-to-normal R-R intervals (SDNN), (2) the root-mean square of differences between adjacent normal R-R intervals in a time interval (RMSSD), and (3) the percentage of adjacent R-R intervals with a difference of duration greater than 50 ms (pNN50). The study also analyzed the frequency domain-low frequency (LF), high frequency (HF), and LF/HF ratio. For the control group, the musical auditory stimulation reduced (1) the SDNN from 52.2 ± 10 ms to 48.4 ± 16 ms (P = .0034); (2) the RMSSD from 45.8 ± 22 ms to 41.2

  13. Inhibition of TNF-α in hypothalamic paraventricular nucleus attenuates hypertension and cardiac hypertrophy by inhibiting neurohormonal excitation in spontaneously hypertensive rats

    Energy Technology Data Exchange (ETDEWEB)

    Song, Xin-Ai; Jia, Lin-Lin [Department of Physiology and Pathophysiology, Xi' an Jiaotong University Cardiovascular Research Center, Xi' an Jiaotong University School of Medicine, Xi' an 710061 (China); Cui, Wei [Department of Endocrinology and Metabolism, First Affiliated Hospital of Xi' an Jiaotong University School of Medicine, Xi' an 710061 (China); Zhang, Meng [Department of Physiology and Pathophysiology, Xi' an Jiaotong University Cardiovascular Research Center, Xi' an Jiaotong University School of Medicine, Xi' an 710061 (China); Chen, Wensheng [Department of Cardiovascular Surgery, Xijing Hospital, Fourth Military Medical University, Xi' an 710032 (China); Yuan, Zu-Yi [Department of Cardiovascular Medicine, First Affiliated Hospital of Xi' an Jiaotong University School of Medicine, Xi' an 710061 (China); Guo, Jing [Department of Physiology and Pathophysiology, Xi' an Jiaotong University Cardiovascular Research Center, Xi' an Jiaotong University School of Medicine, Xi' an 710061 (China); Li, Hui-Hua [Key Laboratory of Remodeling-related Cardiovascular Diseases, Department of Pathology, School of Basic Medical Sciences, Capital Medical University, Beijing 100069 (China); Zhu, Guo-Qing [Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing 210029 (China); Liu, Hao, E-mail: haoliu75@163.com [Department of Neurosurgery, First Affiliated Hospital of Xi' an Jiaotong University School of Medicine, Xi' an 710061 (China); Kang, Yu-Ming, E-mail: ykang@mail.xjtu.edu.cn [Department of Physiology and Pathophysiology, Xi' an Jiaotong University Cardiovascular Research Center, Xi' an Jiaotong University School of Medicine, Xi' an 710061 (China)

    2014-11-15

    We hypothesized that chronic inhibition of tumor necrosis factor-alpha (TNF-α) in the hypothalamic paraventricular nucleus (PVN) delays the progression of hypertension and attenuates cardiac hypertrophy by up-regulating anti-inflammatory cytokines, reducing pro-inflammatory cytokines (PICs), decreasing nuclear factor-κB (NF-κB) p65 and NAD(P)H oxidase activities, as well as restoring the neurotransmitters balance in the PVN of spontaneously hypertensive rats (SHR). Adult normotensive Wistar–Kyoto (WKY) and SHR rats received bilateral PVN infusion of a TNF-α blocker (pentoxifylline or etanercept) or vehicle for 4 weeks. SHR rats showed higher mean arterial pressure and cardiac hypertrophy compared with WKY rats, as indicated by increased whole heart weight/body weight ratio, whole heart weight/tibia length ratio, left ventricular weight/tibia length ratio, and cardiac atrial natriuretic peptide (ANP) and beta-myosin heavy chain (β-MHC) mRNA expressions. Compared with WKY rats, SHR rats had higher PVN levels of tyrosine hydroxylase, PICs, the chemokine monocyte chemoattractant protein-1 (MCP-1), NF-κB p65 activity, mRNA expressions of NOX-2 and NOX-4, and lower PVN levels of IL-10 and 67-kDa isoform of glutamate decarboxylase (GAD67), and higher plasma norepinephrine. PVN infusion of pentoxifylline or etanercept attenuated all these changes in SHR rats. These findings suggest that SHR rats have an imbalance between excitatory and inhibitory neurotransmitters, as well as an imbalance between pro- and anti-inflammatory cytokines in the PVN; and chronic inhibition of TNF-α in the PVN delays the progression of hypertension by restoring the balances of neurotransmitters and cytokines in the PVN, and attenuating PVN NF-κB p65 activity and oxidative stress, thereby attenuating hypertension-induced sympathetic hyperactivity and cardiac hypertrophy. - Highlights: • Spontaneously hypertensive rats exhibit neurohormonal excitation in the PVN. • PVN inhibition of

  14. Chronic infusion of enalaprilat into hypothalamic paraventricular nucleus attenuates angiotensin II-induced hypertension and cardiac hypertrophy by restoring neurotransmitters and cytokines

    International Nuclear Information System (INIS)

    Kang, Yu-Ming; Zhang, Dong-Mei; Yu, Xiao-Jing; Yang, Qing; Qi, Jie; Su, Qing; Suo, Yu-Ping; Yue, Li-Ying; Zhu, Guo-Qing; Qin, Da-Nian

    2014-01-01

    The renin–angiotensin system (RAS) in the brain is involved in the pathogenesis of hypertension. We hypothesized that inhibition of angiotensin-converting enzyme (ACE) in the hypothalamic paraventricular nucleus (PVN) attenuates angiotensin II (ANG II)-induced hypertension via restoring neurotransmitters and cytokines. Rats underwent subcutaneous infusions of ANG II or saline and bilateral PVN infusions of ACE inhibitor enalaprilat (ENL, 2.5 μg/h) or vehicle for 4 weeks. ANG II infusion resulted in higher mean arterial pressure and cardiac hypertrophy as indicated by increased whole heart weight/body weight ratio, whole heart weight/tibia length ratio, left ventricular weight/tibia length ratio, and mRNA expressions of cardiac atrial natriuretic peptide and beta-myosin heavy chain. These ANG II-infused rats had higher PVN levels of glutamate, norepinephrine, tyrosine hydroxylase, pro-inflammatory cytokines (PICs) and the chemokine monocyte chemoattractant protein-1, and lower PVN levels of gamma-aminobutyric acid, interleukin (IL)-10 and the 67-kDa isoform of glutamate decarboxylase (GAD67), and higher plasma levels of PICs, norepinephrine and aldosterone, and lower plasma IL-10, and higher renal sympathetic nerve activity. However, PVN treatment with ENL attenuated these changes. PVN microinjection of ANG II induced increases in IL-1β and IL-6, and a decrease in IL-10 in the PVN, and pretreatment with angiotensin II type 1 receptor (AT1-R) antagonist losartan attenuated these changes. These findings suggest that ANG II infusion induces an imbalance between excitatory and inhibitory neurotransmitters and an imbalance between pro- and anti-inflammatory cytokines in the PVN, and PVN inhibition of the RAS restores neurotransmitters and cytokines in the PVN, thereby attenuating ANG II-induced hypertension and cardiac hypertrophy. - Highlights: • Chronic ANG II infusion results in sympathetic hyperactivity and cardiac hypertrophy. • PVN inhibition of ACE

  15. Chronic infusion of enalaprilat into hypothalamic paraventricular nucleus attenuates angiotensin II-induced hypertension and cardiac hypertrophy by restoring neurotransmitters and cytokines

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Yu-Ming, E-mail: ykang@mail.xjtu.edu.cn [Department of Physiology and Pathophysiology, Xi' an Jiaotong University Cardiovascular Research Center, Xi' an Jiaotong University School of Medicine, Xi' an 710061 (China); Zhang, Dong-Mei [Department of Physiology, Dalian Medical University, Dalian 116044 (China); Yu, Xiao-Jing; Yang, Qing; Qi, Jie; Su, Qing [Department of Physiology and Pathophysiology, Xi' an Jiaotong University Cardiovascular Research Center, Xi' an Jiaotong University School of Medicine, Xi' an 710061 (China); Suo, Yu-Ping [Department of Obstetrics and Gynecology, Shanxi Provincial People' s Hospital, Taiyuan 030012 (China); Yue, Li-Ying [Department of Physiology and Pathophysiology, Xi' an Jiaotong University Cardiovascular Research Center, Xi' an Jiaotong University School of Medicine, Xi' an 710061 (China); Zhu, Guo-Qing [Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing 210029 (China); Qin, Da-Nian, E-mail: dnqin@stu.edu.cn [Department of Physiology, Shantou University Medical College, Shantou 515041 (China)

    2014-02-01

    The renin–angiotensin system (RAS) in the brain is involved in the pathogenesis of hypertension. We hypothesized that inhibition of angiotensin-converting enzyme (ACE) in the hypothalamic paraventricular nucleus (PVN) attenuates angiotensin II (ANG II)-induced hypertension via restoring neurotransmitters and cytokines. Rats underwent subcutaneous infusions of ANG II or saline and bilateral PVN infusions of ACE inhibitor enalaprilat (ENL, 2.5 μg/h) or vehicle for 4 weeks. ANG II infusion resulted in higher mean arterial pressure and cardiac hypertrophy as indicated by increased whole heart weight/body weight ratio, whole heart weight/tibia length ratio, left ventricular weight/tibia length ratio, and mRNA expressions of cardiac atrial natriuretic peptide and beta-myosin heavy chain. These ANG II-infused rats had higher PVN levels of glutamate, norepinephrine, tyrosine hydroxylase, pro-inflammatory cytokines (PICs) and the chemokine monocyte chemoattractant protein-1, and lower PVN levels of gamma-aminobutyric acid, interleukin (IL)-10 and the 67-kDa isoform of glutamate decarboxylase (GAD67), and higher plasma levels of PICs, norepinephrine and aldosterone, and lower plasma IL-10, and higher renal sympathetic nerve activity. However, PVN treatment with ENL attenuated these changes. PVN microinjection of ANG II induced increases in IL-1β and IL-6, and a decrease in IL-10 in the PVN, and pretreatment with angiotensin II type 1 receptor (AT1-R) antagonist losartan attenuated these changes. These findings suggest that ANG II infusion induces an imbalance between excitatory and inhibitory neurotransmitters and an imbalance between pro- and anti-inflammatory cytokines in the PVN, and PVN inhibition of the RAS restores neurotransmitters and cytokines in the PVN, thereby attenuating ANG II-induced hypertension and cardiac hypertrophy. - Highlights: • Chronic ANG II infusion results in sympathetic hyperactivity and cardiac hypertrophy. • PVN inhibition of ACE

  16. Correction

    DEFF Research Database (Denmark)

    Pinkevych, Mykola; Cromer, Deborah; Tolstrup, Martin

    2016-01-01

    [This corrects the article DOI: 10.1371/journal.ppat.1005000.][This corrects the article DOI: 10.1371/journal.ppat.1005740.][This corrects the article DOI: 10.1371/journal.ppat.1005679.].......[This corrects the article DOI: 10.1371/journal.ppat.1005000.][This corrects the article DOI: 10.1371/journal.ppat.1005740.][This corrects the article DOI: 10.1371/journal.ppat.1005679.]....

  17. Correcting attenuated total reflection-fourier transform infrared spectra for water vapor and carbon dioxide

    DEFF Research Database (Denmark)

    Bruun, Susanne Wrang; Kohler, Achim; Adt, Isabelle

    2006-01-01

    an absorption band from either water vapor or CO(2). From two calibration data sets, gas model spectra were estimated in each of the four spectral regions, and these model spectra were applied for correction of gas absorptions in two independent test sets (spectra of aqueous solutions and a yeast biofilm (C...... of the growing yeast biofilm, the gas correction revealed otherwise hidden variations of relevance for modeling the growth dynamics. As the presented method improved the interpretation of the principle component analysis (PCA) models, it has proven to be a valuable tool for filtering atmospheric variation in ATR...

  18. Modifying Spearman's Attenuation Equation to Yield Partial Corrections for Measurement Error--With Application to Sample Size Calculations

    Science.gov (United States)

    Nicewander, W. Alan

    2018-01-01

    Spearman's correction for attenuation (measurement error) corrects a correlation coefficient for measurement errors in either-or-both of two variables, and follows from the assumptions of classical test theory. Spearman's equation removes all measurement error from a correlation coefficient which translates into "increasing the reliability of…

  19. CT vs 68Ge attenuation correction in a combined PET/CT system: evaluation of the effect of lowering the CT tube current

    International Nuclear Information System (INIS)

    Kamel, Ehab; Hany, Thomas F.; Burger, Cyrill; Treyer, Valerie; Schulthess von, Gustav K.; Buck, Alfred; Lonn, Albert H.R.

    2002-01-01

    With the introduction of combined positron emission tomography/computed tomography (PET/CT) systems, several questions have to be answered. In this work we addressed two of these questions: (a) to what value can the CT tube current be reduced while still yielding adequate maps for the attenuation correction of PET emission scans and (b) how do quantified uptake values in tumours derived from CT and germanium-68 attenuation correction compare. In 26 tumour patients, multidetector CT scans were acquired with 10, 40, 80 and 120 mA (CT 10 , CT 40 , CT 80 and CT 120 ) and used for the attenuation correction of a single FDG PET emission scan, yielding four PET scans designated PET CT10 -PET CT120 . In 60 tumorous lesions, FDG uptake and lesion size were quantified on PET CT10 -PET CT120 . In another group of 18 patients, one CT scan acquired with 80 mA and a standard transmission scan acquired using 68 Ge sources were employed for the attenuation correction of the FDG emission scan (PET CT80 , PET 68Ge ). Uptake values and lesion size in 26 lesions were compared on PET CT80 and PET 68Ge . In the first group of patients, analysis of variance revealed no significant effect of CT current on tumour FDG uptake or lesion size. In the second group, tumour FDG uptake was slightly higher using CT compared with 68 Ge attenuation correction, especially in lesions with high FDG uptake. Lesion size was similar on PET CT80 and PET 68Ge . In conclusion, low CT currents yield adequate maps for the attenuation correction of PET emission scans. Although the discrepancy between CT- and 68 Ge-derived uptake values is probably not relevant in most cases, it should be kept in mind if standardised uptake values derived from CT and 68 Ge attenuation correction are compared. (orig.)

  20. An FFT-based Method for Attenuation Correction in Fluorescence Confocal Microscopy

    NARCIS (Netherlands)

    Roerdink, J.B.T.M.; Bakker, M.

    1993-01-01

    A problem in three-dimensional imaging by a confocal scanning laser microscope (CSLM) in the (epi)fluorescence mode is the darkening of the deeper layers due to absorption and scattering of both the excitation and the fluorescence light. In this paper we propose a new method to correct for these

  1. Availability of cardiac surgical care in surgical correction of acquired heart defects in patients of older age group

    Directory of Open Access Journals (Sweden)

    Kubatbek S. Urmanbetov

    2018-02-01

    Full Text Available Objective: A study of accessibility of surgical care to elderly patients (aged 60 and above with valvular heart disease has been conducted at the BSCCS "Bakulev Scientific Center of Cardiovascular Surgery» of the Ministry of Health of the Russian Federation. Methods: A retrospective analysis of structure of hospitalizations of 1726 patients, that were hospitalized between 2009 and 2010 at the BSCCS for surgical correction of valvular heart disease was performed. Results: Our study demonstrated that age, on one hand, is not the most significant barrier in the geographical accessibility of cardiac surgical care. On the other hand, it can influence the availability in general, taking into account other factors (urban / rural areas, the presence of cardiac surgical clinics, and clinical status. Provision of cardiac surgical care for patients with heart defects at the BSCCS per 1 million population varies considerably in the context of federal districts and is 0.4 for the Siberian Federal District 30 for the Central Federal District (the highest is 42 for the Moscow Region. Conclusion: Thus, our study demonstrated accessibility of surgical care for elderly patients is the highest for the urban areas with specialized cardiac surgery centers, where patients referred from rural regions

  2. Effective radiation attenuation calibration for breast density: compression thickness influences and correction

    OpenAIRE

    Thomas Jerry A; Cao Ke; Heine John J

    2010-01-01

    Abstract Background Calibrating mammograms to produce a standardized breast density measurement for breast cancer risk analysis requires an accurate spatial measure of the compressed breast thickness. Thickness inaccuracies due to the nominal system readout value and compression paddle orientation induce unacceptable errors in the calibration. Method A thickness correction was developed and evaluated using a fully specified two-component surrogate breast model. A previously developed calibrat...

  3. Towards Implementing an MR-based PET Attenuation Correction Method for Neurological Studies on the MR-PET Brain Prototype

    Science.gov (United States)

    Catana, Ciprian; van der Kouwe, Andre; Benner, Thomas; Michel, Christian J.; Hamm, Michael; Fenchel, Matthias; Fischl, Bruce; Rosen, Bruce; Schmand, Matthias; Sorensen, A. Gregory

    2013-01-01

    A number of factors have to be considered for implementing an accurate attenuation correction (AC) in a combined MR-PET scanner. In this work, some of these challenges were investigated and an AC method based entirely on the MR data obtained with a single dedicated sequence was developed and used for neurological studies performed with the MR-PET human brain scanner prototype. Methods The focus was on the bone/air segmentation problem, the bone linear attenuation coefficient selection and the RF coil positioning. The impact of these factors on the PET data quantification was studied in simulations and experimental measurements performed on the combined MR-PET scanner. A novel dual-echo ultra-short echo time (DUTE) MR sequence was proposed for head imaging. Simultaneous MR-PET data were acquired and the PET images reconstructed using the proposed MR-DUTE-based AC method were compared with the PET images reconstructed using a CT-based AC. Results Our data suggest that incorrectly accounting for the bone tissue attenuation can lead to large underestimations (>20%) of the radiotracer concentration in the cortex. Assigning a linear attenuation coefficient of 0.143 or 0.151 cm−1 to bone tissue appears to give the best trade-off between bias and variability in the resulting images. Not identifying the internal air cavities introduces large overestimations (>20%) in adjacent structures. Based on these results, the segmented CT AC method was established as the “silver standard” for the segmented MR-based AC method. Particular to an integrated MR-PET scanner, ignoring the RF coil attenuation can cause large underestimations (i.e. up to 50%) in the reconstructed images. Furthermore, the coil location in the PET field of view has to be accurately known. Good quality bone/air segmentation can be performed using the DUTE data. The PET images obtained using the MR-DUTE- and CT-based AC methods compare favorably in most of the brain structures. Conclusion An MR-DUTE-based AC

  4. Andrographis paniculata extract attenuates pathological cardiac hypertrophy and apoptosis in high-fat diet fed mice.

    Science.gov (United States)

    Hsieh, You-Liang; Shibu, Marthandam Asokan; Lii, Chong-Kuei; Viswanadha, Vijaya Padma; Lin, Yi-Lin; Lai, Chao-Hung; Chen, Yu-Feng; Lin, Kuan-Ho; Kuo, Wei-Wen; Huang, Chih-Yang

    2016-11-04

    Andrographis paniculata (Burm. f.) Nees (Acanthaceae) has a considerable medicinal reputation in most parts of Asia as a potent medicine in the treatment of Endocrine disorders, inflammation and hypertension. Water extract of A. paniculata and its active constituent andrographolide are known to possess anti-inflammatory and anti-apoptotic effects. Our aim is to identify whether A. paniculata extract could protect myocardial damage in high-fat diet induced obese mice. The test mice were divided into three groups fed either with normal chow or with high fat diet (obese) or with high fat diet treated with A. paniculata extract (2g/kg/day, through gavage, for a week). We found that the myocardial inflammation pathway related proteins were increased in the obese mouse which potentially contributes to cardiac hypertrophy and myocardial apoptosis. But feeding with A. paniculata extract showed significant inhibition on the effects of high fat diet. Our study strongly suggests that supplementation of A. paniculata extract can be used for prevention and treatment of cardiovascular disease in obese patients. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  5. Targeted NGF siRNA delivery attenuates sympathetic nerve sprouting and deteriorates cardiac dysfunction in rats with myocardial infarction.

    Directory of Open Access Journals (Sweden)

    Hesheng Hu

    Full Text Available Nerve growth factor (NGF is involved in nerve sprouting, hyper-innervation, angiogenesis, anti-apoptosis, and preservation of cardiac function after myocardial infarction (MI. Positively modulating NGF expression may represent a novel pharmacological strategy to improve post-infarction prognosis. In this study, lentivirus encoding NGF short interfering RNA (siRNA was prepared, and MI was modeled in the rat using left anterior descending coronary artery ligation. Rats were randomly grouped to receive intramyocardial injection of lentiviral solution containing NGF-siRNA (n = 19, MI-SiNGF group, lentiviral solution containing empty vector (n = 18, MI-GFP group or 0.9% NaCl solution (n = 18, MI-control group, or to receive thoracotomy and pericardiotomy (n = 17, sham-operated group. At 1, 2, 4, and 8 wk after transduction, rats in the MI-control group had higher levels of NGF mRNA and protein than those in the sham-operated group, rats in the MI-GFP group showed similar levels as the MI-control group, and rats in the MI-SiNGF group had lower levels compared to the MI-GFP group, indicating that MI model was successfully established and NGF siRNA effectively inhibited the expression of NGF. At 8 wk, echocardiographic and hemodynamic studies revealed a more severe cardiac dysfunction in the MI-siRNA group compared to the MI-GFP group. Moreover, rats in the MI-siRNA group had lower mRNA and protein expression levels of tyrosine hydroxylase (TH and growth-associated protein 43-positive nerve fibers (GAP-43 at both the infarcted border and within the non-infarcted left ventricles (LV. NGF silencing also reduced the vascular endothelial growth factor (VEGF expression and decreased the arteriolar and capillary densities at the infarcted border compared to the MI-GFP group. Histological analysis indicated a large infarcted size in the MI-SiNGF group. These findings suggested that endogenous NGF silencing attenuated sympathetic nerve sprouting

  6. Impact of improved attenuation correction featuring a bone atlas and truncation correction on PET quantification in whole-body PET/MR.

    Science.gov (United States)

    Oehmigen, Mark; Lindemann, Maike E; Gratz, Marcel; Kirchner, Julian; Ruhlmann, Verena; Umutlu, Lale; Blumhagen, Jan Ole; Fenchel, Matthias; Quick, Harald H

    2018-04-01

    Recent studies have shown an excellent correlation between PET/MR and PET/CT hybrid imaging in detecting lesions. However, a systematic underestimation of PET quantification in PET/MR has been observed. This is attributable to two methodological challenges of MR-based attenuation correction (AC): (1) lack of bone information, and (2) truncation of the MR-based AC maps (μmaps) along the patient arms. The aim of this study was to evaluate the impact of improved AC featuring a bone atlas and truncation correction on PET quantification in whole-body PET/MR. The MR-based Dixon method provides four-compartment μmaps (background air, lungs, fat, soft tissue) which served as a reference for PET/MR AC in this study. A model-based bone atlas provided bone tissue as a fifth compartment, while the HUGE method provided truncation correction. The study population comprised 51 patients with oncological diseases, all of whom underwent a whole-body PET/MR examination. Each whole-body PET dataset was reconstructed four times using standard four-compartment μmaps, five-compartment μmaps, four-compartment μmaps + HUGE, and five-compartment μmaps + HUGE. The SUV max for each lesion was measured to assess the impact of each μmap on PET quantification. All four μmaps in each patient provided robust results for reconstruction of the AC PET data. Overall, SUV max was quantified in 99 tumours and lesions. Compared to the reference four-compartment μmap, the mean SUV max of all 99 lesions increased by 1.4 ± 2.5% when bone was added, by 2.1 ± 3.5% when HUGE was added, and by 4.4 ± 5.7% when bone + HUGE was added. Larger quantification bias of up to 35% was found for single lesions when bone and truncation correction were added to the μmaps, depending on their individual location in the body. The novel AC method, featuring a bone model and truncation correction, improved PET quantification in whole-body PET/MR imaging. Short reconstruction times, straightforward

  7. Impact of improved attenuation correction featuring a bone atlas and truncation correction on PET quantification in whole-body PET/MR

    Energy Technology Data Exchange (ETDEWEB)

    Oehmigen, Mark; Lindemann, Maike E. [University Hospital Essen, High Field and Hybrid MR Imaging, Essen (Germany); Gratz, Marcel; Quick, Harald H. [University Hospital Essen, High Field and Hybrid MR Imaging, Essen (Germany); University Duisburg-Essen, Erwin L. Hahn Institute for MR Imaging, Essen (Germany); Kirchner, Julian [University Dusseldorf, Department of Diagnostic and Interventional Radiology, Medical Faculty, Dusseldorf (Germany); Ruhlmann, Verena [University Hospital Essen, Department of Nuclear Medicine, Essen (Germany); Umutlu, Lale [University Hospital Essen, Department of Diagnostic and Interventional Radiology and Neuroradiology, Essen (Germany); Blumhagen, Jan Ole; Fenchel, Matthias [Siemens Healthcare GmbH, Erlangen (Germany)

    2018-04-15

    Recent studies have shown an excellent correlation between PET/MR and PET/CT hybrid imaging in detecting lesions. However, a systematic underestimation of PET quantification in PET/MR has been observed. This is attributable to two methodological challenges of MR-based attenuation correction (AC): (1) lack of bone information, and (2) truncation of the MR-based AC maps (μmaps) along the patient arms. The aim of this study was to evaluate the impact of improved AC featuring a bone atlas and truncation correction on PET quantification in whole-body PET/MR. The MR-based Dixon method provides four-compartment μmaps (background air, lungs, fat, soft tissue) which served as a reference for PET/MR AC in this study. A model-based bone atlas provided bone tissue as a fifth compartment, while the HUGE method provided truncation correction. The study population comprised 51 patients with oncological diseases, all of whom underwent a whole-body PET/MR examination. Each whole-body PET dataset was reconstructed four times using standard four-compartment μmaps, five-compartment μmaps, four-compartment μmaps + HUGE, and five-compartment μmaps + HUGE. The SUV{sub max} for each lesion was measured to assess the impact of each μmap on PET quantification. All four μmaps in each patient provided robust results for reconstruction of the AC PET data. Overall, SUV{sub max} was quantified in 99 tumours and lesions. Compared to the reference four-compartment μmap, the mean SUV{sub max} of all 99 lesions increased by 1.4 ± 2.5% when bone was added, by 2.1 ± 3.5% when HUGE was added, and by 4.4 ± 5.7% when bone + HUGE was added. Larger quantification bias of up to 35% was found for single lesions when bone and truncation correction were added to the μmaps, depending on their individual location in the body. The novel AC method, featuring a bone model and truncation correction, improved PET quantification in whole-body PET/MR imaging. Short reconstruction times, straightforward

  8. Comparison of cardiac gating and refocusing pulses for correction of cerebrospinal fluid pulsation artifacts in MR images

    International Nuclear Information System (INIS)

    Modic, M.T.; Haacke, E.M.; Lenz, G.W.; Masaryk, T.; Kaufman, B.; Ross, J.S.

    1986-01-01

    This study compared cardiac gating and additional refocusing gradient pulses in combination or alone for correction of cerebrospinal fluid (CSF) pulsation artifacts in both normal volunteers and in patients with suspected spinal pathology. Refocusing pulses or cardiac gating when used alone produced a decrease in ghosting artifacts on sagittal images and reduced the nonuniformity of the CSF signal on axial images. There is improved thin-section T2 imaging of the cord with long TEs and as few as one excitation. The refocusing pulses reduced ghosting artifacts also from respiratory motion and enhanced the CSF signal with shorter TRs leading to increased CSF contrast. When used together, the results were significantly better than either alone. Refocusing schemes can be used with any TR, do not require gating, and are now routinely employed at the authors' institution

  9. Desmodium gangeticum root extract attenuates isoproterenol-induced cardiac hypertrophic growth in rats.

    Directory of Open Access Journals (Sweden)

    Divya Hitler

    2014-10-01

    Full Text Available Context: Desmodium gangeticum (L DC (Fabaceae; DG, a medicinal plant that grows in tropical habitats, is widely used to treat various ailments including digestive and inflammatory disorders. Aims: To investigate the possible cardioprotective activity of a DG root extract against isoproterenol (ISO-induced left ventricular cardiac hypertrophy (LVH in adult Wistar rats. Methods: Daily intraperitoneal administration of ISO (10 mg/kg body weight, single injection for 7 days induced LVH in rats. The LVH rats were post-treated orally with DG (100 mg/kg body weight for a period of 30 days. Thereafter, changes in heart weight (HW and body weight (BW, HW/BW ratio, percent of hypertrophy, collagen accumulation, activities of matrix metalloproteinase (MMP -2 and -9, superoxide dismutase (SOD and catalase (CAT enzymes, and the level of an oxidative stress marker, lipid peroxide (LPO, were determined. Results: HW/BW ratio, an indicator of hypertrophic growth, was significantly reduced in DG root post-treated LVH rats as compared with that for the non-treated LVH rats. The altered levels of ventricular LPO, collagen, MMPs-2 and -9, and antioxidant enzymes in the ISO-treated animals reverted back to near normal upon DG treatment. Further, the anti-hypertrophic activity of DG was comparable to that of the standard drug losartan (10 mg/kg. Conclusions: The results of the present study suggest that the aqueous root extract of DG exhibited anti-hypertrophic activity in-vivo by inhibiting ISO-induced ROS generation and MMP activities.

