Relationship between signal intensity of blood flow in the pulmonary artery obtained by magnetic resonance imaging and results of right cardiac catheterization in patients with pulmonary disease

Energy Technology Data Exchange (ETDEWEB)

Yuguchi, Yasutoshi; Nagao, Keiichi; Kouno, Norihiro; Tanabe, Nobuhiro; Okita, Shinya; Tojima, Hirokazu; Okada, Osamu; Kuriyama, Takayuki [Chiba Univ. (Japan). School of Medicine; Yamaguchi, Tetsuo

1992-08-01

Electrocardiogram-gated spin-echo magnetic resonance (MR) images of the chest were obtained in five normal controls and 35 patients with pulmonary disease (11 chronic obstructive pulmonary disease, 6 pulmonary thromboembolism, 5 primary pulmonary hypertension, 4 interstitial pulmonary disease, 4 pulmonary hypertension with disturbance of portal circulation, and 5 other diseases) who underwent right cardiac catheterization. In transverse images at the level of the right main pulmonary artery (rPA) and sagittal images at the level through the midsternal line and the spinal cord, the signal intensity of blood flow in the rPA was quantitatively evaluated, and the correlations with the MR signal intensity of intravascular flow and the parameters of hemodynamics were studied. In diastole MR images of both normal controls and patients mostly showed a significant signal and visible flow images. In systolic MR images, the mean values of hemodynamic parameters (mean pulmonary arterial pressure (mPAP), pulmonary arteriolar resistance (PAR), and cardiac index (CI)) were abnormal in patients with significant signal intensity of flow compared with those in patients without sufficient MR signal. The signal intensity was not correlated with mPAP; however, it significantly increased as PAR increased, and it increased as CI decreased both in diastole and in systole. Especially in systole, there was good correlation between the signal intensity in transverse MR images and CI and between signal intensity in sagittal MR images and PAR . These results suggest that the signal intensity of blood flow in the rPA on MR images can be used as an index of the severity of right heart failure associated with pulmonary disease. MR imaging is a useful modality to evaluate pulmonary circulation disturbance because of its ability to assess blood flow in the pulmonary artery noninvasively without interference from other structures such as bone and normal lung. (J.P.N.).

Radiation-induced electron paramagnetic resonance signal and soybean isoflavones content

International Nuclear Information System (INIS)

Oliveira, Marcos R.R. de; Mandarino, José M.G.; Mastro, Nelida L. del

2012-01-01

Electron Paramagnetic Resonance (EPR) is a well-known spectroscopic technique that detects paramagnetic centers and can detect free radicals with high sensitivity. In food, free radicals can be generated by several commonly used industrial processes, such as radiosterilization or heat treatment. EPR spectroscopy is used to detect radioinduced free radicals in food. In this work the relation between EPR signal induced by gamma irradiation treatment and soybean isoflavones content was investigated. Present results did not show correlation between total isoflavones content and the EPR signal. Nevertheless, some isoflavone contents had a negative correlation with the radiation-induced EPR signal. - Highlights: ► Electron Paramagnetic Resonance (EPR) detects free radicals. ► Ionizing radiation as free radicals inducer. ► Total soybean isoflvones do not correlate with radiation-induced EPR intensity but a soybean glucosyl glucoside isoflavone does.

An experimental study on MRI signal intensity of albumin solution

International Nuclear Information System (INIS)

Ahn, In Oak; Chang, Kee Hyun; Han, Moon Hee; Song, Chi Sung; Yeon, Kyung Mo

1990-01-01

This in vitro study attempted to correlate magnetic resonance (MR) signal intensity with concentration of albumin solution in magnetic field strength of 2.0 Tesla (T) and 0.5T. MR imaging of bovine serum albumin solutions of various concentrations ranging from 0 to 40 g/dl was performed on both 2.0T and 0.5T MR units. The relative (with respect to normal saline) signal intensities of each albumin solution were measured in T1-weighted, proton density-weighted and T2-weighted MR images, correlated with albumin concentration on each pulse sequence, and compared between 2.0T and 0.5T. Additionally, the albumin concentrations showing signal intensities identical to those of white matter, cortical gray matter and cerebrospinal fluid (CSF) of normal brain MRI were determined by visual comparison of those images. 1. On T1-weighted (SE 400-500 msec/30 msec) images under 2.0T and 0.5T field strength, the signal intensity increased with increasing albumin concentrations up to about 30-35 g/dl and the decreased. For the solutions ranging from 0 to about 5 g/dl concentration, the signal intensities appeared isointense to normal saline on visual inspection. 2. On proton density-weighted (SE 2000-2500 msec/30 msec) images under 2.0T and 0.5T field strength, the signal intensity slightly increased with increasing albumin concentrations up to about 7.5-10 g/dl, and then gradually decreased. 3. On T2-weighted (SE 2000-2500 msec/80-100 msec) images under 2.0T and 0.5T field strength, the signal intensity slightly increased with increasing albumin concentrations up to about 7.5-10 g/dl, and then gradually decreased. Above the concentration of about 25-30 g/dl, the signal intensity appeared lower than that of normal saline on visual inspection. 4. Compared with the signal intensities of normal brain structures on T1-weighted images under 2.0T and 0.5T field strength, the signal intensities of the albumin solution below 2.5-5 g/dl concentration were similar to that of CSF, and those of

Thermal resonance in signal transmission

International Nuclear Information System (INIS)

Reigada, Ramon; Sarmiento, Antonio; Lindenberg, Katja

2001-01-01

We use temperature tuning to control signal propagation in simple one-dimensional arrays of masses connected by hard anharmonic springs and with no local potentials. In our numerical model a sustained signal is applied at one site of a chain immersed in a thermal environment and the signal-to-noise ratio is measured at each oscillator. We show that raising the temperature can lead to enhanced signal propagation along the chain, resulting in thermal resonance effects akin to the resonance observed in arrays of bistable systems

Thermal resonance in signal transmission

Energy Technology Data Exchange (ETDEWEB)

Reigada, Ramon; Sarmiento, Antonio; Lindenberg, Katja

2001-06-01

We use temperature tuning to control signal propagation in simple one-dimensional arrays of masses connected by hard anharmonic springs and with no local potentials. In our numerical model a sustained signal is applied at one site of a chain immersed in a thermal environment and the signal-to-noise ratio is measured at each oscillator. We show that raising the temperature can lead to enhanced signal propagation along the chain, resulting in thermal resonance effects akin to the resonance observed in arrays of bistable systems.

Association between duration of coronary occlusion and high-intensity signal on T1-weighted magnetic resonance imaging among patients with angiographic total occlusion

Energy Technology Data Exchange (ETDEWEB)

Matsumoto, Kenji; Ehara, Shoichi; Hasegawa, Takao; Sakaguchi, Mikumo; Shimada, Kenei [Osaka City University Graduate School of Medicine, Department of Cardiovascular Medicine, Abeno-ku, Osaka (Japan)

2017-09-15

To evaluate the association between duration of the coronary occlusion and high-intensity signal (HIS) on noncontrast T1-weighted imaging using a 1.5-T magnetic resonance imager among patients with angiographic coronary total occlusion. The signal intensity of the coronary target area divided by the signal intensity of the left ventricular muscle near the target area at each site (TMR) was measured. Areas with a TMR >1.0 were defined as HIS. Thirty five lesions from 33 patients were divided into the following three groups: subacute occlusion (up to 3 months; n = 7), short-duration chronic total occlusion (SD-CTO: 3-6 months; n = 9) and long-duration CTO (LD-CTO: ≥6 months; n = 19). All subacute occlusion lesions showed a HIS within the occlusion site. Among patients with CTO, the frequency of a HIS within the occlusion site was significantly higher in SD-CTO than in LD-CTO lesions (p = 0.013). In multivariate analyses, only an occlusion duration of less than 6 months was an independent factor associated with the presence of HIS (odds ratio 7.6, 95% CI 1.1-54.5; p = 0.044). The presence of a HIS in the occlusion site was associated more with SD-CTO than with LD-CTO among patients with CTO. (orig.)

Association between duration of coronary occlusion and high-intensity signal on T1-weighted magnetic resonance imaging among patients with angiographic total occlusion

International Nuclear Information System (INIS)

Matsumoto, Kenji; Ehara, Shoichi; Hasegawa, Takao; Sakaguchi, Mikumo; Shimada, Kenei

2017-01-01

To evaluate the association between duration of the coronary occlusion and high-intensity signal (HIS) on noncontrast T1-weighted imaging using a 1.5-T magnetic resonance imager among patients with angiographic coronary total occlusion. The signal intensity of the coronary target area divided by the signal intensity of the left ventricular muscle near the target area at each site (TMR) was measured. Areas with a TMR >1.0 were defined as HIS. Thirty five lesions from 33 patients were divided into the following three groups: subacute occlusion (up to 3 months; n = 7), short-duration chronic total occlusion (SD-CTO: 3-6 months; n = 9) and long-duration CTO (LD-CTO: ≥6 months; n = 19). All subacute occlusion lesions showed a HIS within the occlusion site. Among patients with CTO, the frequency of a HIS within the occlusion site was significantly higher in SD-CTO than in LD-CTO lesions (p = 0.013). In multivariate analyses, only an occlusion duration of less than 6 months was an independent factor associated with the presence of HIS (odds ratio 7.6, 95% CI 1.1-54.5; p = 0.044). The presence of a HIS in the occlusion site was associated more with SD-CTO than with LD-CTO among patients with CTO. (orig.)

Simultaneous electrical and mechanical resonance drive for large signal amplification of micro resonators

KAUST Repository

Hasan, M. H.

2018-01-12

Achieving large signal-noise ratio using low levels of excitation signal is key requirement for practical applications of micro and nano electromechanical resonators. In this work, we introduce the double electromechanical resonance drive concept to achieve an order-of-magnitude dynamic signal amplification in micro resonators. The concept relies on simultaneously activating the micro-resonator mechanical and electrical resonance frequencies. We report an input voltage amplification up to 15 times for a micro-resonator when its electrical resonance is tuned to match the mechanical resonance that leads to dynamic signal amplification in air (Quality factor enhancement). Furthermore, using a multi-frequency excitation technique, input voltage and vibrational amplification of up to 30 times were shown for the same micro-resonator while relaxing the need to match its mechanical and electrical resonances.

Simultaneous electrical and mechanical resonance drive for large signal amplification of micro resonators

KAUST Repository

Hasan, M. H.; Alsaleem, F. M.; Jaber, Nizar; Hafiz, Md Abdullah Al; Younis, Mohammad I.

2018-01-01

Achieving large signal-noise ratio using low levels of excitation signal is key requirement for practical applications of micro and nano electromechanical resonators. In this work, we introduce the double electromechanical resonance drive concept to achieve an order-of-magnitude dynamic signal amplification in micro resonators. The concept relies on simultaneously activating the micro-resonator mechanical and electrical resonance frequencies. We report an input voltage amplification up to 15 times for a micro-resonator when its electrical resonance is tuned to match the mechanical resonance that leads to dynamic signal amplification in air (Quality factor enhancement). Furthermore, using a multi-frequency excitation technique, input voltage and vibrational amplification of up to 30 times were shown for the same micro-resonator while relaxing the need to match its mechanical and electrical resonances.

Thirty Minutes of Running Exercise Decreases T2 Signal Intensity but Not Thickness of the Knee Joint Cartilage: A 3.0-T Magnetic Resonance Imaging Study.

Science.gov (United States)

Karanfil, Yiğitcan; Babayeva, Naila; Dönmez, Gürhan; Diren, H Barış; Eryılmaz, Muzaffer; Doral, Mahmut Nedim; Korkusuz, Feza

2018-04-01

Objective Recent studies showed a potential of magnetic resonance imaging (MRI), which can be used as an additional tool for diagnosing cartilage degeneration in the early stage. We designed a cross-sectional study in order to evaluate knee joint cartilage adaptation to running, using 3.0-T MRI equipped with the 3-dimensional turbo spin echo (VISTA = Volume ISotropic Turbo spin echo Acquisition) software. By this thickness (mm) and signal intensity (mean pixel value) can be quantified, which could be closely related to the fluid content of the knee joint cartilage, before and after running. Methods A total of 22 males, aged 18 to 35 years, dominant (right) and nondominant (left) knees were assessed before and after 30 minutes of running. Cartilage thickness and signal intensity of surfaces of the patella, medial and lateral femoral and tibial condyles were measured. Results Cartilage thickness of the lateral condyle decreased at the dominant knee, while it increased at the medial tibial plateau. Signal intensity decreased at all locations, except the lateral patella in both knees. The most obvious decrease in signal intensity (10.6%) was at the medial tibial plateau from 949.8 to 849.0 of the dominant knee. Conclusion There was an increase in thickness measurements and decrease in signal intensity in medial tibial plateau of the dominant knee after 30 minutes of running. This outcome could be related to fluid outflow from the tissue. Greater reductions in the medial tibial plateau cartilage indicate greater load sharing by these areas of the joint during a 30-minute running.

Effect of ion clouds micromotion on measured signal in Fourier transform ion cyclotron resonance: Computer simulation.

Science.gov (United States)

Vladimirov, Gleb; Kostyukevich, Yury; Kharybin, Oleg; Nikolaev, Eugene

2017-08-01

Particle-in-cell-based realistic simulation of Fourier transform ion cyclotron resonance experiments could be used to generate ion trajectories and a signal induced on the detection electrodes. It has been shown recently that there is a modulation of "reduced" cyclotron frequencies in ion cyclotron resonance signal caused by Coulomb interaction of ion clouds. In this work it was proposed to use this modulation in order to determine frequency difference between an ion of known m/z and all other ions generating signal in ion cyclotron resonance cell. It is shown that with an increase of number of ions in ion cyclotron resonance trap, the modulation index increases, which lead to a decrease in the accuracy of determination of peak intensities by super Fourier transform resolution methods such as filter diagonalization method.

Analysis of high signal intensities of nontumorous conditions of corpus callosum on magnetic resonance T2-weighted images

International Nuclear Information System (INIS)

Kang, Moo Song; Kim, Chul Min; Chung, Chun Phil

1995-01-01

To evaluate high signal intensity of nontumorous conditions of corpus callosum on T2-weighted MR images. Forty nine patients with nontumorous high signal intensities involving corpus callosum on sagittal T2-weighted image were retrospectively analyzed. Nontumorous condition of corpus callosum were diffuse axonal injury (DAI, 19 cases), cerebral infarctions (16 cases), multiple sclerosis (MS, 5 cases), Wilson's disease (2 cases) and hydrocephalus (7 cases) that were diagnosed by clinical and MR findings. Numbers, configuration, involved thickness and sites of high signal intensities of corpus callosum were analyzed. DAI and infarctions showed either single or multiple lesions. MS and hydrocephalus showed multiple lesions, but Wilson's diseases showed single lesion. In DAI, infarctions and MS the lesions involved any part of corpus callosum, splenium in Wilson's disease, and all parts of corpus callosum in hydrocephalus. Wilson's disease showed only partial thickness involvement, and others involved partial or full thickness of corpus callosum. Configuration of high signal intensity was linear in most cases of hydrocephalus, and oval in Wilson's disease, and oval and confluent in MS, and variable in DAI and infarctions. High signal intensities of nontumorous conditions of corpus callosum revealed variable findings, and therefore, analysis of nontumorous high signal intensities of corpus callosum is not made by only MR findings but by conjuction with clinical aspects

MRI evaluation of cranial bone marrow signal intensity and thickness in chronic anemia

International Nuclear Information System (INIS)

Yildirim, Tulin; Agildere, A. Muhtesem; Oguzkurt, Levent; Barutcu, Ozlem; Kizilkilic, Osman; Kocak, Rikkat; Alp Niron, Emin

2005-01-01

Background and purpose: The aim is to assess the magnetic resonance imaging (MRI) findings for cranial bone marrow (CBM) signal intensity and thickness in patients with chronic anemia and compared these with findings in healthy subjects. We also investigated the relationships between CBM changes and age, type of anemia (hemolytic versus non-hemolytic), and severity of anemia. Methods: We quantitatively evaluated CBM signal intensity and thickness on images from 40 patients with chronic anemia (20 with congenital hemolytic anemia (HA) and 20 with acquired anemia) and compared these to findings in 28 healthy subjects. The intensity of CBM relative to scalp, white matter (WM), gray matter (GM), and muscle intensity was also investigated in patients and subjects in the control group. The sensitivity and specificity of CBM hypointense to GM and CBM hypointense to WM as markers of anemia were evaluated. Relationships between age and CBM thickness/intensity, and between anemia severity (hemoglobin (Hb) level) and CBM thickness/intensity were evaluated. Results: Cranial bone marrow signal intensity was lower in the chronic anemia patients than in the controls (P 0.05 for both). There were no correlations between age and CBM intensity or thickness, or between anemia severity and CBM intensity or thickness. Conclusion: Patients with chronic anemia exhibit lower CBM signal intensity on MRI than healthy subjects. Patients with hemolytic anemia have thicker CBM than patients with non-hemolytic anemia or healthy individuals. Decreased CBM intensity may indicate that the patient has anemia, and increased CBM thickness may specifically point to hemolytic anemia. These MRI findings may signal the need for further evaluation for the clinician

Intensity-based readout of resonant-waveguide grating biosensors: Systems and nanostructures

Science.gov (United States)

Paulsen, Moritz; Jahns, Sabrina; Gerken, Martina

2017-09-01

Resonant waveguide gratings (RWG) - also called photonic crystal slabs (PCS) - have been established as reliable optical transducers for label-free biochemical assays as well as for cell-based assays. Current readout systems are based on mechanical scanning and spectrometric measurements with system sizes suitable for laboratory equipment. Here, we review recent progress in compact intensity-based readout systems for point-of-care (POC) applications. We briefly introduce PCSs as sensitive optical transducers and introduce different approaches for intensity-based readout systems. Photometric measurements have been realized with a simple combination of a light source and a photodetector. Recently a 96-channel, intensity-based readout system for both biochemical interaction analyses as well as cellular assays was presented employing the intensity change of a near cut-off mode. As an alternative for multiparametric detection, a camera system for imaging detection has been implemented. A portable, camera-based system of size 13 cm × 4.9 cm × 3.5 cm with six detection areas on an RWG surface area of 11 mm × 7 mm has been demonstrated for the parallel detection of six protein binding kinetics. The signal-to-noise ratio of this system corresponds to a limit of detection of 168 M (24 ng/ml). To further improve the signal-to-noise ratio advanced nanostructure designs are investigated for RWGs. Here, results on multiperiodic and deterministic aperiodic nanostructures are presented. These advanced nanostructures allow for the design of the number and wavelengths of the RWG resonances. In the context of intensity-based readout systems they are particularly interesting for the realization of multi-LED systems. These recent trends suggest that compact point-of-care systems employing disposable test chips with RWG functional areas may reach market in the near future.

Stochastic resonance for signal-modulated pump noise in a single-mode laser

Institute of Scientific and Technical Information of China (English)

Liangying Zhang; Li Cao; Fahui Zhu

2006-01-01

By adopting the gain-noise model of the single-mode laser in which with bias and periodical signals serve as inputs, combining with the effect of coloured pump noise, we use the linear approximation method to calculate the power spectrum and signal-to-noise ratio (SNR) of the laser intensity under the condition of pump noise and quantum noise cross-related in the form of δ function. It is found that with the change of pump noise correlation time, both SNR and the output power will occur stochastic resonance (SR). If the bias signal α is very small, changing the intensities of pump noise and quantum noise respectively does not lead to the appearance of SR in the SNR; while α increases to a certain number, SR appears.

Lumber intervertebral disk; Correlation with the signal intensity of magnetic resonance imaging and the histological changes

Energy Technology Data Exchange (ETDEWEB)

Uchida, Ryusei; Takahashi, Sadao; Ando, Tadashi; Kumano, Kiyoshi; Hiranuma, Kenji; Kanazawa, Yousuke; Konishi, Seiji; Eguchi, Masanobu; Tanioka, Hisaya (KantoRosai Hospital, Kawasaki, Kanagawa (Japan))

1989-11-01

We studied to provide precise correlations between the intensity of MRI signals and the degenerative changes of the nucleus pulposes of the L4/5 intervertebral disk herniations. 23 cases with the L4/5 intervertebral disk herniations having surgical treatment were examined using Magnetom H 15 (1.5 tesla) with surface coil. The images were obtained with T2 images (long TR (1000{approx}1600 msec), TE (60{approx}90 msec)). The intensity was measured using FUJI densitometer FD 101 at the lumber vertebral body and the intervertebral disk. We calculated the L4/5 intervertebral disk degeneration ratio (determined by comparing the modified L4/5 MR signal intensity with the modified L2/3 MR signal itensity). Histological changes were examined in the cellular components of the nucleus pulposus (such as the number of the nucleus cells, nucleus cell nesting and HE stainability of the nucleus cell) and the matrics substance (such as fibrillation, hyaline degeneration and granular degeneration). Histochemical studies were performed using Scott's Method (AB-0.4 M MgCl{sub 2} Alcinophilia, AB-09 M, MgCl{sub 2} Alcinophilia) to investigate glycosaminoglycans of the nucleus pulposus. We compared the histological and histochemical changes with the MR L4/5 intervetebral disk degeneration ratio. The decreasing MRI signal intensity of the nucleous pulposus was (1) corresponded to the pathological changes such as the increasing number of the cell nesting, fibrillation and hyaline degeneration of the nucleus polposus. (2) corresponded to the decrease in the total glycosaminoglycans of the nucleus pulposus. (3) corresponded to the early stage of degeneration of the nucleus polposus, but in aging when all levels of intervertebral disk degeneration appeared, we could not know the degree of the disk degeneration from the signal intensity of MRI. (J.P.N.).

MR signal intensity of the perirolandic cirtex in the neonate and infant

International Nuclear Information System (INIS)

Korogi, Y.; Takahashi, M.; Sumi, M.; Hirai, T,; Sakamoto, Y.; Ikushima, I.; Miyayama, H.

1996-01-01

Our purpose was to study the magnetic resonance (MR) signal intensity of the perirolandic gyri perinatally and to correlate it with the histological findings in formalin-fixed brains, focusing on myelination. MRI of 20 neurologically normal neonates and infants, of 37-64 weeks postconception (PCA), were studied retrospectively. We reviewed four formalin-fixed brains of infants 37-46 weeks PCA microscopically. The posterior cortex of the precentral gyrus (P-PRE) and the anterior cortex of the postcentral gyrus (A-PST) had different signal intensity form the adjacent surrounding cortex. On T1-weighted images P-PRE and A-PST gave higher signal 41-44 weeks PCA; on T2-weighted images, they gave lower signal 37-51 weeks PCA. Histological examination revealed very little myelination of the nerve fibres within both the P-PRE and the A-PST, while considerable myelination was present in the internal capsule and central corona radiata. The changes in signal intensity in the perirolandic gyri may reflect not only the degree of myelination but also the more advanced development of the nerve cells, associated with rapid proliferation and formation of oligodendroglial cells, synapses and dendrites. They could be another important landmark for brain maturation. (orig.)

[Diagnostic efficiency of decline rate of signal intensity and apparent diffusion coefficient with different b values for differentiating benign and malignant breast lesions on diffusion-weighted 3.0T magnetic resonance imaging].

Science.gov (United States)

Jiang, Jing; Liu, Wanhua; Ye, Yuanyuan; Wang, Rui; Li, Fengfang; Peng, Chengyu

2014-06-17

To investigate the diagnostic efficiency of decline rate of signal intensity and apparent diffusion coefficient with different b values for differentiating benign and malignant breast lesions on diffusion-weighted 3.0 T magnetic resonance imaging. A total of 152 patients with 162 confirmed histopathologically breast lesions (85 malignant and 77 benign) underwent 3.0 T diffusion-weighted magnetic resonance imaging. Four b values (0, 400, 800 and 1 000 s/mm²) were used. The signal intensity and ADC values of breast lesions were measured respectively. The signal intensity decline rate (SIDR) and apparent diffusion coefficient decline rate (ADCDR) were calculated respectively. SIDR = (signal intensity of lesions with low b value-signal intensity of lesions with high b value)/signal intensity of lesions with low b value, ADCDR = (ADC value of lesions with low b value-ADC value of lesions with high b value) /ADC value of lesions with low b value. The independent sample t-test was employed for statistical analyses and the receiver operating characteristic (ROC) curve for evaluating the diagnosis efficiency of SIDR and ADCDR values. Significant differences were observed in SIDR between benign and malignant breast lesions with b values of 0-400, 400-800 and 800-1 000 s/mm². The sensitivities of SIDR for differentiating benign and malignant breast lesions were 61.2%, 68.2% and 67.1%, the specificities 74.0%, 85.7% and 67.5%, the diagnosis accordance rates 67.3%, 76.5% and 67.3%, the positive predictive values 72.2%, 84.1% and 69.5% and the negative predictive values 63.3%, 71.0% and 65.0% respectively. Significant differences were observed in ADCDR between benign and malignant breast lesions with b values of 400-800 s/mm² and 800-1 000 s/mm². The sensitivities of SDR for differentiating benign and malignant breast lesions were 80.0% and 65.9%, the specificities 72.7% and 65.0%, the diagnostic accordance rates 76.5% and 65.4%, the positive predictive values 76.4% and 67

A study on MR signal intensity of calcifications according to calcium concentration and compound

International Nuclear Information System (INIS)

Chang, Sun Ae; Kim, Jae Hyoung; Chung, Sung Hoon

1996-01-01

The signal of intracranial calcification on magnetic resonance (MR) imaging has been known to be variable. The purpose of this study was to evaluate the MR signal of calcifications according to calcium concentration and compound. T1-weighted, proton density and T2-weighted images were obtained in phantoms with various conposition of calcium carbonate and calcium phosphate. The signal intensities and T1/T2 relaxation times were measured and analyzed according to calcium concentration and compound. The configurations of calcium particles were evaluated by scanning electron microscopy. The signal intensity of calcium carbonate on T1-weighted images gradually decreased as the concentration increased, while that of calcium phosphate showed a biphasic curve with a peak intensity at 0.2g/ml. The signal intensity of both calcium phosphate decreased up to 0.2g/ml and then remained constant. The T2 relaxation time of both calcium compounds decreased in a similar fashion with increasing concentration, Calcium phosphate showed larger surface area on scanning electron microscope. Calcifications show variable MR signal due to difference of T1 and T2 relaxation times according to calcium concentration and compound. Large surface area of calcium particle might cause shortening of T1 relaxation time leading to high signal on T1-weighted image. Understanding of these findings will help interpretation of MR images more precisely

Mis-segmentation in voxel-based morphometry due to a signal intensity change in the putamen.

Science.gov (United States)

Goto, Masami; Abe, Osamu; Miyati, Tosiaki; Aoki, Shigeki; Gomi, Tsutomu; Takeda, Tohoru

2017-12-01

The aims of this study were to demonstrate an association between changes in the signal intensity of the putamen on three-dimensional T1-weighted magnetic resonance images (3D-T1WI) and mis-segmentation, using the voxel-based morphometry (VBM) 8 toolbox. The sagittal 3D-T1WIs of 22 healthy volunteers were obtained for VBM analysis using the 1.5-T MR scanner. We prepared five levels of 3D-T1WI signal intensity (baseline, same level, background level, low level, and high level) in regions of interest containing the putamen. Groups of smoothed, spatially normalized tissue images were compared to the baseline group using a paired t test. The baseline was compared to the other four levels. In all comparisons, significant volume changes were observed around and outside the area that included the signal intensity change. The present study demonstrated an association between a change in the signal intensity of the putamen on 3D-T1WI and changed volume in segmented tissue images.

Evidence on a link between the intensity of Schumann resonance and global surface temperature

Directory of Open Access Journals (Sweden)

M. Sekiguchi

2006-08-01

Full Text Available A correlation is investigated between the intensity of the global electromagnetic oscillations (Schumann resonance with the planetary surface temperature. The electromagnetic signal was monitored at Moshiri (Japan, and temperature data were taken from surface meteorological observations. The series covers the period from November 1998 to May 2002. The Schumann resonance intensity is found to vary coherently with the global ground temperature in the latitude interval from 45° S to 45° N: the relevant cross-correlation coefficient reaches the value of 0.9. It slightly increases when the high-latitude temperature is incorporated. Correspondence among the data decreases when we reduce the latitude interval, which indicates the important role of the middle-latitude lightning in the Schumann resonance oscillations. We apply the principal component (or singular spectral analysis to the electromagnetic and temperature records to extract annual, semiannual, and interannual variations. The principal component analysis (PCA clarifies the links between electromagnetic records and meteorological data.

Mechanical design parameters for detection of nuclear signals by magnetic resonance force microscopy

International Nuclear Information System (INIS)

Moore, G.J.; Hanlon, J.A.; Lamartine, B.; Hawley, M.; Solem, J.C.; Signer, S.; Jarmer, J.J.; Penttila, S.; Sillerud, L.O.; Pryputniewicz, R.J.

1993-01-01

Recent theoretical work has shown that mechanical detection of magnetic resonance from a single nuclear spin is in principle possible. This theory has recently been experimentally validated by the mechanical detection of electron spin resonance signals using microscale cantilevers. Currently we are extending this technology in an attempt to detect nuclear signals which are extending this technology in an attempt to detect nuclear signals which are three orders of magnitude lower in intensity than electron signals. In order to achieve the needed thousand-fold improvement in sensitivity we have undertaken the development of optimized mechanical cantilevers and highly polarized samples. Finite element modeling is used as a tool to simulate cantilever beam dynamics and to optimize the mechanical properties including Q, resonant frequency, amplitude of vibration and spring constant. Simulations are compared to experiments using heterodyne hologram interferometry. Nanofabrication of optimized cantilevers via ion milling will be directed by the outcome of these simulations and experiments. Highly polarized samples are developed using a three-fold approach: (1) high magnetic field strength (2.5T), (2) low temperature (1K), and (3) use of samples polarized by dynamic nuclear polarization. Our recent experiments have demonstrated nuclear polarizations in excess of 50% in molecules of toulene

Effects of iodinated contrast agent, xylocaine and gadolinium concentration on the signal emitted in magnetic resonance arthrography: a samples study

Directory of Open Access Journals (Sweden)

Yvana Lopes Pinheiro da Silva

2015-04-01

Full Text Available Objective: To investigate the effects of dilution of paramagnetic contrast agent with iodinated contrast and xylocaine on the signal intensity during magnetic resonance arthrography, and to improve the paramagnetic contrast agent concentration utilized in this imaging modality. Materials and Methods: Samples specially prepared for the study with three different concentrations of paramagnetic contrast agent diluted in saline, iodinated contrast agent and xylocaine were imaged with fast spin echo T1-weighted sequences with fat saturation. The samples were placed into flasks and graphical analysis of the signal intensity was performed as a function of the paramagnetic contrast concentration. Results: As compared with samples of equal concentrations diluted only with saline, the authors have observed an average signal intensity decrease of 20.67% for iodinated contrast agent, and of 28.34% for xylocaine. However, the increased gadolinium concentration in the samples caused decrease in signal intensity with all the dilutions. Conclusion: Minimizing the use of iodinated contrast media and xylocaine and/or the use of a gadolinium concentration of 2.5 mmol/L diluted in saline will improve the sensitivity of magnetic resonance arthrography.

Half-integer resonance crossing in high-intensity rings

Directory of Open Access Journals (Sweden)

A. V. Fedotov

2002-02-01

Full Text Available A detailed study of the influence of space charge on the crossing of second-order resonances is presented and associated with the space-charge limit of high-intensity rings. Two-dimensional simulation studies are compared with envelope models, which agree in the finding of an increased intensity limit due to the coherent frequency shift. This result is also found for realistic bunched beams with multiturn injection painting. Characteristic features such as the influence of tune splitting, structure resonances, and the role of envelope instabilities are discussed in detail. The theoretical limits are found to be in good agreement with the performance of high-intensity proton machines.

Investigation of defects in In–Ga–Zn oxide thin film using electron spin resonance signals

International Nuclear Information System (INIS)

Nonaka, Yusuke; Kurosawa, Yoichi; Komatsu, Yoshihiro; Ishihara, Noritaka; Oota, Masashi; Nakashima, Motoki; Hirohashi, Takuya; Takahashi, Masahiro; Yamazaki, Shunpei; Obonai, Toshimitsu; Hosaka, Yasuharu; Koezuka, Junichi; Yamauchi, Jun

2014-01-01

In–Ga–Zn oxide (IGZO) is a next-generation semiconductor material seen as an alternative to silicon. Despite the importance of the controllability of characteristics and the reliability of devices, defects in IGZO have not been fully understood. We investigated defects in IGZO thin films using electron spin resonance (ESR) spectroscopy. In as-sputtered IGZO thin films, we observed an ESR signal which had a g-value of g = 2.010, and the signal was found to disappear under thermal treatment. Annealing in a reductive atmosphere, such as N 2 atmosphere, generated an ESR signal with g = 1.932 in IGZO thin films. The temperature dependence of the latter signal suggests that the signal is induced by delocalized unpaired electrons (i.e., conduction electrons). In fact, a comparison between the conductivity and ESR signal intensity revealed that the signal's intensity is related to the number of conduction electrons in the IGZO thin film. The signal's intensity did not increase with oxygen vacancy alone but also with increases in both oxygen vacancy and hydrogen concentration. In addition, first-principle calculation suggests that the conduction electrons in IGZO may be generated by defects that occur when hydrogen atoms are inserted into oxygen vacancies

Investigation of defects in In–Ga–Zn oxide thin film using electron spin resonance signals

Energy Technology Data Exchange (ETDEWEB)

Nonaka, Yusuke; Kurosawa, Yoichi; Komatsu, Yoshihiro; Ishihara, Noritaka; Oota, Masashi; Nakashima, Motoki; Hirohashi, Takuya; Takahashi, Masahiro; Yamazaki, Shunpei [Semiconductor Energy Laboratory Co., Ltd., 398 Hase, Atsugi, Kanagawa 243-0036 (Japan); Obonai, Toshimitsu; Hosaka, Yasuharu; Koezuka, Junichi [Advanced Film Device, Inc., 161-2 Masuzuka, Tsuga-machi, Tochigi, Tochigi 328-0114 (Japan); Yamauchi, Jun [Semiconductor Energy Laboratory Co., Ltd., 398 Hase, Atsugi, Kanagawa 243-0036 (Japan); Emeritus Professor of Kyoto University, Oiwake-cho, Kitashirakawa, Kyoto 606-8502 (Japan)

2014-04-28

In–Ga–Zn oxide (IGZO) is a next-generation semiconductor material seen as an alternative to silicon. Despite the importance of the controllability of characteristics and the reliability of devices, defects in IGZO have not been fully understood. We investigated defects in IGZO thin films using electron spin resonance (ESR) spectroscopy. In as-sputtered IGZO thin films, we observed an ESR signal which had a g-value of g = 2.010, and the signal was found to disappear under thermal treatment. Annealing in a reductive atmosphere, such as N{sub 2} atmosphere, generated an ESR signal with g = 1.932 in IGZO thin films. The temperature dependence of the latter signal suggests that the signal is induced by delocalized unpaired electrons (i.e., conduction electrons). In fact, a comparison between the conductivity and ESR signal intensity revealed that the signal's intensity is related to the number of conduction electrons in the IGZO thin film. The signal's intensity did not increase with oxygen vacancy alone but also with increases in both oxygen vacancy and hydrogen concentration. In addition, first-principle calculation suggests that the conduction electrons in IGZO may be generated by defects that occur when hydrogen atoms are inserted into oxygen vacancies.