  10. Correlation of the myocardial perfusion corrected by attenuation with the coronariography. Preliminary results; Correlacion de la perfusion miocardica corregida por atenuacion con la coronariografia

    Energy Technology Data Exchange (ETDEWEB)

    Garcia C, S.E.; Garcia O, R. [Servicio de Medicina Nuclear, Centro Medico ABC, Campis Observatorio, IAP (Mexico)

    2005-07-01

    The attenuation that suffers the radiation in the soft tissues of the hinders the appropriate interpretation of the myocardial perfusion studies, for what have been implemented attenuation correction systems to reduce the attenuation for soft tissues and to provide myocardial perfusion images more accurate in the diagnosis of coronary illness. The objective was to evaluate the utility of an attenuation correction system (with source of Gadolinium 153) to minimize the devices that look like true defects of myocardial perfusion, caused by soft tissues (mammary tissue, thoracic wall, abdomen, left hemi diaphragm), and to compare those interpretations of the studies with the interpretations of the corresponding coronariographies. The method consists of 95 electronic files which were revised with the concept of heart catheterization, being identified 20 patients from the masculine sex to those that underwent coronariography among May 1999 and December 2002, and that they had study of myocardial perfusion in a maximum period of 3 months foresaw to the invasive procedure. (Author)

  11. Modified Hitschfeld-Bordan Equations for Attenuation-Corrected Radar Rain Reflectivity: Application to Nonuniform Beamfilling at Off-Nadir Incidence

    Science.gov (United States)

    Meneghini, Robert; Liao, Liang

    2013-01-01

    As shown by Takahashi et al., multiple path attenuation estimates over the field of view of an airborne or spaceborne weather radar are feasible for off-nadir incidence angles. This follows from the fact that the surface reference technique, which provides path attenuation estimates, can be applied to each radar range gate that intersects the surface. This study builds on this result by showing that three of the modified Hitschfeld-Bordan estimates for the attenuation-corrected radar reflectivity factor can be generalized to the case where multiple path attenuation estimates are available, thereby providing a correction to the effects of nonuniform beamfilling. A simple simulation is presented showing some strengths and weaknesses of the approach.

  12. Skull segmentation of UTE MR images by probabilistic neural network for attenuation correction in PET/MR

    Energy Technology Data Exchange (ETDEWEB)

    Santos Ribeiro, A. [Institute of Biophysics and Biomedical Engineering, Lisbon (Portugal); Forschungszentrum Juelich, INM4, Juelich (Germany); Rota Kops, E., E-mail: e.rota.kops@fz-juelich.de [Forschungszentrum Juelich, INM4, Juelich (Germany); Herzog, H. [Forschungszentrum Juelich, INM4, Juelich (Germany); Almeida, P. [Institute of Biophysics and Biomedical Engineering, Lisbon (Portugal)

    2013-02-21

    Aim: Due to space and technical limitations in PET/MR scanners one of the difficulties is the generation of an attenuation correction (AC) map to correct the PET image data. Different methods have been suggested that make use of the images acquired with an ultrashort echo time (UTE) sequence. However, in most of them precise thresholds need to be defined and these may depend on the sequence parameters. In this study an algorithm based on a probabilistic neural network (PNN) is presented requiring little user interaction. Material and methods: An MR UTE sequence delivering two images (UTE1 and UTE2) by using two different echo times (0.07 ms and 2.46 ms, respectively) was acquired. The input features for the PNN algorithm consist of two patches of MR intensities chosen in both the co-registered UTE1 and UTE2 images. At the end, the PNN generates an image classified into four different classes: brain+soft tissue, air, csf, and bone. CT and MR data were acquired in four subjects, whereby the CT data were used for comparison. For each patient co-classification of the different classified classes and the Dice coefficients (D) were calculated between the MR segmented image and the respective CT image. Results: An overall voxel classification accuracy (compared with CT) of 92% was obtained. Also, the resulting D with regard to the skull and calculated for the four subjects show a mean of 0.83 and a standard deviation of 0.07. Discussion: Our results show that a reliable bone segmentation of MRI images as well as the generation of a reliable attenuation map is possible. Conclusion: The developed algorithms possess several advantages over current methods using UTE sequence such as a quick and an easy optimization for different sequence parameters.

  13. Skull segmentation of UTE MR images by probabilistic neural network for attenuation correction in PET/MR

    International Nuclear Information System (INIS)

    Santos Ribeiro, A.; Rota Kops, E.; Herzog, H.; Almeida, P.

    2013-01-01

    Aim: Due to space and technical limitations in PET/MR scanners one of the difficulties is the generation of an attenuation correction (AC) map to correct the PET image data. Different methods have been suggested that make use of the images acquired with an ultrashort echo time (UTE) sequence. However, in most of them precise thresholds need to be defined and these may depend on the sequence parameters. In this study an algorithm based on a probabilistic neural network (PNN) is presented requiring little user interaction. Material and methods: An MR UTE sequence delivering two images (UTE1 and UTE2) by using two different echo times (0.07 ms and 2.46 ms, respectively) was acquired. The input features for the PNN algorithm consist of two patches of MR intensities chosen in both the co-registered UTE1 and UTE2 images. At the end, the PNN generates an image classified into four different classes: brain+soft tissue, air, csf, and bone. CT and MR data were acquired in four subjects, whereby the CT data were used for comparison. For each patient co-classification of the different classified classes and the Dice coefficients (D) were calculated between the MR segmented image and the respective CT image. Results: An overall voxel classification accuracy (compared with CT) of 92% was obtained. Also, the resulting D with regard to the skull and calculated for the four subjects show a mean of 0.83 and a standard deviation of 0.07. Discussion: Our results show that a reliable bone segmentation of MRI images as well as the generation of a reliable attenuation map is possible. Conclusion: The developed algorithms possess several advantages over current methods using UTE sequence such as a quick and an easy optimization for different sequence parameters

  14. CT synthesis in the head & neck region for PET/MR attenuation correction: an iterative multi-atlas approach

    Energy Technology Data Exchange (ETDEWEB)

    Burgos, Ninon [Translational Imaging Group, Centre for Medical Image Computing, University College London, London (United Kingdom); Cardoso, M Jorge; Modat, Marc [Translational Imaging Group, Centre for Medical Image Computing, University College London, London (United Kingdom); Dementia Research Centre, University College London, London (United Kingdom); Punwani, Shonit [Division of Imaging, University College London Hospitals, London (United Kingdom); Centre for Medical Imaging, University College London, London (United Kingdom); Atkinson, David [Centre for Medical Imaging, University College London, London (United Kingdom); Arridge, Simon R [Centre for Medical Image Computing, University College London, London (United Kingdom); Hutton, Brian F [Institute of Nuclear Medicine, University College London Hospitals, London (United Kingdom); Ourselin, Sébastien [Translational Imaging Group, Centre for Medical Image Computing, University College London, London (United Kingdom); Dementia Research Centre, University College London, London (United Kingdom)

    2015-05-18

    In this work, we propose to tackle the problem of attenuation correction in the head and neck by synthesising CT from MR images using an iterative multi-atlas approach. The proposed method relies on pre-acquired T2-weighted MRI and CT images of the neck. For each subject, the MRI is non-rigidly mapped to the CT. To synthesise a pseudo CT, all the MRIs in the database are first registered to the target MRI. This registration consists of a robust affine followed by a non-rigid registration. The pseudo CT is obtained by fusing the mapped atlases according to their morphological similarity to the target. In contrast to CTs, T2 images do not provide a good estimate of the bone location. Combining multiple modalities at both the registration and image similarity stages is expected to provide more realistic mappings and to reduce the bias. An initial pseudo CT (pCT) is combined with the target MRI to form a MRI-pCT pair. The MRI-pCT pair is registered to all the MRI-CT pairs from the database. An improved pseudo CT is obtained by fusing the mapped MRI-CT pairs according to their morphological similarity to the target MRI-pCT pair. Results showed that the proposed CT synthesis algorithm based on a multi-atlas information propagation scheme and iterative process is able to synthesise pseudo CT images in a region challenging for registration algorithms. The results also demonstrate that the robust affine decreases the absolute error compared to the classic approach and that the bone refinement process reduces the bias in the bone region. The proposed method could be used to correct for attenuation PET/MR data, but also for dosimetry calculations in the context of MR-based radiotherapy treatment planning.

  15. The problem in 180 deg data sampling and radioactivity decay correction in gated cardiac blood pool scanning using SPECT

    International Nuclear Information System (INIS)

    Ohtake, Tohru; Watanabe, Toshiaki; Nishikawa, Junichi

    1986-01-01

    In cardiac blood pool scanning using SPECT, half 180 deg data collection (HD) vs. full 360 deg data collection (FD) and Tc-99m decay are problems in quantifying the ejection count (EC) (end-diastolic count - end-systolic count) of both ventricles and the ratio of the ejection count of the right and left ventricles (RVEC/LVEC). We studied the change produced by altering the starting position of data sampling in HD scans. In our results of phantom and 4 clinical cases, when the cardiac axis deviation was not large and there was not remarkable cardiac enlargement, the change in LVEC, RVEC and RVEC/LVEC was small (1 - 4 %) within 12 degree change of the starting position, and the difference between the results of HD scan with a good starting position (the average of LV peak and RV peak) and FD scan was not large (less than 7 %). Because of this, we think HD scan can be used in those cases. But when the cardiac axis deviation was large or there was remarkable cardiac enlargement, the change of LVEC, RVEC and RVEC/LVEC was large (more than 10 %) even within 12 degree change of the starting position. So we think FD scan would be better in those cases. In our results of 6 patients, the half-life of Tc-99m labeled albumin in blood varied from 2 to 4 hr (3.03 ± 0.59 hr, mean ± s.d.). Using a program for radioactivity (RA) decay correction, we studied the change in LVEC, RVEC and LVEC/RVEC in 11 cases. When RA decay correction was performed using a halflife of 3.0 hr, LVEC increased 7.5 %, RVEC increased 8.7 % and RVEC/LVEC increased 0.9 % on the average in HD scans of 8 cases (LPO to RAO, 32 views, 60 beat/1 view). We think RA decay correction would not be needed in quantifying RVEC/LVEC in most cases because the change of RVEC/LVEC was very small. (author)

  16. Dapagliflozin, a selective SGLT2 Inhibitor, attenuated cardiac fibrosis by regulating the macrophage polarization via STAT3 signaling in infarcted rat hearts.

    Science.gov (United States)

    Lee, Tsung-Ming; Chang, Nen-Chung; Lin, Shinn-Zong

    2017-03-01

    During myocardial infarction, infiltrated macrophages have pivotal roles in cardiac remodeling and delayed M1 toward M2 macrophage phenotype transition is considered one of the major factors for adverse ventricular remodeling. We investigated whether dapagliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor, attenuates cardiac fibrosis via regulating macrophage phenotype by a reactive oxygen and nitrogen species (RONS)/STAT3-dependent pathway in postinfarcted rats. Normoglycemic male Wistar rats were subjected to coronary ligation and then randomized to either saline, dapagliflozin (a specific SGLT2 inhibitor), phlorizin (a nonspecific SGLT1/2 inhibitor), dapagliflozin + S3I-201 (a STAT3 inhibitor), or phlorizin + S3I-201 for 4 weeks. There were similar infarct sizes among the infarcted groups at the acute and chronic stages of infarction. At day 3 after infarction, post-infarction was associated with increased levels of superoxide and nitrotyrosine, which can be inhibited by administering either dapagliflozin or phlorizin. SGLT2 inhibitors significantly increased STAT3 activity, STAT3 nuclear translocation, myocardial IL-10 levels and the percentage of M2 macrophage infiltration. At day 28 after infarction, SGLT2 inhibitors were associated with attenuated myofibroblast infiltration and cardiac fibrosis. Although phlorizin decreased myofibroblast infiltration, the effect of dapagliflozin on attenuated myofibroblast infiltration was significantly higher than phlorizin. The effects of SGLT2 inhibitors on cardiac fibrosis were nullified by adding S3I-201. Furthermore, the effects of dapagliflozin on STAT3 activity and myocardial IL-10 levels can be reversed by 3-morpholinosydnonimine, a peroxynitrite generator. Taken together, these observations provide a novel mechanism of SGLT2 inhibitors-mediated M2 polarization through a RONS-dependent STAT3-mediated pathway and selective SGLT2 inhibitors are more effective in attenuating myofibroblast infiltration during

  17. Passive Heating Attenuates Post-exercise Cardiac Autonomic Recovery in Healthy Young Males

    Directory of Open Access Journals (Sweden)

    Tiago Peçanha

    2017-12-01

    Full Text Available Post-exercise heart rate (HR recovery (HRR presents a biphasic pattern, which is mediated by parasympathetic reactivation and sympathetic withdrawal. Several mechanisms regulate these post-exercise autonomic responses and thermoregulation has been proposed to play an important role. The aim of this study was to test the effects of heat stress on HRR and HR variability (HRV after aerobic exercise in healthy subjects. Twelve healthy males (25 ± 1 years, 23.8 ± 0.5 kg/m2 performed 14 min of moderate-intensity cycling exercise (40–60% HRreserve followed by 5 min of loadless active recovery in two conditions: heat stress (HS and normothermia (NT. In HS, subjects dressed in a whole-body water-perfused tube-lined suit to increase internal temperature (Tc by ~1°C. In NT, subjects did not wear the suit. HR, core and skin temperatures (Tc and Tsk, mean arterial pressure (MAP skin blood flow (SKBF, and cutaneous vascular conductance (CVC were measured throughout and analyzed during post-exercise recovery. HRR was assessed through calculations of HR decay after 60 and 300 s of recovery (HRR60s and HRR300s, and the short- and long-term time constants of HRR (T30 and HRRt. Post-exercise HRV was examined via calculations of RMSSD (root mean square of successive RR intervals and RMS (root mean square residual of RR intervals. The HS protocol promoted significant thermal stress and hemodynamic adjustments during the recovery (HS-NT differences: Tc = +0.7 ± 0.3°C; Tsk = +3.2 ± 1.5°C; MAP = −12 ± 14 mmHg; SKBF = +90 ± 80 a.u; CVC = +1.5 ± 1.3 a.u./mmHg. HRR and post-exercise HRV were significantly delayed in HS (e.g., HRR60s = 27 ± 9 vs. 44 ± 12 bpm, P < 0.01; HRR300s = 39 ± 12 vs. 59 ± 16 bpm, P < 0.01. The effects of heat stress (e.g., the HS-NT differences on HRR were associated with its effects on thermal and hemodynamic responses. In conclusion, heat stress delays HRR, and this effect seems to be mediated by an attenuated parasympathetic

  18. [F-18]2-fluoro-2-deoxyglucose (FDG) positron emission tomography after limb salvage surgery: post-surgical appearance, attenuation correction and local complications

    Energy Technology Data Exchange (ETDEWEB)

    Gelfand, Michael J.; Sharp, Susan E. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, Nuclear Medicine Division, Cincinnati, OH (United States)

    2015-08-15

    Metal endoprostheses and internal fixation devices cause significant artifacts on CT after limb salvage surgery; positron emission tomography (PET) images should be evaluated for artifacts. (1) To describe [F-18]2-fluoro-2-deoxyglucose (FDG) PET uptake patterns after limb salvage surgery. (2) To determine whether metal endoprostheses and fixation hardware cause significant artifacts on CT attenuation-corrected PET that interfere with diagnostic use of PET/CT after limb salvage surgery. We reviewed 92 studies from 18 patients ages 5-21 years. Diagnoses were osteogenic sarcoma in 14, Ewing sarcoma in 3, and malignant peripheral nerve sheath tumor originating in bone in 1. Nine patients had distal femur/knee endoprostheses, five had lower-extremity bone allografts secured by large metal plates and four had upper-extremity limb salvage procedures. Maximum standardized uptake value was calculated at lower-extremity soft-tissue-endoprosthesis interfaces. In 15 patients with PET/CT imaging, the first PET/CT scan after limb salvage surgery was reviewed for metal artifacts on CT images and for artifacts at locations on PET corresponding to the CT metal artifacts. Increased FDG uptake was consistently present at soft-tissue interfaces with endoprostheses, allografts and internal fixation devices, with little or no FDG uptake at cemented endoprosthesis-bone interfaces. Maximum standardized uptake value at margins of femur/knee endoprostheses ranged from 1.4 to 5.7. In four patients with distal femur/knee endoprostheses, minimal artifact was noted on attenuation-corrected PET images, but image interpretation was not affected. In the other 11 patients who had CT attenuation correction, we detected no artifacts caused by the attenuation correction. CT attenuation correction did not cause artifacts that affected interpretation of attenuation-corrected PET images. (orig.)

  19. [F-18]2-fluoro-2-deoxyglucose (FDG) positron emission tomography after limb salvage surgery: post-surgical appearance, attenuation correction and local complications

    International Nuclear Information System (INIS)

    Gelfand, Michael J.; Sharp, Susan E.

    2015-01-01

    Metal endoprostheses and internal fixation devices cause significant artifacts on CT after limb salvage surgery; positron emission tomography (PET) images should be evaluated for artifacts. (1) To describe [F-18]2-fluoro-2-deoxyglucose (FDG) PET uptake patterns after limb salvage surgery. (2) To determine whether metal endoprostheses and fixation hardware cause significant artifacts on CT attenuation-corrected PET that interfere with diagnostic use of PET/CT after limb salvage surgery. We reviewed 92 studies from 18 patients ages 5-21 years. Diagnoses were osteogenic sarcoma in 14, Ewing sarcoma in 3, and malignant peripheral nerve sheath tumor originating in bone in 1. Nine patients had distal femur/knee endoprostheses, five had lower-extremity bone allografts secured by large metal plates and four had upper-extremity limb salvage procedures. Maximum standardized uptake value was calculated at lower-extremity soft-tissue-endoprosthesis interfaces. In 15 patients with PET/CT imaging, the first PET/CT scan after limb salvage surgery was reviewed for metal artifacts on CT images and for artifacts at locations on PET corresponding to the CT metal artifacts. Increased FDG uptake was consistently present at soft-tissue interfaces with endoprostheses, allografts and internal fixation devices, with little or no FDG uptake at cemented endoprosthesis-bone interfaces. Maximum standardized uptake value at margins of femur/knee endoprostheses ranged from 1.4 to 5.7. In four patients with distal femur/knee endoprostheses, minimal artifact was noted on attenuation-corrected PET images, but image interpretation was not affected. In the other 11 patients who had CT attenuation correction, we detected no artifacts caused by the attenuation correction. CT attenuation correction did not cause artifacts that affected interpretation of attenuation-corrected PET images. (orig.)

  20. Effects of attenuation and scatter corrections in cat brain PET images using microPET R4 scanner

    International Nuclear Information System (INIS)

    Kim, Jin Su; Lee, Jae Sung; Lee, Jong Jin

    2006-01-01

    The aim of this study was to examine the effects of attenuation correction (AC) and scatter correction (SC) on the quantification of PET count rates. To assess the effects of AC and SC, 18 F-FDG PET images of phantom and cat brain were acquired using microPET R4 scanner. Thirty-minute transmission images using 68 Ge source and emission images after injection of FDG were acquired. PET images were reconstructed using. 2D OSEM. AC and SC were applied. Regional count rates were measured using ROls drawn on cerebral cortex including frontal, parietal, and latral temporal lobes and deep gray matter including head of caudate nucleus, putamen and thalamus for pre- and post-AC and SC images. The count rates were then normalized with the injected dose per body weight. To assess the effects of AC, count ratio of 'deep gray matter/cerebral cortex' was calculated. To assess the effects of SC, ROls were also drawn on the gray matter (GM) and white matter (WM), and contrast between them ((GM-WM)/GM) was measured. After the AC, count ratio of 'deep gray matter/cerebral cortex' was increased by 17±7%. After the SC, contrast was also increased by 12±3%. Relative count of deep gray matter and contrast between gray and white matters were increased after AC and SC, suggesting that the AC would be critical for the quantitative analysis of cat brain PET data

  1. Comparing 511 keV Attenuation Maps Obtained from Different Energy Mapping Methods for CT Based Attenuation Correction of PET Data

    Directory of Open Access Journals (Sweden)

    Maryam Shirmohammad

    2008-06-01

    Full Text Available Introduction:  The  advent  of  dual-modality  PET/CT  scanners  has  revolutionized  clinical  oncology  by  improving lesion localization and facilitating treatment planning for radiotherapy. In addition, the use of  CT images for CT-based attenuation correction (CTAC decreases the overall scanning time and creates  a noise-free  attenuation  map  (6map.  CTAC  methods  include  scaling,  segmentation,  hybrid  scaling/segmentation, bilinear and dual energy methods. All CTAC methods require the transformation  of CT Hounsfield units (HU to linear attenuation coefficients (LAC at 511 keV. The aim of this study is  to compare the results of implementing different methods of energy mapping in PET/CT scanners.   Materials and Methods: This study was conducted in 2 phases, the first phase in a phantom and the  second  one  on  patient  data.  To  perform  the  first  phase,  a  cylindrical  phantom  with  different  concentrations of K2HPO4 inserts was CT scanned and energy mapping methods were implemented on  it. For performing the second phase, different energy  mapping  methods  were implemented on several  clinical studies and compared to the transmission (TX image derived using Ga-68 radionuclide source  acquired on the GE Discovery LS PET/CT scanner.   Results: An ROI analysis was performed on different positions of the resultant 6maps and the average  6value of each ROI was compared to the reference value. The results of the 6maps obtained for 511 keV  compared to the theoretical  values showed that in the phantom for low  concentrations  of K 2 HPO 4 all  these  methods  produce  511  keV  attenuation  maps  with  small  relative  difference  compared  to  gold  standard. The relative difference for scaling, segmentation, hybrid, bilinear and dual energy methods was  4.92,  3.21,  4.43,  2.24  and  2.29%,  respectively.  Although  for  high  concentration

  2. Calculation of the flux attenuation and multiple scattering correction factors in time of flight technique for double differential cross section measurements

    International Nuclear Information System (INIS)

    Martin, G.; Coca, M.; Capote, R.

    1996-01-01

    Using Monte Carlo method technique , a computer code which simulates the time of flight experiment to measure double differential cross section was developed. The correction factor for flux attenuation and multiple scattering, that make a deformation to the measured spectrum, were calculated. The energy dependence of the correction factor was determined and a comparison with other works is shown. Calculations for Fe 56 at two different scattering angles were made. We also reproduce the experiment performed at the Nuclear Analysis Laboratory for C 12 at 25 celsius degree and the calculated correction factor for the is measured is shown. We found a linear relation between the scatter size and the correction factor for flux attenuation

  3. Early detection of cardiac ischemia using a conductometric pCO2 sensor: real-time drift correction and parameterization

    International Nuclear Information System (INIS)

    Tronstad, Christian; Martinsen, Ørjan G; Grimnes, Sverre; Pischke, Soeren E; Holhjem, Lars; Tønnessen, Tor Inge

    2010-01-01

    For detection of cardiac ischemia based on regional pCO 2 measurement, sensor drift becomes a problem when monitoring over several hours. A real-time drift correction algorithm was developed based on utilization of the time-derivative to distinguish between physiological responses and the drift, customized by measurements from a myocardial infarction porcine model (6 pigs, 23 sensors). IscAlert(TM) conductometric pCO 2 sensors were placed in the myocardial regions supplied by the left anterior descending coronary artery (LAD) and the left circumflex artery (LCX) while the LAD artery was fully occluded for 1, 3, 5 and 15 min leading to ischemia in the LAD-dependent region. The measured pCO 2 , the drift-corrected pCO 2 (ΔpCO 2 ) and its time-derivative (TDpCO 2 ) were compared with respect to detection ability. Baseline stability in the ΔpCO 2 led to earlier, more accurate detection. The TDpCO 2 featured the earliest sensitivity, but with a lower specificity. Combining ΔpCO 2 and TDpCO 2 enables increased accuracy. Suggestions are given for the utilization of the parameters for an automated early warning and alarming system. In conclusion, early detection of cardiac ischemia is feasible using the conductometric pCO 2 sensor together with parameterization methods

  4. Fluid overload correction and cardiac history influence brain natriuretic peptide evolution in incident haemodialysis patients.

    Science.gov (United States)

    Chazot, Charles; Vo-Van, Cyril; Zaoui, Eric; Vanel, Thierry; Hurot, Jean Marc; Lorriaux, Christie; Mayor, Brice; Deleaval, Patrick; Jean, Guillaume

    2011-08-01

    Brain natriuretic peptide (BNP) is a cardiac peptide secreted by ventricle myocardial cells under stretch constraint. Increased BNP has been shown associated with increased mortality in end-stage renal disease patients. In patients starting haemodialysis (HD), both fluid overload and cardiac history are frequently present and may be responsible for a high BNP plasma level. We report in this study the evolution of BNP levels in incident HD patients, its relationship with fluid removal and cardiac history as well as its prognostic value. Forty-six patients (female/male: 21/25; 68.6 ± 14.5 years old) surviving at least 6 months after HD treatment onset were retrospectively analysed. Plasma BNP (Chemoluminescent Microparticule ImmunoAssay on i8200 Architect Abbott, Paris, France; normal value < 100 pg/mL) was assessed at HD start and during the second quarter of HD treatment (Q2). At dialysis start, the plasma BNP level was 1041 ± 1178 pg/mL (range: 14-4181 pg/mL). It was correlated with age (P = 0.0017) and was significantly higher in males (P = 0.0017) and in patients with cardiac disease history (P = 0.001). The plasma BNP level at baseline was not related to the mortality risk. At Q2, predialysis systolic blood pressure (BP) decreased from 140.5 ± 24.5 to 129.4 ± 20.6 mmHg (P = 0.0001) and the postdialysis body weight by 7.6 ± 8.4% (P < 0.0001). The BNP level decreased to 631 ± 707 pg/mL (P = 0.01) at Q2. Its variation was significantly correlated with systolic BP decrease (P = 0.006). A high BNP level was found associated with an increased risk of mortality. Hence, plasma BNP levels decreased during the first months of HD treatment during the dry weight quest. Whereas initial BNP values were not associated with increased mortality risk, the BNP level at Q2 was independently predictive of mortality. Hence, BNP is a useful tool to follow patient dehydration after dialysis start. Initial fluid overload may act as a confounding factor for its value as a

  5. Influence of OSEM and segmented attenuation correction in the calculation of standardised uptake values for [18F]FDG PET

    International Nuclear Information System (INIS)

    Visvikis, D.; Costa, D.C.; Bomanji, J.; Gacinovic, S.; Ell, P.J.; Cheze-LeRest, C.