Scaled signal intensity of uterine fibroids based on T2-weighted MR images: a potential objective method to determine the suitability for magnetic resonance-guided focused ultrasound surgery of uterine fibroids.

Science.gov (United States)

Park, Hyun; Yoon, Sang-Wook; Sokolov, Amit

2015-12-01

Magnetic Resonance-guided Focused Ultrasound Surgery (MRgFUS) is a non-invasive method to treat uterine fibroids. To help determine the patient suitability for MRgFUS, we propose a new objective measure: the scaled signal intensity (SSI) of uterine fibroids in T2 weighted MR images (T2WI). Forty three uterine fibroids in 40 premenopausal women were included in this retrospective study. SSI of each fibroid was measured from the screening T2WI by standardizing its mean signal intensity to a 0-100 scale, using reference intensities of rectus abdominis muscle (0) and subcutaneous fat (100). Correlation between the SSI and the non-perfused volume (NPV) ratio (a measure for treatment success) was calculated. Pre-treatment SSI showed a significant inverse-correlation with post treatment NPV ratio (p < 0.05). When dichotomizing NPV ratio at 45 %, the optimal cut off value of the SSI was found to be 16.0. A fibroid with SSI value 16.0 or less can be expected to have optimal responses. The SSI of uterine fibroids in T2WI can be suggested as an objective parameter to help in patient selection for MRgFUS. • Signal intensity of fibroid in MR images predicts treatment response to MRgFUS. • Signal intensity is standardized into scaled form using adjacent tissues as references. • Fibroids with SSI less than 16.0 are expected to have optimal responses.

Magnetic resonance imaging of infectious myositis

Energy Technology Data Exchange (ETDEWEB)

Yun, Ji Young; Kim, Jee Young; Kim, Sang Heum; Jung, Youn Ju; Cha, Eun Suk; Park, Joung Mi; Park, Young Ha [The Catholic Univ., College of Medicine, Suwon (Korea, Republic of)

1998-09-01

To describe the findings of magnetic resonance imaging in infectious myositis and to determine their value for differentiation between ruberculous and bacterial myositis. Magnetic resonance images of ten proven cases of infectious myositis (five tuberculous and five bacterial) were retrospectively reviewed in the light of clinical and laboratory findings. On the basis of magnetic resonance images, signal intensity of the mass, the presence or absence of an abscess, signal intensity of the peripheral wall, patterns of contrast enhancement, and associated findings were evaluated. Compared with those of bacterial myositis, the symptoms of tuberculous myositis lasted longer but there were no difinite local inflammatory signs. In three of five cases of bacterial myositis there were specific medical records;trauma in two cases and systemic lupus erythematosus in one. All tuberculous myositis cases involved a single muscle, but bacterial myositis affected multipe muscles in three cases(60%). All but one case showed a mass in the involved muscles. In one bacterial case, there was diffuse swelling in the involved muscle. On T1-weighted images, eight infectious cases showed low signal intensity;two, of the bactrerial type, showed subtle increased signal intensity. all cases demonstrated high signal intensity on t2-weighted images. The signal intensity of peripheral wall was slightly increased on T1-weighted images, but low on T2-weighted. In four cases there was associated cellulitis, and in one case each, adjacent joint effusion and deep vein thrombosis were seen. After gadolinium infusion, peripheral rim enhancement was noted in nine cases and heterogeneous enhancement in one. After magnetic resonance imaging of infectious myositis, the characteristic finding was an abscessed lesion, with the peripheral wall showing high signal intensity on T1-weighted images and low signal intensity on T2 weighted. Although we found it difficult to differentiate bacterial from tuberculous

Magnetic resonance imaging of infectious myositis

International Nuclear Information System (INIS)

Yun, Ji Young; Kim, Jee Young; Kim, Sang Heum; Jung, Youn Ju; Cha, Eun Suk; Park, Joung Mi; Park, Young Ha

1998-01-01

To describe the findings of magnetic resonance imaging in infectious myositis and to determine their value for differentiation between ruberculous and bacterial myositis. Magnetic resonance images of ten proven cases of infectious myositis (five tuberculous and five bacterial) were retrospectively reviewed in the light of clinical and laboratory findings. On the basis of magnetic resonance images, signal intensity of the mass, the presence or absence of an abscess, signal intensity of the peripheral wall, patterns of contrast enhancement, and associated findings were evaluated. Compared with those of bacterial myositis, the symptoms of tuberculous myositis lasted longer but there were no difinite local inflammatory signs. In three of five cases of bacterial myositis there were specific medical records;trauma in two cases and systemic lupus erythematosus in one. All tuberculous myositis cases involved a single muscle, but bacterial myositis affected multipe muscles in three cases(60%). All but one case showed a mass in the involved muscles. In one bacterial case, there was diffuse swelling in the involved muscle. On T1-weighted images, eight infectious cases showed low signal intensity;two, of the bactrerial type, showed subtle increased signal intensity. all cases demonstrated high signal intensity on t2-weighted images. The signal intensity of peripheral wall was slightly increased on T1-weighted images, but low on T2-weighted. In four cases there was associated cellulitis, and in one case each, adjacent joint effusion and deep vein thrombosis were seen. After gadolinium infusion, peripheral rim enhancement was noted in nine cases and heterogeneous enhancement in one. After magnetic resonance imaging of infectious myositis, the characteristic finding was an abscessed lesion, with the peripheral wall showing high signal intensity on T1-weighted images and low signal intensity on T2 weighted. Although we found it difficult to differentiate bacterial from tuberculous

MR imaging of degenerative lumbar disc disease emphasizing on signal intensity changes in vertebral body

International Nuclear Information System (INIS)

Toyoda, Keiko; Ida, Masahiro; Murakami, Yoshitaka; Harada, Junta; Tada, Shimpei

1992-01-01

Magnetic resonance imaging was performed in 400 patients with degenerative disc disease. Signal changes and their sites in the vertebral body were classified and referred to narrowing of the intervertebral disc space. MR findings were compared with those of plain roentgenograms of the lumbar spine. Signal changes in the vertebral body were noted in 83 cases (102 vertebral bodies). Low-intensity abnormality on both T1- and T2-weighted images (WI) was the most common finding, and was most frequently seen at the end plate and/or the angle. These changes were correlated with narrowing of the disc space and osteosclerosis on the plain roentgenogram of the lumbar spine. Signal changes occasionally occurred in the inner region of the vertebral body, and these lesions tended to show a high-intensity abnormality on T1-WI. We conclude that signal changes in degenerative disc disease are not specific, but are sometimes difficult to distinguish from the signal changes in other conditions such as spinal tumor or bone marrow disorder. (author)

Appearance of low signal intensity lines in MRI of silicone breast implants.

Science.gov (United States)

Stroman, P W; Rolland, C; Dufour, M; Grondin, P; Guidoin, R G

1996-05-01

Magnetic resonance (MR) images of five explanted mammary prostheses were obtained with a 1.5 T GE Signa system using a conventional spin-echo pulse sequence, in order to investigate the low-intensity curvilinear lines which may be observed in MR images of silicone gel-filled breast implants under pressure from fibrous capsules. MR images showed ellipsoid prostheses, often containing multiple low-intensity curvilinear lines which in some cases presented an appearance very similar to that of the linguine sign. Upon opening the fibrous capsules, however, all of the prostheses were found to be completely intact demonstrating that the appearance of multiple low signal intensity curvilinear lines in MR images of silicone gel-filled prostheses is not necessarily a sign of prosthesis rupture. The MR image features which are specific to the linguine sign must be more precisely defined.

Investigation on phase noise of the signal from a singly resonant optical parametric oscillator

Science.gov (United States)

Jinxia, Feng; Yuanji, Li; Kuanshou, Zhang

2018-04-01

The phase noise of the signal from a singly resonant optical parametric oscillator (SRO) is investigated theoretically and experimentally. An SRO based on periodically poled lithium niobate is built up that generates the signal with a maximum power of 5.2 W at 1.5 µm. The intensity noise of the signal reaches the shot noise level for frequencies above 5 MHz. The phase noise of the signal oscillates depending on the analysis frequency, and there are phase noise peaks above the shot noise level at the peak frequencies. To explain the phase noise feature of the signal, a semi-classical theoretical model of SROs including the guided acoustic wave Brillouin scattering effect within the nonlinear crystal is developed. The theoretical predictions are in good agreement with the experimental results.

Improved stochastic resonance algorithm for enhancement of signal-to-noise ratio of high-performance liquid chromatographic signal

International Nuclear Information System (INIS)

Xie Shaofei; Xiang Bingren; Deng Haishan; Xiang Suyun; Lu Jun

2007-01-01

Based on the theory of stochastic resonance, an improved stochastic resonance algorithm with a new criterion for optimizing system parameters to enhance signal-to-noise ratio (SNR) of HPLC/UV chromatographic signal for trace analysis was presented in this study. Compared with the conventional criterion in stochastic resonance, the proposed one can ensure satisfactory SNR as well as good peak shape of chromatographic peak in output signal. Application of the criterion to experimental weak signals of HPLC/UV was investigated and the results showed an excellent quantitative relationship between different concentrations and responses

Observation of ferromagnetic resonance in a microscopic sample using magnetic resonance force microscopy

International Nuclear Information System (INIS)

Zhang, Z.; Hammel, P.C.; Wigen, P.E.

1996-01-01

We report the observation of a ferromagnetic resonance signal arising from a microscopic (∼20μmx40μm) particle of thin (3μm) yttrium iron garnet film using magnetic resonance force microscopy (MRFM). The large signal intensity in the resonance spectra suggests that MRFM could become a powerful microscopic ferromagnetic resonance technique with a micron or sub-micron resolution. We also observe a very strong nonresonance signal which occurs in the field regime where the sample magnetization readily reorients in response to the modulation of the magnetic field. This signal will be the main noise source in applications where a magnet is mounted on the cantilever. copyright 1996 American Institute of Physics

MR imaging of the biliary tract with Gd-EOB-DTPA: Effect of liver function on signal intensity

Energy Technology Data Exchange (ETDEWEB)

Takao, Hidemasa, E-mail: takaoh-tky@umin.ac.jp [Department of Radiology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan); Akai, Hiroyuki; Tajima, Taku [Department of Radiology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan); Kiryu, Shigeru [Department of Radiology, Institute of Medical Science, University of Tokyo, 74-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639 (Japan); Watanabe, Yasushi [Department of Radiological Technology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan); Imamura, Hiroshi [Department of Hepatobiliary-Pancreatic Surgery, Juntendo University School of Medicine, 3-1-3 Hongo, Bunkyo-ku, Tokyo 113-8431 (Japan); Akahane, Masaaki; Yoshioka, Naoki [Department of Radiology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan); Kokudo, Norihiro [Hepato-Biliary-Pancreatic Surgery Division, Department of Surgery, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan); Ohtomo, Kuni [Department of Radiology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan)

2011-02-15

Objective: To quantitatively evaluate the signal intensity of the biliary tract in gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance (MR) imaging and to investigate the effect of liver function on the signal intensity of the biliary tract. Materials and methods: A total of 32 patients with and without chronic liver disease (normal liver group, n = 15; chronic liver disease group, n = 17) were included in this study. All patients were prospectively enrolled for evaluation of known or suspected focal liver lesions. In the chronic liver disease group, the etiologies were chronic hepatitis C virus infection (n = 12) and chronic hepatitis B virus infection (n = 5). The median Child-Pugh score was 5 (range, 5-7). Each patient received the standard dose of Gd-EOB-DTPA (0.025 mmol/kg of body weight). Post-contrast T1-weighted MR images were obtained at 5, 10, 15, 20, 25, and 30 min after administration of Gd-EOB-DTPA. Maximum signal intensities (SIs) of the right and left hepatic ducts, common hepatic duct, and common bile duct were measured. Relative signal intensity was calculated as follows: relative SI = maximum SI{sub bileduct}/mean SI{sub muscle}. Serum albumin level, serum total bilirubin level, prothrombin time, indocyanine green retention rate at 15 min (ICG-R15), and estimated glomerular filtration rate were entered into regression analysis. Results: The signal intensity of the bile duct reached a peak 30 min after administration of Gd-EOB-DTPA. The mean relative signal intensity of the right and left hepatic ducts at the peak time point was not significantly different between the two groups, while increase in signal intensity was delayed in the chronic liver disease group. The mean relative signal intensity of the common hepatic duct and that of the common bile duct at the peak time point were significantly different between the two groups (Wilcoxon rank-sum test, P = 0.03, respectively). Stepwise regression

MR imaging of the biliary tract with Gd-EOB-DTPA: Effect of liver function on signal intensity

International Nuclear Information System (INIS)

Takao, Hidemasa; Akai, Hiroyuki; Tajima, Taku; Kiryu, Shigeru; Watanabe, Yasushi; Imamura, Hiroshi; Akahane, Masaaki; Yoshioka, Naoki; Kokudo, Norihiro; Ohtomo, Kuni

2011-01-01

Objective: To quantitatively evaluate the signal intensity of the biliary tract in gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance (MR) imaging and to investigate the effect of liver function on the signal intensity of the biliary tract. Materials and methods: A total of 32 patients with and without chronic liver disease (normal liver group, n = 15; chronic liver disease group, n = 17) were included in this study. All patients were prospectively enrolled for evaluation of known or suspected focal liver lesions. In the chronic liver disease group, the etiologies were chronic hepatitis C virus infection (n = 12) and chronic hepatitis B virus infection (n = 5). The median Child-Pugh score was 5 (range, 5-7). Each patient received the standard dose of Gd-EOB-DTPA (0.025 mmol/kg of body weight). Post-contrast T1-weighted MR images were obtained at 5, 10, 15, 20, 25, and 30 min after administration of Gd-EOB-DTPA. Maximum signal intensities (SIs) of the right and left hepatic ducts, common hepatic duct, and common bile duct were measured. Relative signal intensity was calculated as follows: relative SI = maximum SI bileduct /mean SI muscle . Serum albumin level, serum total bilirubin level, prothrombin time, indocyanine green retention rate at 15 min (ICG-R15), and estimated glomerular filtration rate were entered into regression analysis. Results: The signal intensity of the bile duct reached a peak 30 min after administration of Gd-EOB-DTPA. The mean relative signal intensity of the right and left hepatic ducts at the peak time point was not significantly different between the two groups, while increase in signal intensity was delayed in the chronic liver disease group. The mean relative signal intensity of the common hepatic duct and that of the common bile duct at the peak time point were significantly different between the two groups (Wilcoxon rank-sum test, P = 0.03, respectively). Stepwise regression analysis

Non-stationarity of resonance signals from magnetospheric and ionospheric plasmas

International Nuclear Information System (INIS)

Higel, Bernard

1975-01-01

Rocket observations of resonance signals from ionospheric plasma were made during EIDI relaxation sounding experiments. It appeared that their amplitude, phase, and frequency characteristics are not stationary as a function of the receipt time. The measurement of these nonstationary signals increases the interest presented by resonance phenomena in spatial plasma diagnostics, but this measurement is not easy for frequency non-stationarities. A new method, entirely numerical, is proposed for automatic recognition of these signals. It will be used for the selecting and real-time processing of signals of the same type to be observed during relaxation sounding experiments on board of the futur GEOS satellite. In this method a statistical discrimination is done on the values taken by several parameters associated with the non-stationarities of the observed resonance signals [fr

Bilateral Pulvinar Signal Intensity Decrease on T2-Weighted Images in Patients with Aspartylglucosaminuria

International Nuclear Information System (INIS)

Autti, T.; Loennqvist, T.; Joensuu, R.

2008-01-01

Background: Aspartylglucosaminuria (AGU) is an autosomal recessive lysosomal disease caused by deficiency of aspartylglucosaminidase. A thalamic T2 signal intensity decrease is associated with lysosomal diseases. Purpose: To investigate thalamic signal intensity in AGU by performing a retrospective review of brain magnetic resonance (MR) imaging studies of AGU patients. Material and Methods: A total of 25 MR examinations were available for 11 patients aged between 3 and 32 years (four patients underwent bone marrow transplantation). Of these, 13 examinations were performed after bone marrow transplantation. Five patients had from two to six examinations, and six patients had one examination each. In every patient, the diagnosis of AGU was confirmed by blood and urine tests. Eighteen examinations were performed with a 1.0T imager including dual spin-echo T2 and proton density (PD) axial and coronal images, and 10 examinations also included T1-weighted images. Seven examinations were performed with a 1.5T imager including turbo spin-echo axial and coronal T2-weighted images and axial fluid-attenuated inversion recovery (FLAIR) images; three examinations included T1-weighted three-dimensional magnetization-prepared rapid acquisition gradient-echo (3D MPRAGE) images. The signal intensity of the thalamus and pulvinar in every sequence was compared to that of the putamina. Results: In AGU, thalamic alterations were first detectable on T2-weighted images (25 examinations in 11 patients) from the age of 3 years 6 months, showing decreased signal intensity in 21 of 24 examinations. T1-weighted images (13 examinations) showed slightly increased thalamic signal intensity in five out of seven examinations from the age of 7 years, and PD images (19 examinations) showed decreased signal intensity from the age of 16 years (three examinations). The pulvinar showed decreased signal intensity on spin-echo T2-weighted images for 14 of 18 examinations or on FLAIR sequences for seven

Intensity and directionality of bat echolocation signals

DEFF Research Database (Denmark)

Jakobsen, Lasse; Brinkløv, Signe; Surlykke, Annemarie

2013-01-01

will increase signal directionality in the field along with intensity thus increasing sonar range. During the last phase of prey pursuit, vespertilionid bats broaden their echolocation beam considerably, probably to counter evasive maneuvers of eared prey. We highlight how multiple call parameters (frequency......The paper reviews current knowledge of intensity and directionality of bat echolocation signals. Recent studies have revealed that echolocating bats can be much louder than previously believed. Bats previously dubbed "whispering" can emit calls with source levels up to 110 dB SPL at 10 cm......, duration, intensity, and directionality of echolocation signals) in unison define the search volume probed by bats and in turn how bats perceive their surroundings. Small changes to individual parameters can, in combination, drastically change the bat's perception, facilitating successful navigation...

Orientation-dependent changes in MR signal intensity of articular cartilage: a manifestation of the ``magic angle`` effect

Energy Technology Data Exchange (ETDEWEB)

Wacker, F.K.; Bolze, X.; Felsenberg, D.; Wolf, K.J. [Department of Radiology, Benjamin Franklin University Hospital, Free University Berlin, D-12200 Berlin (Germany)

1998-06-01

Objective: To study magnetic resonance (MR) imaging pattern of normal hyaline articular cartilage in the knee joint with regard to the contribution of the ``magic angle`` effect to the MR signal. Design. Thirty-two healthy volunteers were imaged in a standard supine position in a 1.5-T unit using spin echo and gradient echo sequences. Nine volunteers were reimaged with the knee flexed. The signal behavior of the hyaline cartilage of the femoral condyles was evaluated qualitatively and quantitatively. The extended and flexed positions of the nine volunteers were compared. Results. A superficial and a deep hyperintense layer and a hypointense middle cartilage layer were observed. Segments of increased signal intensity were visible along the condyles; a magic angle effect on signal intensity was evident in the hypointense middle layer with both gradient echo and spin echo images. Conclusion. The MR signal behavior of hyaline cartilage is influenced by the alignment of the collagen fibers within the cartilage in relation to the magnetic field. Failure to recognize this effect may lead to inaccurate diagnosis. (orig.) With 4 figs., 17 refs.

Scaled signal intensity of uterine fibroids based on T2-weighted MR images: a potential objective method to determine the suitability for magnetic resonance-guided focused ultrasound surgery of uterine fibroids

Energy Technology Data Exchange (ETDEWEB)

Park, Hyun [CHA University, Comprehensive Gynecologic Cancer Center, CHA Bundang Medical Center, Gyunggi-do (Korea, Republic of); Yoon, Sang-Wook [CHA University, Department of Diagnostic Radiology, CHA Bundang Medical Center, Sungnam-si, Gyunggi-do (Korea, Republic of); Sokolov, Amit [InSightec Ltd., Haifa (Israel)

2015-12-15

Magnetic Resonance-guided Focused Ultrasound Surgery (MRgFUS) is a non-invasive method to treat uterine fibroids. To help determine the patient suitability for MRgFUS, we propose a new objective measure: the scaled signal intensity (SSI) of uterine fibroids in T2 weighted MR images (T2WI). Forty three uterine fibroids in 40 premenopausal women were included in this retrospective study. SSI of each fibroid was measured from the screening T2WI by standardizing its mean signal intensity to a 0-100 scale, using reference intensities of rectus abdominis muscle (0) and subcutaneous fat (100). Correlation between the SSI and the non-perfused volume (NPV) ratio (a measure for treatment success) was calculated. Pre-treatment SSI showed a significant inverse-correlation with post treatment NPV ratio (p < 0.05). When dichotomizing NPV ratio at 45 %, the optimal cut off value of the SSI was found to be 16.0. A fibroid with SSI value 16.0 or less can be expected to have optimal responses. The SSI of uterine fibroids in T2WI can be suggested as an objective parameter to help in patient selection for MRgFUS. (orig.)

Response of resonant gravitational wave detectors to damped sinusoid signals

International Nuclear Information System (INIS)

Pai, A; Celsi, C; Pallottino, G V; D'Antonio, S; Astone, P

2007-01-01

Till date, the search for burst signals with resonant gravitational wave (GW) detectors has been done using the δ-function approximation for the signal, which was reasonable due to the very small bandwidth of these detectors. However, now with increased bandwidth (of the order of 10 or more Hz) and with the possibility of comparing results with interferometric GW detectors (broad-band), it is very important to exploit the resonant detectors' capability to detect also signals with specific wave shapes. As a first step, we present a study of the response of resonant GW detectors to damped sinusoids with given frequency and decay time and report on the development of a filter matched to these signals. This study is a preliminary step towards the comprehension of the detector response and of the filtering for signals such as the excitation of stellar quasi-normal modes

Unusual Presentation of Popliteal Cyst on Magnetic Resonance Imaging

Directory of Open Access Journals (Sweden)

Tsuyoshi Ohishi

2016-01-01

Full Text Available Popliteal cyst commonly presents as an ellipsoid mass with uniform low signal intensity on T1-weighted magnetic resonance images and high signal intensity on T2-weighted images. Here, we describe a popliteal cyst with unusual appearance on magnetic resonance imaging, including heterogeneous intermediate signal intensity on T2-weighted images. Arthroscopic cyst decompression revealed that the cyst was filled with necrotic synovial villi, indicative of rheumatoid arthritis. Arthroscopic enlargement of unidirectional valvular slits with synovectomy was useful for the final diagnosis and treatment.

Correlation between neurohypophyseal vasopressin content and signal intensity on T1-weighted magnetic resonance images. An experimental study of vasopressin depletion model using dehydrated rabbits

International Nuclear Information System (INIS)

Kurokawa, Hiroaki; Nakano, Yoshihisa; Ikeda, Koshi; Tanaka, Yoshimasa; Fujisawa, Ichiro

1998-01-01

We investigated the correlation between the signal intensity on T 1 -weighted MR images and vasopressin (VP) content in the posterior pituitary lobe. Fourteen rabbits were studied. There were 12 water-deprived rabbits (48, 72, 96, 120, 144 and 168 hours: 2 each) and 2 controls. Sagittal T 1 -weighted SE (spin-echo) MR images were obtained before and after dehydration. The signal intensity ratio of the posterior pituitary lobe to the pons was correlated with the VP content in the posterior lobe as measured by radioimmunoassay. Before water deprivation, high signal intensity in the posterior lobe was demonstrated clearly in all 14 rabbits. After water deprivation, the hyperintense signal gradually decreased and became indistinguishable from anterior lobe in four animals. The mean signal intensity ratio before water deprivation was 1.55±0.12 (mean±SD) and after water deprivation, gradually decreased over time and reached to 1.19 after 168 hours of water deprivation. Pituitary VP content and concentration decreased in parallel with the signal intensity ratio of the posterior pituitary. Significantly correlation was observed between the signal intensity ratio and VP concentration of posterior pituitary (r=0.809, p 1 -weighted image may reflect a indicator of pituitary VP content and thus may enable evaluation of disorders of water metabolism. (author)

Correlation between neurohypophyseal vasopressin content and signal intensity on T{sub 1}-weighted magnetic resonance images. An experimental study of vasopressin depletion model using dehydrated rabbits

Energy Technology Data Exchange (ETDEWEB)

Kurokawa, Hiroaki; Nakano, Yoshihisa; Ikeda, Koshi; Tanaka, Yoshimasa [Kansai Medical Univ., Moriguchi, Osaka (Japan); Fujisawa, Ichiro

1998-06-01

We investigated the correlation between the signal intensity on T{sub 1}-weighted MR images and vasopressin (VP) content in the posterior pituitary lobe. Fourteen rabbits were studied. There were 12 water-deprived rabbits (48, 72, 96, 120, 144 and 168 hours: 2 each) and 2 controls. Sagittal T{sub 1}-weighted SE (spin-echo) MR images were obtained before and after dehydration. The signal intensity ratio of the posterior pituitary lobe to the pons was correlated with the VP content in the posterior lobe as measured by radioimmunoassay. Before water deprivation, high signal intensity in the posterior lobe was demonstrated clearly in all 14 rabbits. After water deprivation, the hyperintense signal gradually decreased and became indistinguishable from anterior lobe in four animals. The mean signal intensity ratio before water deprivation was 1.55{+-}0.12 (mean{+-}SD) and after water deprivation, gradually decreased over time and reached to 1.19 after 168 hours of water deprivation. Pituitary VP content and concentration decreased in parallel with the signal intensity ratio of the posterior pituitary. Significantly correlation was observed between the signal intensity ratio and VP concentration of posterior pituitary (r=0.809, p<0.001) . In conclusion, the results indicate that the signal intensity ratio on T{sub 1}-weighted image may reflect a indicator of pituitary VP content and thus may enable evaluation of disorders of water metabolism. (author)

Universal and local time components in Schumann resonance intensity

Directory of Open Access Journals (Sweden)

A. P. Nickolaenko

2008-05-01

Full Text Available We extend the technique suggested by Sentman and Fraser (1991 and discussed by Pechony and Price (2006, the technique for separating the local and universal time variations in the Schumann resonance intensity. Initially, we simulate the resonance oscillations in a uniform Earth-ionosphere cavity with the distribution of lightning strokes based on the OTD satellite data. Different field components were used in the Dayside source model for the Moshiri (Japan, geographic coordinates: 44.365° N, 142.24° E and Lehta (Karelia, Russia, 64.427° N, 33.974° E observatories. We use the extended Fourier series for obtaining the modulating functions. Simulations show that the algorithm evaluates the impact of the source proximity in the resonance intensity. Our major goal was in estimating the universal alteration factors, which reflect changes in the global thunderstorm activity. It was achieved by compensating the local factors present in the initial data. The technique is introduced with the model Schumann resonance data and afterwards we use the long-term experimental records at the above sites for obtaining the diurnal/monthly variations of the global thunderstorms.

Magnetic resonance signal moment determination using the Earth's magnetic field

KAUST Repository

Fridjonsson, Einar Orn; Creber, Sarah A.; Vrouwenvelder, Johannes S.; Johns, Michael L.

2015-01-01

We demonstrate a method to manipulate magnetic resonance data such that the moments of the signal spatial distribution are readily accessible. Usually, magnetic resonance imaging relies on data acquired in so-called k-space which is subsequently Fourier transformed to render an image. Here, via analysis of the complex signal in the vicinity of the centre of k-space we are able to access the first three moments of the signal spatial distribution, ultimately in multiple directions. This is demonstrated for biofouling of a reverse osmosis (RO) membrane module, rendering unique information and an early warning of the onset of fouling. The analysis is particularly applicable for the use of mobile magnetic resonance spectrometers; here we demonstrate it using an Earth's magnetic field system.

Magnetic resonance signal moment determination using the Earth's magnetic field

KAUST Repository

Fridjonsson, Einar Orn

2015-03-01

We demonstrate a method to manipulate magnetic resonance data such that the moments of the signal spatial distribution are readily accessible. Usually, magnetic resonance imaging relies on data acquired in so-called k-space which is subsequently Fourier transformed to render an image. Here, via analysis of the complex signal in the vicinity of the centre of k-space we are able to access the first three moments of the signal spatial distribution, ultimately in multiple directions. This is demonstrated for biofouling of a reverse osmosis (RO) membrane module, rendering unique information and an early warning of the onset of fouling. The analysis is particularly applicable for the use of mobile magnetic resonance spectrometers; here we demonstrate it using an Earth\\'s magnetic field system.

Evaluation of signal intensity of various thyroid tissues on MR imaging

Energy Technology Data Exchange (ETDEWEB)

Baba, Koichiro; Imanishi, Yoshimasa [St. Marianna Univ., Kawasaki, Kanagawa (Japan). School of Medicine; Igarashi, Ryuukou; Shinagawa, Toshihito

2001-08-01

Although normal thyroid mainly consists of thyroid follicles and has large amount of water in them, it shows low signal intensity on T2 weighted MR image. In this paper, we analysed the signal intensity of the thyroid in clinical cases and investigated the relationship between signal intensity and iodine concentration. In forty-one patients who have clinically suspected thyroid diseases, fifty-three MRI examinations of the neck and forty-three thyroid CT examinations were performed. The MR imaging of the neck was performed with T1 weighted image, T2 weighted image, and STIR image. Iodine concentration of the thyroid was measured by the CT software which was originally made by one of the authors (Y.I.). The signal intensity on T2 weighted image negatively correlated with iodine concentration, although there was no relationship between iodine concentration and its signal intensity on T1 weighted image. On T2 weighted image, the intensity of thyroid with high iodine concentration showed a low signal and that of thyroid with low iodine concentration presented a high signal. The thyroid with chronic thyroiditis showed higher signal intensity than normal thyroid and adenmatous goiter on T2 weighted image and STIR image. On T2 weighted image and STIR image, the signal intensity of any thyroid nodules were higher than that of normal thyroid. In addition, follicular adenoma and partially malignant nodules showed a higher signal intensity than thyroid carcinomas. According to previous reports, decreased iodine concentration in thyroid follicles represents decreased concentration of iodine-binding proteins in follicles as well as decreased volume of follicular content in the thyroid. On MR imaging, very high concentration of protein in water solution does not only cause shortening of T1 relaxation time but also shortening of T2 relaxation time resulting in low signal intensity. In the present study, our data seem to suggest that very high concentration of iodine

Evaluation of signal intensity of various thyroid tissues on MR imaging

International Nuclear Information System (INIS)

Baba, Koichiro; Imanishi, Yoshimasa; Igarashi, Ryuukou; Shinagawa, Toshihito

2001-01-01

Although normal thyroid mainly consists of thyroid follicles and has large amount of water in them, it shows low signal intensity on T2 weighted MR image. In this paper, we analysed the signal intensity of the thyroid in clinical cases and investigated the relationship between signal intensity and iodine concentration. In forty-one patients who have clinically suspected thyroid diseases, fifty-three MRI examinations of the neck and forty-three thyroid CT examinations were performed. The MR imaging of the neck was performed with T1 weighted image, T2 weighted image, and STIR image. Iodine concentration of the thyroid was measured by the CT software which was originally made by one of the authors (Y.I.). The signal intensity on T2 weighted image negatively correlated with iodine concentration, although there was no relationship between iodine concentration and its signal intensity on T1 weighted image. On T2 weighted image, the intensity of thyroid with high iodine concentration showed a low signal and that of thyroid with low iodine concentration presented a high signal. The thyroid with chronic thyroiditis showed higher signal intensity than normal thyroid and adenmatous goiter on T2 weighted image and STIR image. On T2 weighted image and STIR image, the signal intensity of any thyroid nodules were higher than that of normal thyroid. In addition, follicular adenoma and partially malignant nodules showed a higher signal intensity than thyroid carcinomas. According to previous reports, decreased iodine concentration in thyroid follicles represents decreased concentration of iodine-binding proteins in follicles as well as decreased volume of follicular content in the thyroid. On MR imaging, very high concentration of protein in water solution does not only cause shortening of T1 relaxation time but also shortening of T2 relaxation time resulting in low signal intensity. In the present study, our data seem to suggest that very high concentration of iodine

Signal intensity enhancement of laser ablated volume holograms

Science.gov (United States)

Versnel, J. M.; Williams, C.; Davidson, C. A. B.; Wilkinson, T. D.; Lowe, C. R.

2017-11-01

Conventional volume holographic gratings (VHGs) fabricated in photosensitive emulsions such as gelatin containing silver salts enable the facile visualization of the holographic image in ambient lighting. However, for the fabrication of holographic sensors, which require more defined and chemically-functionalised polymer matrices, laser ablation has been introduced to create the VHGs and thereby broaden their applications, although the replay signal can be challenging to detect in ambient lighting. When traditional photochemical bleaching solutions used to reduce light scattering and modulate refractive index within the VHG are applied to laser ablated volume holographic gratings, these procedures decrease the holographic peak intensity. This is postulated to occur because both light and dark fringes contain a proportion of metal particles, which upon solubilisation are converted immediately to silver iodide, yielding no net refractive index modulation. This research advances a hypothesis that the reduced intensity of holographic replay signals is linked to a gradient of different sized metal particles within the emulsion, which reduces the holographic signal and may explain why traditional bleaching processes result in a reduction in intensity. In this report, a novel experimental protocol is provided, along with simulations based on an effective medium periodic 1D stack, that offers a solution to increase peak signal intensity of holographic sensors by greater than 200%. Nitric acid is used to etch the silver nanoparticles within the polymer matrix and is thought to remove the smaller particles to generate more defined metal fringes containing a soluble metal salt. Once the grating efficiency has been increased, this salt can be converted to a silver halide, to modulate the refractive index and increase the intensity of the holographic signal. This new protocol has been tested in a range of polymer chemistries; those containing functional groups that help to

MRI of the normal brain from early childhood to middle age. Pt. 2. Age dependence of signal intensity changes on T2-weighted images

International Nuclear Information System (INIS)

Autti, T.; Raininko, R.; Vanhanen, S.L.; Kallio, M.; Santavuori, P.