    2001-01-01

    Standardised Uptake Values (SUVs) are widely used in positron emission tomography (PET) as a semi-quantitative index of fluorine-18 labelled fluorodeoxyglucose uptake. The objective of this study was to investigate any bias introduced in the calculation of SUVs as a result of employing ordered subsets-expectation maximisation (OSEM) image reconstruction and segmented attenuation correction (SAC). Variable emission and transmission time durations were investigated. Both a phantom and a clinical evaluation of the bias were carried out. The software implemented in the GE Advance PET scanner was used. Phantom studies simulating tumour imaging conditions were performed. Since a variable count rate may influence the results obtained using OSEM, similar acquisitions were performed at total count rates of 34 kcps and 12 kcps. Clinical data consisted of 100 patient studies. Emission datasets of 5 and 15 min duration were combined with 15-, 3-, 2- and 1-min transmission datasets for the reconstruction of both phantom and patient studies. Two SUVs were estimated using the average (SUV avg ) and the maximum (SUV max ) count density from regions of interest placed well inside structures of interest. The percentage bias of these SUVs compared with the values obtained using a reference image was calculated. The reference image was considered to be the one produced by filtered backprojection (FBP) image reconstruction with measured attenuation correction using the 15-min emission and transmission datasets for each phantom and patient study. A bias of 5%-20% was found for the SUV avg and SUV max in the case of FBP with SAC using variable transmission times. In the case of OSEM with SAC, the bias increased to 10%-30%. An overall increase of 5%-10% was observed with the use of SUV max . The 5-min emission dataset led to an increase in the bias of 25%-100%, with the larger increase recorded for the SUV max . The results suggest that OSEM and SAC with 3 and 2 min transmission may be

  6. SU-C-9A-06: The Impact of CT Image Used for Attenuation Correction in 4D-PET

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Y; Bowsher, J; Yan, S; Cai, J; Das, S; Yin, F [Duke University Medical Center, Durham, NC (United States)

    2014-06-01

    Purpose: To evaluate the appropriateness of using 3D non-gated CT image for attenuation correction (AC) in a 4D-PET (gated PET) imaging protocol used in radiotherapy treatment planning simulation. Methods: The 4D-PET imaging protocol in a Siemens PET/CT simulator (Biograph mCT, Siemens Medical Solutions, Hoffman Estates, IL) was evaluated. CIRS Dynamic Thorax Phantom (CIRS Inc., Norfolk, VA) with a moving glass sphere (8 mL) in the middle of its thorax portion was used in the experiments. The glass was filled with {sup 18}F-FDG and was in a longitudinal motion derived from a real patient breathing pattern. Varian RPM system (Varian Medical Systems, Palo Alto, CA) was used for respiratory gating. Both phase-gating and amplitude-gating methods were tested. The clinical imaging protocol was modified to use three different CT images for AC in 4D-PET reconstruction: first is to use a single-phase CT image to mimic actual clinical protocol (single-CT-PET); second is to use the average intensity projection CT (AveIP-CT) derived from 4D-CT scanning (AveIP-CT-PET); third is to use 4D-CT image to do the phase-matched AC (phase-matching- PET). Maximum SUV (SUVmax) and volume of the moving target (glass sphere) with threshold of 40% SUVmax were calculated for comparison between 4D-PET images derived with different AC methods. Results: The SUVmax varied 7.3%±6.9% over the breathing cycle in single-CT-PET, compared to 2.5%±2.8% in AveIP-CT-PET and 1.3%±1.2% in phasematching PET. The SUVmax in single-CT-PET differed by up to 15% from those in phase-matching-PET. The target volumes measured from single- CT-PET images also presented variations up to 10% among different phases of 4D PET in both phase-gating and amplitude-gating experiments. Conclusion: Attenuation correction using non-gated CT in 4D-PET imaging is not optimal process for quantitative analysis. Clinical 4D-PET imaging protocols should consider phase-matched 4D-CT image if available to achieve better accuracy.

  7. SU-C-9A-06: The Impact of CT Image Used for Attenuation Correction in 4D-PET

    International Nuclear Information System (INIS)

    Cui, Y; Bowsher, J; Yan, S; Cai, J; Das, S; Yin, F

    2014-01-01

    Purpose: To evaluate the appropriateness of using 3D non-gated CT image for attenuation correction (AC) in a 4D-PET (gated PET) imaging protocol used in radiotherapy treatment planning simulation. Methods: The 4D-PET imaging protocol in a Siemens PET/CT simulator (Biograph mCT, Siemens Medical Solutions, Hoffman Estates, IL) was evaluated. CIRS Dynamic Thorax Phantom (CIRS Inc., Norfolk, VA) with a moving glass sphere (8 mL) in the middle of its thorax portion was used in the experiments. The glass was filled with 18 F-FDG and was in a longitudinal motion derived from a real patient breathing pattern. Varian RPM system (Varian Medical Systems, Palo Alto, CA) was used for respiratory gating. Both phase-gating and amplitude-gating methods were tested. The clinical imaging protocol was modified to use three different CT images for AC in 4D-PET reconstruction: first is to use a single-phase CT image to mimic actual clinical protocol (single-CT-PET); second is to use the average intensity projection CT (AveIP-CT) derived from 4D-CT scanning (AveIP-CT-PET); third is to use 4D-CT image to do the phase-matched AC (phase-matching- PET). Maximum SUV (SUVmax) and volume of the moving target (glass sphere) with threshold of 40% SUVmax were calculated for comparison between 4D-PET images derived with different AC methods. Results: The SUVmax varied 7.3%±6.9% over the breathing cycle in single-CT-PET, compared to 2.5%±2.8% in AveIP-CT-PET and 1.3%±1.2% in phasematching PET. The SUVmax in single-CT-PET differed by up to 15% from those in phase-matching-PET. The target volumes measured from single- CT-PET images also presented variations up to 10% among different phases of 4D PET in both phase-gating and amplitude-gating experiments. Conclusion: Attenuation correction using non-gated CT in 4D-PET imaging is not optimal process for quantitative analysis. Clinical 4D-PET imaging protocols should consider phase-matched 4D-CT image if available to achieve better accuracy

  8. Reduction of artefacts caused by hip implants in CT-based attenuation-corrected PET images using 2-D interpolation of a virtual sinogram on an irregular grid

    NARCIS (Netherlands)

    Abdoli, Mehrsima; de Jong, Johan R.; Pruim, Jan; Dierckx, Rudi A. J. O.; Zaidi, Habib

    2011-01-01

    Purpose Metallic prosthetic replacements, such as hip or knee implants, are known to cause strong streaking artefacts in CT images. These artefacts likely induce over-or underestimation of the activity concentration near the metallic implants when applying CT-based attenuation correction of positron

  9. Mechanical ventilation with high tidal volumes attenuates myocardial dysfunction by decreasing cardiac edema in a rat model of LPS-induced peritonitis

    Directory of Open Access Journals (Sweden)

    Smeding Lonneke

    2012-03-01

    Full Text Available Abstract Background Injurious mechanical ventilation (MV may augment organ injury remote from the lungs. During sepsis, myocardial dysfunction is common and increased endothelial activation and permeability can cause myocardial edema, which may, among other factors, hamper myocardial function. We investigated the effects of MV with injuriously high tidal volumes on the myocardium in an animal model of sepsis. Methods Normal rats and intraperitoneal (i.p. lipopolysaccharide (LPS-treated rats were ventilated with low (6 ml/kg and high (19 ml/kg tidal volumes (Vt under general anesthesia. Non-ventilated animals served as controls. Mean arterial pressure (MAP, central venous pressure (CVP, cardiac output (CO and pulmonary plateau pressure (Pplat were measured. Ex vivo myocardial function was measured in isolated Langendorff-perfused hearts. Cardiac expression of endothelial vascular cell adhesion molecule (VCAM-1 and edema were measured to evaluate endothelial inflammation and leakage. Results MAP decreased after LPS-treatment and Vt-dependently, both independent of each other and with interaction. MV Vt-dependently increased CVP and Pplat and decreased CO. LPS-induced peritonitis decreased myocardial function ex vivo but MV attenuated systolic dysfunction Vt-dependently. Cardiac endothelial VCAM-1 expression was increased by LPS treatment independent of MV. Cardiac edema was lowered Vt-dependently by MV, particularly after LPS, and correlated inversely with systolic myocardial function parameters ex vivo. Conclusion MV attenuated LPS-induced systolic myocardial dysfunction in a Vt-dependent manner. This was associated with a reduction in cardiac edema following a lower transmural coronary venous outflow pressure during LPS-induced coronary inflammation.

  10. Visual and semiquantitative analysis of 18F-fluorodeoxyglucose positron emission tomography using a partial-ring tomograph without attenuation correction to differentiate benign and malignant pulmonary nodules

    International Nuclear Information System (INIS)

    Skehan, S.J.; Coates, G.; Otero, C.; O'Donovan, N.; Pelling, M.; Nahmias, C.

    2001-01-01

    Many studies have reported the use of attenuation-corrected positron emission tomography with 18 F-fluorodeoxyglucose (FDG PET) with full-ring tomographs to differentiate between benign and malignant pulmonary nodules. We sought to evaluate FDG PET using a partial-ring tomograph without attenuation correction. A retrospective review of PET images from 77 patients (range 38-84 years of age) with proven benign or malignant pulmonary nodules was undertaken. All images were obtained using a Siemens/CTI ECAT ART tomograph, without attenuation correction, after 185 MBq 18 F-FDG was injected. Images were visually graded on a 5-point scale from 'definitely malignant' to 'definitely benign,' and lesion-to-background (LB) ratios were calculated using region of interest analysis. Visual and semiquantitative analyses were compared using receiver operating characteristic analysis. Twenty lesions were benign and 57 were malignant. The mean LB ratio for benign lesions was 1.5 (range 1.0-5.7) and for malignant lesions 5.7 (range 1.2-14.1) (p < 0.001). The area under the ROC curve for LB ratio analysis was 0.95, and for visual analysis 0.91 (p = 0.39). The optimal cut-off ratio with LB ratio analysis was 1.8, giving a sensitivity of 95% and a specificity of 85%. For lesions thought to be 'definitely malignant' on visual analysis, the sensitivity was 93% and the specificity 85%. Three proven infective lesions were rated as malignant by both techniques (LB ratio 2.6-5.7). FDG PET without attenuation correction is accurate for differentiating between benign and malignant lung nodules. Results using simple LB ratios without attenuation correction compare favourably with the published sensitivity and specificity for standard uptake ratios. Visual analysis is equally accurate. (author)

  11. Improved attenuation correction for respiratory gated PET/CT with extended-duration cine CT: a simulation study

    Science.gov (United States)

    Zhang, Ruoqiao; Alessio, Adam M.; Pierce, Larry A.; Byrd, Darrin W.; Lee, Tzu-Cheng; De Man, Bruno; Kinahan, Paul E.

    2017-03-01

    Due to the wide variability of intra-patient respiratory motion patterns, traditional short-duration cine CT used in respiratory gated PET/CT may be insufficient to match the PET scan data, resulting in suboptimal attenuation correction that eventually compromises the PET quantitative accuracy. Thus, extending the duration of cine CT can be beneficial to address this data mismatch issue. In this work, we propose to use a long-duration cine CT for respiratory gated PET/CT, whose cine acquisition time is ten times longer than a traditional short-duration cine CT. We compare the proposed long-duration cine CT with the traditional short-duration cine CT through numerous phantom simulations with 11 respiratory traces measured during patient PET/CT scans. Experimental results show that, the long-duration cine CT reduces the motion mismatch between PET and CT by 41% and improves the overall reconstruction accuracy by 42% on average, as compared to the traditional short-duration cine CT. The long-duration cine CT also reduces artifacts in PET images caused by misalignment and mismatch between adjacent slices in phase-gated CT images. The improvement in motion matching between PET and CT by extending the cine duration depends on the patient, with potentially greater benefits for patients with irregular breathing patterns or larger diaphragm movements.

  12. Description and assessment of a registration-based approach to include bones for attenuation correction of whole-body PET/MRI.

    Science.gov (United States)

    Marshall, Harry R; Patrick, John; Laidley, David; Prato, Frank S; Butler, John; Théberge, Jean; Thompson, R Terry; Stodilka, Robert Z

    2013-08-01

    Attenuation correction for whole-body PET/MRI is challenging. Most commercial systems compute the attenuation map from MRI using a four-tissue segmentation approach. Bones, the most electron-dense tissue, are neglected because they are difficult to segment. In this work, the authors build on this segmentation approach by adding bones using a registration technique and assessing its performance on human PET images. Twelve oncology patients were imaged with FDG PET/CT and MRI using a Turbo-FLASH pulse sequence. A database of 121 attenuation correction quality CT scans was also collected. Each patient MRI was compared to the CT database via weighted heuristic measures to find the "most similar" CT in terms of body geometry. The similar CT was aligned to the MRI with a deformable registration method. Two MRI-based attenuation maps were computed. One was a standard four-tissue segmentation (air, lung, fat, and lean tissue) using basic image processing techniques. The other was identical, except the bones from the aligned CT were added. The PET data were reconstructed with the patient's CT-based attenuation map (the silver standard) and both MRI-based attenuation maps. The relative errors of the MRI-based attenuation corrections were computed in 14 standardized volumes of interest, in lesions, and over whole tissues. The squared Pearson correlation coefficient was also calculated over whole tissues. Statistical testing was done with ANOVAs and paired t-tests. The MRI-based attenuation correction ignoring bone had relative errors ranging from -37% to -8% in volumes of interest containing bone. By including bone, the magnitude of the relative error was reduced in all cases (pbone was improved from a mean of -7.5% to 2% (pbone reduced the magnitude of relative error in three cases (pbone slightly increased relative error in lung from 7.7% to 8.0% (p=0.002), in fat from 8.5% to 9.2% (pbone from -14.6% to 1.3% (pbone was included or not. The approach to include bones in MRI

  13. Cardiac motion correction based on partial angle reconstructed images in x-ray CT

    International Nuclear Information System (INIS)

    Kim, Seungeon; Chang, Yongjin; Ra, Jong Beom

    2015-01-01

    Purpose: Cardiac x-ray CT imaging is still challenging due to heart motion, which cannot be ignored even with the current rotation speed of the equipment. In response, many algorithms have been developed to compensate remaining motion artifacts by estimating the motion using projection data or reconstructed images. In these algorithms, accurate motion estimation is critical to the compensated image quality. In addition, since the scan range is directly related to the radiation dose, it is preferable to minimize the scan range in motion estimation. In this paper, the authors propose a novel motion estimation and compensation algorithm using a sinogram with a rotation angle of less than 360°. The algorithm estimates the motion of the whole heart area using two opposite 3D partial angle reconstructed (PAR) images and compensates the motion in the reconstruction process. Methods: A CT system scans the thoracic area including the heart over an angular range of 180° + α + β, where α and β denote the detector fan angle and an additional partial angle, respectively. The obtained cone-beam projection data are converted into cone-parallel geometry via row-wise fan-to-parallel rebinning. Two conjugate 3D PAR images, whose center projection angles are separated by 180°, are then reconstructed with an angular range of β, which is considerably smaller than a short scan range of 180° + α. Although these images include limited view angle artifacts that disturb accurate motion estimation, they have considerably better temporal resolution than a short scan image. Hence, after preprocessing these artifacts, the authors estimate a motion model during a half rotation for a whole field of view via nonrigid registration between the images. Finally, motion-compensated image reconstruction is performed at a target phase by incorporating the estimated motion model. The target phase is selected as that corresponding to a view angle that is orthogonal to the center view angles of

  14. Cardiac motion correction based on partial angle reconstructed images in x-ray CT

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seungeon; Chang, Yongjin; Ra, Jong Beom, E-mail: jbra@kaist.ac.kr [Department of Electrical Engineering, KAIST, Daejeon 305-701 (Korea, Republic of)

    2015-05-15

    Purpose: Cardiac x-ray CT imaging is still challenging due to heart motion, which cannot be ignored even with the current rotation speed of the equipment. In response, many algorithms have been developed to compensate remaining motion artifacts by estimating the motion using projection data or reconstructed images. In these algorithms, accurate motion estimation is critical to the compensated image quality. In addition, since the scan range is directly related to the radiation dose, it is preferable to minimize the scan range in motion estimation. In this paper, the authors propose a novel motion estimation and compensation algorithm using a sinogram with a rotation angle of less than 360°. The algorithm estimates the motion of the whole heart area using two opposite 3D partial angle reconstructed (PAR) images and compensates the motion in the reconstruction process. Methods: A CT system scans the thoracic area including the heart over an angular range of 180° + α + β, where α and β denote the detector fan angle and an additional partial angle, respectively. The obtained cone-beam projection data are converted into cone-parallel geometry via row-wise fan-to-parallel rebinning. Two conjugate 3D PAR images, whose center projection angles are separated by 180°, are then reconstructed with an angular range of β, which is considerably smaller than a short scan range of 180° + α. Although these images include limited view angle artifacts that disturb accurate motion estimation, they have considerably better temporal resolution than a short scan image. Hence, after preprocessing these artifacts, the authors estimate a motion model during a half rotation for a whole field of view via nonrigid registration between the images. Finally, motion-compensated image reconstruction is performed at a target phase by incorporating the estimated motion model. The target phase is selected as that corresponding to a view angle that is orthogonal to the center view angles of

  15. Impact of CT attenuation correction method on quantitative respiratory-correlated (4D) PET/CT imaging

    Energy Technology Data Exchange (ETDEWEB)

    Nyflot, Matthew J., E-mail: nyflot@uw.edu [Department of Radiation Oncology, University of Washington, Seattle, Washington 98195-6043 (United States); Lee, Tzu-Cheng [Department of Bioengineering, University of Washington, Seattle, Washington 98195-6043 (United States); Alessio, Adam M.; Kinahan, Paul E. [Department of Radiology, University of Washington, Seattle, Washington 98195-6043 (United States); Wollenweber, Scott D.; Stearns, Charles W. [GE Healthcare, Waukesha, Wisconsin 53188 (United States); Bowen, Stephen R. [Department of Radiation Oncology, University of Washington, Seattle, Washington 98195-6043 and Department of Radiology, University of Washington, Seattle, Washington 98195-6043 (United States)

    2015-01-15

    Purpose: Respiratory-correlated positron emission tomography (PET/CT) 4D PET/CT is used to mitigate errors from respiratory motion; however, the optimal CT attenuation correction (CTAC) method for 4D PET/CT is unknown. The authors performed a phantom study to evaluate the quantitative performance of CTAC methods for 4D PET/CT in the ground truth setting. Methods: A programmable respiratory motion phantom with a custom movable insert designed to emulate a lung lesion and lung tissue was used for this study. The insert was driven by one of five waveforms: two sinusoidal waveforms or three patient-specific respiratory waveforms. 3DPET and 4DPET images of the phantom under motion were acquired and reconstructed with six CTAC methods: helical breath-hold (3DHEL), helical free-breathing (3DMOT), 4D phase-averaged (4DAVG), 4D maximum intensity projection (4DMIP), 4D phase-matched (4DMATCH), and 4D end-exhale (4DEXH) CTAC. Recovery of SUV{sub max}, SUV{sub mean}, SUV{sub peak}, and segmented tumor volume was evaluated as RC{sub max}, RC{sub mean}, RC{sub peak}, and RC{sub vol}, representing percent difference relative to the static ground truth case. Paired Wilcoxon tests and Kruskal–Wallis ANOVA were used to test for significant differences. Results: For 4DPET imaging, the maximum intensity projection CTAC produced significantly more accurate recovery coefficients than all other CTAC methods (p < 0.0001 over all metrics). Over all motion waveforms, ratios of 4DMIP CTAC recovery were 0.2 ± 5.4, −1.8 ± 6.5, −3.2 ± 5.0, and 3.0 ± 5.9 for RC{sub max}, RC{sub peak}, RC{sub mean}, and RC{sub vol}. In comparison, recovery coefficients for phase-matched CTAC were −8.4 ± 5.3, −10.5 ± 6.2, −7.6 ± 5.0, and −13.0 ± 7.7 for RC{sub max}, RC{sub peak}, RC{sub mean}, and RC{sub vol}. When testing differences between phases over all CTAC methods and waveforms, end-exhale phases were significantly more accurate (p = 0.005). However, these differences were driven by

  16. Impaired cardiac ischemic tolerance in spontaneously hypertensive rats is attenuated by adaptation to chronic and acute stress.

    Science.gov (United States)

    Ravingerová, T; Bernátová, I; Matejíková, J; Ledvényiová, V; Nemčeková, M; Pecháňová, O; Tribulová, N; Slezák, J

    2011-01-01

    Chronic hypertension may have a negative impact on the myocardial response to ischemia. On the other hand, intrinsic ischemic tolerance may persist even in the pathologically altered hearts of hypertensive animals, and may be modified by short- or long-term adaptation to different stressful conditions. The effects of long-term limitation of living space (ie, crowding stress [CS]) and brief ischemia-induced stress on cardiac response to ischemia/reperfusion (I/R) injury are not yet fully characterized in hypertensive subjects. The present study was designed to test the influence of chronic and acute stress on the myocardial response to I/R in spontaneously hypertensive rats (SHR) compared with their effects in normotensive counterparts. In both groups, chronic, eight-week CS was induced by caging five rats per cage in cages designed for two rats (200 cm(2)/rat), while controls (C) were housed four to a cage in cages designed for six animals (480 cm(2)/rat). Acute stress was evoked by one cycle of I/R (5 min each, ischemic preconditioning) before sustained I/R in isolated Langendorff-perfused hearts of normotensive and SHR rats. At baseline conditions, the effects of CS were manifested only as a further increase in blood pressure in SHR, and by marked limitation of coronary perfusion in normotensive animals, while no changes in heart mechanical function were observed in any of the groups. Postischemic recovery of contractile function, severity of ventricular arrhythmias and lethal injury (infarction size) were worsened in the hypertrophied hearts of C-SHR compared with normotensive C. However, myo-cardial stunning and reperfusion-induced ventricular arrhythmias were attenuated by CS in SHR, which was different from deterioration of I/R injury in the hearts of normotensive animals. In contrast, ischemic preconditioning conferred an effective protection against I/R in both groups, although the extent of anti-infarct and anti-arrhythmic effects was lower in SHR. Both

  17. Corrections.

    Science.gov (United States)

    2016-02-01

    In the October In Our Unit article by Cooper et al, “Against All Odds: Preventing Pressure Ulcers in High-Risk Cardiac Surgery Patients” (Crit Care Nurse. 2015;35[5]:76–82), there was an error in the reference citation on page 82. At the top of that page, reference 18 cited on the second line should be reference 23, which also should be added to the References list: 23. AHRQ website. Prevention and treatment program integrates actionable reports into practice, significantly reducing pressure ulcers in nursing home residents. November 2008. https://innovations.ahrq.gov/profiles/prevention-and-treatment-program-integrates-actionable-reports-practice-significantly. Accessed November 18, 2015

  18. Electrocardiography-triggered high-resolution CT for reducing cardiac motion artifact. Evaluation of the extent of ground-glass attenuation in patients with idiopathic pulmonary fibrosis

    International Nuclear Information System (INIS)

    Nishiura, Motoko; Johkoh, Takeshi; Yamamoto, Shuji

    2007-01-01

    The aim of this study was to evaluate the decreasing of cardiac motion artifact and whether the extent of ground-glass attenuation of idiopathic pulmonary fibrosis (IPF) was accurately assessed by electrocardiography (ECG)-triggered high-resolution computed tomography (HRCT) by 0.5-s/rotation multidetector-row CT (MDCT). ECG-triggered HRCT were scanned at the end-diastolic phase by a MDCT scanner with the following scan parameters; axial four-slice mode, 0.5 mm collimation, 0.5-s/rotation, 120 kVp, 200 mA/rotation, high-frequency algorithm, and half reconstruction. In 42 patients with IPF, both conventional HRCT (ECG gating (-), full reconstruction) and ECG-triggered HRCT were performed at the same levels (10-mm intervals) with the above scan parameters. The correlation between percent diffusion of carbon monoxide of the lung (%DLCO) and the mean extent of ground-glass attenuation on both conventional HRCT and ECG-triggered HRCT was evaluated with the Spearman rank correlation coefficient test. The correlation between %DLCO and the mean extent of ground-glass attenuation on ECG-triggered HRCT (observer A: r=-0.790, P<0.0001; observer B: r=-0.710, P<0.0001) was superior to that on conventional HRCT (observer A: r=-0.395, P<0.05; observer B: r=-0.577, P=0.002) for both observers. ECG-triggered HRCT by 0.5 s/rotation MDCT can reduce the cardiac motion artifact and is useful for evaluating the extent of ground-glass attenuation of IPF. (author)

  19. Correction for tissue attenuation in radionuclide gastric emptying studies: a comparison of a lateral image method and a geometric mean method

    Energy Technology Data Exchange (ETDEWEB)

    Collins, P.J.; Chatterton, B.E. (Royal Adelaide Hospital (Australia)); Horowitz, M.; Shearman, D.J.C. (Adelaide Univ. (Australia). Dept. of Medicine)

    1984-08-01

    Variation in depth of radionuclide within the stomach may result in significant errors in the measurement of gastric emptying if no attempt is made to correct for gamma-ray attenuation by the patient's tissues. A method of attenuation correction, which uses a single posteriorly located scintillation camera and correction factors derived from a lateral image of the stomach, was compared with a two-camera geometric mean method, in phantom studies and in five volunteer subjects. A meal of 100 g of ground beef containing /sup 99/Tcsup(m)-chicken liver, and 150 ml of water was used in the in vivo studies. In all subjects the geometric mean data showed that solid food emptied in two phases: an initial lag period, followed by a linear emptying phase. Using the geometric mean data as a standard, the anterior camera overestimated the 50% emptying time (T/sub 50/) by an average of 15% (range 5-18) and the posterior camera underestimated this parameter by 15% (4-22). The posterior data, corrected for attenuation using the lateral image method, underestimated the T/sub 50/ by 2% (-7 to +7). The difference in the distances of the proximal and distal stomach from the posterior detector was large in all subjects (mean 5.7 cm, range 3.9-7.4).

  20. Motion Correction using Coil Arrays (MOCCA) for Free-Breathing Cardiac Cine MRI

    Science.gov (United States)

    Hu, Peng; Hong, Susie; Moghari, Mehdi H.; Goddu, Beth; Goepfert, Lois; Kissinger, Kraig V.; Hauser, Thomas H.; Manning, Warren J; Nezafat, Reza

    2014-01-01

    In this study, we present a motion compensation technique based on coil arrays (MOCCA) and evaluate its application in free-breathing respiratory self-gated cine MRI. MOCCA takes advantages of the fact that motion-induced changes in k-space signal are modulated by individual coil sensitivity profiles. In the proposed implementation of MOCCA self-gating for free-breathing cine MRI, the k-space center line is acquired at the beginning of each k-space segment for each cardiac cycle with 4 repetitions. For each k-space segment, the k-space center line acquired immediately before was used to select one of the 4 acquired repetitions to be included in the final self-gated cine image by calculating the cross-correlation between the k-space center line with a reference line. The proposed method was tested on a cohort of healthy adult subjects for subjective image quality and objective blood-myocardium border sharpness. The method was also tested on a cohort of patients to compare the left and right ventricular volumes and ejection fraction measurements with that of standard breath-hold cine MRI. Our data indicate that the proposed MOCCA method provides significantly improved image quality and sharpness compared to free-breathing cine without respiratory self-gating, and provides similar volume measurements compared with breath-hold cine MRI. PMID:21773986

  1. Different Modes of Monitoring and Correction of Cardiac Function During Operations Under Extracorporeal Circulation

    Directory of Open Access Journals (Sweden)

    L. A. Krichevsky

    2007-01-01

    Full Text Available Objective: to comparatively evaluate the efficiency of intensive care measures chosen on the basis of traditional monitoring of central hemodynamics (CH or on that of the data of transesophageal echocardiography (TE echoCG.Materials and methods: 50 patients were examined at coronary bypass surgery under extracorporeal circulation. Under a prospective comparative analysis were two algorithms of treatment policy: maintenance of cardiac index, by using the maximum volemic load, or that of left ventricular systolic function under guidance of transesophageal echocardiography.Results: Significantly (p<0.05 larger doses of dopamine and/or dobutamine were required to maintain adequate left ventricular systolic function. However, this treatment policy showed much better (p<0.05 circulatory parameters in the postperfusion period. At the same time the duration of postoperative inotropic therapy in these patients proved to be significantly (p<0.05 less.Conclusion. The treatment policy based on the maintenance of left ventricular systolic function under guidance of TE echoCG leads to the shortest circulatory stabilization during myocardial revascularization. The application of a volemic load and the expectant use of inotropic drugs result in a longer restoration of operated heart function. 