1994-01-01

We examined 66 healthy volunteers aged 4 to 50 years by magnetic resonance imaging (MRI) and the signal intensity was measured on T2-weighted images in numerous sites and correlated with age and sex. Using distilled water and cerebrospinal fluid (CSF) as references on each slice, we calculated the signal intensities of the brain structures. Calculated ratios between structures did not change with age, except for those of the globus pallidus and thalamus, in which the signal intensities decreased more rapidly. The signal intensities of other brain structures changed equally but this could not be discerned visually and quantitative measurements were required. The signal intensities in the white and deep grey matter decreased rapidly in the first decade and then gradually to reach a plateau after the age of 18 years. Maturation of the brain thus seems to continue until near the end of the second decade of life. No sex differences were found. Quantitative analysis requires intensity references. The CSF in the tips of the frontal horns seems to be as reliable as an external fluid reference for intensity, and can be used in routine examinations provided the frontal horns are large enough to avoid partial volume effect. (orig.)

Fast storage of nuclear quadrupole resonance signals

International Nuclear Information System (INIS)

Anferov, V.P.; Molchanov, S.V.; Levchun, O.D.

1988-01-01

Fast multichannel storage of nuclear quadrupole resonance (NQR) signals is described. Analog-to-digital converter, arithmetic-logical unit, internal memory device (IMD) selection-storage unit and control unit are the storage main units. The storage is based on 43 microcircuits and provides for record and storage of NQR-signals at the contributed operation with Mera-60 microcomputer. Time of analog-to-digital conversion and signal recording into IMD is ∼ 1 mks. Capacity of analog-to-digital converter constitutes 8-10 bits. IMD capacity is 4 K bitsx16. Number of storage channels is 4

A study on CT attenuation and MR signal intensity of protein solution

International Nuclear Information System (INIS)

Kim, Joung Hae; Choi, Dae Seob; Kim, Soon; Lee, Hyeon Kyeong; Oh, Hyeon Hee; Kim, Seung Hyeon; Lee, Sung Woo; Chang, Kee Hyun; Chung, Jun Ho

2001-01-01

To correlate CT attenuation and MR signal intensity with concentration of protein solution. CT and MR examinations of a phantom containing bovine serum albumin solutions of various concentrations ranging from 0 to 55% were performed. CT Hounsfield units(HUs), MR signal intensities, and apparent diffusion coefficients (ADCs) of each albumin solution were measured, and CT HUs and MR signal intensities of the solutions were compared with those of cerebrospinal fluid (CSF), white matter, and cortical gray matter. CT HU increased gradually with increasing albumin concentration. On T1-weighted images(T1WI), signal intensity increased with increasing albumin concentrations of up to 35% but then decreased. On T2-weighted images(T2Wl), gradually decreasing signal intensity and increasing albumin concentration were observed Fluid-attenuated inversion recovery (FLAIR) and diffusion-weighted images (DWls) showed that signal intensity peaked at a concentration of 10% and then gradually decreased. The ADC of the solution gradually decreased as concentration increased. Compared with those of normal brain structures, the CT HUs of solutions at concentrations of over 20% were higher than those of white and gray matter. At T1WI, the signal intensities of 10-45% solutions were similar to or higher than that of the gray matter. At T2Wl, the signal intensities of solutions above 25, 35, and 40% were lower than those of CSF, gray matter, and white matter, respectively. FLAIR images showed that the signal intensities of 5-35% solutions were higher than that of gray matter. The CT attenuation of albumin solution increased gradually with increasing concentration. MR signal intensities peaked at 35% concentration on T1WI and at 10% on FLAIR and DW images, respectively, and then gradually decreased. T2Wl and ADC map images showed gradually decreasing signal intensity and ADC as albumin concentration increased

Experimental study of intense radiation in terahertz region based on cylindrical surface wave resonator

International Nuclear Information System (INIS)

Gong, Shaoyan; Ogura, Kazuo; Yambe, Kiyoyuki; Nomizu, Shintaro; Shirai, Akihiro; Yamazaki, Kosuke; Kawamura, Jun; Miura, Takuro; Takanashi, Sho; San, Min Thu

2015-01-01

Periodical corrugations structured on a cylindrical conductor have cylindrical surface waves (CSWs), which are reflected at the corrugation ends and form a CSW-resonator. In this paper, intense radiations in terahertz region based on the CSW-resonator are reported. The CSW-resonators with upper cut off frequencies in the modern IEEE G-band (110–300 GHz) are excited by a coaxially injected annular beam in a weakly relativistic region less than 100 kV. It is shown that there exists an oscillation starting energy for the CSW-resonator. Above the starting energy, very intense terahertz radiations on the order of kW are obtained. The operation frequencies in the range of 166–173 GHz and 182–200 GHz are obtained using two types of CSW-resonator with the different corrugation amplitude. Electromagnetic properties of the CSW-resonator can be controlled by the artificial structure and may play an important role in high-intensity terahertz generations and applications

Proton nuclear magnetic resonance imaging of regionally ischemic canine hearts: effects of paramagnetic proton signal enhancement

International Nuclear Information System (INIS)

Brady, T.J.; Goldman, M.R.; Pykett, I.L.; Buonanno, F.S.; Kistler, J.P.; Newhouse, J.H.; Burt, C.T.; Hinshaw, W.S.; Pohost, G.M.

1982-01-01

In a study to evaluate the potential of proton nuclear magnetic resonance (NMR) imaging with and without manganese contrast enhancement for detecting acute myocardial infarction, 12 dogs underwent 90-minute occlusion of the left circumflex coronary artery. Transverse-section NMR images of the excised, nonbeating heart were obtained at 1-cm intervals using the steady-state-free-precession (SSFP) technique. All NMR images revealed detailed structure of the heart. The three hearts without manganese showed no difference in intensity between the normal and the ischemic posterior regions, whereas those with manganese demonstrated a clearly demarcated zone of reduced signal intensity consistent with the ischemic zone. It is concluded that high-resolution tomograms of the excised canine myocardium can be obtained using proton NMR imaging. With the SSFP imaging technique, proton signal enhancement with manganese infusion is necessary to differentiate between ischemic and nonischemic myocardium after 90 minutes of coronary occlusion

A paradoxical signal intensity increase in fatty livers using opposed-phase gradient echo imaging with fat-suppression pulses

International Nuclear Information System (INIS)

Mulkern, Robert V.; Voss, Stephan; Loeb Salsberg, Sandra; Krauel, Marta Ramon; Ludwig, David S.

2008-01-01

With the increase in obese and overweight children, nonalcoholic fatty liver disease has become more prevalent in the pediatric population. Appreciating subtleties of magnetic resonance (MR) signal intensity behavior from fatty livers under different imaging conditions thus becomes important to pediatric radiologists. We report an initially confusing signal behavior - increased signal from fatty livers when fat-suppression pulses are applied in an opposed-phase gradient echo imaging sequence - and seek to explain the physical mechanisms for this paradoxical signal intensity behavior. Abdominal MR imaging at 3 T with a 3-D volumetric interpolated breath-hold (VIBE) sequence in the opposed-phase condition (TR/TE 3.3/1.3 ms) was performed in five obese boys (14±2 years of age, body mass index >95th percentile for age and sex) with spectroscopically confirmed fatty livers. Two VIBE acquisitions were performed, one with and one without the use of chemical shift selective (CHESS) pulse fat suppression. The ratios of fat-suppressed over non-fat-suppressed signal intensities were assessed in regions-of-interest (ROIs) in five tissues: subcutaneous fat, liver, vertebral marrow, muscle and spleen. The boys had spectroscopically estimated hepatic fat levels between 17% and 48%. CHESS pulse fat suppression decreased subcutaneous fat signals dramatically, by more than 85% within regions of optimal fat suppression. Fatty liver signals, in contrast, were elevated by an average of 87% with CHESS pulse fat suppression. Vertebral marrow signal was also significantly elevated with CHESS pulse fat suppression, while spleen and muscle signals demonstrated only small signal increases on the order of 10%. We demonstrated that CHESS pulse fat suppression actually increases the signal intensity from fatty livers in opposed-phase gradient echo imaging conditions. The increase can be attributed to suppression of one partner of the opposed-phase pair that normally contributes to the

A paradoxical signal intensity increase in fatty livers using opposed-phase gradient echo imaging with fat-suppression pulses

Energy Technology Data Exchange (ETDEWEB)

Mulkern, Robert V.; Voss, Stephan [Harvard Medical School, Department of Radiology, Children' s Hospital Boston, Boston, MA (United States); Loeb Salsberg, Sandra; Krauel, Marta Ramon; Ludwig, David S. [Harvard Medical School, Department of Medicine, Children' s Hospital Boston, Boston, MA (United States)

2008-10-15

With the increase in obese and overweight children, nonalcoholic fatty liver disease has become more prevalent in the pediatric population. Appreciating subtleties of magnetic resonance (MR) signal intensity behavior from fatty livers under different imaging conditions thus becomes important to pediatric radiologists. We report an initially confusing signal behavior - increased signal from fatty livers when fat-suppression pulses are applied in an opposed-phase gradient echo imaging sequence - and seek to explain the physical mechanisms for this paradoxical signal intensity behavior. Abdominal MR imaging at 3 T with a 3-D volumetric interpolated breath-hold (VIBE) sequence in the opposed-phase condition (TR/TE 3.3/1.3 ms) was performed in five obese boys (14{+-}2 years of age, body mass index >95th percentile for age and sex) with spectroscopically confirmed fatty livers. Two VIBE acquisitions were performed, one with and one without the use of chemical shift selective (CHESS) pulse fat suppression. The ratios of fat-suppressed over non-fat-suppressed signal intensities were assessed in regions-of-interest (ROIs) in five tissues: subcutaneous fat, liver, vertebral marrow, muscle and spleen. The boys had spectroscopically estimated hepatic fat levels between 17% and 48%. CHESS pulse fat suppression decreased subcutaneous fat signals dramatically, by more than 85% within regions of optimal fat suppression. Fatty liver signals, in contrast, were elevated by an average of 87% with CHESS pulse fat suppression. Vertebral marrow signal was also significantly elevated with CHESS pulse fat suppression, while spleen and muscle signals demonstrated only small signal increases on the order of 10%. We demonstrated that CHESS pulse fat suppression actually increases the signal intensity from fatty livers in opposed-phase gradient echo imaging conditions. The increase can be attributed to suppression of one partner of the opposed-phase pair that normally contributes to the

Stochastic resonance in multi-stable coupled systems driven by two driving signals

Science.gov (United States)

Xu, Pengfei; Jin, Yanfei

2018-02-01

The stochastic resonance (SR) in multi-stable coupled systems subjected to Gaussian white noises and two different driving signals is investigated in this paper. Using the adiabatic approximation and the perturbation method, the coupled systems with four-well potential are transformed into the master equations and the amplitude of the response is obtained. The signal-to-noise ratio (SNR) is calculated numerically to demonstrate the occurrence of SR. For the case of two driving signals with different amplitudes, the interwell resonance between two wells S1 and S3 emerges for strong coupling. The SR can appear in the subsystem with weaker signal amplitude or even without driving signal with the help of coupling. For the case of two driving signals with different frequencies, the effects of SR in two subsystems driven by high and low frequency signals are both weakened with an increase in coupling strength. The stochastic multi-resonance phenomenon is observed in the subsystem subjected to the low frequency signal. Moreover, an effective scheme for phase suppressing SR is proposed by using a relative phase between two driving signals.

Estimation of signal intensity for online measurement X-ray pinhole camera

International Nuclear Information System (INIS)

Dong Jianjun; Liu Shenye; Yang Guohong; Yu Yanning

2009-01-01

The signal intensity was estimated for on-line measurement X-ray pinhole camera with CCD as measurement equipment. The X-ray signal intensity counts after the attenuation of thickness-varied Be filters and different material flat mirrors respectively were estimated using the energy spectrum of certain laser prototype and the quantum efficiency curve of PI-SX1300 CCD camera. The calculated results indicate that Be filters no thicker than 200 μm can only reduce signal intensity by one order of magnitude, and so can Au flat mirror with 3 degree incident angle, Ni, C and Si flat mirrors with 5 degree incident angle,but the signal intensity counts for both attenuation methods are beyond the saturation counts of the CCD camera. We also calculated the attenuation of signal intensity for different thickness Be filters combined with flat mirrors, indicates that the combination of Be filters with the thickness between 20 and 40 μm and Au flat mirror with 3 degree incident angle or Ni flat mirror with 5 degree incident angle is a good choice for the attenuation of signal intensity. (authors)

Moderate plasma treatment enhances the quality of optically detected magnetic resonance signals of nitrogen-vacancy centres in nanodiamonds

Science.gov (United States)

Sotoma, Shingo; Igarashi, Ryuji; Shirakawa, Masahiro

2016-05-01

We demonstrate that a moderate plasma treatment increases the quality of optically detected magnetic resonance (ODMR) signals from negatively charged nitrogen-vacancy centres in nanodiamonds (NDs). We measured the statistics of the ODMR spectra of 50-nm-size NDs before and after plasma treatment. We then evaluated each ODMR spectrum in terms of fluorescence and ODMR intensities, line width and signal-to-noise (SN) ratio. Our results showed that plasma treatment for more than 10 min contributes to higher-quality ODMR signals, i.e. signals that are brighter, stronger, sharper and have a higher SN ratio. We showed that such signal improvement is due to alteration of the surface chemical states of the NDs by the plasma treatment. Our study contributes to the advancement of biosensing applications using ODMR of NDs.

Self-resonant wakefield excitation by intense laser pulse in plasmas

International Nuclear Information System (INIS)

Andreev, N.E.; Pogosova, A.A.; Gorbunov, L.M.; Ramazashvili, R.R.; Kirsanov, V.I.

1993-01-01

It is demonstrated by theoretical analysis and numerical calculations that in an underdense plasma the process of three-dimensional evolution of the short and strong laser pulse (with duration equal to several plasma periods) leads to compression and self-modulation of the pulse, so that during a fairly long period of time beats of pulse amplitude generates resonantly a strong and stable plasma wakefield. The intensity of the wake-field is so high that it can provide a new promising outlook for the plasma based accelerator concept. Linear analysis of dispersion relation predicts that taking into account transverse component of wavenumber considerably increases the growth rate of resonance instability of the pulse. The numerical simulations demonstrate that considered self-focusing and resonant-modulation instability are essentially three dimensional processes. Laser field evolution in each transverse cross section of the pulse is synchronized by the regular structure of plasma wave that is excited by the pulse. The considered effect of resonant modulation has a threshold. For the pulses with the intensity below the threshold the refraction dominates and no modulation appears. The studied phenomenon can be referred to as the Self-Resonant Wakefield (SRWF) excitation that is driven by self-focusing and self-modulation of laser pulse with quite a moderate initial duration. In fact, this method of excitation differs from both suggested in Ref.1 (PBWA) and in Refs.2,3 (LWFA), being even more than the combination of these concepts. Unlike the first scheme it does not require initially the two-frequency laser pulse, since the modulation here appears in the most natural way due to evolution of the pulse. In contrast with the LWFA, the considered SRWF generation scheme gives the possibility to raise the intensity of wake-excitation due to pulse self-focusing ( initial stage) and self modulation (second stage)

Signal intensity at unenhanced T1-weighted magnetic resonance in the globus pallidus and dentate nucleus after serial administrations of a macrocyclic gadolinium-based contrast agent in children

Energy Technology Data Exchange (ETDEWEB)

Rossi Espagnet, Maria Camilla; Bernardi, Bruno; Figa-Talamanca, Lorenzo [Ospedale Pediatrico Bambino Gesu, IRCCS, Neuroradiology Unit, Imaging Department, Rome (Italy); Pasquini, Luca [Ospedale Pediatrico Bambino Gesu, IRCCS, Neuroradiology Unit, Imaging Department, Rome (Italy); University Sapienza, Neuroradiology Unit, Azienda Ospedaliera Sant' Andrea, Rome (Italy); Toma, Paolo [Ospedale Pediatrico Bambino Gesu, IRCCS, Department of Imaging, Rome (Italy); Napolitano, Antonio [Ospedale Pediatrico Bambino Gesu, IRCCS, Enterprise Risk Management, Medical Physics Department, Rome (Italy)

2017-09-15

Few studies have been conducted on the relations between T1-weighted signal intensity changes in the pediatric brain following gadolinium-based contrast agent (GBCA) exposure. The purpose of this study is to investigate the effect of multiple administrations of a macrocyclic GBCA on signal intensity in the globus pallidus and dentate nucleus of the pediatric brain on unenhanced T1-weighted MR images. This retrospective study included 50 patients, mean age: 8 years (standard deviation: 4.8 years), with normal renal function exposed to ≥6 administrations of the same macrocyclic GBCA (gadoterate meglumine) and a control group of 59 age-matched GBCA-naive patients. The globus pallidus-to-thalamus signal intensity ratio and dentate nucleus-to-pons signal intensity ratio were calculated from unenhanced T1-weighted images for both patients and controls. A mixed linear model was used to evaluate the effects on signal intensity ratios of the number of GBCA administrations, the time interval between administrations, age, radiotherapy and chemotherapy. T-test analyses were performed to compare signal intensity ratio differences between successive administrations and baseline MR signal intensity ratios in patients compared to controls. P-values were considered significant if <0.05. A significant effect of the number of GBCA administrations on relative signal intensities globus pallidus-to-thalamus (F[8]=3.09; P=0.002) and dentate nucleus-to-pons (F[8]=2.36; P=0.021) was found. The relative signal intensities were higher at last MR examination than at baseline (P<0.001). Quantitative analysis evaluation of globus pallidus:thalamus and dentate nucleus:pons of the pediatric brain demonstrated an increase after serial administrations of macrocyclic GBCA. Further research is necessary to fully understand GBCA pharmacokinetic in children. (orig.)

High signal intensity of fat on fast spin echo imaging

International Nuclear Information System (INIS)

Ogura, Akio; Yamazaki, Masaru; Hongoh, Takaharu; Inoue, Hiroshi; Ishikuro, Akihiro

2000-01-01

The fast spin echo (FSE) technique of producing T 2 -weighted images in greatly reduced imaging times has recently been used for routine clinical study. FSE images show contrast that is very similar in most tissues to that of conventional SE images. However, fat shows a high signal intensity that is influenced by j-coupling and the magnetization transfer effect. The purpose of this study was to assess whether the higher signal intensity of fat is different among MRI systems and to examine the effects of j-coupling and magnetization transfer on the high signal intensity of fat on FSE. The contrast in signal intensity between fat and water was measured for various echo train lengths (ETL) with and without multislicing on FSE using a contrast phantom. Measurements were obtained with four different MRI systems. In addition, the effective T 2 values of fat were calculated for the above conditions. Results indicated that contrast for fat and water was reduced with increased ETL and by using multislicing and was different among the four MRI systems. The effective T 2 values of fat were extended for increased ETL and were not dependent on multislicing. They also differed among the four MRI systems. The extent of effective T 2 values was affected by j-coupling. In this study, it was indicated that the degree of the high signal intensity of fat on FSE differed for different MRI systems. In addition, the reasons for the high signal intensity of fat on FSE were related to the effects of j-coupling and magnetization transfer. (author)

Control of stochastic resonance in bistable systems by using periodic signals

International Nuclear Information System (INIS)

Min, Lin; Li-Min, Fang; Yong-Jun, Zheng

2009-01-01

According to the characteristic structure of double wells in bistable systems, this paper analyses stochastic fluctuations in the single potential well and probability transitions between the two potential wells and proposes a method of controlling stochastic resonance by using a periodic signal. Results of theoretical analysis and numerical simulation show that the phenomenon of stochastic resonance happens when the time scales of the periodic signal and the noise-induced probability transitions between the two potential wells achieve stochastic synchronization. By adding a bistable system with a controllable periodic signal, fluctuations in the single potential well can be effectively controlled, thus affecting the probability transitions between the two potential wells. In this way, an effective control can be achieved which allows one to either enhance or realize stochastic resonance

Preliminary study on electron paramagnetic resonance (EPR) signal properties of mobile phone components for dose estimation in radiation accident

Energy Technology Data Exchange (ETDEWEB)

Park, Byeong Ryong; Ha, Wi Ho; Park, Sun Hoo; Lee, Jin Kyeong; Lee, Seung Sook [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)

2015-12-15

We have investigated the EPR signal properties in 12 components of two mobile phones (LCD, OLED) using electron paramagnetic resonance (EPR) spectrometer in this study.EPR measurements were performed at normal atmospheric conditions using Bruker EXEXSYS-II E500 spectrometer with X-band bridge, and samples were irradiated by {sup 137}C{sub s} gamma-ray source. To identify the presence of radiation-induced signal (RIS), the EPR spectra of each sample were measured unirradiated and irradiated at 50 Gy. Then, dose-response curve and signal intensity variating by time after irradiation were measured. As a result, the signal intensity increased after irradiation in all samples except the USIM plastic and IC chip. Among the samples, cover glass(CG), lens, light guide plate(LGP) and diffusion sheet have shown fine linearity (R{sup 2} > 0.99). Especially, the LGP had ideal characteristics for dosimetry because there were no signal in 0 Gy and high rate of increase in RIS. However, this sample showed weakness in fading. Signal intensity of LGP and Diffusion Sheet decreased by 50% within 72 hours after irradiation, while signals of Cover Glass and Lens were stably preserved during the short period of time. In order to apply rapidly EPR dosimetry using mobile phone components in large-scale radiation accidents, further studies on signal differences for same components of the different mobile phone, fading, pretreatment of samples and processing of background signal are needed. However, it will be possible to do dosimetry by dose-additive method or comparative method using unirradiated same product in small-scale accident.

A study on magnetic relaxation times of various organs and body fluids using superconducting magnetic resonance imaging system part I: measurement of relative signal intensity and T2 relaxation time in various portions of brain and cerebrospinal fluid

International Nuclear Information System (INIS)

Chang, Kee Hyun; Lee, Ghi Jai; Han, Moon Hee; Kim, Jae Ho; Han, Man Chang; Kim, Chu Wan

1988-01-01

This study was undertake to determine if routine clinical magnetic resonance imaging sequences using only two different repetition times (TRs) and with only two sequential echo times (TEs) can be used to measure reproducible relative signal intensity and T2 relaxation time for normal brain tissues and cerebrospinal fluid using a 2.0T superconducting system. In 47 patients 6 different anatomic sites were measured. For each anatomic location, the mean and standard deviation of these values were determined. On T1-weighted (SE 500msec/30msec) images, in globus pallidus and thalamus, of the CSF, cortical gray matter and retrobulbar fat tissue varied more, with a standard deviation of 11-14% on T1-weighted images. On T2-weighted (SE 3000msec/30msec and 3000msec/80msec) images, the relative signal intensity of all anatomic regions varied more than on T1-weighted images. The standard deviation of T2 relaxation times also varied from 10% (fat tissue) to 18% (CSF). These variations might be due to partial volume averaging, signal alteration of CSF secondary to CSF pulsatile motion, etc. Knowing that relative signal intensity and T2 relaxation times calculated from routine imaging sequences are reproducible in only limited area, these normal ranges can be used to investigate changes occurring in disease states of the limited regions.

Aperiodic signals processing via parameter-tuning stochastic resonance in a photorefractive ring cavity

Directory of Open Access Journals (Sweden)

Xuefeng Li

2014-04-01

Full Text Available Based on solving numerically the generalized nonlinear Langevin equation describing the nonlinear dynamics of stochastic resonance by Fourth-order Runge-Kutta method, an aperiodic stochastic resonance based on an optical bistable system is numerically investigated. The numerical results show that a parameter-tuning stochastic resonance system can be realized by choosing the appropriate optical bistable parameters, which performs well in reconstructing aperiodic signals from a very high level of noise background. The influences of optical bistable parameters on the stochastic resonance effect are numerically analyzed via cross-correlation, and a maximum cross-correlation gain of 8 is obtained by optimizing optical bistable parameters. This provides a prospective method for reconstructing noise-hidden weak signals in all-optical signal processing systems.

Influence of Signal Intensity Non-Uniformity on Brain Volumetry Using an Atlas-Based Method

International Nuclear Information System (INIS)

Takao, Hidemasa; Kunimatsu, Akira; Mori, Harushi

2012-01-01

Many studies have reported pre-processing effects for brain volumetry; however, no study has investigated whether non-parametric non-uniform intensity normalization (N3) correction processing results in reduced system dependency when using an atlas-based method. To address this shortcoming, the present study assessed whether N3 correction processing provides reduced system dependency in atlas-based volumetry. Contiguous sagittal T1-weighted images of the brain were obtained from 21 healthy participants, by using five magnetic resonance protocols. After image preprocessing using the Statistical Parametric Mapping 5 software, we measured the structural volume of the segmented images with the WFU-PickAtlas software. We applied six different bias-correction levels (Regularization 10, Regularization 0.0001, Regularization 0, Regularization 10 with N3, Regularization 0.0001 with N3, and Regularization 0 with N3) to each set of images. The structural volume change ratio (%) was defined as the change ratio (%) = (100 X[measured volume - mean volume of five magnetic resonance protocols] / mean volume of five magnetic resonance protocols) for each bias-correction level. A low change ratio was synonymous with lower system dependency. The results showed that the images with the N3 correction had a lower change ratio compared with those without the N3 correction. The present study is the first atlas-based volumetry study to show that the precision of atlas-based volumetry improves when using N3-corrected images. Therefore, correction for signal intensity non-uniformity is strongly advised for multi-scanner or multi-site imaging trials.

Influence of signal intensity non-uniformity on brain volumetry using an atlas-based method.

Science.gov (United States)

Goto, Masami; Abe, Osamu; Miyati, Tosiaki; Kabasawa, Hiroyuki; Takao, Hidemasa; Hayashi, Naoto; Kurosu, Tomomi; Iwatsubo, Takeshi; Yamashita, Fumio; Matsuda, Hiroshi; Mori, Harushi; Kunimatsu, Akira; Aoki, Shigeki; Ino, Kenji; Yano, Keiichi; Ohtomo, Kuni

2012-01-01

Many studies have reported pre-processing effects for brain volumetry; however, no study has investigated whether non-parametric non-uniform intensity normalization (N3) correction processing results in reduced system dependency when using an atlas-based method. To address this shortcoming, the present study assessed whether N3 correction processing provides reduced system dependency in atlas-based volumetry. Contiguous sagittal T1-weighted images of the brain were obtained from 21 healthy participants, by using five magnetic resonance protocols. After image preprocessing using the Statistical Parametric Mapping 5 software, we measured the structural volume of the segmented images with the WFU-PickAtlas software. We applied six different bias-correction levels (Regularization 10, Regularization 0.0001, Regularization 0, Regularization 10 with N3, Regularization 0.0001 with N3, and Regularization 0 with N3) to each set of images. The structural volume change ratio (%) was defined as the change ratio (%) = (100 × [measured volume - mean volume of five magnetic resonance protocols] / mean volume of five magnetic resonance protocols) for each bias-correction level. A low change ratio was synonymous with lower system dependency. The results showed that the images with the N3 correction had a lower change ratio compared with those without the N3 correction. The present study is the first atlas-based volumetry study to show that the precision of atlas-based volumetry improves when using N3-corrected images. Therefore, correction for signal intensity non-uniformity is strongly advised for multi-scanner or multi-site imaging trials.

Influence of Signal Intensity Non-Uniformity on Brain Volumetry Using an Atlas-Based Method

Energy Technology Data Exchange (ETDEWEB)

Takao, Hidemasa; Kunimatsu, Akira; Mori, Harushi [University of Tokyo Hospital, Tokyo (Japan); and others

2012-07-15

Many studies have reported pre-processing effects for brain volumetry; however, no study has investigated whether non-parametric non-uniform intensity normalization (N3) correction processing results in reduced system dependency when using an atlas-based method. To address this shortcoming, the present study assessed whether N3 correction processing provides reduced system dependency in atlas-based volumetry. Contiguous sagittal T1-weighted images of the brain were obtained from 21 healthy participants, by using five magnetic resonance protocols. After image preprocessing using the Statistical Parametric Mapping 5 software, we measured the structural volume of the segmented images with the WFU-PickAtlas software. We applied six different bias-correction levels (Regularization 10, Regularization 0.0001, Regularization 0, Regularization 10 with N3, Regularization 0.0001 with N3, and Regularization 0 with N3) to each set of images. The structural volume change ratio (%) was defined as the change ratio (%) = (100 X[measured volume - mean volume of five magnetic resonance protocols] / mean volume of five magnetic resonance protocols) for each bias-correction level. A low change ratio was synonymous with lower system dependency. The results showed that the images with the N3 correction had a lower change ratio compared with those without the N3 correction. The present study is the first atlas-based volumetry study to show that the precision of atlas-based volumetry improves when using N3-corrected images. Therefore, correction for signal intensity non-uniformity is strongly advised for multi-scanner or multi-site imaging trials.

Sensitivity and spatial resolution for electron-spin-resonance detection by magnetic resonance force microscopy

International Nuclear Information System (INIS)

Zhang, Z.; Roukes, M.L.; Hammel, P.C.

1996-01-01

The signal intensity of electron spin resonance in magnetic resonance force microscopy (MRFM) experiments employing periodic saturation of the electron spin magnetization is determined by four parameters: the rf field H 1 , the modulation level of the bias field H m , the spin relaxation time τ 1 , and the magnetic size R(∂H/∂z) of the sample. Calculations of the MRFM spectra obtained from a 2,2-diphenyl-1-picrylhydrazyl particle have been performed for various conditions. The results are compared with experimental data and excellent agreement is found. The systematic variation of the signal intensity as a function of H 1 and H m provides a powerful tool to characterize the MRFM apparatus. copyright 1996 American Institute of Physics

Resonant Self-Trapping and Absorption of Intense Bessel Beams

International Nuclear Information System (INIS)

Fan, J.; Parra, E.; Milchberg, H. M.

2000-01-01

We report the observation of resonant self-trapping and enhanced laser-plasma heating resulting from propagation of high intensity Bessel beams in neutral gas. The enhancement in absorption and plasma heating is directly correlated to the spatial trapping of laser radiation. (c) 2000 The American Physical Society

Analysis of small-signal intensity modulation of semiconductor ...

Indian Academy of Sciences (India)

This paper demonstrates theoretical characterization of intensity modulation of semiconductor lasers (SL's). The study is based on a small-signal model to solve the laser rate equations taking into account suppression of optical gain. Analytical forms of the small-signal modulation response and modulation bandwidth are ...

Magnetic resonance imaging of Parkinsonism

International Nuclear Information System (INIS)

Mukai, Eiichiro; Makino, Naoki; Fujishiro, Kenichiro.

1989-01-01

We have analyzed magnetic resonance images in 33 patients; 18 patients with Parkinson's disease, 1 patient with diurnally fluctuating progressive dystonia, 1 patient with pure akinesia, 6 patients with multiple system atrophy, 1 patient with flunarizine induced parkinsonism, and 4 patients with unclassified parkinsonism. The MR images were obtained using a 1.5-T GE MR System. A spin-echo pulse sequence was used with a TE of 30 msec and 80 msec and a TR of 2000 msec. No signal abnormalities were seen in any patient with Parkinson's disease but 3 showed slightly decreased signal intensity of the putamen on T2-weighted sequences. Patients with diurnally fluctuating progressive dystonia and pure akinesia evidensed no abnormal findings. All six patients with multiple system atrophy demonstrated decreased signal intensity of the putamen, particularly along their lateral and posterior portions, and an enlarged substantia nigra. Atrophy of the pons and cerebellum was detected in all cases with multiple system atrophy. One case of flunarizine induced parkinsonism showed slightly decreased signal intensity of the putamen. Four cases of unclassified parkinsonism showed decreased signal in the putamen on T2-weighted sequences. Magnetic resonance imaging has the potential to become a useful diagnostic tool in the management of parkinsonism. (author)

Magnetic resonance imaging of Parkinsonism

Energy Technology Data Exchange (ETDEWEB)

Mukai, Eiichiro [National Hospital of Nagoya (Japan); Makino, Naoki; Fujishiro, Kenichiro

1989-06-01

We have analyzed magnetic resonance images in 33 patients; 18 patients with Parkinson's disease, 1 patient with diurnally fluctuating progressive dystonia, 1 patient with pure akinesia, 6 patients with multiple system atrophy, 1 patient with flunarizine induced parkinsonism, and 4 patients with unclassified parkinsonism. The MR images were obtained using a 1.5-T GE MR System. A spin-echo pulse sequence was used with a TE of 30 msec and 80 msec and a TR of 2000 msec. No signal abnormalities were seen in any patient with Parkinson's disease but 3 showed slightly decreased signal intensity of the putamen on T2-weighted sequences. Patients with diurnally fluctuating progressive dystonia and pure akinesia evidensed no abnormal findings. All six patients with multiple system atrophy demonstrated decreased signal intensity of the putamen, particularly along their lateral and posterior portions, and an enlarged substantia nigra. Atrophy of the pons and cerebellum was detected in all cases with multiple system atrophy. One case of flunarizine induced parkinsonism showed slightly decreased signal intensity of the putamen. Four cases of unclassified parkinsonism showed decreased signal in the putamen on T2-weighted sequences. Magnetic resonance imaging has the potential to become a useful diagnostic tool in the management of parkinsonism. (author).

Cascadability of Silicon Microring Resonators for40-Gbit/s OOK and DPSK Optical Signals

DEFF Research Database (Denmark)

Ozolins, Oskars; An, Yi; Lali-Dastjerdi, Zohreh

2012-01-01

The cascadability of a single silicon micro-ring resonator for CSRZ-OOK and CSRZ-DPSK signals is experimentally demonstrated at 40 Gbit/s for the first time. Error-free performance is obtained for both modulation formats after 5 cascaded resonators.......The cascadability of a single silicon micro-ring resonator for CSRZ-OOK and CSRZ-DPSK signals is experimentally demonstrated at 40 Gbit/s for the first time. Error-free performance is obtained for both modulation formats after 5 cascaded resonators....