  2. Associations between N-terminal pro-B-type natriuretic peptide and cardiac function in adults with corrected tetralogy of Fallot

    NARCIS (Netherlands)

    J.A. Eindhoven (Jannet); M.E. Menting (Myrthe); A.E. van den Bosch (Annemien); J.A.A.E. Cuypers (Judith); T.P.E. Ruys (Titia); M. Witsenburg (Maarten); J.S. Vletter-McGhie (Jackie); H. Boersma (Eric); J.W. Roos-Hesselink (Jolien)

    2014-01-01

    textabstractBackground Amino-terminal B-type natriuretic peptide (NT-proBNP) may detect early cardiac dysfunction in adults with tetralogy of Fallot (ToF) late after corrective surgery. We aimed to determine the value of NT-proBNP in adults with ToF and establish its relationship with

  3. Correction

    CERN Multimedia

    2002-01-01

    Tile Calorimeter modules stored at CERN. The larger modules belong to the Barrel, whereas the smaller ones are for the two Extended Barrels. (The article was about the completion of the 64 modules for one of the latter.) The photo on the first page of the Bulletin n°26/2002, from 24 July 2002, illustrating the article «The ATLAS Tile Calorimeter gets into shape» was published with a wrong caption. We would like to apologise for this mistake and so publish it again with the correct caption.

  4. Restoration of Circulating MFGE8 (Milk Fat Globule-EGF Factor 8) Attenuates Cardiac Hypertrophy Through Inhibition of Akt Pathway.

    Science.gov (United States)

    Deng, Ke-Qiong; Li, Jing; She, Zhi-Gang; Gong, Jun; Cheng, Wen-Lin; Gong, Fu-Han; Zhu, Xue-Yong; Zhang, Yan; Wang, Zhihua; Li, Hongliang

    2017-10-01

    Cardiac hypertrophy occurs in response to numerous stimuli like neurohumoral stress, pressure overload, infection, and injury, and leads to heart failure. Mfge8 (milk fat globule-EGF factor 8) is a secreted protein involved in various human diseases, but its regulation and function during cardiac hypertrophy remain unexplored. Here, we found that circulating MFGE8 levels declined significantly in failing hearts from patients with dilated cardiomyopathy. Correlation analyses revealed that circulating MFGE8 levels were negatively correlated with the severity of cardiac dysfunction and remodeling in affected patients. Deleting Mfge8 in mice maintained normal heart function at basal level but substantially exacerbated the hypertrophic enlargement of cardiomyocytes, reprogramming of pathological genes, contractile dysfunction, and myocardial fibrosis after aortic banding surgery. In contrast, cardiac-specific Mfge8 overexpression in transgenic mice significantly blunted aortic banding-induced cardiac hypertrophy. Whereas MAPK (mitogen-activated protein kinase) pathways were unaffected in either Mfge8 -knockout or Mfge8 -overexpressing mice, the activated Akt/PKB (protein kinase B)-Gsk-3β (glycogen synthase kinase-3β)/mTOR (mammalian target of rapamycin) pathway after aortic banding was significantly potentiated by Mfge8 deficiency but suppressed by Mfge8 overexpression. Inhibition of Akt with MK-2206 blocked the prohypertrophic effects of Mfge8 deficiency in angiotensin II-treated neonatal rat cardiomyocytes. Finally, administering a recombinant human MFGE8 in mice in vivo alleviated cardiac hypertrophy induced by aortic banding. Our findings indicate that Mfge8 is an endogenous negative regulator of pathological cardiac hypertrophy and may, thus, have potential both as a novel biomarker and as a therapeutic target for treatment of cardiac hypertrophy. © 2017 American Heart Association, Inc.

  5. Correction

    Directory of Open Access Journals (Sweden)

    2012-01-01

    Full Text Available Regarding Gorelik, G., & Shackelford, T.K. (2011. Human sexual conflict from molecules to culture. Evolutionary Psychology, 9, 564–587: The authors wish to correct an omission in citation to the existing literature. In the final paragraph on p. 570, we neglected to cite Burch and Gallup (2006 [Burch, R. L., & Gallup, G. G., Jr. (2006. The psychobiology of human semen. In S. M. Platek & T. K. Shackelford (Eds., Female infidelity and paternal uncertainty (pp. 141–172. New York: Cambridge University Press.]. Burch and Gallup (2006 reviewed the relevant literature on FSH and LH discussed in this paragraph, and should have been cited accordingly. In addition, Burch and Gallup (2006 should have been cited as the originators of the hypothesis regarding the role of FSH and LH in the semen of rapists. The authors apologize for this oversight.

  6. Correction

    CERN Multimedia

    2002-01-01

    The photo on the second page of the Bulletin n°48/2002, from 25 November 2002, illustrating the article «Spanish Visit to CERN» was published with a wrong caption. We would like to apologise for this mistake and so publish it again with the correct caption.   The Spanish delegation, accompanied by Spanish scientists at CERN, also visited the LHC superconducting magnet test hall (photo). From left to right: Felix Rodriguez Mateos of CERN LHC Division, Josep Piqué i Camps, Spanish Minister of Science and Technology, César Dopazo, Director-General of CIEMAT (Spanish Research Centre for Energy, Environment and Technology), Juan Antonio Rubio, ETT Division Leader at CERN, Manuel Aguilar-Benitez, Spanish Delegate to Council, Manuel Delfino, IT Division Leader at CERN, and Gonzalo León, Secretary-General of Scientific Policy to the Minister.

  7. Correction

    Directory of Open Access Journals (Sweden)

    2014-01-01

    Full Text Available Regarding Tagler, M. J., and Jeffers, H. M. (2013. Sex differences in attitudes toward partner infidelity. Evolutionary Psychology, 11, 821–832: The authors wish to correct values in the originally published manuscript. Specifically, incorrect 95% confidence intervals around the Cohen's d values were reported on page 826 of the manuscript where we reported the within-sex simple effects for the significant Participant Sex × Infidelity Type interaction (first paragraph, and for attitudes toward partner infidelity (second paragraph. Corrected values are presented in bold below. The authors would like to thank Dr. Bernard Beins at Ithaca College for bringing these errors to our attention. Men rated sexual infidelity significantly more distressing (M = 4.69, SD = 0.74 than they rated emotional infidelity (M = 4.32, SD = 0.92, F(1, 322 = 23.96, p < .001, d = 0.44, 95% CI [0.23, 0.65], but there was little difference between women's ratings of sexual (M = 4.80, SD = 0.48 and emotional infidelity (M = 4.76, SD = 0.57, F(1, 322 = 0.48, p = .29, d = 0.08, 95% CI [−0.10, 0.26]. As expected, men rated sexual infidelity (M = 1.44, SD = 0.70 more negatively than they rated emotional infidelity (M = 2.66, SD = 1.37, F(1, 322 = 120.00, p < .001, d = 1.12, 95% CI [0.85, 1.39]. Although women also rated sexual infidelity (M = 1.40, SD = 0.62 more negatively than they rated emotional infidelity (M = 2.09, SD = 1.10, this difference was not as large and thus in the evolutionary theory supportive direction, F(1, 322 = 72.03, p < .001, d = 0.77, 95% CI [0.60, 0.94].

  8. Stimulation of ganglionated plexus attenuates cardiac neural remodeling and heart failure progression in a canine model of acute heart failure post-myocardial infarction.

    Science.gov (United States)

    Luo, Da; Hu, Huihui; Qin, Zhiliang; Liu, Shan; Yu, Xiaomei; Ma, Ruisong; He, Wenbo; Xie, Jing; Lu, Zhibing; He, Bo; Jiang, Hong

    2017-12-01

    Heart failure (HF) is associated with autonomic dysfunction. Vagus nerve stimulation has been shown to improve cardiac function both in HF patients and animal models of HF. The purpose of this present study is to investigate the effects of ganglionated plexus stimulation (GPS) on HF progression and autonomic remodeling in a canine model of acute HF post-myocardial infarction. Eighteen adult mongrel male dogs were randomized into the control (n=8) and GPS (n=10) groups. All dogs underwent left anterior descending artery ligation followed by 6-hour high-rate (180-220bpm) ventricular pacing to induce acute HF. Transthoracic 2-dimensional echocardiography was performed at different time points. The plasma levels of norepinephrine, B-type natriuretic peptide (BNP) and Ang-II were measured using ELISA kits. C-fos and nerve growth factor (NGF) proteins expressed in the left stellate ganglion as well as GAP43 and TH proteins expressed in the peri-infarct zone were measured using western blot. After 6h of GPS, the left ventricular end-diastolic volume, end-systolic volume and ejection fraction showed no significant differences between the 2 groups, but the interventricular septal thickness at end-systole in the GPS group was significantly higher than that in the control group. The plasma levels of norepinephrine, BNP, Ang-II were increased 1h after myocardial infarction while the increase was attenuated by GPS. The expression of c-fos and NGF proteins in the left stellate ganglion as well as GAP43 and TH proteins in cardiac peri-infarct zone in GPS group were significantly lower than that in control group. GPS inhibits cardiac sympathetic remodeling and attenuates HF progression in canines with acute HF induced by myocardial infarction and ventricular pacing. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Generation of a Four-Class Attenuation Map for MRI-Based Attenuation Correction of PET Data in the Head Area Using a Novel Combination of STE/Dixon-MRI and FCM Clustering.

    Science.gov (United States)

    Khateri, Parisa; Saligheh Rad, Hamidreza; Jafari, Amir Homayoun; Fathi Kazerooni, Anahita; Akbarzadeh, Afshin; Shojae Moghadam, Mohsen; Aryan, Arvin; Ghafarian, Pardis; Ay, Mohammad Reza

    2015-12-01

    The aim of this study is to generate a four-class magnetic resonance imaging (MRI)-based attenuation map (μ-map) for attenuation correction of positron emission tomography (PET) data of the head area using a novel combination of short echo time (STE)/Dixon-MRI and a dedicated image segmentation method. MR images of the head area were acquired using STE and two-point Dixon sequences. μ-maps were derived from MRI images based on a fuzzy C-means (FCM) clustering method along with morphologic operations. Quantitative assessment was performed to evaluate generated MRI-based μ-maps compared to X-ray computed tomography (CT)-based μ-maps. The voxel-by-voxel comparison of MR-based and CT-based segmentation results yielded an average of more than 95 % for accuracy and specificity in the cortical bone, soft tissue, and air region. MRI-based μ-maps show a high correlation with those derived from CT scans (R (2) > 0.95). Results indicate that STE/Dixon-MRI data in combination with FCM-based segmentation yields precise MR-based μ-maps for PET attenuation correction in hybrid PET/MRI systems.

  10. Exercise attenuates intermittent hypoxia-induced cardiac fibrosis associated with sodium-hydrogen exchanger-1 in rats

    Directory of Open Access Journals (Sweden)

    Tsung-I Chen

    2016-10-01

    Full Text Available Purpose: To investigate the role of sodium–hydrogen exchanger-1 (NHE-1 and exercise training on intermittent hypoxia-induced cardiac fibrosis in obstructive sleep apnea (OSA, using an animal model mimicking the intermittent hypoxia of OSA. Methods: Eight-week-old male Sprague–Dawley rats were randomly assigned to control (CON, intermittent hypoxia (IH, exercise (EXE or IH combined with exercise (IHEXE groups. These groups were randomly assigned to subgroups receiving either a vehicle or the NHE-1 inhibitor cariporide. The EXE and IHEXE rats underwent exercise training on an animal treadmill for 10 weeks (5 days/week, 60 minutes/day, 24–30 m/minute, 2–10% grade. The IH and IHEXE rats were exposed to 14 days of IH (30 seconds of hypoxia - nadir of 2-6% O2 - followed by 45 seconds of normoxia for 8 hours/day. At the end of 10 weeks, rats were sacrificed and then hearts were removed to determine the myocardial levels of fibrosis index, oxidative stress, antioxidant capacity and NHE-1 activation. Results: Compared to the CON rats, IH induced higher cardiac fibrosis, lower myocardial catalase and superoxidative dismutase activities, higher myocardial lipid and protein peroxidation and higher NHE-1 activation (p < 0.05 for each, which were all abolished by cariporide. Compared to the IH rats, lower cardiac fibrosis, higher myocardial antioxidant capacity, lower myocardial lipid and protein peroxidation and lower NHE-1 activation were found in the IHEXE rats (p < 0.05 for each. Conclusion: IH-induced cardiac fibrosis was associated with NHE-1 hyperactivity. However, exercise training and cariporide exerted an inhibitory effect to prevent myocardial NHE-1 hyperactivity, which contributed to reduced IH-induced cardiac fibrosis. Therefore, NHE-1 plays a critical role in the effect of exercise on IH-induced increased cardiac fibrosis.

  11. A proposal for PET/MRI attenuation correction with μ-values measured using a fixed-position radiation source and MRI segmentation

    International Nuclear Information System (INIS)

    Kawaguchi, Hiroshi; Hirano, Yoshiyuki; Yoshida, Eiji; Kershaw, Jeff; Shiraishi, Takahiro; Suga, Mikio; Ikoma, Yoko; Obata, Takayuki; Ito, Hiroshi; Yamaya, Taiga

    2014-01-01

    Several MRI-based attenuation correction methods have been reported for PET/MRI; these methods are expected to make efficient use of high-quality anatomical MRIs and reduce the radiation dose for PET/MRI scanning. The accuracy of the attenuation map (μ-map) from an MRI depends on the accuracy of tissue segmentation and the attenuation coefficients to be assigned (μ-values). In this study, we proposed an MRI-based μ-value estimation method with a non-rotational radiation source to construct a suitable μ-map for PET/MRI. The proposed method uses an accurately segmented tissue map, the partial path length of each tissue, and detected intensities of attenuated radiation from a fixed-position (rather than a rotating) radiation source to obtain the μ-map. We estimated the partial path length from a virtual blank scan of fixed-point radiation with the same scanner geometry using the known tissue map from MRI. The μ-values of every tissue were estimated by inverting a linear relationship involving the partial path lengths and measured radioactivity intensity. Validation of the proposed method was performed by calculating a fixed- point data set based upon real a real transmission scan. The root-mean-square error between the μ-values derived from a conventional transmission scan and those obtained with our proposed method were 2.4±1.4%, 17.4±9.1% and 6.6±4.3% for brain, bone and soft tissue other than brain, respectively. Although the error estimates for bone and soft tissue are not insignificant, the method we propose is able to estimate the brain μ-value accurately and it is this factor that most strongly affects the quantitative value of PET images because of the large volumetric ratio of the brain. -- Highlights: • An MRI-derived µ-map for the attenuation correction of PET images is proposed. • Method relies on segmentation of MRI and a fixed-point source transmission scan. • Tissue segmentation reduces the number of unknown µ-values. • Method

  12. A proposal for PET/MRI attenuation correction with μ-values measured using a fixed-position radiation source and MRI segmentation

    Energy Technology Data Exchange (ETDEWEB)

    Kawaguchi, Hiroshi, E-mail: kwgc@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Hirano, Yoshiyuki, E-mail: yhirano@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Yoshida, Eiji, E-mail: rush@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Kershaw, Jeff, E-mail: len@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Shiraishi, Takahiro, E-mail: tshira@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Suga, Mikio, E-mail: mikio.suga@faculty.chiba-u.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Graduate School of Engineering of Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Ikoma, Yoko, E-mail: ikoma@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Obata, Takayuki, E-mail: t_obata@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Ito, Hiroshi, E-mail: hito@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Yamaya, Taiga, E-mail: taiga@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan)

    2014-01-11

    Several MRI-based attenuation correction methods have been reported for PET/MRI; these methods are expected to make efficient use of high-quality anatomical MRIs and reduce the radiation dose for PET/MRI scanning. The accuracy of the attenuation map (μ-map) from an MRI depends on the accuracy of tissue segmentation and the attenuation coefficients to be assigned (μ-values). In this study, we proposed an MRI-based μ-value estimation method with a non-rotational radiation source to construct a suitable μ-map for PET/MRI. The proposed method uses an accurately segmented tissue map, the partial path length of each tissue, and detected intensities of attenuated radiation from a fixed-position (rather than a rotating) radiation source to obtain the μ-map. We estimated the partial path length from a virtual blank scan of fixed-point radiation with the same scanner geometry using the known tissue map from MRI. The μ-values of every tissue were estimated by inverting a linear relationship involving the partial path lengths and measured radioactivity intensity. Validation of the proposed method was performed by calculating a fixed- point data set based upon real a real transmission scan. The root-mean-square error between the μ-values derived from a conventional transmission scan and those obtained with our proposed method were 2.4±1.4%, 17.4±9.1% and 6.6±4.3% for brain, bone and soft tissue other than brain, respectively. Although the error estimates for bone and soft tissue are not insignificant, the method we propose is able to estimate the brain μ-value accurately and it is this factor that most strongly affects the quantitative value of PET images because of the large volumetric ratio of the brain. -- Highlights: • An MRI-derived µ-map for the attenuation correction of PET images is proposed. • Method relies on segmentation of MRI and a fixed-point source transmission scan. • Tissue segmentation reduces the number of unknown µ-values. • Method

  13. Determination of the mass attenuation coefficients for X-ray fluorescence measurements correction by the Rayleigh to Compton scattering ratio

    Science.gov (United States)

    Conti, C. C.; Anjos, M. J.; Salgado, C. M.

    2014-09-01

    X-ray fluorescence technique plays an important role in nondestructive analysis nowadays. The development of equipment, including portable ones, enables a wide assortment of possibilities for analysis of stable elements, even in trace concentrations. Nevertheless, despite of the advantages, one important drawback is radiation self-attenuation in the sample being measured, which needs to be considered in the calculation for the proper determination of elemental concentration. The mass attenuation coefficient can be determined by transmission measurement, but, in this case, the sample must be in slab shape geometry and demands two different setups and measurements. The Rayleigh to Compton scattering ratio, determined from the X-ray fluorescence spectrum, provides a link to the mass attenuation coefficient by means of a polynomial type equation. This work presents a way to construct a Rayleigh to Compton scattering ratio versus mass attenuation coefficient curve by using the MCNP5 Monte Carlo computer code. The comparison between the calculated and literature values of the mass attenuation coefficient for some known samples showed to be within 15%. This calculation procedure is available on-line at www.macx.net.br.

  14. Evaluation of a direct motion estimation/correction method in respiratory-gated PET/MRI with motion-adjusted attenuation.

    Science.gov (United States)

    Bousse, Alexandre; Manber, Richard; Holman, Beverley F; Atkinson, David; Arridge, Simon; Ourselin, Sébastien; Hutton, Brian F; Thielemans, Kris

    2017-06-01

    Respiratory motion compensation in PET/CT and PET/MRI is essential as motion is a source of image degradation (motion blur, attenuation artifacts). In previous work, we developed a direct method for joint image reconstruction/motion estimation (JRM) for attenuation-corrected (AC) respiratory-gated PET, which uses a single attenuation-map (μ-map). This approach was successfully implemented for respiratory-gated PET/CT, but since it relied on an accurate μ-map for motion estimation, the question of its applicability in PET/MRI is open. The purpose of this work is to investigate the feasibility of JRM in PET/MRI and to assess the robustness of the motion estimation when a degraded μ-map is used. We performed a series of JRM reconstructions from simulated PET data using a range of simulated Dixon MRI sequence derived μ-maps with wrong attenuation values in the lungs, from -100% (no attenuation) to +100% (double attenuation), as well as truncated arms. We compared the estimated motions with the one obtained from JRM in ideal conditions (no noise, true μ-map as an input). We also applied JRM on 4 patient datasets of the chest, 3 of them containing hot lesions. Patient list-mode data were gated using a principal component analysis method. We compared SUV max values of the JRM reconstructed activity images and non motion-corrected images. We also assessed the estimated motion fields by comparing the deformed JRM-reconstructed activity with individually non-AC reconstructed gates. Experiments on simulated data showed that JRM-motion estimation is robust to μ-map degradation in the sense that it produces motion fields similar to the ones obtained when using the true μ-map, regardless of the attenuation errors in the lungs (PET/MRI clinical datasets. It provides a potential alternative to existing methods where the motion fields are pre-estimated from separate MRI measurements. © 2017 University College London (UCL). Medical Physics published by Wiley Periodicals, Inc

  15. [Radiometers performance attenuation and data correction in long-term observation of total radiation and photosynthetically active radiation in typical forest ecosystems in China].

    Science.gov (United States)

    Zhu, Zhi-Lin; Sun, Xiao-Min; Yu, Gui-Rui; Wen, Xue-Fa; Zhang, Yi-Ping; Han, Shi-Jie; Yan, Jun-Hua; Wang, Hui-Min

    2011-11-01

    Based on the total radiation and photosynthetically active radiation (PAR) observations with net radiometer (CNR1) and quantum sensor (Li-190SB) in 4 ChinaFLUX forest sites (Changbaishan, Qianyanzhou, Dinghushan, and Xishuangbanna) in 2003-2008, this paper analyzed the uncertainties and the radiometers performance changes in long-term and continuous field observation. The results showed that the 98% accuracy of the total radiation measured with CNR1 (Q(cNR1)) could satisfy the technical criterion for the sites except Xishuangbanna where the Q(CNR1) was averagely about 7% lower than Q(CM11), the radiation measured with high accuracy pyranometer CM11. For most sites, though the temperature had definite effects on the performance of CNR1, the effects were still within the allowable range of the accuracy of the instrument. Besides temperature, the seasonal fog often occurred in tropical rain forests in Xishuangbanna also had effects on the performance of CNR1. Based on the long-term variations of PAR, especially its ratio to total radiation in the 4 sites, it was found that quantum sensor (Li-190SB) had obvious performance attenuation, with the mean annual attenuation rate being about 4%. To correct the observation error caused by Li-190SB, an attempt was made to give a post-correction of the PAR observations, which could basically eliminate the quantum sensor's performance attenuation due to long-term field measurement.

  16. Motion-compensated PET image reconstruction with respiratory-matched attenuation correction using two low-dose inhale and exhale CT images

    International Nuclear Information System (INIS)

    Nam, Woo Hyun; Ahn, Il Jun; Ra, Jong Beom; Kim, Kyeong Min; Kim, Byung Il

    2013-01-01

    Positron emission tomography (PET) is widely used for diagnosis and follow up assessment of radiotherapy. However, thoracic and abdominal PET suffers from false staging and incorrect quantification of the radioactive uptake of lesion(s) due to respiratory motion. Furthermore, respiratory motion-induced mismatch between a computed tomography (CT) attenuation map and PET data often leads to significant artifacts in the reconstructed PET image. To solve these problems, we propose a unified framework for respiratory-matched attenuation correction and motion compensation of respiratory-gated PET. For the attenuation correction, the proposed algorithm manipulates a 4D CT image virtually generated from two low-dose inhale and exhale CT images, rather than a real 4D CT image which significantly increases the radiation burden on a patient. It also utilizes CT-driven motion fields for motion compensation. To realize the proposed algorithm, we propose an improved region-based approach for non-rigid registration between body CT images, and we suggest a selection scheme of 3D CT images that are respiratory-matched to each respiratory-gated sinogram. In this work, the proposed algorithm was evaluated qualitatively and quantitatively by using patient datasets including lung and/or liver lesion(s). Experimental results show that the method can provide much clearer organ boundaries and more accurate lesion information than existing algorithms by utilizing two low-dose CT images. (paper)

  17. Probucol Attenuates Cyclophosphamide-induced Oxidative Apoptosis, p53 and Bax Signal Expression in Rat Cardiac Tissues

    Directory of Open Access Journals (Sweden)

    Yousif A. Asiri

    2010-01-01

    Full Text Available Cyclophosphamide (CP is a widely used drug in cancer chemotherapy and immunosuppression, which could cause toxicity of the normal cells due to its toxic metabolites. Probucol, a cholesterol-lowering drug, acts as potential inhibitor of DNA damage and shows to protect against doxorubicin-induced cardiomyopathy by enhancing the endogenous antioxidant system including glutathione peroxidase, catalase and superoxide dismutase. This study examined the possible protective effects of probucol, a lipid-lowering compound with strong antioxidant properties, against CPinduced cardiotoxicity. This objective could be achieved through studying the gene expression-based on the possible protective effects of probucol against CP-induced cardiac failure in rats. Adult male Wistar albino rats were assigned into four treatment groups: Animals in the first (control and second (probucol groups were injected intraperitoneally with corn oil and probucol (61 mg/kg/day, respectively, for two weeks. Animals in the third (CP and fourth (probucol plus CP groups were injected with the same doses of corn oil and probucol (61 mg/kg/day, respectively, for one week before and one week after a single dose of CP (200 mg/kg, I.P.. The p53, Bax, Bcl2 and oxidative genes signal expression were measured by real time PCR. CP-induced cardiotoxicity was clearly observed by a significant increase in serum creatine phosphokinase isoenzyme (CK-MB (117%, lactate dehydrogenase (LDH (64%, free (69% and esterified cholesterol (42% and triglyceride (69% compared to control group. In cardiac tissues, CP significantly increases the mRNA expression levels of apoptotic genes, p53 with two-fold and Bax with 1.6-fold, and decreases the anti-apoptotic gene Bcl2 with 0.5-fold. Moreover, CP caused downregulation of antioxidant genes, glutathione peroxidase, catalase, and superoxide dismutase and increased the lipid peroxidation and decreased adenosine triphosphate (ATP (40% and ATP/ADP (44% in cardiac

  18. Resveratrol Co-Treatment Attenuates the Effects of HIV Protease Inhibitors on Rat Body Weight and Enhances Cardiac Mitochondrial Respiration.

    Directory of Open Access Journals (Sweden)

    Burger Symington

    Full Text Available Since the early 1990s human immunodeficiency virus (HIV/acquired immunodeficiency syndrome (AIDS emerged as a global health pandemic, with sub-Saharan Africa the hardest hit. While the successful roll-out of antiretroviral (ARV therapy provided significant relief to HIV-positive individuals, such treatment can also elicit damaging side-effects. Here especially HIV protease inhibitors (PIs are implicated in the onset of cardio-metabolic complications such as type-2 diabetes and coronary heart disease. As there is a paucity of data regarding suitable co-treatments within this context, this preclinical study investigated whether resveratrol (RSV, aspirin (ASP or vitamin C (VitC co-treatment is able to blunt side-effects in a rat model of chronic PI exposure (Lopinavir/Ritonavir treatment for 4 months. Body weights and weight gain, blood metabolite levels (total cholesterol, HDL, LDL, triglycerides, echocardiography and cardiac mitochondrial respiration were assessed in PI-treated rats ± various co-treatments. Our data reveal that PI treatment significantly lowered body weight and cardiac respiratory function while no significant changes were found for heart function and blood metabolite levels. Moreover, all co-treatments ameliorated the PI-induced decrease in body weight after 4 months of PI treatment, while RSV co-treatment enhanced cardiac mitochondrial respiratory capacity in PI-treated rats. This pilot study therefore provides novel hypotheses regarding RSV co-treatment that should be further assessed in greater detail.

  19. Diosmin Attenuates Methotrexate-Induced Hepatic, Renal, and Cardiac Injury: A Biochemical and Histopathological Study in Mice

    Science.gov (United States)

    Khalifa, Hesham A.; Al-Quraishy, Saleh A.