Analysis of factors causing signal loss in the measurement of lung tissue water by nuclear magnetic resonance

International Nuclear Information System (INIS)

Fukuzaki, Minoru; Shioya, Sumie; Haida, Munetaka

1997-01-01

The water content of lung, brain, and muscle tissue was measured by nuclear magnetic resonance (NMR) and compared with gravimetric determinations. The NMR signal intensity of water was measured by a single 90 degree pulse and by a spin-echo sequence. The absolute water content was determined by the difference in the sample's weight before and after desiccation. The NMR detectable water in each tissue was expressed as a percentage of the signal intensity for an equal weight of distilled water. Using the single pulse measurement, 67% of the gravimetrically-measured water was detected in collapsed lung samples (consisting of about 47% retained air), in contrast to 96% for brain and 98% for muscle. For degassed lung samples, the NMR detectability of water increased to 87% with the single pulse measurement and to 90% with the spin-echo measurement, but the values remained significantly less than those of brain or muscle. Factors that caused the NMR signal loss of 33% in collapsed lung samples were: air-tissue interfaces (20%), microscopic field inhomogeneity (3%), and a water component with an extremely short magnetization decay time constant (10%). (author)

Self-contained inflatable penile prosthesis: magnetic resonance appearance

International Nuclear Information System (INIS)

Levin, M.F.; Munk, P.L.; Vellet, A.D.; Chin, J.L.

1994-01-01

The appearance of an inflatable penile prosthesis, visualized on a short tau inversion recovery sequence, is reported, in a patient who had magnetic resonance imaging for pelvic pain subsequent to radical cystoprostatectomy for bladder carcinoma. With suppression of adjacent fat signal, the prosthesis is well delineated from adjacent structures. The fluid-containing cylinders of the prosthesis are of very bright signal intensity, with the relief valve assembly of low signal intensity. 5 refs., 2 figs

Volume Change and Liver Parenchymal Signal Intensity in Gd-EOB-DTPA-Enhanced Magnetic Resonance Imaging after Portal Vein Embolization prior to Hepatectomy

Directory of Open Access Journals (Sweden)

Ayako Akiba

2014-01-01

Full Text Available Purpose. To investigate the liver volume change and the potential of early evaluation by contrast-enhanced magnetic resonance imaging (MRI using gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA after portal vein embolization (PVE. Materials and Methods. Retrospective evaluations of computed tomography (CT volumetry of total liver and nonembolized areas were performed before and 3 weeks after PVE in 37 cases. The percentage of future liver remnant (%FLR and the change ratio of %FLR (%FLR ratio were calculated. Prospective evaluation of signal intensities (SIs was performed to estimate the role of Gd-EOB-DTPA-enhanced MRI as a predictor of hypertrophy in 16 cases. The SI contrast between embolized and nonembolized areas was calculated 1 week after PVE. The change in SI contrast before and after PVE (SI ratio was also calculated in 11 cases. Results. %FLR ratio significantly increased, and SI ratio significantly decreased (both P<0.01. There were significant negative correlations between %FLR and SI contrast and between %FLR and SI ratio (both P<0.01. Conclusion. Hypertrophy in the nonembolized area after PVE was indicated by CT volumetry, and measurement of SI contrast and SI ratio in Gd-EOB-DTPA-enhanced MRI early after PVE may be useful to predict the potential for hepatic hypertrophy.

Direct measurement of the signal intensity of diffusion-weighted magnetic resonance imaging for preoperative grading and treatment guidance for brain gliomas

Directory of Open Access Journals (Sweden)

Chih-Chun Wu

2012-11-01

Conclusion: The proposed method – direct measuring of tumor signal intensity of DWI on PACS monitors – is feasible for grading gliomas in clinical neuro-oncology imaging services and has a high level of reliability and reproducibility.

Altered carotid plaque signal among different repetition times on T1-weighted magnetic resonance plaque imaging with self-navigated radial-scan technique

Energy Technology Data Exchange (ETDEWEB)

Narumi, Shinsuke; Ohba, Hideki; Mori, Kiyofumi; Ohura, Kazumasa; Ono, Ayumi; Terayama, Yasuo [Iwate Medical University, Department of Neurology and Gerontology, Morioka (Japan); Sasaki, Makoto [Iwate Medical University, Advanced Medical Research Center, Morioka (Japan); Ogasawara, Kuniaki [Iwate Medical University, Department of Neurosurgery, Morioka (Japan); Hitomi, Jiro [Iwate Medical University, Department of Anatomy, Morioka (Japan)

2010-04-15

Magnetic resonance (MR) plaque imaging for carotid arteries is usually performed by using an electrocardiograph (ECG)-gating technique to eliminate pulsation-related artifacts, which can affect the plaque signals because of varied repetition time (TR) among patients. Hence, we investigated whether differences in TR causes signal alterations of the carotid plaque by using a non-gated plaque imaging technique. We prospectively examined 19 patients with carotid stenosis by using a T1-weighted self-navigated radial-scan technique with TRs of 500, 700, and 900 ms. The signal intensity of the carotid plaque was measured, and the contrast ratio (CR) relative to the adjacent muscle was calculated. CRs of the carotid plaques were 1.39 {+-} 0.39, 1.29 {+-} 0.29, and 1.23 {+-} 0.24 with TRs of 500, 700, and 900 ms, respectively, and were significantly different. Among the plaques, those with a hyperintensity signal (CR > 1.5) and moderate-intensity signal (CR 1.2-1.5) at 500 ms showed a TR-dependent signal decrease (hyperintensity plaques, 1.82 {+-} 0.26; 1.61 {+-} 0.19; and 1.48 {+-} 0.17; moderate-intensity plaques, 1.33 {+-} 0.08; 1.26 {+-} 0.08; and 1.19 {+-} 0.07), while those with an isointensity signal (CR < 1.2) remained unchanged regardless of TR (0.96 {+-} 0.12, 0.96 {+-} 0.11, and 0.97 {+-} 0.13). The signal intensity of the carotid plaque on T1-weighted imaging significantly varies among different TRs and tends to decrease with longer TR. MR plaque imaging with short and constant TR settings that the ECG-gating method cannot realize would be preferable for evaluating plaque characteristics. (orig.)

Optimal sequence for magnetic resonance cholangiopancreatography

Energy Technology Data Exchange (ETDEWEB)

Kanzaki, Hiroshi; Akata, Soichi; Ozuki, Taizo; Abe, Kimihiko [Tokyo Medical Coll. (Japan)

2001-09-01

Magnetic resonance cholangiopancreatography (MRCP) has attracted attention as a useful examination for abnormalities of the pancreaticobiliary system, because it is a simple procedure. Since there are few detailed reports on optimal sequences for MRCP, we attempted to clarify the topic. The magnetic resonance imaging (MRI) equipment we used was a 1.0 Tesla super-conductive type. A fast spin echo (16 echo train) was used, and the echo space was set at 17 msec. TE was changed from 17 msec to 272 msec in 17 msec increments. TR was changed from 1,000 msec to 9,000 msec by 1,000 msec increments. Bile juice which had been collected from the PTCD tube of a patient with common bile duct cancer, was put in a test tube of 10 mm internal diameter. Saline was used as a substitute for pancreatic juice, because collection of pancreatic juice was difficult. Fat was used for contrast. Each signal intensity inside the test tube was measured and evaluated. We attempted to evaluate the signal of gastric juice by adding blueberry juice, making use of its manganese ion (Mn{sup ++}). With longer TR, the signal intensities of bile and pancreas juice increased. As TE became longer, the signal intensities of bile and pancreas juice decreased slightly, while that of fat decreased much more. In MRCP, it is necessary to set up a long TE to increase the relative signal intensity difference of fat in bile and pancreas juice. The signal intensity of gastric juice was made to disappear by the addition of blueberry juice diluted to a ratio of 1:3. (author)

Optimal sequence for magnetic resonance cholangiopancreatography

International Nuclear Information System (INIS)

Kanzaki, Hiroshi; Akata, Soichi; Ozuki, Taizo; Abe, Kimihiko

2001-01-01

Magnetic resonance cholangiopancreatography (MRCP) has attracted attention as a useful examination for abnormalities of the pancreaticobiliary system, because it is a simple procedure. Since there are few detailed reports on optimal sequences for MRCP, we attempted to clarify the topic. The magnetic resonance imaging (MRI) equipment we used was a 1.0 Tesla super-conductive type. A fast spin echo (16 echo train) was used, and the echo space was set at 17 msec. TE was changed from 17 msec to 272 msec in 17 msec increments. TR was changed from 1,000 msec to 9,000 msec by 1,000 msec increments. Bile juice which had been collected from the PTCD tube of a patient with common bile duct cancer, was put in a test tube of 10 mm internal diameter. Saline was used as a substitute for pancreatic juice, because collection of pancreatic juice was difficult. Fat was used for contrast. Each signal intensity inside the test tube was measured and evaluated. We attempted to evaluate the signal of gastric juice by adding blueberry juice, making use of its manganese ion (Mn ++ ). With longer TR, the signal intensities of bile and pancreas juice increased. As TE became longer, the signal intensities of bile and pancreas juice decreased slightly, while that of fat decreased much more. In MRCP, it is necessary to set up a long TE to increase the relative signal intensity difference of fat in bile and pancreas juice. The signal intensity of gastric juice was made to disappear by the addition of blueberry juice diluted to a ratio of 1:3. (author)

Parametric Amplification Protocol for Frequency-Modulated Magnetic Resonance Force Microscopy Signals

Science.gov (United States)

Harrell, Lee; Moore, Eric; Lee, Sanggap; Hickman, Steven; Marohn, John

2011-03-01

We present data and theoretical signal and noise calculations for a protocol using parametric amplification to evade the inherent tradeoff between signal and detector frequency noise in force-gradient magnetic resonance force microscopy signals, which are manifested as a modulated frequency shift of a high- Q microcantilever. Substrate-induced frequency noise has a 1 / f frequency dependence, while detector noise exhibits an f2 dependence on modulation frequency f . Modulation of sample spins at a frequency that minimizes these two contributions typically results in a surface frequency noise power an order of magnitude or more above the thermal limit and may prove incompatible with sample spin relaxation times as well. We show that the frequency modulated force-gradient signal can be used to excite the fundamental resonant mode of the cantilever, resulting in an audio frequency amplitude signal that is readily detected with a low-noise fiber optic interferometer. This technique allows us to modulate the force-gradient signal at a sufficiently high frequency so that substrate-induced frequency noise is evaded without subjecting the signal to the normal f2 detector noise of conventional demodulation.

Intensity of prolactinoma on T2-weighted magnetic resonance imaging: towards another gender difference

International Nuclear Information System (INIS)

Kreutz, Julie; Vroonen, Laurent; Petrossians, Patrick; Rostomyan, Liliya; Beckers, Albert; Cattin, Francoise; Thiry, Albert; Tshibanda, Luaba; Bonneville, Jean-Francois

2015-01-01

Clinical presentations of prolactinomas are quite different between genders. In comparison with women's prolactinoma, those in men showed predominance of large tumors with high prolactin (PRL) levels. This preponderance could be attributed to a greater proliferative potential of the tumors. Differences in magnetic resonance imaging (MRI) signal at diagnosis have not been yet clearly evaluated. We conduct a retrospective study comparing MRI signal intensity (SI) on T2-weighted images (T2-WI) between 41 men and 41 women to investigate whether or not men prolactinoma present specific features. In addition to the size of the adenoma and PRL levels (P < 0001), prolactinomas in men also exhibit differences from those in women in signal on T2-WI on MRI (P < 0001). Women's prolactinomas are mostly of high SI on T2-WI while men's prolactinomas exhibit a more heterogeneous pattern of SI on T2-WI. Prolactinomas presenting with low SI on T2-WI are almost exclusively encountered in men. Presence of T2-WI hypointensities in pituitary adenoma can be predictive of a different subtype of prolactinoma almost encountered in men and possibly translate the presence of spherical amyloid deposits, in agreement with the literature. (orig.)

Intensity of prolactinoma on T2-weighted magnetic resonance imaging: towards another gender difference

Energy Technology Data Exchange (ETDEWEB)

Kreutz, Julie [University Hospital Sart-Tilman, Department of Radiology, Liege (Belgium); Centre Hospitalier Universitaire de Liege, Domaine Universitaire du Sart Tilman, Service d' Imagerie Medicale, Liege (Belgium); Vroonen, Laurent; Petrossians, Patrick; Rostomyan, Liliya; Beckers, Albert [University Hospital Sart-Tilman, Department of Endocrinology, Liege (Belgium); Cattin, Francoise [University Hospital Besancon, Department of Radiology, Besancon (France); Thiry, Albert [University Hospital Sart-Tilman, Department of Pathology, Liege (Belgium); Tshibanda, Luaba [University Hospital Sart-Tilman, Department of Radiology, Liege (Belgium); Bonneville, Jean-Francois [University Hospital Sart-Tilman, Department of Radiology, Liege (Belgium); University Hospital Sart-Tilman, Department of Endocrinology, Liege (Belgium)

2015-07-15

Clinical presentations of prolactinomas are quite different between genders. In comparison with women's prolactinoma, those in men showed predominance of large tumors with high prolactin (PRL) levels. This preponderance could be attributed to a greater proliferative potential of the tumors. Differences in magnetic resonance imaging (MRI) signal at diagnosis have not been yet clearly evaluated. We conduct a retrospective study comparing MRI signal intensity (SI) on T2-weighted images (T2-WI) between 41 men and 41 women to investigate whether or not men prolactinoma present specific features. In addition to the size of the adenoma and PRL levels (P < 0001), prolactinomas in men also exhibit differences from those in women in signal on T2-WI on MRI (P < 0001). Women's prolactinomas are mostly of high SI on T2-WI while men's prolactinomas exhibit a more heterogeneous pattern of SI on T2-WI. Prolactinomas presenting with low SI on T2-WI are almost exclusively encountered in men. Presence of T2-WI hypointensities in pituitary adenoma can be predictive of a different subtype of prolactinoma almost encountered in men and possibly translate the presence of spherical amyloid deposits, in agreement with the literature. (orig.)

Method for increasing nuclear magnetic resonance signals in living biological tissue

International Nuclear Information System (INIS)

Krongrad, A.

1995-01-01

A method of enhancing a magnetic resonance comprising the steps of administering a quantity of a selected magnetic isotope to a living biological tissue at a concentration greater than the naturally occurring concentration of such isotope and detecting magnetic resonance signal from the administered magnetic isotope in the living biological tissue. (author)

Interpreting intensities in vibrational sum frequency generation (SFG) spectroscopy: CO adsorption on Pd surfaces

Science.gov (United States)

Morkel, M.; Unterhalt, H.; Klüner, T.; Rupprechter, G.; Freund, H.-J.

2005-07-01

The lineshape and intensity of SFG signals of CO adsorbed on supported Pd nanoparticles and Pd(1 1 1) are analyzed. For CO/Pd(1 1 1) nearly symmetric lorentzian lineshapes were observed. Applying two different visible wavelengths for excitation, asymmetric lineshapes observed for the CO/Pd/Al 2O 3/NiAl(1 1 0) system are explained by a lower resonant and a higher non-resonant SFG signal and a change in the phase between resonant and non-resonant signals, most likely originating from an interband transition in the NiAl substrate. The relative intensity of different CO species (hollow, bridge, on-top) was modeled by DFT calculations of IR transition moments and Raman activities. While the (experimental) sensitivity of SFG towards different CO species strongly varies, the calculated IR and Raman activities are rather similar. The inability to exactly reproduce experimental SFG intensities suggests a strong coverage dependence of Raman activities or that non-linear effects occur that can currently not be properly accounted for.

Impact of low signal intensity assessed by cine magnetic resonance imaging on detection of poorly viable myocardium in patients with prior myocardial infarction.

Science.gov (United States)

Ota, Shingo; Tanimoto, Takashi; Orii, Makoto; Hirata, Kumiko; Shiono, Yasutsugu; Shimamura, Kunihiro; Matsuo, Yoshiki; Yamano, Takashi; Ino, Yasushi; Kitabata, Hironori; Yamaguchi, Tomoyuki; Kubo, Takashi; Tanaka, Atsushi; Imanishi, Toshio; Akasaka, Takashi

2015-05-13

Late gadolinium enhancement magnetic resonance imaging (LGE-MRI) has been established as a modality to detect myocardial infarction (MI). However, the use of gadolinium contrast is limited in patients with advanced renal dysfunction. Although the signal intensity (SI) of infarct area assessed by cine MRI is low in some patients with prior MI, the prevalence and clinical significance of low SI has not been evaluated. The aim of this study was to evaluate how low SI assessed by cine MRI may relate to the myocardial viability in patients with prior MI. Fifty patients with prior MI underwent both cine MRI and LGE-MRI. The left ventricle was divided into 17 segments. The presence of low SI and the wall motion score (WMS) of each segment were assessed by cine MRI. The transmural extent of infarction was evaluated by LGE-MRI. LGE was detected in 329 of all 850 segments (39%). The low SI assessed by cine MRI was detected in 105 of 329 segments with LGE (32%). All segments with low SI had LGE. Of all 329 segments with LGE, the segments with low SI showed greater transmural extent of infarction (78 [72 - 84] % versus 53 [38 - 72] %, P cine MRI may be effective for detecting poorly viable myocardium in patients with prior MI.