    2017-01-01

    The current study was designed to investigate the beneficial role of diosmin, a biologically active flavonoid, against methotrexate- (MTX-) induced hepatic, renal, and cardiac injuries in mice. Male Swiss albino mice received a single intraperitoneal injection of MTX (at 20 mg/kg, body weight) either alone or in combination with oral diosmin (at 50 or 100 mg/kg body weight, for 10 days). Serum was used to evaluate tissue injury markers, while hepatic, renal, and cardiac tissue samples were obtained for determination of antioxidant activity as well as histopathological examination. Diosmin treatment ameliorated the MTX-induced elevation of serum alkaline phosphatase, aminotransferases, urea, creatinine, lactate dehydrogenase, and creatine kinases as well as plasma proinflammatory cytokines (interleukin-1-beta, interleukin-6, and tumor necrosis factor-alpha). Additionally, both diosmin doses significantly reduced tissue levels of malondialdehyde and nitric oxide and increased those of glutathione, glutathione peroxidase, glutathione reductase, glutathione S-transferase, superoxide dismutase, and catalase, compared to the MTX-intoxicated group. Histopathological examination showed that diosmin significantly minimized the MTX-induced histological alterations and nearly restored the normal architecture of hepatic, renal, and cardiac tissues. Based on these findings, diosmin may be a promising agent for protection against MTX-induced cytotoxicity in patients with cancer and autoimmune diseases. PMID:28819543

  20. SU-F-T-452: Influence of Dose Calculation Algorithm and Heterogeneity Correction On Risk Categorization of Patients with Cardiac Implanted Electronic Devices Undergoing Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Iwai, P; Lins, L Nadler [AC Camargo Cancer Center, Sao Paulo (Brazil)

    2016-06-15

    Purpose: There is a lack of studies with significant cohort data about patients using pacemaker (PM), implanted cardioverter defibrillator (ICD) or cardiac resynchronization therapy (CRT) device undergoing radiotherapy. There is no literature comparing the cumulative doses delivered to those cardiac implanted electronic devices (CIED) calculated by different algorithms neither studies comparing doses with heterogeneity correction or not. The aim of this study was to evaluate the influence of the algorithms Pencil Beam Convolution (PBC), Analytical Anisotropic Algorithm (AAA) and Acuros XB (AXB) as well as heterogeneity correction on risk categorization of patients. Methods: A retrospective analysis of 19 3DCRT or IMRT plans of 17 patients was conducted, calculating the dose delivered to CIED using three different calculation algorithms. Doses were evaluated with and without heterogeneity correction for comparison. Risk categorization of the patients was based on their CIED dependency and cumulative dose in the devices. Results: Total estimated doses at CIED calculated by AAA or AXB were higher than those calculated by PBC in 56% of the cases. In average, the doses at CIED calculated by AAA and AXB were higher than those calculated by PBC (29% and 4% higher, respectively). The maximum difference of doses calculated by each algorithm was about 1 Gy, either using heterogeneity correction or not. Values of maximum dose calculated with heterogeneity correction showed that dose at CIED was at least equal or higher in 84% of the cases with PBC, 77% with AAA and 67% with AXB than dose obtained with no heterogeneity correction. Conclusion: The dose calculation algorithm and heterogeneity correction did not change the risk categorization. Since higher estimated doses delivered to CIED do not compromise treatment precautions to be taken, it’s recommend that the most sophisticated algorithm available should be used to predict dose at the CIED using heterogeneity correction.

  1. SU-F-T-452: Influence of Dose Calculation Algorithm and Heterogeneity Correction On Risk Categorization of Patients with Cardiac Implanted Electronic Devices Undergoing Radiotherapy

    International Nuclear Information System (INIS)

    Iwai, P; Lins, L Nadler

    2016-01-01

    Purpose: There is a lack of studies with significant cohort data about patients using pacemaker (PM), implanted cardioverter defibrillator (ICD) or cardiac resynchronization therapy (CRT) device undergoing radiotherapy. There is no literature comparing the cumulative doses delivered to those cardiac implanted electronic devices (CIED) calculated by different algorithms neither studies comparing doses with heterogeneity correction or not. The aim of this study was to evaluate the influence of the algorithms Pencil Beam Convolution (PBC), Analytical Anisotropic Algorithm (AAA) and Acuros XB (AXB) as well as heterogeneity correction on risk categorization of patients. Methods: A retrospective analysis of 19 3DCRT or IMRT plans of 17 patients was conducted, calculating the dose delivered to CIED using three different calculation algorithms. Doses were evaluated with and without heterogeneity correction for comparison. Risk categorization of the patients was based on their CIED dependency and cumulative dose in the devices. Results: Total estimated doses at CIED calculated by AAA or AXB were higher than those calculated by PBC in 56% of the cases. In average, the doses at CIED calculated by AAA and AXB were higher than those calculated by PBC (29% and 4% higher, respectively). The maximum difference of doses calculated by each algorithm was about 1 Gy, either using heterogeneity correction or not. Values of maximum dose calculated with heterogeneity correction showed that dose at CIED was at least equal or higher in 84% of the cases with PBC, 77% with AAA and 67% with AXB than dose obtained with no heterogeneity correction. Conclusion: The dose calculation algorithm and heterogeneity correction did not change the risk categorization. Since higher estimated doses delivered to CIED do not compromise treatment precautions to be taken, it’s recommend that the most sophisticated algorithm available should be used to predict dose at the CIED using heterogeneity correction.

  2. Exact fan-beam and 4π-acquisition cone-beam SPECT algorithms with uniform attenuation correction

    International Nuclear Information System (INIS)

    Tang Qiulin; Zeng, Gengsheng L.; Wu Jiansheng; Gullberg, Grant T.

    2005-01-01

    This paper presents analytical fan-beam and cone-beam reconstruction algorithms that compensate for uniform attenuation in single photon emission computed tomography. First, a fan-beam algorithm is developed by obtaining a relationship between the two-dimensional (2D) Fourier transform of parallel-beam projections and fan-beam projections. Using this relationship, 2D Fourier transforms of equivalent parallel-beam projection data are obtained from the fan-beam projection data. Then a quasioptimal analytical reconstruction algorithm for uniformly attenuated Radon data, developed by Metz and Pan, is used to reconstruct the image. A cone-beam algorithm is developed by extending the fan-beam algorithm to 4π solid angle geometry. The cone-beam algorithm is also an exact algorithm

  3. Quantification accuracy and partial volume effect in dependence of the attenuation correction of a state-of-the-art small animal PET scanner

    International Nuclear Information System (INIS)

    Mannheim, Julia G; Judenhofer, Martin S; Schmid, Andreas; Pichler, Bernd J; Tillmanns, Julia; Stiller, Detlef; Sossi, Vesna

    2012-01-01

    Quantification accuracy and partial volume effect (PVE) of the Siemens Inveon PET scanner were evaluated. The influence of transmission source activities (40 and 160 MBq) on the quantification accuracy and the PVE were determined. Dynamic range, object size and PVE for different sphere sizes, contrast ratios and positions in the field of view (FOV) were evaluated. The acquired data were reconstructed using different algorithms and correction methods. The activity level of the transmission source and the total emission activity in the FOV strongly influenced the attenuation maps. Reconstruction algorithms, correction methods, object size and location within the FOV had a strong influence on the PVE in all configurations. All evaluated parameters potentially influence the quantification accuracy. Hence, all protocols should be kept constant during a study to allow a comparison between different scans. (paper)

  4. Remote ischemic preconditioning differentially attenuates post-ischemic cardiac arrhythmia in streptozotocin-induced diabetic versus nondiabetic rats.

    Science.gov (United States)

    Hu, Zhaoyang; Chen, Mou; Zhang, Ping; Liu, Jin; Abbott, Geoffrey W

    2017-04-26

    Sudden cardiac death (SCD), a leading cause of global mortality, most commonly arises from a substrate of cardiac ischemia, but requires an additional trigger. Diabetes mellitus (DM) predisposes to SCD even after adjusting for other DM-linked cardiovascular pathology such as coronary artery disease. We previously showed that remote liver ischemia preconditioning (RLIPC) is highly protective against cardiac ischemia reperfusion injury (IRI) linked ventricular arrhythmias and myocardial infarction, via induction of the cardioprotective RISK pathway, and specifically, inhibitory phosphorylation of GSK-3β (Ser 9). We evaluated the impact of acute streptozotocin-induced DM on coronary artery ligation IRI-linked ventricular arrhythmogenesis and RLIPC therapy in rats. Post-IRI arrhythmia induction was similar in nondiabetic and DM rats, but, unexpectedly, DM rats exhibited lower incidence of SCD during reperfusion (41 vs. 100%), suggesting uncontrolled hyperglycemia does not acutely predispose to SCD. RLIPC was highly effective in both nondiabetic and DM rats at reducing incidence and duration of, and increasing latency to, all classes of ventricular tachyarrhythmias. In contrast, atrioventricular block (AVB) was highly responsive to RLIPC in nondiabetic rats (incidence reduced from 72 to 18%) but unresponsive in DM rats. RISK pathway induction was similar in nondiabetic and DM rats, thus not explaining the DM-specific resistance of AVB to therapy. Our findings uncover important acute DM-specific differences in responsiveness to remote preconditioning for ventricular tachyarrhythmias versus AVB, which may have clinical significance given that AVB is a malignant arrhythmia twofold more common in human diabetics than nondiabetics, and correlated to plasma glucose levels >10 mmol/L.

  5. The morphology of the coronary sinus in patients with congenitally corrected transposition: implications for cardiac catheterisation and re-synchronisation therapy.

    Science.gov (United States)

    Aiello, Vera D; Ferreira, Flávia C N; Scanavacca, Mauricio I; Anderson, Robert H; D'Avila, André

    2016-02-01

    Patients with congenitally corrected transposition frequently benefit from re-synchronisation therapy or ablation procedures. This is likely to require catheterisation of the coronary sinus. Its anatomy, however, is not always appreciated, despite being well-described. With this caveat in mind, we have evaluated its location and structure in hearts with congenitally corrected transposition in order to reinforce the guidance needed by the cardiac interventionist. We dissected and inspected the coronary sinus, the oblique vein of the left atrium, and the left-sided-circumflex venous channel in eight heart specimens with corrected transposition and eight controls, measuring the orifice and length of the sinus and the atrioventricular valves. In two-thirds of the malformed hearts, the sinus deviated from its anticipated course in the atrioventricular groove, ascending obliquely on the left atrial inferior wall to meet the left oblique vein. The maximal deviation coincided in all hearts with the point where the left oblique vein joined the left-sided-circumflex vein to form the coronary sinus. We describe a circumflex vein, rather than the great cardiac vein, as the latter venous channel is right-sided in the setting of corrected transposition. The length of the sinus correlated positively with the diameter of the tricuspid valve (p=0.02). Compared with controls, the left oblique vein in the malformed hearts joined the circumflex venous channel significantly closer to the mouth of the sinus. The unexpected course of the coronary sinus in corrected transposition and the naming of the cardiac veins have important implications for venous cannulation and interpretation of images.

  6. Pitavastatin-attenuated cardiac dysfunction in mice with dilated cardiomyopathy via regulation of myocardial calcium handling proteins

    Directory of Open Access Journals (Sweden)

    Hu Wei

    2014-03-01

    Full Text Available C57BL/6 mice with dilated cardiomyopathy (DCM were randomly divided to receive placebo or pitavastatin at a dose of 1 or 3 mg kg-1d-1. After 8 weeks treatment, mice with dilated cardiomyopathy developed serious cardiac dysfunction characterized by significantly enhanced left ventricular end-diastolic diameter (LVIDd, decreased left ventricular ejection fraction (LVEF as well as left ventricular short axis fractional shortening (LVFS, accompanied with enlarged cardiomyocytes, and increased plasma levels of N-terminal pro-B type natriuretic peptide (NT-proBNP and plasma angiotensin II (AngII concentration. Moreover, myocardium sarcoplasmic reticulum Ca2+ pump (SERCA-2 activity was decreased. The ratio of phosphorylated phospholamban (PLB to total PLB decreased significantly with the down-regulation of SERCA- -2a and ryanodine receptor (RyR2 expression. Pitavastatin was found to ameliorate the cardiac dysfunction in mice with dilated cardiomyopathy by reversing the changes in the ratios of phosphorylated PLB to total PLB, SERCA-2a and RyR2 via reducing the plasma AngII concentration and the expressions of myocardium angiotensin II type 1 receptor (AT1R and protein kinase C (PKCb2. The possible underlying mechanism might be the regulation of myocardial AT1R-PKCb2-Ca2+ handling proteins.

  7. MR-based attenuation correction for PET/MRI neurological studies with continuous-valued attenuation coefficients for bone through a conversion from R2* to CT-Hounsfield units.

    Science.gov (United States)

    Juttukonda, Meher R; Mersereau, Bryant G; Chen, Yasheng; Su, Yi; Rubin, Brian G; Benzinger, Tammie L S; Lalush, David S; An, Hongyu

    2015-05-15

    MR-based correction for photon attenuation in PET/MRI remains challenging, particularly for neurological applications requiring quantitation of data. Existing methods are either not sufficiently accurate or are limited by the computation time required. The goal of this study was to develop an MR-based attenuation correction method that accurately separates bone tissue from air and provides continuous-valued attenuation coefficients for bone. PET/MRI and CT datasets were obtained from 98 subjects (mean age [±SD]: 66yrs [±9.8], 57 females) using an IRB-approved protocol and with informed consent. Subjects were injected with 352±29MBq of (18)F-Florbetapir tracer, and PET acquisitions were begun either immediately or 50min after injection. CT images of the head were acquired separately using a PET/CT system. Dual echo ultrashort echo-time (UTE) images and two-point Dixon images were acquired. Regions of air were segmented via a threshold of the voxel-wise multiplicative inverse of the UTE echo 1 image. Regions of bone were segmented via a threshold of the R2* image computed from the UTE echo 1 and UTE echo 2 images. Regions of fat and soft tissue were segmented using fat and water images decomposed from the Dixon images. Air, fat, and soft tissue were assigned linear attenuation coefficients (LACs) of 0, 0.092, and 0.1cm(-1), respectively. LACs for bone were derived from a regression analysis between corresponding R2* and CT values. PET images were reconstructed using the gold standard CT method and the proposed CAR-RiDR method. The RiDR segmentation method produces mean Dice coefficient±SD across subjects of 0.75±0.05 for bone and 0.60±0.08 for air. The CAR model for bone LACs greatly improves accuracy in estimating CT values (28.2%±3.0 mean error) compared to the use of a constant CT value (46.9%±5.8, punits. From our analysis, we conclude that the proposed method closely approaches (<3% error) the gold standard CT-scaled method in PET reconstruction accuracy

  8. Quantitative Evaluation of Atlas-based Attenuation Correction for Brain PET in an Integrated Time-of-Flight PET/MR Imaging System.

    Science.gov (United States)

    Yang, Jaewon; Jian, Yiqiang; Jenkins, Nathaniel; Behr, Spencer C; Hope, Thomas A; Larson, Peder E Z; Vigneron, Daniel; Seo, Youngho

    2017-07-01

    Purpose To assess the patient-dependent accuracy of atlas-based attenuation correction (ATAC) for brain positron emission tomography (PET) in an integrated time-of-flight (TOF) PET/magnetic resonance (MR) imaging system. Materials and Methods Thirty recruited patients provided informed consent in this institutional review board-approved study. All patients underwent whole-body fluorodeoxyglucose PET/computed tomography (CT) followed by TOF PET/MR imaging. With use of TOF PET data, PET images were reconstructed with four different attenuation correction (AC) methods: PET with patient CT-based AC (CTAC), PET with ATAC (air and bone from an atlas), PET with ATAC patientBone (air and tissue from the atlas with patient bone), and PET with ATAC boneless (air and tissue from the atlas without bone). For quantitative evaluation, PET mean activity concentration values were measured in 14 1-mL volumes of interest (VOIs) distributed throughout the brain and statistical significance was tested with a paired t test. Results The mean overall difference (±standard deviation) of PET with ATAC compared with PET with CTAC was -0.69 kBq/mL ± 0.60 (-4.0% ± 3.2) (P PET with ATAC boneless (-9.4% ± 3.7) was significantly worse than that of PET with ATAC (-4.0% ± 3.2) (P PET with ATAC patientBone (-1.5% ± 1.5) improved over that of PET with ATAC (-4.0% ± 3.2) (P PET/MR imaging achieves similar quantification accuracy to that from CTAC by means of atlas-based bone compensation. However, patient-specific anatomic differences from the atlas causes bone attenuation differences and misclassified sinuses, which result in patient-dependent performance variation of ATAC. © RSNA, 2017 Online supplemental material is available for this article.

  9. Diagnosis of myocardial viability by dual-head coincidence gamma camera fluorine-18 fluorodeoxyglucose positron emission tomography with and without non-uniform attenuation correction

    International Nuclear Information System (INIS)

    Nowak, B.; Zimmy, M.; Kaiser, H.-J.; Schaefer, W.; Reinartz, P.; Buell, U.; Schwarz, E.R.; Dahl, J. vom

    2000-01-01

    This study assessed a dual-head coincidence gamma camera (hybrid PET) equipped with single-photon transmission for myocardial fluorine-18 fluorodeoxyglucose (FDG) imaging by comparing this technique with conventional positron emission tomography (PET) using a dedicated ring PET scanner. Twenty-one patients were studied with dedicated FDG ring PET and FDG hybrid PET for evaluation of myocardial glucose metabolism, as well as technetium-99 m tetrofosmin single-photon emission tomography (SPET) to estimate myocardial perfusion. All patients underwent transmitted attenuation correction using germanium-68 rod sources for ring PET and caesium-137 point sources for hybrid PET. Ring PET and hybrid PET emission scans were started 61±12 and 98±15 min, respectively, after administration of 154±31 MBq FDG. Attenuation-corrected images were reconstructed iteratively for ring PET and hybrid PET (ac-hybrid PET), and non-attenuation-corrected images for hybrid PET (non-ac-hybrid PET) only. Tracer distribution was analysed semiquantitatively using a volumetric vector sampling method dividing the left ventricular wall into 13 segments. FDG distribution in non-ac-hybrid PET and ring PET correlated with r=0.36 (P<0.0001), and in ac-hybrid PET and ring PET with r=0.79 (P<0.0001). Non-ac-hybrid PET significantly overestimated FDG uptake in the apical and supra-apical segments, and underestimated FDG uptake in the remaining segments, with the exception of one lateral segment. Ac-hybrid PET significantly overestimated FDG uptake in the apical segment, and underestimated FDG uptake in only three posteroseptal segments. A three-grade score was used to classify diagnosis of viability by FDG PET in 136 segments with reduced perfusion as assessed by SPET. Compared with ring PET, non-ac-hybrid PET showed concordant diagnoses in 80 segments (59%) and ac-hybrid PET in 101 segments (74%) (P<0.001). Agreement between ring PET and non-ac-hybrid PET was best in the basal lateral wall and in the

  10. Correction of quantification errors in pelvic and spinal lesions caused by ignoring higher photon attenuation of bone in [{sup 18}F]NaF PET/MR

    Energy Technology Data Exchange (ETDEWEB)

    Schramm, Georg, E-mail: georg.schramm@kuleuven.be; Maus, Jens; Hofheinz, Frank; Petr, Jan; Lougovski, Alexandr [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Dresden 01328 (Germany); Beuthien-Baumann, Bettina; Oehme, Liane [Department of Nuclear Medicine, University Hospital Carl Gustav Carus, Dresden 01307 (Germany); Platzek, Ivan [Department of Radiology, University Hospital Carl Gustav Carus, Dresden 01307 (Germany); Hoff, Jörg van den [Helmholtz-Zentrum Dresden-Rossendorf, Institute for Radiopharmaceutical Cancer Research, Dresden 01328 (Germany); Department of Nuclear Medicine, University Hospital Carl Gustav Carus, Dresden 01307 (Germany)

    2015-11-15

    Purpose: MR-based attenuation correction (MRAC) in routine clinical whole-body positron emission tomography and magnetic resonance imaging (PET/MRI) is based on tissue type segmentation. Due to lack of MR signal in cortical bone and the varying signal of spongeous bone, standard whole-body segmentation-based MRAC ignores the higher attenuation of bone compared to the one of soft tissue (MRAC{sub nobone}). The authors aim to quantify and reduce the bias introduced by MRAC{sub nobone} in the standard uptake value (SUV) of spinal and pelvic lesions in 20 PET/MRI examinations with [{sup 18}F]NaF. Methods: The authors reconstructed 20 PET/MR [{sup 18}F]NaF patient data sets acquired with a Philips Ingenuity TF PET/MRI. The PET raw data were reconstructed with two different attenuation images. First, the authors used the vendor-provided MRAC algorithm that ignores the higher attenuation of bone to reconstruct PET{sub nobone}. Second, the authors used a threshold-based algorithm developed in their group to automatically segment bone structures in the [{sup 18}F]NaF PET images. Subsequently, an attenuation coefficient of 0.11 cm{sup −1} was assigned to the segmented bone regions in the MRI-based attenuation image (MRAC{sub bone}) which was used to reconstruct PET{sub bone}. The automatic bone segmentation algorithm was validated in six PET/CT [{sup 18}F]NaF examinations. Relative SUV{sub mean} and SUV{sub max} differences between PET{sub bone} and PET{sub nobone} of 8 pelvic and 41 spinal lesions, and of other regions such as lung, liver, and bladder, were calculated. By varying the assigned bone attenuation coefficient from 0.11 to 0.13 cm{sup −1}, the authors investigated its influence on the reconstructed SUVs of the lesions. Results: The comparison of [{sup 18}F]NaF-based and CT-based bone segmentation in the six PET/CT patients showed a Dice similarity of 0.7 with a true positive rate of 0.72 and a false discovery rate of 0.33. The [{sup 18}F]NaF-based bone

  11. Assessment of myocardial bridge by cardiac CT: Intracoronary transluminal attenuation gradient derived from diastolic phase predicts systolic compression

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Meng Meng; Zhang, Yang; Li, Yue Hua; Li, Wen Bin; Li, Ming Hua; Zhang, Jiayin [Institute of Diagnostic and Interventional Radiology, Shanghai Jiao Tong University Affiliated Sixth People' s Hospital, Shangha (China)

    2017-08-01

    To study the predictive value of transluminal attenuation gradient (TAG) derived from diastolic phase of coronary computed tomography angiography (CCTA) for identifying systolic compression of myocardial bridge (MB). Consecutive patients diagnosed with MB based on CCTA findings and without obstructive coronary artery disease were retrospectively enrolled. In total, 143 patients with 144 MBs were included in the study. Patients were classified into three groups: without systolic compression, with systolic compression < 50%, and with systolic compression ≥ 50%. TAG was defined as the linear regression coefficient between intraluminal attenuation in Hounsfield units (HU) and length from the vessel ostium. Other indices such as the length and depth of the MB were also recorded. TAG was the lowest in MB patients with systolic compression ≥ 50% (-19.9 ± 8.7 HU/10 mm). Receiver operating characteristic curve analysis was performed to determine the optimal cutoff values for identifying systolic compression ≥ 50%. The result indicated an optimal cutoff value of TAG as -18.8 HU/10 mm (area under curve = 0.778, p < 0.001), which yielded higher sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy (54.1, 80.5, 72.8, and 75.0%, respectively). In addition, the TAG of MB with diastolic compression was significantly lower than the TAG of MB without diastolic compression (-21.4 ± 4.8 HU/10 mm vs. -12.7 ± 8 HU/10 mm, p < 0.001). TAG was a better predictor of MB with systolic compression ≥ 50%, compared to the length or depth of the MB. The TAG of MB with persistent diastolic compression was significantly lower than the TAG without diastolic compression.

  12. Toward implementing an MRI-based PET attenuation-correction method for neurologic studies on the MR-PET brain prototype.

    Science.gov (United States)

    Catana, Ciprian; van der Kouwe, Andre; Benner, Thomas; Michel, Christian J; Hamm, Michael; Fenchel, Matthias; Fischl, Bruce; Rosen, Bruce; Schmand, Matthias; Sorensen, A Gregory

    2010-09-01

    Several factors have to be considered for implementing an accurate attenuation-correction (AC) method in a combined MR-PET scanner. In this work, some of these challenges were investigated, and an AC method based entirely on the MRI data obtained with a single dedicated sequence was developed and used for neurologic studies performed with the MR-PET human brain scanner prototype. The focus was on the problem of bone-air segmentation, selection of the linear attenuation coefficient for bone, and positioning of the radiofrequency coil. The impact of these factors on PET data quantification was studied in simulations and experimental measurements performed on the combined MR-PET scanner. A novel dual-echo ultrashort echo time (DUTE) MRI sequence was proposed for head imaging. Simultaneous MR-PET data were acquired, and the PET images reconstructed using the proposed DUTE MRI-based AC method were compared with the PET images that had been reconstructed using a CT-based AC method. Our data suggest that incorrectly accounting for the bone tissue attenuation can lead to large underestimations (>20%) of the radiotracer concentration in the cortex. Assigning a linear attenuation coefficient of 0.143 or 0.151 cm(-1) to bone tissue appears to give the best trade-off between bias and variability in the resulting images. Not identifying the internal air cavities introduces large overestimations (>20%) in adjacent structures. On the basis of these results, the segmented CT AC method was established as the silver standard for the segmented MRI-based AC method. For an integrated MR-PET scanner, in particular, ignoring the radiofrequency coil attenuation can cause large underestimations (i.e.,

  13. Influences of reconstruction and attenuation correction in brain SPECT images obtained by the hybrid SPECT/CT device: evaluation with a 3-dimensional brain phantom

    International Nuclear Information System (INIS)

    Akamatsu, Mana; Yamashita, Yasuo; Akamatsu, Go; Tsutsui, Yuji; Ohya, Nobuyoshi; Nakamura, Yasuhiko; Sasaki, Masayuki

    2014-01-01

    The aim of this study was to evaluate the influences of reconstruction and attenuation correction on the differences in the radioactivity distributions in 123 I brain SPECT obtained by the hybrid SPECT/CT device. We used the 3-dimensional (3D) brain phantom, which imitates the precise structure of gray matter, white matter and bone regions. It was filled with 123 I solution (20.1 kBq/mL) in the gray matter region and with K 2 HPO 4 in the bone region. The SPECT/CT data were acquired by the hybrid SPECT/CT device. SPECT images were reconstructed by using filtered back projection with uniform attenuation correction (FBP-uAC), 3D ordered-subsets expectation-maximization with uniform AC (3D-OSEM-uAC) and 3D OSEM with CT-based non-uniform AC (3D-OSEM-CTAC). We evaluated the differences in the radioactivity distributions among these reconstruction methods using a 3D digital phantom, which was developed from CT images of the 3D brain phantom, as a reference. The normalized mean square error (NMSE) and regional radioactivity were calculated to evaluate the similarity of SPECT images to the 3D digital phantom. The NMSE values were 0.0811 in FBP-uAC, 0.0914 in 3D-OSEM-uAC and 0.0766 in 3D-OSEM-CTAC. The regional radioactivity of FBP-uAC was 11.5% lower in the middle cerebral artery territory, and that of 3D-OSEM-uAC was 5.8% higher in the anterior cerebral artery territory, compared with the digital phantom. On the other hand, that of 3D-OSEM-CTAC was 1.8% lower in all brain areas. By using the hybrid SPECT/CT device, the brain SPECT reconstructed by 3D-OSEM with CT attenuation correction can provide an accurate assessment of the distribution of brain radioactivity

  14. Atlas-based analysis of cardiac shape and function: correction of regional shape bias due to imaging protocol for population studies.

    Science.gov (United States)

    Medrano-Gracia, Pau; Cowan, Brett R; Bluemke, David A; Finn, J Paul; Kadish, Alan H; Lee, Daniel C; Lima, Joao A C; Suinesiaputra, Avan; Young, Alistair A

    2013-09-13

    Cardiovascular imaging studies generate a wealth of data which is typically used only for individual study endpoints. By pooling data from multiple sources, quantitative comparisons can be made of regional wall motion abnormalities between different cohorts, enabling reuse of valuable data. Atlas-based analysis provides precise quantification of shape and motion differences between disease groups and normal subjects. However, subtle shape differences may arise due to differences in imaging protocol between studies. A mathematical model describing regional wall motion and shape was used to establish a coordinate system registered to the cardiac anatomy. The atlas was applied to data contributed to the Cardiac Atlas Project from two independent studies which used different imaging protocols: steady state free precession (SSFP) and gradient recalled echo (GRE) cardiovascular magnetic resonance (CMR). Shape bias due to imaging protocol was corrected using an atlas-based transformation which was generated from a set of 46 volunteers who were imaged with both protocols. Shape bias between GRE and SSFP was regionally variable, and was effectively removed using the atlas-based transformation. Global mass and volume bias was also corrected by this method. Regional shape differences between cohorts were more statistically significant after removing regional artifacts due to imaging protocol bias. Bias arising from imaging protocol can be both global and regional in nature, and is effectively corrected using an atlas-based transformation, enabling direct comparison of regional wall motion abnormalities between cohorts acquired in separate studies.

  15. [The role of information and training for workers on the correct use of earplugs in assessing real noise attenuation with E-A-RfitTM system].

    Science.gov (United States)

    Cassano, Filippo; Aloise, Ingrid; Labianca, Graziano; Gaccione, Vincenzo; Mazzotta, Cosimo; Cardascia, Francesco; Garavaglia, Michela; Germano, Candida; Dentamaro, Antonella; Di Lorenzo, Luigi

    2015-07-08

    Laboratory levels of perceived noise attenuation as heard using earplugs are always higher than the real levels that can be achieved at the workplace. The employer is bound by law to supply individual hearing protection devices (HPDs), to assess their efficiency and efficacy, and also to inform and train workers on the correct use of HPDs. This study assessed the real "personal attenuation rating" (PAR) of HPDs  used by workers at the workplace, before (PAR A) and after (PAR B) specific and individual training. These values were also compared with the theoretical  "single number rating" (SNR) provided by the manufacturer. The study covered all the 65 male employees of an awnings factory, using the E-A-RfitTM computerized method, which can measure PARs, based on the difference between sound pressures recorded by an "outside" microphone and an "inside" microphone placed in the auditory canal, with earplugs inserted, before (PAR A) and after (PAR B), i.e., the specific and individual training described above. PARs B were always definitely higher than PARs A, both for all tested frequencies and the corresponding average values, which were automatically detected by E-A-RfitTM. Furthermore the same PARs B were  decidedly lower than the respective SNRs supplied by the manufacturer on the basis of laboratory assessments. These data prove that specific and individual training for workers improves the performance of earplugs, contributing to a more appropriate secondary prevention of the effects of noise on hearing; they also prove that the real attenuation recorded in workers are always lower than those supplied by the manufacturer of the devices. It is recommended that the E-A-RfitTM system, which allowed these results to be achieved objectively, should be normally used to assess exposure to noise in workers, when HPDs are worn.

  16. Extracts of Crataegus oxyacantha and Rosmarinus officinalis Attenuate Ischemic Myocardial Damage by Decreasing Oxidative Stress and Regulating the Production of Cardiac Vasoactive Agents

    Directory of Open Access Journals (Sweden)

    Raúl Enrique Cuevas-Durán

    2017-11-01

    Full Text Available Numerous studies have supported a role for oxidative stress in the development of ischemic damage and endothelial dysfunction. Crataegus oxyacantha (Co and Rosmarinus officinalis (Ro extracts are polyphenolic-rich compounds that have proven to be efficient in the treatment of cardiovascular diseases. We studied the effect of extracts from Co and Ro on the myocardial damage associated with the oxidative status and to the production of different vasoactive agents. Rats were assigned to the following groups: (a sham; (b vehicle-treated myocardial infarction (MI (MI-V; (c Ro extract-treated myocardial infarction (MI-Ro; (d Co extract-treated myocardial infarction (MI-Co; or (e Ro+Co-treated myocardial infarction (MI-Ro+Co. Ro and Co treatments increased total antioxidant capacity, the expression of superoxide dismutase (SOD-Cu2+/Zn2+, SOD-Mn2+, and catalase, with the subsequent decline of malondialdehyde and 8-hydroxy-2′-deoxyguanosine levels. The extracts diminished vasoconstrictor peptide levels (angiotensin II and endothelin-1, increased vasodilators agents (angiotensin 1–7 and bradikinin and improved nitric oxide metabolism. Polyphenol treatment restored the left intraventricular pressure and cardiac mechanical work. We conclude that Ro and Co treatment attenuate morphological and functional ischemic-related changes by both an oxidant load reduction and improvement of the balance between vasoconstrictors and vasodilators.

  17. k-space sampling optimization for ultrashort TE imaging of cortical bone: Applications in radiation therapy planning and MR-based PET attenuation correction

    International Nuclear Information System (INIS)

    Hu, Lingzhi; Traughber, Melanie; Su, Kuan-Hao; Pereira, Gisele C.; Grover, Anu; Traughber, Bryan; Muzic, Raymond F. Jr.

    2014-01-01

    Purpose: The ultrashort echo-time (UTE) sequence is a promising MR pulse sequence for imaging cortical bone which is otherwise difficult to image using conventional MR sequences and also poses strong attenuation for photons in radiation therapy and PET imaging. The authors report here a systematic characterization of cortical bone signal decay and a scanning time optimization strategy for the UTE sequence through k-space undersampling, which can result in up to a 75% reduction in acquisition time. Using the undersampled UTE imaging sequence, the authors also attempted to quantitatively investigate the MR properties of cortical bone in healthy volunteers, thus demonstrating the feasibility of using such a technique for generating bone-enhanced images which can be used for radiation therapy planning and attenuation correction with PET/MR. Methods: An angularly undersampled, radially encoded UTE sequence was used for scanning the brains of healthy volunteers. Quantitative MR characterization of tissue properties, including water fraction and R2 ∗ = 1/T2 ∗ , was performed by analyzing the UTE images acquired at multiple echo times. The impact of different sampling rates was evaluated through systematic comparison of the MR image quality, bone-enhanced image quality, image noise, water fraction, and R2 ∗ of cortical bone. Results: A reduced angular sampling rate of the UTE trajectory achieves acquisition durations in proportion to the sampling rate and in as short as 25% of the time required for full sampling using a standard Cartesian acquisition, while preserving unique MR contrast within the skull at the cost of a minimal increase in noise level. The R2 ∗ of human skull was measured as 0.2–0.3 ms −1 depending on the specific region, which is more than ten times greater than the R2 ∗ of soft tissue. The water fraction in human skull was measured to be 60%–80%, which is significantly less than the >90% water fraction in brain. High-quality, bone

  18. An SPM8-based approach for attenuation correction combining segmentation and nonrigid template formation: application to simultaneous PET/MR brain imaging.

    Science.gov (United States)

    Izquierdo-Garcia, David; Hansen, Adam E; Förster, Stefan; Benoit, Didier; Schachoff, Sylvia; Fürst, Sebastian; Chen, Kevin T; Chonde, Daniel B; Catana, Ciprian

    2014-11-01

    We present an approach for head MR-based attenuation correction (AC) based on the Statistical Parametric Mapping 8 (SPM8) software, which combines segmentation- and atlas-based features to provide a robust technique to generate attenuation maps (μ maps) from MR data in integrated PET/MR scanners. Coregistered anatomic MR and CT images of 15 glioblastoma subjects were used to generate the templates. The MR images from these subjects were first segmented into 6 tissue classes (gray matter, white matter, cerebrospinal fluid, bone, soft tissue, and air), which were then nonrigidly coregistered using a diffeomorphic approach. A similar procedure was used to coregister the anatomic MR data for a new subject to the template. Finally, the CT-like images obtained by applying the inverse transformations were converted to linear attenuation coefficients to be used for AC of PET data. The method was validated on 16 new subjects with brain tumors (n = 12) or mild cognitive impairment (n = 4) who underwent CT and PET/MR scans. The μ maps and corresponding reconstructed PET images were compared with those obtained using the gold standard CT-based approach and the Dixon-based method available on the Biograph mMR scanner. Relative change (RC) images were generated in each case, and voxel- and region-of-interest-based analyses were performed. The leave-one-out cross-validation analysis of the data from the 15 atlas-generation subjects showed small errors in brain linear attenuation coefficients (RC, 1.38% ± 4.52%) compared with the gold standard. Similar results (RC, 1.86% ± 4.06%) were obtained from the analysis of the atlas-validation datasets. The voxel- and region-of-interest-based analysis of the corresponding reconstructed PET images revealed quantification errors of 3.87% ± 5.0% and 2.74% ± 2.28%, respectively. The Dixon-based method performed substantially worse (the mean RC values were 13.0% ± 10.25% and 9.38% ± 4.97%, respectively). Areas closer to the skull showed

  19. RESOLUTE PET/MRI Attenuation Correction for O-(2-F-fluoroethyl)-L-tyrosine (FET) in Brain Tumor Patients with Metal Implants

    DEFF Research Database (Denmark)

    Ladefoged, Claes N; Andersen, Flemming L; Kjær, Andreas

    2017-01-01

    of agreement for TMAX/B was for RESOLUTE (-3%; 4%), Dixon (-9%; 16%), and UTE (-7%; 10%). The absolute error when measuring BTV was 0.7 ± 1.9 mL (N.S) with RESOLUTE, 5.3 ± 10 mL using Dixon, and 1.7 ± 3.7 mL using UTE. RESOLUTE performed best in the identification of the location of peak activity and in brain...... to be quantitatively correct in order to be used clinically, which require accurate attenuation correction (AC) in PET/MRI. The aim of this study was to evaluate the use of the subject-specific MR-derived AC method RESOLUTE in post-operative brain tumor patients.Methods:We analyzed 51 post-operative brain tumor...... patients (68 examinations, 200 MBq [18F]-FET) investigated in a PET/MRI scanner. MR-AC maps were acquired using: (1) the Dixon water fat separation sequence, (2) the ultra short echo time (UTE) sequences, (3) calculated using our new RESOLUTE methodology, and (4) a same day low-dose CT used as reference...

  20. Dose calculation in eye brachytherapy with Ir-192 threads using the Sievert integral and corrected by attenuation and scattering with the Meisberg polynomials

    International Nuclear Information System (INIS)

    Vivanco, M.G. Bernui de; Cardenas R, A.

    2006-01-01

    The ocular brachytherapy many times unique alternative to conserve the visual organ in patients of ocular cancer, one comes carrying out in the National Institute of Neoplastic Illnesses (INEN) using threads of Iridium 192; those which, they are placed in radial form on the interior surface of a spherical cap of gold of 18 K; the cap remains in the eye until reaching the prescribed dose by the doctor. The main objective of this work is to be able to calculate in a correct and practical way the one time that the treatment of ocular brachytherapy should last to reach the dose prescribed by the doctor. To reach this objective I use the Sievert integral corrected by attenuation effects and scattering (Meisberg polynomials); calculating it by the Simpson method. In the calculations by means of the Sievert integral doesn't take into account the scattering produced by the gold cap neither the variation of the constant of frequency of exposure with the distance. The calculations by means of Sievert integral are compared with those obtained using the Monte Carlo Penelope simulation code, where it is observed that they agree at distances of the surface of the cap greater or equal to 2mm. (Author)

  1. An SPM8-based Approach for Attenuation Correction Combining Segmentation and Non-rigid Template Formation: Application to Simultaneous PET/MR Brain Imaging

    Science.gov (United States)

    Izquierdo-Garcia, David; Hansen, Adam E.; Förster, Stefan; Benoit, Didier; Schachoff, Sylvia; Fürst, Sebastian; Chen, Kevin T.; Chonde, Daniel B.; Catana, Ciprian

    2014-01-01

    We present an approach for head MR-based attenuation correction (MR-AC) based on the Statistical Parametric Mapping (SPM8) software that combines segmentation- and atlas-based features to provide a robust technique to generate attenuation maps (µ-maps) from MR data in integrated PET/MR scanners. Methods Coregistered anatomical MR and CT images acquired in 15 glioblastoma subjects were used to generate the templates. The MR images from these subjects were first segmented into 6 tissue classes (gray and white matter, cerebro-spinal fluid, bone and soft tissue, and air), which were then non-rigidly coregistered using a diffeomorphic approach. A similar procedure was used to coregister the anatomical MR data for a new subject to the template. Finally, the CT-like images obtained by applying the inverse transformations were converted to linear attenuation coefficients (LACs) to be used for AC of PET data. The method was validated on sixteen new subjects with brain tumors (N=12) or mild cognitive impairment (N=4) who underwent CT and PET/MR scans. The µ-maps and corresponding reconstructed PET images were compared to those obtained using the gold standard CT-based approach and the Dixon-based method available on the Siemens Biograph mMR scanner. Relative change (RC) images were generated in each case and voxel- and region of interest (ROI)-based analyses were performed. Results The leave-one-out cross-validation analysis of the data from the 15 atlas-generation subjects showed small errors in brain LACs (RC=1.38%±4.52%) compared to the gold standard. Similar results (RC=1.86±4.06%) were obtained from the analysis of the atlas-validation datasets. The voxel- and ROI-based analysis of the corresponding reconstructed PET images revealed quantification errors of 3.87±5.0% and 2.74±2.28%, respectively. The Dixon-based method performed substantially worse (the mean RC values were 13.0±10.25% and 9.38±4.97%, respectively). Areas closer to skull showed the largest

  2. Simulation of a MR–PET protocol for staging of head-and-neck cancer including Dixon MR for attenuation correction

    Energy Technology Data Exchange (ETDEWEB)

    Eiber, Matthias, E-mail: matthias.eiber@tum.de [Department of Radiology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 Munich (Germany); Souvatzoglou, Michael, E-mail: msouvatz@yahoo.de [Department of Nuclear Medicine, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 Munich (Germany); Pickhard, Anja, E-mail: a.pickhard@lrz.tum.de [Department of Otorhinolaryngology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 Munich (Germany); Loeffelbein, Denys J., E-mail: denys.loeffelbein@gmx.de [Department of Maxillofacial Surgery, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 Munich (Germany); Knopf, Andreas, E-mail: andreas.knopf@tum.de [Department of Otorhinolaryngology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 Munich (Germany); Holzapfel, Konstantin, E-mail: holzapfel@roe.med.tum.de [Department of Radiology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 Munich (Germany); Martinez-Möller, Axel, E-mail: a.martinez-moller@lrz.tu-muenchen.de [Department of Nuclear Medicine, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 Munich (Germany); and others

    2012-10-15

    Purpose: To simulate and optimize a MR protocol for squamous cell cancer of the head and neck (HNSCC) patients for potential future use in an integrated whole-body MR–PET scanner. Materials and methods: On a clinical 3T scanner, which is the basis for a recently introduced fully integrated whole-body MR–PET, 20 patients with untreated HNSCC routinely staged with 18F-FDG PET/CT underwent a dedicated MR protocol for the neck. Moreover, a whole-body Dixon MR-sequence was applied, which is used for attenuation correction on a recently introduced hybrid MR–PET scanner. In a subset of patients volume-interpolated-breathhold (VIBE) T1w-sequences for lungs and liver were added. Total imaging time was analyzed for both groups. The quality of the delineation of the primary tumor (scale 0–3) and the presence or absence of lymph node metastases (scale 1–5) was evaluated for CT, MR, PET/CT and a combination of MR and PET to ensure that the MR–PET fusion does not cause a loss of diagnostic capability. PET was used to identify distant metastases. The PET dataset for simulated MR/PET was based on a segmentation of the CT data into 4 classes according to the approach of the Dixon MR-sequence for MR–PET. Standard of reference was histopathology in 19 cases. In one case no histopathological confirmation of a primary tumor could be achieved. Results: Mean imaging time was 35:17 min (range: 31:08–42:42 min) for the protocol including sequences for local staging and attenuation correction and 44:17 min (range: 35:44–54:58) for the extended protocol. Although not statistically significant a combination of MR and PET performed better in the delineation of the primary tumor (mean 2.20) compared to CT (mean 1.40), MR (1.95) and PET/CT (2.15) especially in patients with dental implants. PET/CT and combining MR and PET performed slightly better than CT and MR for the assessment of lymph node metastases. Two patients with distant metastases were only identified by PET

  3. Development of a new technic for breast attenuation correction in myocardial perfusion scintigraphy using computational methods; Desenvolvimento de uma nova tecnica para correcao da atenuacao por tecidos moles em cintilografia de perfusao miocardica utilizando metodos computacionais

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Anderson de

    2015-07-01

    Introduction: One of the limitations of nuclear medicine studies are false-positive results that lead to unnecessary exams and procedures associated to morbidity and costs to the individual and society. One of the most frequent causes for reducing the specificity of myocardial perfusion imaging (MPI) is photon attenuation, especially by breast in women. Objective: To develop a new technique to compensate the photon attenuation by women breasts in myocardial perfusion imaging with {sup 99m}Tc-sestamibi, using computational methods. Materials and methods: A procedure was proposed which integrates Monte Carlo simulation, computational methods and experimental techniques. Initially, were obtained the chest attenuation correction percentages using a phantom Jaszczak and breast attenuation percentages by Monte Carlo simulation method, using the EGS4 program. The percentages of attenuation correction were linked to individual patients' characteristics by an artificial neural network and a multivariate analysis. A preliminary technical validation was done by comparing the results of the MPI and catheterism (CAT), before and after applying the technique to 4 patients. The t test for parametric data, Wilcoxon, Mann-Whitney and X{sup 2} for the others were used. Probability values less than 0.05 were considered statistically significant. Results: Each increment of 1 cm in the thickness of breast was associated to an average increment of 6% on photon attenuation, while the maximum increase related to breast composition was about 2%. The average chest attenuation percentage per unit was 2.9%. Both, the artificial neural network and linear regression, showed an error less than 3% as predictive models for percentage of female attenuation. The anatomical-functional correlation between MPI and CAT was maintained after the use of the technique. Conclusion: Results suggest that the proposed technique is promising and could be a possible alternative to other conventional methods

  4. Comparative study of short-term cardiovascular autonomic control in cardiac surgery patients who underwent coronary artery bypass grafting or correction of valvular heart disease.

    Science.gov (United States)

    Shvartz, Vladimir A; Kiselev, Anton R; Karavaev, Anatoly S; Vulf, Kristina A; Borovkova, Ekaterina I; Prokhorov, Mikhail D; Petrosyan, Andrey D; Bockeria, Olga L

    2018-01-01

    Introduction: Our aim was to perform a comparative study of short-term cardiovascular autonomic control in cardiac surgery patients who underwent coronary artery bypass grafting (CABG) or surgical correction of valvular heart disease (SCVHD ). Methods: The synchronous 15 minutes records of heart rate variability (HRV) and finger's photoplethysmographic waveform variability (PPGV) were performed in 42 cardiac surgery patients (12 women) aged 61.8 ± 8.6 years (mean ± standard deviation), who underwent CABG, and 36 patients (16 women) aged 54.2 ± 14.9 years, who underwent SCVHD , before surgery and in 5-7 days after surgery. Conventional time and frequency domain measures of HRV and index S of synchronization between the slow oscillations in PPGV and HRV were analyzed. We also calculated personal dynamics of these indices after surgery. Results: We found no differences ( Р > 0.05) in all studied autonomic indices (preoperative and post-surgery) between studied patients' groups, except for the preoperative heart rate, which was higher in patients who underwent SCVHD ( P = 0.013). We have shown a pronounced preoperative and post-surgery variability (magnitude of inter-quartile ranges) of all autonomic indices in studied patients. In the cluster analysis based on cardiovascular autonomic indices (preoperative and post-surgery), we divided all patients into two clusters (38 and 40 subjects) which did not differ in all clinical characteristics (except for the preoperative hematocrit, P = 0.038), index S, and all post-surgery HRV indices. First cluster (38 patients) had higher preoperative values of the HR, TP, HF, and HF%, and lower preoperative values of the LF% and LF/HF. Conclusion: The variability of cardiovascular autonomic indices in on-pump cardiac surgery patients (two characteristic clusters were identified based on preoperative indices) was not associated with their clinical characteristics and features of surgical procedure (including cardioplegia).

  5. Focused and Corrective Feedback Versus Structured and Supported Debriefing in a Simulation-Based Cardiac Arrest Team Training: A Pilot Randomized Controlled Study.

    Science.gov (United States)

    Kim, Ji-Hoon; Kim, Young-Min; Park, Seong Heui; Ju, Eun A; Choi, Se Min; Hong, Tai Yong

    2017-06-01

    The aim of the study was to compare the educational impact of two postsimulation debriefing methods-focused and corrective feedback (FCF) versus Structured and Supported Debriefing (SSD)-on team dynamics in simulation-based cardiac arrest team training. This was a pilot randomized controlled study conducted at a simulation center. Fourth-year medical students were randomly assigned to the FCF or SSD group, with each team composed of six students and a confederate. Each team participated in two simulations and the assigned debriefing (FCF or SSD) sessions and then underwent a test simulation. Two trained raters blindly assessed all of the recorded simulations using checklists. The primary outcome was the improvement in team dynamics scores between baseline and test simulation. The secondary outcomes were improvements before and after training in team clinical performance scores, self-assessed comprehension of and confidence in cardiac arrest management and team dynamics, as well as evaluations of the postsimulation debriefing intervention. In total, 95 students participated [FCF (8 teams, n = 47) and SSD (8 teams, n = 48)]. The SSD team dynamics score during the test simulation was higher than at baseline [baseline: 74.5 (65.9-80.9), test: 85.0 (71.9-87.6), P = 0.035]. However, there were no differences in the improvement in the team dynamics or team clinical performance scores between the two groups (P = 0.328, respectively). There was no significant difference in improvement in team dynamics scores during the test simulation compared with baseline between the SSD and FCF groups in a simulation-based cardiac arrest team training in fourth-year Korean medical students.

  6. Zero-Echo-Time and Dixon Deep Pseudo-CT (ZeDD CT): Direct Generation of Pseudo-CT Images for Pelvic PET/MRI Attenuation Correction Using Deep Convolutional Neural Networks with Multiparametric MRI.

    Science.gov (United States)

    Leynes, Andrew P; Yang, Jaewon; Wiesinger, Florian; Kaushik, Sandeep S; Shanbhag, Dattesh D; Seo, Youngho; Hope, Thomas A; Larson, Peder E Z

    2018-05-01

    Accurate quantification of uptake on PET images depends on accurate attenuation correction in reconstruction. Current MR-based attenuation correction methods for body PET use a fat and water map derived from a 2-echo Dixon MRI sequence in which bone is neglected. Ultrashort-echo-time or zero-echo-time (ZTE) pulse sequences can capture bone information. We propose the use of patient-specific multiparametric MRI consisting of Dixon MRI and proton-density-weighted ZTE MRI to directly synthesize pseudo-CT images with a deep learning model: we call this method ZTE and Dixon deep pseudo-CT (ZeDD CT). Methods: Twenty-six patients were scanned using an integrated 3-T time-of-flight PET/MRI system. Helical CT images of the patients were acquired separately. A deep convolutional neural network was trained to transform ZTE and Dixon MR images into pseudo-CT images. Ten patients were used for model training, and 16 patients were used for evaluation. Bone and soft-tissue lesions were identified, and the SUV max was measured. The root-mean-squared error (RMSE) was used to compare the MR-based attenuation correction with the ground-truth CT attenuation correction. Results: In total, 30 bone lesions and 60 soft-tissue lesions were evaluated. The RMSE in PET quantification was reduced by a factor of 4 for bone lesions (10.24% for Dixon PET and 2.68% for ZeDD PET) and by a factor of 1.5 for soft-tissue lesions (6.24% for Dixon PET and 4.07% for ZeDD PET). Conclusion: ZeDD CT produces natural-looking and quantitatively accurate pseudo-CT images and reduces error in pelvic PET/MRI attenuation correction compared with standard methods. © 2018 by the Society of Nuclear Medicine and Molecular Imaging.

  7. Robust, fully automatic delineation of the head contour by stereotactical normalization for attenuation correction according to Chang in dopamine transporter scintigraphy

    Energy Technology Data Exchange (ETDEWEB)

    Lange, Catharina; Brenner, Winfried; Buchert, Ralph [Charite - Universitaetsmedizin Berlin, Department of Nuclear Medicine, Berlin (Germany); Kurth, Jens; Schwarzenboeck, Sarah; Krause, Bernd J. [Universitaetsmedizin Rostock, Department of Nuclear Medicine, Rostock (Germany); Seese, Anita; Steinhoff, Karen; Sabri, Osama; Hesse, Swen [Universitaetsklinikum Leipzig, Department of Nuclear Medicine, Leipzig (Germany); Umland-Seidler, Bert [GE Healthcare Buchler GmbH and Co. KG, Munich (Germany)

    2015-09-15

    Chang's method, the most widely used attenuation correction (AC) in brain single-photon emission computed tomography (SPECT), requires delineation of the outer contour of the head. Manual and automatic threshold-based methods are prone to errors due to variability of tracer uptake in the scalp. The present study proposes a new method for fully automated delineation of the head based on stereotactical normalization. The method was validated for SPECT with I-123-ioflupane. The new method was compared to threshold-based delineation in 62 unselected patients who had received I-123-ioflupane SPECT at one of 3 centres. The impact on diagnostic power was tested for semi-quantitative analysis and visual reading of the SPECT images (six independent readers). The two delineation methods produced highly consistent semi-quantitative results. This was confirmed by receiver operating characteristic analyses in which the putamen specific-to-background ratio achieved highest area under the curve with negligible effect of the delineation method: 0.935 versus 0.938 for stereotactical normalization and threshold-based delineation, respectively. Visual interpretation of DVR images was also not affected by the delineation method. Delineation of the head contour by stereotactical normalization appears useful for Chang AC in I-123-ioflupane SPECT. It is robust and does not require user interaction. (orig.)

  8. Attenuation corrections through energy spectra analysis of whole body and partial body measurements applying gamma spectroscopy; Schwaechungskorrektur bei gammaspektroskopischen Ganz- und Teilkoerpermessungen durch Analyse der Energiespektren

    Energy Technology Data Exchange (ETDEWEB)

    Schelper, L.F.; Lassmann, M.; Haenscheid, H.; Reiners, C. [Wuerzburg Univ. (Germany). Klinik und Poliklinik fuer Nuklearmedizin

    1997-12-01

    The study was carried out within the framework of activities for testing means of direct determination of radioactivity levels in the human body due to incorporated, inhomogenously distributed radionuclides. A major task was to derive the average depth of activity distributions, particularly from photon radiation at energies below 500 keV, for the purpose of making suitable attenuation corrections. The paper presents two applicable methods which yield information on the mean depths of activity distributions, obtained through additional analyses of the energy spectra. The analyses are based on measuring the dependence of intensity of the Compton radiation on the length of pathways of the photons penetrating the soft tissue, or on measuring the energy-dependent absorption effects with photons. (orig./CB) [Deutsch] Im Rahmen der direkten Aktivitaetsbestimmung bei inhomogener Radionukliddeposition im menschlichen Koerper mittels Ganz- oder Teilkoerpermessanlagen im klinischen Bereich oder im Strahlenschutz sollte besonders bei Photonenstrahlung mit Energien von weniger als 500 keV eine Ermittlung der mittleren Tiefe der Aktivitaetsverteilung zur Schwaechungskorrektur erfolgen. Im klinischen Umfeld ist es haeufig moeglich, zur Tiefenkorrektur die mittlere Organtiefe und damit die schwaechende Gewebsschicht mittels Ultraschall zu bestimmen. Ergaenzend hierzu werden im Folgenden zwei Methoden vorgestellt, welche Aussagen ueber die mittlere Tiefe von Aktivitaetsverteilungen durch Gewinnung von Zusatzinformationen aus dem Energiespektrum im Rahmen von gamma-spektroskopischen Personenmessungen ermoeglichen. Dazu werden einerseits die Abhaengigkeit der Intensitaet der Comptonstrahlung von der Laenge der Wegstrecke von Photonen durch Weichgewebe und andererseits energieabhaengige Absorptionseffekte bei Photonen als Grundlage herangezogen. (orig.)

  9. Local detection of prostate cancer by positron emission tomography with 2-fluorodeoxyglucose comparison of filtered back projection and iterative reconstruction with segmented attenuation correction

    International Nuclear Information System (INIS)

    Turlakow, A.; Larson, S. M.; Coakley, F.; Akhurst, T.; Macapinlac, H. A.; Hricak, H.; Gonen, M.; Kelly, W.; Scher, H.; Leibel, S.; Humm, J.; Scardino, P.

    2001-01-01

    To compare filtered back projection (FBP) and iterative reconstruction with segmented attenuation correction (IRSAC) in the local imaging of prostate cancer by positron emission tomography with 2-fluorodeoxyglucose (FDG-PET). 13 patients with primary (n=7) or recurrent (n=6) prostate cancer who had increased uptake in the prostate on FDG-PET performed without urinary catheterization, contemporaneous biopsy confirming the presence of active tumor in the prostate, were retrospectively identified. Two independent nuclear medicine physicians separately rated FBP and IRSAC images for visualization of prostatic activity on a 4-point scale. Results were compared using biopsy and cross-sectional imaging findings as the standard of reference. IRSAC images were significantly better that FBP in terms of visualization of prostatic activity in 12 of 13 patients, and were equivalent in 1 patient (p<0.001, Wilcoxon signed ranks test). In particular, 2 foci of tumor activity in 2 different patients seen on IRSAC images were not visible on FBP images. In 11 patients who had a gross tumor mass evident on cross-sectional imaging, there was good agreement between PET and cross-sectional anatomic imaging with respect to tumor localization. In selected patients, cancer can be imaged within the prostate using FDG-PET, and IRSAC is superior to FBP in image reconstruction for local tumor visualization

  10. Diagnostic value of thallium-201 myocardial perfusion IQ-SPECT without and with computed tomography-based attenuation correction to predict clinically significant and insignificant fractional flow reserve

    Science.gov (United States)

    Tanaka, Haruki; Takahashi, Teruyuki; Ohashi, Norihiko; Tanaka, Koichi; Okada, Takenori; Kihara, Yasuki

    2017-01-01

    Abstract The aim of this study was to clarify the predictive value of fractional flow reserve (FFR) determined by myocardial perfusion imaging (MPI) using thallium (Tl)-201 IQ-SPECT without and with computed tomography-based attenuation correction (CT-AC) for patients with stable coronary artery disease (CAD). We assessed 212 angiographically identified diseased vessels using adenosine-stress Tl-201 MPI-IQ-SPECT/CT in 84 consecutive, prospectively identified patients with stable CAD. We compared the FFR in 136 of the 212 diseased vessels using visual semiquantitative interpretations of corresponding territories on MPI-IQ-SPECT images without and with CT-AC. FFR inversely correlated most accurately with regional summed difference scores (rSDS) in images without and with CT-AC (r = −0.584 and r = −0.568, respectively, both P system can predict FFR at an optimal cut-off of <0.80, and we propose a novel application of CT-AC to MPI-IQ-SPECT for predicting clinically significant and insignificant FFR even in nonobese patients. PMID:29390486

  11. Cardiorespiratory fitness attenuates risk for major adverse cardiac events in hyperlipidemic men and women independent of statin therapy: The Henry Ford ExercIse Testing Project.

    Science.gov (United States)

    Hung, Rupert K; Al-Mallah, Mouaz H; Qadi, Mohamud A; Shaya, Gabriel E; Blumenthal, Roger S; Nasir, Khurram; Brawner, Clinton A; Keteyian, Steven J; Blaha, Michael J

    2015-08-01

    We sought to evaluate the effect of cardiorespiratory fitness (CRF) in predicting mortality, myocardial infarction (MI), and revascularization in patients with hyperlipidemia after stratification by gender and statin therapy. This retrospective cohort study included 33,204 patients with hyperlipidemia (57 ± 12 years old, 56% men, 25% black) who underwent physician-referred treadmill stress testing at the Henry Ford Health System from 1991 to 2009. Patients were stratified by gender, baseline statin therapy, and estimated metabolic equivalents from stress testing. We computed hazard ratios using Cox regression models after adjusting for demographics, cardiac risk factors, comorbidities, pertinent medications, interaction terms, and indication for stress testing. There were 4,851 deaths, 1,962 MIs, and 2,686 revascularizations over a median follow-up of 10.3 years. In men and women not on statin therapy and men and women on statin therapy, each 1-metabolic equivalent increment in CRF was associated with hazard ratios of 0.86 (95% CI 0.85-0.88), 0.83 (95% CI 0.81-0.85), 0.85 (95% CI 0.83-0.87), and 0.84 (95% CI 0.81-0.87) for mortality; 0.93 (95% CI 0.90-0.96), 0.87 (95% CI 0.83-0.91), 0.89 (95% CI 0.86-0.92), and 0.90 (95% CI 0.86-0.95) for MI; and 0.91 (95% CI 0.88-0.93), 0.87 (95% CI 0.83-0.91), 0.89 (95% CI 0.87-0.92), and 0.90 (95% CI 0.86-0.94) for revascularization, respectively. No significant interactions were observed between CRF and statin therapy (P > .23). Higher CRF attenuated risk for mortality, MI, and revascularization independent of gender and statin therapy in patients with hyperlipidemia. These results reinforce the prognostic value of CRF and support greater promotion of CRF in this patient population. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Value of a dixon-based MR/PET attenuation correction sequence for the localization and evaluation of PET-positive lesions

    International Nuclear Information System (INIS)

    Eiber, Matthias; Holzapfel, Konstantin; Rummeny, Ernst J.; Martinez-Moeller, Axel; Souvatzoglou, Michael; Ziegler, Sibylle; Schwaiger, Markus; Nekolla, Stephan G.; Beer, Ambros J.; Pickhard, Anja; Loeffelbein, Dennys; Santi, Ivan

    2011-01-01

    In this study, the potential contribution of Dixon-based MR imaging with a rapid low-resolution breath-hold sequence, which is a technique used for MR-based attenuation correction (AC) for MR/positron emission tomography (PET), was evaluated for anatomical correlation of PET-positive lesions on a 3T clinical scanner compared to low-dose CT. This technique is also used in a recently installed fully integrated whole-body MR/PET system. Thirty-five patients routinely scheduled for oncological staging underwent 18 F-fluorodeoxyglucose (FDG) PET/CT and a 2-point Dixon 3-D volumetric interpolated breath-hold examination (VIBE) T1-weighted MR sequence on the same day. Two PET data sets reconstructed using attenuation maps from low-dose CT (PET AC C T ) or simulated MR-based segmentation (PET AC M R ) were evaluated for focal PET-positive lesions. The certainty for the correlation with anatomical structures was judged in the low-dose CT and Dixon-based MRI on a 4-point scale (0-3). In addition, the standardized uptake values (SUVs) for PET AC C T and PET AC M R were compared. Statistically, no significant difference could be found concerning anatomical localization for all 81 PET-positive lesions in low-dose CT compared to Dixon-based MR (mean 2.51 ± 0.85 and 2.37 ± 0.87, respectively; p = 0.1909). CT tended to be superior for small lymph nodes, bone metastases and pulmonary nodules, while Dixon-based MR proved advantageous for soft tissue pathologies like head/neck tumours and liver metastases. For the PET AC C T - and PET AC M R -based SUVs (mean 6.36 ± 4.47 and 6.31 ± 4.52, respectively) a nearly complete concordance with a highly significant correlation was found (r = 0.9975, p < 0.0001). Dixon-based MR imaging for MR AC allows for anatomical allocation of PET-positive lesions similar to low-dose CT in conventional PET/CT. Thus, this approach appears to be useful for future MR/PET for body regions not fully covered by diagnostic MRI due to potential time

  13. MO-AB-BRA-04: Correct Identification of Low-Attenuation Intracranial Hemorrhage and Calcification Using Dual-Energy Computed Tomography in a Phantom System

    Energy Technology Data Exchange (ETDEWEB)

    Nute, J; Jacobsen, M; Popnoe, D [UT MD Anderson Cancer Center, Department of Imaging Physics, Houston, TX (United States); UT Graduate School of Biomedical Sciences at Houston, Houston, TX (United States); Wei, W [UT MD Anderson Cancer Center, Department of Biostatistics, Houston, TX (United States); Baiu, C [Gammex Inc., Middleton, WI (United States); Schellingerhout, D [MD Anderson Cancer Center, Department of Diagnostic Radiology, Houston, TX (United States); Cody, D [UT MD Anderson Cancer Center, Department of Imaging Physics, Houston, TX (United States)

    2015-06-15

    Purpose: Intracranial hemorrhage and calcification with Single-Energy CT (SECT) attenuation below 100HU cannot be reliably identified using currently clinically available means. Calcification is typically benign but hemorrhage can carry a risk of intracranial bleeding and contraindicate use of anticoagulant therapies. A biologically-relevant phantom was used to investigate identification of unknown intracranial lesions using dual-energy CT (DECT) as a verification of prior lesion differentiation results. Methods: Prior phantom work investigating calcification and hemorrhage differentiation resulted in 3D-DECT raw data (water density, calcium density, 68keV) for a range of DECT protocol variations: image thicknesses (1.25, 2.5, 3.75, 5mm), CTDIvol (36.7 to 132.6mGy) and reconstruction algorithms (Soft, Standard, Detail). Acquisition-specific raw data were used to create a plane of optimal differentiation based on the geometric bisector of 3D-linear regression of the two lesion distributions. Verification hemorrhage and calcification lesions, ranging in size from 0.5 to 1.5cm, were created at varying attenuation from 50 to 100HU. Lesions were inserted into a biologically-relevant brain phantom and scanned using SECT (3.75mm images, Standard, 67mGy) and a range of DECT protocols (3.75mm images, Standard, [67, 105.6, 132.6mGy]). 3D-DECT data were collected and blinded for analysis. The 3D-DECT distribution of the lesion was then compared to the acquisition-matched geometric bisector plane and the mean lesion value’s position relative to the plane, indicating lesion identity, and the percentage of voxels on the identified side of the plane, indicating identification confidence, were derived. Results: 98% of the 120 lesions investigated were identified correctly as hemorrhage or calcification. 74% were identified with greater than 80% confidence. Increases in CTDIvol and lesion diameter were associated with increased identification confidence. Conclusion: Intracranial

  14. Nanotized PPARα Overexpression Targeted to Hypertrophied Myocardium Improves Cardiac Function by Attenuating the p53-GSK3β-Mediated Mitochondrial Death Pathway.

    Science.gov (United States)

    Rana, Santanu; Datta, Ritwik; Chaudhuri, Ratul Datta; Chatterjee, Emeli; Chawla-Sarkar, Mamta; Sarkar, Sagartirtha

    2018-05-09

    Metabolic remodeling of cardiac muscles during pathological hypertrophy is characterized by downregulation of fatty acid oxidation (FAO) regulator, peroxisome proliferator-activated receptor alpha (PPARα). Thereby, we hypothesized that a cardiac-specific induction of PPARα might restore the FAO-related protein expression and resultant energy deficit. In the present study, consequences of PPARα augmentation were evaluated for amelioration of chronic oxidative stress, myocyte apoptosis, and cardiac function during pathological cardiac hypertrophy. Nanotized PPARα overexpression targeted to myocardium was done by a stearic acid-modified carboxymethyl-chitosan (CMC) conjugated to a 20-mer myocyte-targeted peptide (CMCP). Overexpression of PPARα ameliorated pathological hypertrophy and improved cardiac function. Augmented PPARα in hypertrophied myocytes revealed downregulated p53 acetylation (lys 382), leading to reduced apoptosis. Such cells showed increased binding of PPARα with p53 that in turn reduced interaction of p53 with glycogen synthase kinase-3β (GSK3β), which upregulated inactive phospho-GSK3β (serine [Ser]9) expression within mitochondrial protein fraction. Altogether, the altered molecular milieu in PPARα-overexpressed hypertrophy groups restored mitochondrial structure and function both in vitro and in vivo. Cardiomyocyte-targeted overexpression of a protein of interest (PPARα) by nanotized plasmid has been described for the first time in this study. Our data provide a novel insight towards regression of pathological hypertrophy by ameliorating mitochondrial oxidative stress in targeted PPARα-overexpressed myocardium. PPARα-overexpression during pathological hypertrophy showed substantial betterment of mitochondrial structure and function, along with downregulated apoptosis. Myocardium-targeted overexpression of PPARα during pathological cardiac hypertrophy led to an overall improvement of cardiac energy deficit and subsequent cardiac

  15. A multi-centre evaluation of eleven clinically feasible brain PET/MRI attenuation correction techniques using a large cohort of patients.

    Science.gov (United States)

    Ladefoged, Claes N; Law, Ian; Anazodo, Udunna; St Lawrence, Keith; Izquierdo-Garcia, David; Catana, Ciprian; Burgos, Ninon; Cardoso, M Jorge; Ourselin, Sebastien; Hutton, Brian; Mérida, Inés; Costes, Nicolas; Hammers, Alexander; Benoit, Didier; Holm, Søren; Juttukonda, Meher; An, Hongyu; Cabello, Jorge; Lukas, Mathias; Nekolla, Stephan; Ziegler, Sibylle; Fenchel, Matthias; Jakoby, Bjoern; Casey, Michael E; Benzinger, Tammie; Højgaard, Liselotte; Hansen, Adam E; Andersen, Flemming L

    2017-02-15

    To accurately quantify the radioactivity concentration measured by PET, emission data need to be corrected for photon attenuation; however, the MRI signal cannot easily be converted into attenuation values, making attenuation correction (AC) in PET/MRI challenging. In order to further improve the current vendor-implemented MR-AC methods for absolute quantification, a number of prototype methods have been proposed in the literature. These can be categorized into three types: template/atlas-based, segmentation-based, and reconstruction-based. These proposed methods in general demonstrated improvements compared to vendor-implemented AC, and many studies report deviations in PET uptake after AC of only a few percent from a gold standard CT-AC. Using a unified quantitative evaluation with identical metrics, subject cohort, and common CT-based reference, the aims of this study were to evaluate a selection of novel methods proposed in the literature, and identify the ones suitable for clinical use. In total, 11 AC methods were evaluated: two vendor-implemented (MR-AC DIXON and MR-AC UTE ), five based on template/atlas information (MR-AC SEGBONE (Koesters et al., 2016), MR-AC ONTARIO (Anazodo et al., 2014), MR-AC BOSTON (Izquierdo-Garcia et al., 2014), MR-AC UCL (Burgos et al., 2014), and MR-AC MAXPROB (Merida et al., 2015)), one based on simultaneous reconstruction of attenuation and emission (MR-AC MLAA (Benoit et al., 2015)), and three based on image-segmentation (MR-AC MUNICH (Cabello et al., 2015), MR-AC CAR-RiDR (Juttukonda et al., 2015), and MR-AC RESOLUTE (Ladefoged et al., 2015)). We selected 359 subjects who were scanned using one of the following radiotracers: [ 18 F]FDG (210), [ 11 C]PiB (51), and [ 18 F]florbetapir (98). The comparison to AC with a gold standard CT was performed both globally and regionally, with a special focus on robustness and outlier analysis. The average performance in PET tracer uptake was within ±5% of CT for all of the proposed

  16. Discrimination and anatomical mapping of PET-positive lesions: comparison of CT attenuation-corrected PET images with coregistered MR and CT images in the abdomen

    Energy Technology Data Exchange (ETDEWEB)

    Kuhn, Felix P.; Crook, David W.; Mader, Caecilia E.; Appenzeller, Philippe; Schulthess, G.K. von; Schmid, Daniel T. [University Hospital Zurich, Department of Medical Radiology, Zurich (Switzerland)

    2013-01-15

    PET/MR has the potential to become a powerful tool in clinical oncological imaging. The purpose of this prospective study was to evaluate the performance of a single T1-weighted (T1w) fat-suppressed unenhanced MR pulse sequence of the abdomen in comparison with unenhanced low-dose CT images to characterize PET-positive lesions. A total of 100 oncological patients underwent sequential whole-body {sup 18}F-FDG PET with CT-based attenuation correction (AC), 40 mAs low-dose CT and two-point Dixon-based T1w 3D MRI of the abdomen in a trimodality PET/CT-MR system. PET-positive lesions were assessed by CT and MRI with regard to their anatomical location, conspicuity and additional relevant information for characterization. From among 66 patients with at least one PET-positive lesion, 147 lesions were evaluated. No significant difference between MRI and CT was found regarding anatomical lesion localization. The MR pulse sequence used performed significantly better than CT regarding conspicuity of liver lesions (p < 0.001, Wilcoxon signed ranks test), whereas no difference was noted for extrahepatic lesions. For overall lesion characterization, MRI was considered superior to CT in 40 % of lesions, equal to CT in 49 %, and inferior to CT in 11 %. Fast Dixon-based T1w MRI outperformed low-dose CT in terms of conspicuity and characterization of PET-positive liver lesions and performed similarly in extrahepatic tumour manifestations. Hence, under the assumption that the technical issue of MR AC for whole-body PET examinations is solved, in abdominal PET/MR imaging the replacement of low-dose CT by a single Dixon-based MR pulse sequence for anatomical lesion correlation appears to be valid and robust. (orig.)

  17. Discrimination and anatomical mapping of PET-positive lesions: comparison of CT attenuation-corrected PET images with coregistered MR and CT images in the abdomen

    International Nuclear Information System (INIS)

    Kuhn, Felix P.; Crook, David W.; Mader, Caecilia E.; Appenzeller, Philippe; Schulthess, G.K. von; Schmid, Daniel T.

    2013-01-01

    PET/MR has the potential to become a powerful tool in clinical oncological imaging. The purpose of this prospective study was to evaluate the performance of a single T1-weighted (T1w) fat-suppressed unenhanced MR pulse sequence of the abdomen in comparison with unenhanced low-dose CT images to characterize PET-positive lesions. A total of 100 oncological patients underwent sequential whole-body 18 F-FDG PET with CT-based attenuation correction (AC), 40 mAs low-dose CT and two-point Dixon-based T1w 3D MRI of the abdomen in a trimodality PET/CT-MR system. PET-positive lesions were assessed by CT and MRI with regard to their anatomical location, conspicuity and additional relevant information for characterization. From among 66 patients with at least one PET-positive lesion, 147 lesions were evaluated. No significant difference between MRI and CT was found regarding anatomical lesion localization. The MR pulse sequence used performed significantly better than CT regarding conspicuity of liver lesions (p < 0.001, Wilcoxon signed ranks test), whereas no difference was noted for extrahepatic lesions. For overall lesion characterization, MRI was considered superior to CT in 40 % of lesions, equal to CT in 49 %, and inferior to CT in 11 %. Fast Dixon-based T1w MRI outperformed low-dose CT in terms of conspicuity and characterization of PET-positive liver lesions and performed similarly in extrahepatic tumour manifestations. Hence, under the assumption that the technical issue of MR AC for whole-body PET examinations is solved, in abdominal PET/MR imaging the replacement of low-dose CT by a single Dixon-based MR pulse sequence for anatomical lesion correlation appears to be valid and robust. (orig.)

  18. Gallic acid attenuates hypertension, cardiac remodeling, and fibrosis in mice with NG-nitro-L-arginine methyl ester-induced hypertension via regulation of histone deacetylase 1 or histone deacetylase 2.

    Science.gov (United States)

    Jin, Li; Lin, Ming Quan; Piao, Zhe Hao; Cho, Jae Yeong; Kim, Gwi Ran; Choi, Sin Young; Ryu, Yuhee; Sun, Simei; Kee, Hae Jin; Jeong, Myung Ho

    2017-07-01

    Gallic acid, a natural chemical found in plants, has been reported to show antioxidant, anticancer, and anti-inflammatory effects. We investigated the efficacy of a short-term or long-term treatment with gallic acid in N-nitro-L-arginine methyl ester (L-NAME)-induced hypertensive mice and the underlying regulatory mechanism. Hypertension was sufficiently induced after 2 weeks of L-NAME administration. Cardiac remodeling was assessed by echocardiography. Hypertrophic markers, transcription factors, and fibrosis-related gene expression were evaluated by quantitative real-time polymerase chain reaction and western blotting. Gallic acid effectively lowered SBP, regardless of the administration route (intraperitoneal or oral). L-NAME increased the left ventricular (LV) thickness without an increase in the total heart weight. Weekly echocardiography demonstrated that gallic acid significantly reduced LV posterior wall and septum thickness in chronic L-NAME mice from 3 to 7 weeks. The administration of gallic acid to mice showed a dual preventive and therapeutic effect on the L-NAME-induced LV remodeling. The effect was associated with the suppression of the gene expression of hypertrophy markers and the GATA-binding factor 6 (GATA6) transcription factor. Short-term or long-term treatment with gallic acid attenuated cardiac fibrosis and reduced the expression of histone deacetylase 1 and 2 in H9c2 cells and in rat primary cardiac fibroblasts, as well as in vivo. Small interfering RNA knockdown confirmed the association of these enzymes with L-NAME-induced cardiac remodeling and fibrosis. These results suggested that gallic acid may be a potential therapeutic agent for the treatment of cardiovascular diseases with hypertension and cardiac fibrosis.

  19. Omega-3 Fatty Acid Supplementation Appears to Attenuate Particulate Air Pollution-induced Cardiac Effects and Lipid Changes in Healthy Middle-aged Adults.

    Science.gov (United States)

    Context: Air pollution exposure has been associated with adverse cardiovascular effects. A recent epidemiologic study reported that omega-3 fatty acid (fish oil) supplementation blunted the cardiac responses to air pollution exposure. Objective: To evaluate in a randomized contro...

  20. RESOLUTE PET/MRI Attenuation Correction for O-(2-18F-fluoroethyl-L-tyrosine (FET in Brain Tumor Patients with Metal Implants

    Directory of Open Access Journals (Sweden)

    Claes N. Ladefoged

    2017-08-01

    Full Text Available Aim: Positron emission tomography (PET imaging is a useful tool for assisting in correct differentiation of tumor progression from reactive changes, and the radiolabeled amino acid analog tracer O-(2-18F-fluoroethyl-L-tyrosine (FET-PET is amongst the most frequently used. The FET-PET images need to be quantitatively correct in order to be used clinically, which require accurate attenuation correction (AC in PET/MRI. The aim of this study was to evaluate the use of the subject-specific MR-derived AC method RESOLUTE in post-operative brain tumor patients.Methods: We analyzed 51 post-operative brain tumor patients (68 examinations, 200 MBq [18F]-FET investigated in a PET/MRI scanner. MR-AC maps were acquired using: (1 the Dixon water fat separation sequence, (2 the ultra short echo time (UTE sequences, (3 calculated using our new RESOLUTE methodology, and (4 a same day low-dose CT used as reference “gold standard.” For each subject and each AC method the tumor was delineated by isocontouring tracer uptake above a tumor(T-to-brain background (B activity ratio of 1.6. We measured B, tumor mean and maximal activity (TMEAN, TMAX, biological tumor volume (BTV, and calculated the clinical metrics TMEAN/B and TMAX/B.Results: When using RESOLUTE 5/68 studies did not meet our predefined acceptance criteria of TMAX/B difference to CT-AC < ±0.1 or 5%, TMEAN/B < ±0.05 or 5%, and BTV < ±2 mL or 10%. In total, 46/68 studies failed our acceptance criteria using Dixon, and 26/68 using UTE. The 95% limits of agreement for TMAX/B was for RESOLUTE (−3%; 4%, Dixon (−9%; 16%, and UTE (−7%; 10%. The absolute error when measuring BTV was 0.7 ± 1.9 mL (N.S with RESOLUTE, 5.3 ± 10 mL using Dixon, and 1.7 ± 3.7 mL using UTE. RESOLUTE performed best in the identification of the location of peak activity and in brain tumor follow-up monitoring using clinical FET PET metrics.Conclusions: Overall, we found RESOLUTE to be the AC method that most robustly

  1. Multiphase contrast-enhanced CT with highly concentrated contrast agent can be used for PET attenuation correction in integrated PET/CT imaging

    International Nuclear Information System (INIS)

    Aschoff, Philip; Plathow, Christian; Lichy, Matthias P.; Claussen, Claus D.; Pfannenberg, Christina; Beyer, Thomas; Erb, Gunter; Oeksuez, Mehmet Oe.

    2012-01-01

    State-of-the-art positron emission tomography/computed tomography (PET/CT) systems incorporate multislice CT technology, thus facilitating the acquisition of multiphase, contrast-enhanced CT data as part of integrated PET/CT imaging protocols. We assess the influence of a highly concentrated iodinated contrast medium (CM) on quantification and image quality following CT-based attenuation correction (CT-AC) in PET/CT. Twenty-eight patients with suspected malignant liver lesions were enrolled prospectively. PET/CT was performed 60 min after injection of 400 MBq of 18 F-fluorodeoxyglucose (FDG) and following the biphasic administration of an intravenous CM (400 mg iodine/ml, Iomeron 400). PET images were reconstructed with CT-AC using any of four acquired CT image sets: non-enhanced, pre-contrast (n-PET), arterial phase (art-PET), portal venous phase (pv-PET) and late phase (late-PET). Normal tissue activity and liver lesions were assessed visually and quantitatively on each PET/CT image set. Visual assessment of PET following CT-AC revealed no noticeable difference in image appearance or quality when using any of the four CT data sets for CT-AC. A total of 44 PET-positive liver lesions was identified in 21 of 28 patients. There were no false-negative or false-positive lesions on PET. Mean standardized uptake values (SUV) in 36 evaluable lesions were: 5.5 (n-PET), 5.8 (art-PET), 5.8 (pv-PET) and 5.8 (late-PET), with the highest mean increase in mean SUV of 6%. Mean SUV changes in liver background increased by up to 10% from n-PET to pv-PET. Multiphase CT data acquired with the use of highly concentrated CM can be used for qualitative assessment of liver lesions in torso FDG PET/CT. The influence on quantification of FDG uptake is small and negligible for most clinical applications. (orig.)

  2. SU-E-I-86: Ultra-Low Dose Computed Tomography Attenuation Correction for Pediatric PET CT Using Adaptive Statistical Iterative Reconstruction (ASiR™)

    Energy Technology Data Exchange (ETDEWEB)

    Brady, S; Shulkin, B [St. Jude Children’s Research Hospital, Memphis, TN (United States)

    2015-06-15

    Purpose: To develop ultra-low dose computed tomography (CT) attenuation correction (CTAC) acquisition protocols for pediatric positron emission tomography CT (PET CT). Methods: A GE Discovery 690 PET CT hybrid scanner was used to investigate the change to quantitative PET and CT measurements when operated at ultra-low doses (10–35 mAs). CT quantitation: noise, low-contrast resolution, and CT numbers for eleven tissue substitutes were analyzed in-phantom. CT quantitation was analyzed to a reduction of 90% CTDIvol (0.39/3.64; mGy) radiation dose from baseline. To minimize noise infiltration, 100% adaptive statistical iterative reconstruction (ASiR) was used for CT reconstruction. PET images were reconstructed with the lower-dose CTAC iterations and analyzed for: maximum body weight standardized uptake value (SUVbw) of various diameter targets (range 8–37 mm), background uniformity, and spatial resolution. Radiation organ dose, as derived from patient exam size specific dose estimate (SSDE), was converted to effective dose using the standard ICRP report 103 method. Effective dose and CTAC noise magnitude were compared for 140 patient examinations (76 post-ASiR implementation) to determine relative patient population dose reduction and noise control. Results: CT numbers were constant to within 10% from the non-dose reduced CTAC image down to 90% dose reduction. No change in SUVbw, background percent uniformity, or spatial resolution for PET images reconstructed with CTAC protocols reconstructed with ASiR and down to 90% dose reduction. Patient population effective dose analysis demonstrated relative CTAC dose reductions between 62%–86% (3.2/8.3−0.9/6.2; mSv). Noise magnitude in dose-reduced patient images increased but was not statistically different from pre dose-reduced patient images. Conclusion: Using ASiR allowed for aggressive reduction in CTAC dose with no change in PET reconstructed images while maintaining sufficient image quality for co

  3. Phantom studies on the artifacts of barium on 18F-FDG DHC/CT images induced by X-ray attenuation correction

    International Nuclear Information System (INIS)

    Wang Wei; Zhu Jiarui; Wang Xinqiang; Zhao Wenrui; Chuan Ling; Xu Genxiang; Gao Chunhua; Fang Tingzheng

    2007-01-01

    Objective: Attenuation correction (AC) based on X-ray transmission map may result in false positive readings or artifacts on PET images, some of them due to the internal residue of high density contrast media used in diagnostic X-ray imaging. The aim of this study was to experimentally estimate the impacts of different concentrations and volumes of barium contrast on X-CT AC (CTAC) for dual-head coincidence (DHC/CT) images. Methods: A cylindrical phantom containing 18 F solution (3.7 kBq/ml), in which plastic fingertips enclosed with different concentrations (0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 1.0, 2.0, 3.0 kg/L)and volumes(0.5, 1.0, 1.5, 2.0, 2.5 ml) of BaSO 4 contrast media were inserted, was used to modulate routine 18 F-fluorodeoxyglucose (FDG) imaging study on a DHC/CT scanner (GE Discovery VH). Sequential 18 F emission and X-CT transmission acquisitions followed by data processing and reconstruction were carried out in clinical settings. For comparison, both visual and quantitative analyses were performed on CTAC and non-AC (NAC) images of the phantom. Results: In NAC images, the radioactivity distribution within the whole phantom was non-uniform with lower counts in the center; the plastic fingertips were all seen as 'cold spots' with much lower counts in the contrast region than in their surrounding areas. On the contrary, in CTAC images, the radioactivity distribution within the whole phantom was almost uniform; while most plastic fingertips with media concentration ≥0.1 kg/L and volume >0.5 ml were all depicted as 'hot spots' with higher counts than in surrounding areas. Conclusions: Barium contrast with relative high concentration or large volume can induce artifacts on CTAC DHC/CT images. In clinical setting, proper interpretation of CTAC DHC/CT images should refer to NAC DHC/CT images to exclude any artifacts related to the contrast media residues. (authors)

  4. Optimization of transmission-scan time for the FixER method: a MR-based PET attenuation correction with a weak fixed-position external radiation source

    Energy Technology Data Exchange (ETDEWEB)

    Kawaguchi, Hiroshi; Hirano, Yoshiyuki; Kershaw, Jeff; Yoshida, Eiji [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba (Japan); Shiraishi, Takahiro [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba (Japan); Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan); Suga, Mikio [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba (Japan); Center for Frontier Medical Engineering, Chiba University (Japan); Obata, Takayuki [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba (Japan); Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan); Ito, Hiroshi; Yamaya, Taiga [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba (Japan)

    2014-07-29

    In recent work, we proposed an MRI-based attenuation-coefficient (μ-value) estimation method that uses a weak fixed-position external radiation source to construct an attenuation map for PET/MRI. In this presentation we refer to this method as FixER, and perform a series of simulations to investigate the duration of the transmission scan required to accurately estimate μ-values.

  5. Optimization of transmission-scan time for the FixER method: a MR-based PET attenuation correction with a weak fixed-position external radiation source

    International Nuclear Information System (INIS)

    Kawaguchi, Hiroshi; Hirano, Yoshiyuki; Kershaw, Jeff; Yoshida, Eiji; Shiraishi, Takahiro; Suga, Mikio; Obata, Takayuki; Ito, Hiroshi; Yamaya, Taiga

    2014-01-01

    In recent work, we proposed an MRI-based attenuation-coefficient (μ-value) estimation method that uses a weak fixed-position external radiation source to construct an attenuation map for PET/MRI. In this presentation we refer to this method as FixER, and perform a series of simulations to investigate the duration of the transmission scan required to accurately estimate μ-values.

  6. Associations between N-terminal pro-B-type natriuretic peptide and cardiac function in adults with corrected tetralogy of Fallot.

    Science.gov (United States)

    Eindhoven, Jannet A; Menting, Myrthe E; van den Bosch, Annemien E; Cuypers, Judith A A E; Ruys, Titia P E; Witsenburg, Maarten; McGhie, Jackie S; Boersma, Eric; Roos-Hesselink, Jolien W

    2014-07-01

    Amino-terminal B-type natriuretic peptide (NT-proBNP) may detect early cardiac dysfunction in adults with tetralogy of Fallot (ToF) late after corrective surgery. We aimed to determine the value of NT-proBNP in adults with ToF and establish its relationship with echocardiography and exercise capacity. NT-proBNP measurement, electrocardiography and detailed 2D-echocardiography were performed on the same day in 177 consecutive adults with ToF (mean age 34.6 ± 11.8 years, 58% male, 89% NYHA I, 29.3 ± 8.5 years after surgical correction). Thirty-eight percent of the patients also underwent a cardiopulmonary-exercise test. Median NT-proBNP was 16 [IQR 6.7-33.6] pmol/L, and was elevated in 55%. NT-proBNP correlated with right ventricular (RV) dilatation (r = 0.271, p present in 69 patients (39%). Moderate or severe pulmonary regurgitation was not associated with higher NT-proBNP. Tricuspid and pulmonary regurgitation peak velocities correlated with NT-proBNP (r = 0.305, p < 0.001 and r = 0.186, p = 0.045, respectively). LV twist was measured with speckle-tracking echocardiography in 71 patients. An abnormal LV twist (20 patients, 28%) was associated with elevated NT-proBNP (p = 0.030). No relationship between NT-proBNP and exercise capacity was found. NT-proBNP levels are elevated in more than 50% of adults with corrected ToF, while they are in stable clinical condition. Higher NT-proBNP is most strongly associated with elevated pulmonary pressures, and with LV dysfunction rather than RV dysfunction. NT-proBNP has the potential to become routine examination in patients with ToF to monitor ventricular function and may be used for timely detection of clinical deterioration. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  7. Impact of missing attenuation and scatter corrections on 99m Tc-MAA SPECT 3D dosimetry for liver radioembolization using the patient relative calibration methodology: A retrospective investigation on clinical images.

    Science.gov (United States)

    Botta, Francesca; Ferrari, Mahila; Chiesa, Carlo; Vitali, Sara; Guerriero, Francesco; Nile, Maria Chiara De; Mira, Marta; Lorenzon, Leda; Pacilio, Massimiliano; Cremonesi, Marta

    2018-04-01

    To investigate the clinical implication of performing pre-treatment dosimetry for 90 Y-microspheres liver radioembolization on 99m Tc-MAA SPECT images reconstructed without attenuation or scatter correction and quantified with the patient relative calibration methodology. Twenty-five patients treated with SIR-Spheres ® at Istituto Europeo di Oncologia and 31 patients treated with TheraSphere ® at Istituto Nazionale Tumori were considered. For each acquired 99m Tc-MAA SPECT, four reconstructions were performed: with attenuation and scatter correction (AC_SC), only attenuation (AC_NoSC), only scatter (NoAC_SC) and without corrections (NoAC_NoSC). Absorbed dose maps were calculated from the activity maps, quantified applying the patient relative calibration to the SPECT images. Whole Liver (WL) and Tumor (T) regions were drawn on CT images. Injected Liver (IL) region was defined including the voxels receiving absorbed dose >3.8 Gy/GBq. Whole Healthy Liver (WHL) and Healthy Injected Liver (HIL) regions were obtained as WHL = WL - T and HIL = IL - T. Average absorbed dose to WHL and HIL were calculated, and the injection activity was derived following each Institute's procedure. The values obtained from AC_NoSC, NoAC_SC and NoAC_NoSC images were compared to the reference value suggested by AC_SC images using Bland-Altman analysis and Wilcoxon paired test (5% significance threshold). Absorbed-dose maps were compared to the reference map (AC_SC) in global terms using the Voxel Normalized Mean Square Error (%VNMSE), and at voxel level by calculating for each voxel the normalized difference with the reference value. The uncertainty affecting absorbed dose at voxel level was accounted for in the comparison; to this purpose, the voxel counts fluctuation due to Poisson and reconstruction noise was estimated from SPECT images of a water phantom acquired and reconstructed as patient images. NoAC_SC images lead to activity prescriptions not significantly different from the

  8. HSF1 and NF-κB p65 participate in the process of exercise preconditioning attenuating pressure overload-induced pathological cardiac hypertrophy

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tongyi [Department of Cardiothoracic Surgery, No. 401 Hospital of PLA, Qingdao (China); Department of Cardiothoracic Surgery, Changhai Hospital, Second Military Medical University, Shanghai (China); Zhang, Ben [Centre of Cardiovascular Surgery, Guangzhou General Hospital of Guangzhou Military Region, Guangzhou (China); Department of Cardiothoracic Surgery, Changhai Hospital, Second Military Medical University, Shanghai (China); Yang, Fan; Cai, Chengliang; Wang, Guokun [Department of Cardiothoracic Surgery, Changhai Hospital, Second Military Medical University, Shanghai (China); Han, Qingqi, E-mail: handoctor@gmail.com [Department of Cardiothoracic Surgery, Changhai Hospital, Second Military Medical University, Shanghai (China); Zou, Liangjian, E-mail: zouliangjiansh@gmail.com [Department of Cardiothoracic Surgery, Changhai Hospital, Second Military Medical University, Shanghai (China)

    2015-05-08

    Pathological cardiac hypertrophy, often accompanied by hypertension, aortic stenosis and valvular defects, is typically associated with myocyte remodeling and cardiac dysfunction. Exercise preconditioning (EP) has been proven to enhance the tolerance of the myocardium to cardiac ischemia-reperfusion injury. However, the effects of EP in pathological cardiac hypertrophy are rarely reported. 10-wk-old male Sprague–Dawley rats (n = 80) were randomly divided into four groups: sham, TAC, EP + sham and EP + TAC. Two EP groups were subjected to 4 weeks of treadmill training, and the EP + TAC and TAC groups were followed by TAC operations. The sham and EP + sham groups underwent the same operation without aortic constriction. Eight weeks after the surgery, we evaluated the effects of EP by echocardiography, morphology, and histology and observed the expressions of the associated proteins. Compared with the respective control groups, hypertrophy-related indicators were significantly increased in the TAC and EP + TAC groups (p < 0.05). However, between the TAC and EP + TAC groups, all of these changes were effectively inhibited by EP treatment (p < 0.05). Furthermore, EP treatment upregulated the expression of HSF1 and HSP70, increased the HSF1 levels in the nuclear fraction, inhibited the expression of the NF-κB p65 subunit, decreased the NF-κB p65 subunit levels in the nuclear fraction, and reduced the IL2 levels in the myocardia of rats. EP could effectively reduce the cardiac hypertrophic responses induced by TAC and may play a protective role by upregulating the expressions of HSF1 and HSP70, activating HSF1 and then inhibiting the expression of NF-κB p65 and nuclear translocation. - Highlights: • EP could effectively reduce the cardiac hypertrophic responses induced by TAC. • EP may play a protective role by upregulating the expressions of HSF1 and HSP70 and then activating HSF1. • EP may play a protective role by inhibiting the expression

  9. The effect of metal artefact reduction on CT-based attenuation correction for PET imaging in the vicinity of metallic hip implants : a phantom study

    NARCIS (Netherlands)

    Harnish, Roy; Prevrhal, Sven; Alavi, Abass; Zaidi, Habib; Lang, Thomas F.

    To determine if metal artefact reduction (MAR) combined with a priori knowledge of prosthesis material composition can be applied to obtain CT-based attenuation maps with sufficient accuracy for quantitative assessment of F-18-fluorodeoxyglucose uptake in lesions near metallic prostheses. A custom

  10. An SPM8-Based Approach for Attenuation Correction Combining Segmentation and Nonrigid Template Formation: Application to Simultaneous PET/MR Brain Imaging

    DEFF Research Database (Denmark)

    Izquierdo-Garcia, David; Hansen, Adam E; Förster, Stefan

    2014-01-01

    coregistered using a diffeomorphic approach. A similar procedure was used to coregister the anatomic MR data for a new subject to the template. Finally, the CT-like images obtained by applying the inverse transformations were converted to linear attenuation coefficients to be used for AC of PET data...

  11. How to simplify transmission-based scatter correction for clinical application

    International Nuclear Information System (INIS)

    Baccarne, V.; Hutton, B.F.

    1998-01-01

    Full text: The performances of ordered subsets (OS) EM reconstruction including attenuation, scatter and spatial resolution correction are evaluated using cardiac Monte Carlo data. We demonstrate how simplifications in the scatter model allow one to correct SPECT data for scatter in terms of quantitation and quality in a reasonable time. Initial reconstruction of the 20% window is performed including attenuation correction (broad beam μ values), to estimate the activity quantitatively (accuracy 3%), but not spatially. A rough reconstruction with 2 iterations (subset size: 8) is sufficient for subsequent scatter correction. Estimation of primary photons is obtained by projecting the previous distribution including attenuation (narrow beam μ values). Estimation of the scatter is obtained by convolving the primary estimates by a depth dependent scatter kernel, and scaling the result by a factor calculated from the attenuation map. The correction can be accelerated by convolving several adjacent planes with the same kernel, and using an average scaling factor. Simulation of the effects of the collimator during the scatter correction was demonstrated to be unnecessary. Final reconstruction is performed using 6 iterations OSEM, including attenuation (narrow beam μ values) and spatial resolution correction. Scatter correction is implemented by incorporating the estimated scatter as a constant offset in the forward projection step. The total correction + reconstruction (64 proj. 40x128 pixel) takes 38 minutes on a Sun Sparc 20. Quantitatively, the accuracy is 7% in a reconstructed slice. The SNR inside the whole myocardium (defined from the original object), is equal to 2.1 and 2.3 - in the corrected and the primary slices respectively. The scatter correction preserves the myocardium to ventricle contrast (primary: 0.79, corrected: 0.82). These simplifications allow acceleration of correction without influencing the quality of the result

  12. Acquisition and automated 3-D segmentation of respiratory/cardiac-gated PET transmission images

    International Nuclear Information System (INIS)

    Reutter, B.W.; Klein, G.J.; Brennan, K.M.; Huesman, R.H.

    1996-01-01

    To evaluate the impact of respiratory motion on attenuation correction of cardiac PET data, we acquired and automatically segmented gated transmission data for a dog breathing on its own under gas anesthesia. Data were acquired for 20 min on a CTI/Siemens ECAT EXACT HR (47-slice) scanner configured for 12 gates in a static study, Two respiratory gates were obtained using data from a pneumatic bellows placed around the dog's chest, in conjunction with 6 cardiac gates from standard EKG gating. Both signals were directed to a LabVIEW-controlled Macintosh, which translated them into one of 12 gate addresses. The respiratory gating threshold was placed near end-expiration to acquire 6 cardiac-gated datasets at end-expiration and 6 cardiac-gated datasets during breaths. Breaths occurred about once every 10 sec and lasted about 1-1.5 sec. For each respiratory gate, data were summed over cardiac gates and torso and lung surfaces were segmented automatically using a differential 3-D edge detection algorithm. Three-dimensional visualizations showed that lung surfaces adjacent to the heart translated 9 mm inferiorly during breaths. Our results suggest that respiration-compensated attenuation correction is feasible with a modest amount of gated transmission data and is necessary for accurate quantitation of high-resolution gated cardiac PET data

  13. Probiotic-fermented purple sweet potato yogurt activates compensatory IGF‑IR/PI3K/Akt survival pathways and attenuates cardiac apoptosis in the hearts of spontaneously hypertensive rats.

    Science.gov (United States)

    Lin, Pei-Pei; Hsieh, You-Miin; Kuo, Wei-Wen; Lin, Yueh-Min; Yeh, Yu-Lan; Lin, Chien-Chung; Tsai, Fuu-Jen; Tsai, Chang-Hai; Huang, Chih-Yang; Tsai, Cheng-Chih

    2013-12-01

    Apoptosis is recognized as a predictor of adverse outcomes in subjects with cardiac diseases. The aim of this study was to explore the effects of probiotic-fermented purple sweet potato yogurt (PSPY) with high γ-aminobutyric acid (GABA) content on cardiac apoptosis in spontaneously hypertensive rat (SHR) hearts. The rats were orally adminsitered with 2 different concentrations of PSPY (10 and 100%) or captopril, 15.6 mg/kg, body weight (BW)/day. The control group was administered distilled water. DAPI and TUNEL staining were used to detect the numbers of apoptotic cells. A decrease in the number of TUNEL-positive cardiac myocytes was observed in the SHR-PSPY (10 and 100%) groups. In addition, the levels of key components of the Fas receptor- and mitochondrial-dependent apoptotic pathways were determined by western blot analysis. The results revealed that the levels of the key components of the Fas receptor- and mitochondrial-dependent apoptotic pathway were significantly decreased in the SHR-captopril, and 10 and 100% PSPY groups. Additionally, the levels of phosphorylated insulin-like growth factor‑I receptor (p-IGF‑IR) were increased in SHR hearts from the SHR-control group; however, no recovery in the levels of downstream signaling components was observed. In addition, the levels of components of the compensatory IGF-IR-dependent survival pathway (p-PI3K and p-Akt) were all highly enhanced in the left ventricles in the hearts form the SHR-10 and 100% PSPY groups. Therefore, the oral administration of PSPY may attenuate cardiomyocyte apoptosis in SHR hearts by activating IGF‑IR-dependent survival signaling pathways.

  14. Morning surge of ventricular arrhythmias in a new arrhythmogenic canine model of chronic heart failure is associated with attenuation of time-of-day dependence of heart rate and autonomic adaptation, and reduced cardiac chaos.

    Science.gov (United States)

    Zhu, Yujie; Hanafy, Mohamed A; Killingsworth, Cheryl R; Walcott, Gregory P; Young, Martin E; Pogwizd, Steven M

    2014-01-01

    Patients with chronic heart failure (CHF) exhibit a morning surge in ventricular arrhythmias, but the underlying cause remains unknown. The aim of this study was to determine if heart rate dynamics, autonomic input (assessed by heart rate variability (HRV)) and nonlinear dynamics as well as their abnormal time-of-day-dependent oscillations in a newly developed arrhythmogenic canine heart failure model are associated with a morning surge in ventricular arrhythmias. CHF was induced in dogs by aortic insufficiency & aortic constriction, and assessed by echocardiography. Holter monitoring was performed to study time-of-day-dependent variation in ventricular arrhythmias (PVCs, VT), traditional HRV measures, and nonlinear dynamics (including detrended fluctuations analysis α1 and α2 (DFAα1 & DFAα2), correlation dimension (CD), and Shannon entropy (SE)) at baseline, as well as 240 days (240 d) and 720 days (720 d) following CHF induction. LV fractional shortening was decreased at both 240 d and 720 d. Both PVCs and VT increased with CHF duration and showed a morning rise (2.5-fold & 1.8-fold increase at 6 AM-noon vs midnight-6 AM) during CHF. The morning rise in HR at baseline was significantly attenuated by 52% with development of CHF (at both 240 d & 720 d). Morning rise in the ratio of low frequency to high frequency (LF/HF) HRV at baseline was markedly attenuated with CHF. DFAα1, DFAα2, CD and SE all decreased with CHF by 31, 17, 34 and 7%, respectively. Time-of-day-dependent variations in LF/HF, CD, DFA α1 and SE, observed at baseline, were lost during CHF. Thus in this new arrhythmogenic canine CHF model, attenuated morning HR rise, blunted autonomic oscillation, decreased cardiac chaos and complexity of heart rate, as well as aberrant time-of-day-dependent variations in many of these parameters were associated with a morning surge of ventricular arrhythmias.

  15. Morning surge of ventricular arrhythmias in a new arrhythmogenic canine model of chronic heart failure is associated with attenuation of time-of-day dependence of heart rate and autonomic adaptation, and reduced cardiac chaos.

    Directory of Open Access Journals (Sweden)

    Yujie Zhu

    Full Text Available Patients with chronic heart failure (CHF exhibit a morning surge in ventricular arrhythmias, but the underlying cause remains unknown. The aim of this study was to determine if heart rate dynamics, autonomic input (assessed by heart rate variability (HRV and nonlinear dynamics as well as their abnormal time-of-day-dependent oscillations in a newly developed arrhythmogenic canine heart failure model are associated with a morning surge in ventricular arrhythmias. CHF was induced in dogs by aortic insufficiency & aortic constriction, and assessed by echocardiography. Holter monitoring was performed to study time-of-day-dependent variation in ventricular arrhythmias (PVCs, VT, traditional HRV measures, and nonlinear dynamics (including detrended fluctuations analysis α1 and α2 (DFAα1 & DFAα2, correlation dimension (CD, and Shannon entropy (SE at baseline, as well as 240 days (240 d and 720 days (720 d following CHF induction. LV fractional shortening was decreased at both 240 d and 720 d. Both PVCs and VT increased with CHF duration and showed a morning rise (2.5-fold & 1.8-fold increase at 6 AM-noon vs midnight-6 AM during CHF. The morning rise in HR at baseline was significantly attenuated by 52% with development of CHF (at both 240 d & 720 d. Morning rise in the ratio of low frequency to high frequency (LF/HF HRV at baseline was markedly attenuated with CHF. DFAα1, DFAα2, CD and SE all decreased with CHF by 31, 17, 34 and 7%, respectively. Time-of-day-dependent variations in LF/HF, CD, DFA α1 and SE, observed at baseline, were lost during CHF. Thus in this new arrhythmogenic canine CHF model, attenuated morning HR rise, blunted autonomic oscillation, decreased cardiac chaos and complexity of heart rate, as well as aberrant time-of-day-dependent variations in many of these parameters were associated with a morning surge of ventricular arrhythmias.

  16. Strategies to reduce radiation dose in cardiac PET/CT

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Tung Hsin; Wu, Nien-Yun [Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan (China); Wang, Shyh-Jen [Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan (China); Department of Nuclear Medicine, Taipei Veterans General Hospital, Taipei, Taiwan (China); Wu, Jay [Institute of Radiological science, Central Taiwan University of Science and Technology, Taichung, Taiwan (China); Mok, Greta S.P. [Department of Electrical and Electronics Engineering, Faculty of Science and Technology, University of Macau, Macau (China); Yang, Ching-Ching, E-mail: g39220003@yahoo.com.tw [Department of Radiological Technology, Tzu Chi College of Technology, 880, Sec.2, Chien-kuo Rd. Hualien 970, Taiwan (China); Huang, Tzung-Chi, E-mail: tzungchi.huang@mail.cmu.edu.tw [Department of Biomedical Imaging and Radiological Science, China Medical University, No.91 Hsueh-Shih Road, Taichung 40402, Taiwan (China)

    2011-08-21

    Background: Our aim was to investigate CT dose reduction strategies on a hybrid PET/CT scanner for cardiac applications. Materials: Image quality and dose estimation of different CT scanning protocols for CT coronary angiography (CTCA), and CT-based attenuation correction for PET imaging were investigated. Fifteen patients underwent CTCA, perfusion PET imaging at rest and under stress, and FDG PET for myocardial viability. These patients were divided into three groups based on the CTCA technique performed: retrospectively gated helical (RGH), ECG tube current modulation (ETCM), and prospective gated axial (PGA) acquisitions. All emission images were corrected for photon attenuation using CT images obtained by default setting and an ultra-low dose CT (ULDCT) scan. Results: Radiation dose in RGH technique was 22.2{+-}4.0 mSv. It was reduced to 10.95{+-}0.82 and 4.13{+-}0.31 mSv using ETCM and PGA techniques, respectively. Radiation dose in CT transmission scan was reduced by 96.5% (from 4.53{+-}0.5 to 0.16{+-}0.01 mSv) when applying ULDCT as compared to the default CT. No significant difference in terms of image quality was found among various protocols. Conclusion: The proposed CT scanning strategies, i.e. ETCM or PGA for CTCA and ULDCT for PET attenuation correction, could reduce radiation dose up to 47% without degrading imaging quality in an integrated cardiac PET/CT coronary artery examination.

  17. Dual energy cardiac CT.

    Science.gov (United States)

    Carrascosa, Patricia; Deviggiano, Alejandro; Rodriguez-Granillo, Gastón

    2017-06-01

    Conventional single energy CT suffers from technical limitations related to the polychromatic nature of X-rays. Dual energy cardiac CT (DECT) shows promise to attenuate and even overcome some of these limitations, and might broaden the scope of patients eligible for cardiac CT towards the inclusion of higher risk patients. This might be achieved as a result of both safety (contrast reduction) and physiopathological (myocardial perfusion and characterization) issues. In this article, we will review the main clinical cardiac applications of DECT, that can be summarized in two core aspects: coronary artery evaluation, and myocardial evaluation.

  18. Butanolic fraction of Moringa oleifera Lam. (Moringaceae) attenuates isoprotrenol-induced cardiac necrosis and oxidative stress in rats: an EPR study

    Science.gov (United States)

    Panda, Sunanda

    2015-01-01

    The preventive effect of Moringa oleifera polyphenolic fraction (MOPF) on cardiac damage was evaluated in isoproterenol (ISO) induced cardiotoxicity model of Wistar rats. Male rats in different groups were treated with MOPF orally at the dose of 50, 100 and 150 mg/kg/day for 28 days and were subsequently administered (s.c.) with ISO (85 mg/kg body weight) for the last two days. At the end of the experiment levels of serum troponin-T, creatine kinase-MB, lactate dehydrogenase, content of malondialdehyde (MDA), activities/levels of different cellular antioxidants were estimated in control and experimental groups. Additionally, scavenging potential to the hydroxyl radical of the fraction was measured by electron paramagnetic resonance (EPR). ISO administered rats showed significant increase in the levels of serum troponin-I, creatine kinase, lactate dehydrogenase, and heart tissue MDA content. Furthermore, marked reduction in the activities of antioxidants such as superoxide dismutase, catalase, glutathione peroxidase and reduced glutathione levels were observed. EPR study showed an increase in signal intensity in ISO-induced rats. Triphenyl tetrazolium chloride (TTC) staining of heart section revealed a marked increase in infarcted area in ISO-induced rats. Histological features of the heart also indicated a disruption in the structure of cardiac myofibrils in these animals. MOPF (100 mg/kg body weight) pretreatment prevented all these adverse effects of ISO. Present results show that the rich polyphenolic content of Moringa oleifera significantly reduced the myocardial damage and decreased the oxidative stress, possibly through hydroxyl radical scavenging activity as evidenced from the EPR spectra. PMID:26417351

  19. Whole-body FDG PET-MR oncologic imaging: pitfalls in clinical interpretation related to inaccurate MR-based attenuation correction.

    Science.gov (United States)

    Attenberger, Ulrike; Catana, Ciprian; Chandarana, Hersh; Catalano, Onofrio A; Friedman, Kent; Schonberg, Stefan A; Thrall, James; Salvatore, Marco; Rosen, Bruce R; Guimaraes, Alexander R

    2015-08-01

    Simultaneous data collection for positron emission tomography and magnetic resonance imaging (PET/MR) is now a reality. While the full benefits of concurrently acquiring PET and MR data and the potential added clinical value are still being evaluated, initial studies have identified several important potential pitfalls in the interpretation of fluorodeoxyglucose (FDG) PET/MRI in oncologic whole-body imaging, the majority of which being related to the errors in the attenuation maps created from the MR data. The purpose of this article was to present such pitfalls and artifacts using case examples, describe their etiology, and discuss strategies to overcome them. Using a case-based approach, we will illustrate artifacts related to (1) Inaccurate bone tissue segmentation; (2) Inaccurate air cavities segmentation; (3) Motion-induced misregistration; (4) RF coils in the PET field of view; (5) B0 field inhomogeneity; (6) B1 field inhomogeneity; (7) Metallic implants; (8) MR contrast agents.

  20. Determination of position and shape of flexible mri surface coils using the Microsoft Kinect for attenuation correction in PET/MRI

    Energy Technology Data Exchange (ETDEWEB)

    Frohwein, Lynn; He, Mirco; Buther, Florian; Safers, Klaus [European Institute for Molecular Imaging, University of Muenster (Germany)

    2015-05-18

    Due to the varying position and shape of flexible MRI RF surface coils, the creation of attenuation maps for these coils is a challenging task. Nevertheless, coil material (metal, plastic, rubber) attenuates the PET signal to a considerable amount. Thus, including a coil μ-map into the human μ-map is essential. In this work, we present a method to determine the position and shape of flexible coils with the help of the Microsoft Kinect depth camera. Phantom PET/MRI (Siemens Biograph mMR) and CT scans (Siemens Biograph mCT) were performed with and without the flexible 32-channel coil equipped with 15 markers visible in CT and Kinect. Prior to the PET/MRI acquisition, Kinect data is acquired of the phantom with the coil on top. The manually extracted marker positions from CT and Kinect are used to non-rigidly transform the template CT according to the Kinect marker positions describing the shape of the coil during PET/MRI acquisition. An appropriate μ-map can then be calculated from the transformed CT dataset. Subsequently, the μ-map is placed in relation to the patient table according to the Kinect-derived marker positions. First results show that the coi