Discoscopic Findings of High Signal Intensity Zones on Magnetic Resonance Imaging of Lumbar Intervertebral Discs

Directory of Open Access Journals (Sweden)

Kosuke Sugiura

2014-01-01

Full Text Available A 32-year-old man underwent radiofrequency thermal annuloplasty (TA with percutaneous endoscopic discectomy (PED under local anesthesia for chronic low back pain. His diagnosis was discogenic pain with a high signal intensity zone (HIZ in the posterior corner of the L4-5 disc. Flexion pain was sporadic, and steroid injection was given twice for severe pain. After the third episode of strong pain, PED and TA were conducted. The discoscope was inserted into the posterior annulus and revealed a migrated white nucleus pulposus which was stained blue. Then, after moving the discoscope to the site of the HIZ, a migrated slightly red nucleus pulposus was found, suggesting inflammation and/or new vessels penetrating the mass. After removing the fragment, the HIZ site was ablated by TA. To our knowledge, this is the first report of the discoscopic findings of HIZ of the lumbar intervertebral disc.

A clinico-radiological study on 254 cases of pontine high signals on magnetic resonance imaging in relation to brain stem semiology

Energy Technology Data Exchange (ETDEWEB)

Watanabe, Masaki; Takahashi, Akira (Nagoya Univ. (Japan). Faculty of Medicine); Arahata, Yutaka; Motegi, Yoshimasa; Furuse, Masahiro

1993-11-01

A total of 254 patients who were proved to have pontine high intensity areas on T[sub 2]-weighted magnetic resonance imaging (MRI) were analyzed in relation to brain stem semiology. A comparative study on MRI and MR angiography was made between 254 patients with pontine high signals and 276 control cases showing no abnormality either on T[sub 1] or T[sub 2]-weighted images. Of the 254 patients, 62 had transient subjective complaints such as vertigo-dizziness. Supratentorial high signals, basilar artery tortuousness and vertebral artery asymmetry on MR angiography were seen more frequently in patients with pontine high signals than in the controls. In conclusion, pontine high signals may result from diffuse arteriosclerosis and MR angiography is considered to be a useful screening method. (author).

An experimental study on MRI signal intensity vs concentration of water-soluble contrast media

International Nuclear Information System (INIS)

Lee, Ghi Jai; Han, Chang Yul; Chang, Kee Hyun; Han, Moon Hee; Han, Man Chung

1991-01-01

There has been only one report that water-soluble contrast media containing iodine and used in conventional X -ray radiography reduce T1-and T2-relaxation times. We evaluated the relationship between signal intensity (relative signal intensity to normal saline) and T2-relaxation time of MRI and the concentration of 3 water-soluble contrast media [meglumine ioxithalamate (Telebrix 30), iopromide (Ultravist 300), iotrolan (Isovist 300)] through the phantom study, using both 2.0T and 0.5T MR units. We found that the signal intensity increased significantly on the T1-weighted images as the concentration of contrast media increased. The degree of the increase was larger on 0.5T MR than on 2.0T MR. The signal intensity on proton density image showed no significant difference at various concentrations. However, there were significant decreases of both signal intensity on the T2-weighted images and T2-relaxation time as the concentration of contrast media increased, which was more prominent on 2.0T MR than 0.5T MR. Between the contrast media of the same concentration, there was no significant difference in signal intensity and T2-relaxation time

Repeated intravenous administration of gadobutrol does not lead to increased signal intensity on unenhanced T1-weighted images - a voxel-based whole brain analysis

Energy Technology Data Exchange (ETDEWEB)

Langner, Soenke; Kromrey, Marie-Luise [University Medicine Greifswald, Institute of Diagnostic Radiology and Neuroradiology, Greifswald (Germany); Kuehn, Jens-Peter [University Medicine Greifswald, Institute of Diagnostic Radiology and Neuroradiology, Greifswald (Germany); University Hospital, Carl Gustav Carus University Dresden, Institute for Radiology, Dresden (Germany); Grothe, Matthias [University Medicine Greifswald, Department of Neurology, Greifswald (Germany); Domin, Martin [University Medicine Greifswald, Functional Imaging Unit, Institute of Diagnostic Radiology and Neuroradiology, Greifswald (Germany)

2017-09-15

To identify a possible association between repeated intravenous administration of gadobutrol and increased signal intensity in the grey and white matter using voxel-based whole-brain analysis. In this retrospective single-centre study, 217 patients with a clinically isolated syndrome underwent baseline brain magnetic resonance imaging and at least one annual follow-up examination with intravenous administration of 0.1 mmol/kg body weight of gadobutrol. Using the ''Diffeomorphic Anatomical Registration using Exponentiated Lie algebra'' (DARTEL) normalisation process, tissue templates for grey matter (GM), white matter (WM), and cerebrospinal fluid (CSF) were calculated, as were GM-CSF and WM-CSF ratios. Voxel-based whole-brain analysis was used to calculate the signal intensity for each voxel in each data set. Paired t-test was applied to test differences to baseline MRI for significance. Voxel-based whole-brain analysis demonstrated no significant changes in signal intensity of grey and white matter after up to five gadobutrol administrations. There was no significant change in GM-CSF and grey WM-CSF ratios. Voxel-based whole-brain analysis did not demonstrate increased signal intensity of GM and WM on unenhanced T1-weighted images after repeated gadobutrol administration. The molecular structure of gadolinium-based contrast agent preparations may be an essential factor causing SI increase on unenhanced T1-weighted images. (orig.)

Magnetic resonance imaging of myositis ossificans: Analysis of seven cases

International Nuclear Information System (INIS)

De Smet, A.A.; Norris, M.A.; Fisher, D.R.

1992-01-01

Since magnetic resonance imaging (MRI) is commonly used to evaluate soft tissue masses, we analyzed eight MR examinations in seven patients with myositis ossificans to determine if typical patterns were present. One acute lesion had homogeneous intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Two subacute lesions had low signal intensity margins with slightly increased signal intensity centers on T1-weighted images and very high signal intensity on T2-weighted images. Five chronic lesions had two different patterns. All five were well-defined with low signal intensity borders. Three had signal intensity patterns characteristic of fat on T1-weighted and T2-weighted images. The other two lesions had intermediate signal intensity on T1-weighted images and slightly increased signal intensity on T2-weighted images. We conclude that typical MR appearances of myositis ossificans do exist. A low signal intensity rim is a common finding. However, these patterns are not unique to myositis ossificans and resemble those that have been reported in other lesions. It is important to be aware of the spectrum of MR findings of myositis ossificans when considering the differential diagnosis of a soft tissue mass. (orig./MG)

Elastofibroma dorsi: magnetic resonance imaging findings in two cases

OpenAIRE

KARAGÜLLE, A. Tuba; ERDEN, M.İlhan; ERDEN, Ayşe; KARADAĞ, Demet

2002-01-01

Elastofibroma dorsi is a pseudotumoral mass of unknown pathogenesis that is usually seen in elderly patients. We report two cases of histologically proven elastofibroma dorsi, each presenting with painful periscapular masses. Magnetic resonance imagingshowed periscapular tumoral mass with low to intermediate signal intensity with interspersed areas of high signal intensity on both T1 and T2 weighted images. After I.V. administration of gadopentate dimeglumine, these lesions demonstrated mild ...

MR imaging of lumbar spondylolysis: signal intensity change in the pars interarticularis and adjacent structures

Energy Technology Data Exchange (ETDEWEB)

Jang, Suk Whan; Lee, Ghi Jai; Shim, Jae Chan; Kim, Ho Kyun [Inje Univ. College of Medicine, Kimhae (Korea, Republic of)

2001-05-01

To assess changes in MR signal intensity in the pars interarticularis and adjacent structures in patients with lumbar spondylolysis. The MR images of 36 patients with lumbar spondylolysis, confirmed by plain radiographs, were retrospectively analyzed. Using a 1.0T unit, we evaluated the signal intensity of a total of 216 parts interarticulares and adjacent structures from L3 to L5, as seen on sagittal images, and differences between areas with and without spondylolysis. The signal intensity of T1-and T2-weighted images was graded 0(more hypointense than spinal body), 1(as isointense as spinal body), 2(more hyperintense than spinal body and more hypointense than epidural fat), or 3(as isointense as epidural fat). Signal intensity change in endplates and degree of spondylolisthesis were analyzed, and the relationship between these factors was determined. Spondylolysis was noted at L5 in 61 cases, at L4 in 22, and of L3 in no case. In three cases spondylolysis was unilateral, and in the remainder it was bilateral. The degree of signal intensity was the same on T1-and T2-weighted images, and no case was grade 0. Eighty-six of 133 areas without spondylolysis were grade 1, 43 were grade 2, and four were grade 3. In 42 of 47 cases, signal intensity change was localized at pedicles. Among 83 areas with spondylolysis,on the other hand, nine were grade 1, 48 were grade 2, and 26 were grade 3. Signal intensity change was most commonly observed at the pars interarticularis, pedicle, and lamina(50/74)({rho}<0.001). Signal intensity change at the pars interarticularis and adjacent structures was accompanied in most cases by degenerative endplate change(10/11) and spondylolisthesis(11/13)({rho}<0.001). In patients with spondylolysis, signal intensity was frequently higher at the pars interarticularis and adjacent structures, and is thought to have a close relationship with degenerative endplate change and spondylolisthesis. Increases in signal intensity at the pars

MR imaging of lumbar spondylolysis: signal intensity change in the pars interarticularis and adjacent structures

International Nuclear Information System (INIS)

Jang, Suk Whan; Lee, Ghi Jai; Shim, Jae Chan; Kim, Ho Kyun

2001-01-01

To assess changes in MR signal intensity in the pars interarticularis and adjacent structures in patients with lumbar spondylolysis. The MR images of 36 patients with lumbar spondylolysis, confirmed by plain radiographs, were retrospectively analyzed. Using a 1.0T unit, we evaluated the signal intensity of a total of 216 parts interarticulares and adjacent structures from L3 to L5, as seen on sagittal images, and differences between areas with and without spondylolysis. The signal intensity of T1-and T2-weighted images was graded 0(more hypointense than spinal body), 1(as isointense as spinal body), 2(more hyperintense than spinal body and more hypointense than epidural fat), or 3(as isointense as epidural fat). Signal intensity change in endplates and degree of spondylolisthesis were analyzed, and the relationship between these factors was determined. Spondylolysis was noted at L5 in 61 cases, at L4 in 22, and of L3 in no case. In three cases spondylolysis was unilateral, and in the remainder it was bilateral. The degree of signal intensity was the same on T1-and T2-weighted images, and no case was grade 0. Eighty-six of 133 areas without spondylolysis were grade 1, 43 were grade 2, and four were grade 3. In 42 of 47 cases, signal intensity change was localized at pedicles. Among 83 areas with spondylolysis,on the other hand, nine were grade 1, 48 were grade 2, and 26 were grade 3. Signal intensity change was most commonly observed at the pars interarticularis, pedicle, and lamina(50/74)(ρ<0.001). Signal intensity change at the pars interarticularis and adjacent structures was accompanied in most cases by degenerative endplate change(10/11) and spondylolisthesis(11/13)(ρ<0.001). In patients with spondylolysis, signal intensity was frequently higher at the pars interarticularis and adjacent structures, and is thought to have a close relationship with degenerative endplate change and spondylolisthesis. Increases in signal intensity at the pars interarticularis and

Histologic correlation of MR signal intensity in parathyroid adenomas

International Nuclear Information System (INIS)

Rumancik, W.M.; Khan, A.; Mir, R.N.; Attie, J.N.; Davis, J.E.; Ashtari, M.; Herman, P.G.

1988-01-01

The classic MR signal intensity pattern of parathyroid adenoma (PTA) is bright enhancement on T2-weighted images. However, variations in SI pattern have been observed in clinical practice. The purpose of this report is to describe the histologic characteristics of surgically removed PTAs as correlated with their in vivo MR imaging appearance. From May 1987 to April 1988, 51 consecutive patients with primary hyperparathyroidism were evaluated with MR imaging for preoperative localization of PTA. Surgical confirmation was obtained in all patients, with histologic evaluation available in 40. MR imaging was performed on 1.0-T system (Siemens, Magnetom) using a Helmhotz surface coil positioned at the neck. Spin-echo T1-weighted and T2-weighted multisection images were evaluated retrospectively. Signal intensities of PTA, adjacent thyroid, fat, and skeletal muscle were obtained (1) from direct region of interest determinations, and (2) visually as respective relationships of PTA to thyroid, fat, and muscle. Histologic classification was graded for (1) predominant cell type (i.e., chief or oxyphil cells), (2) acinar or solid growth pattern, (3) cystic change, (4) presence or absence of residual fat, (5) cell count per high power field, (6) heterogeneous histology, (7) gland weight, and (8) giant size (≥3 cm). The relationship of MR signal intensity to histology appears multifactorial

A basic characteristic of signal intensity in MRI

International Nuclear Information System (INIS)

Doi, Tsukasa

2009-01-01

For evaluation of the significance of signal intensity and contrast which determine the MR imaging quality, SNR (signal-to-noise ratio) and CNR (contrast-to-noise ratio) were studied as their respective measures on the cross-talk artifact (CTA), partial volume effect (PVE), intensity of the fast spin echo (SE) imaging and contrast in the 3T field area (Con). The machine used was 3.0T Signa HDx (GE). CTA, the SNR-reducing coherence between neighboring slices at multi-slice imaging, was studied with a series of phantoms of 0.75-4 mm diameter acrylic pins in cupric sulfate solution with various imaging modes and slice numbers to calculate CNR and contrast (C) involving SNR factor. PVE, the determinant of the intensity depending on the mixture of different tissues within a voxel (slice thickness), was studied with similar phantoms to above with 1-12 mm thick slices and different slice gaps to obtain CNR and C. The intensity of fast SE image was studied with phantoms in a brain-equivalent 0.125 mM Gd solution of sealed water, 0.25-0.5mM Gd, butter, salad oil and detergent on magnetization transfer, J-coupling and diffusion. Con in the 3T machine was studied with the same phantoms as above on the image contrasts at the central and peripheral imaging areas and the intensity/contrast changes by different coils. Presented data of above examinations revealed the effects of characteristic of each environmental factor, and of which recognition was concluded necessary to exactly read the obtained images. (K.T.)

Intensity ratio curve analysis of small renal masses on T2-weighted magnetic resonance imaging: Differentiation of fat-poor angiomyolipoma from renal cell carcinoma.

Science.gov (United States)

Moriyama, Shingo; Yoshida, Soichiro; Tanaka, Hajime; Tanaka, Hiroshi; Yokoyama, Minato; Ishioka, Junichiro; Matsuoka, Yoh; Saito, Kazutaka; Kihara, Kazunori; Fujii, Yasuhisa

2018-03-25

To assess the diagnostic ability of a pixel intensity-based analysis in evaluating the magnetic resonance imaging characteristics of small renal masses, especially in differentiating fat-poor angiomyolipoma from renal cell carcinoma. T2-weighted images from 121 solid small renal masses (ratio curve was plotted using intensity ratios, which were ratios of signal intensities of tumor pixels (each pixel along a linear region of interest drawn across the renal tumor on T2-weighted image) to the signal intensity of a normal renal cortex. The diagnostic ability of the intensity ratio curve analysis was evaluated. The tumors were classified into three types: intensity ratio fat-poor angiomyolipoma (n = 19) with no pseudocapsule, iso-low intensity and no heterogeneity; intensity ratio clear cell renal cell carcinoma (n = 76) with a pseudocapsule, iso-high intensity and heterogeneity; and other type of intensity ratio (n = 26), including tumors that did not fall into the above two categories. The sensitivity/specificity/accuracy of the intensity ratio curve analysis in diagnosing fat-poor angiomyolipoma was 93%/94%/94%, respectively. When the intensity ratio curve analysis was applied only to the tumor with undetermined radiological diagnosis, the sensitivity for diagnosing fat-poor angiomyolipoma compared with subjective reading alone significantly improved (93% vs 50%; P = 0.014). Our novel semiquantitative model for combined assessment of key features of fat-poor angiomyolipoma, including low intensity, homogeneity and absence of a pseudocapsule on T2-weighted image, might make diagnosis of fat-poor angiomyolipoma more accurate. © 2018 The Japanese Urological Association.

Parenchymal signal intensity in 3-T body MRI of dogs with hematopoietic neoplasia.

Science.gov (United States)

Feeney, Daniel A; Sharkey, Leslie C; Steward, Susan M; Bahr, Katherine L; Henson, Michael S; Ito, Daisuke; O'Brien, Timothy D; Jessen, Carl R; Husbands, Brian D; Borgatti, Antonella; Modiano, Jaime F

2013-04-01

We performed a preliminary study involving 10 dogs to assess the applicability of body MRI for staging of canine diffuse hematopoietic neoplasia. T1-weighted (before and after intravenous gadolinium), T2-weighted, in-phase, out-of-phase, and short tau inversion recovery pulse sequences were used. By using digital region of interest (ROI) and visual comparison techniques, relative parenchymal organ (medial iliac lymph nodes, liver, spleen, kidney cortex, and kidney medulla) signal intensity was quantified as less than, equal to, or greater than that of skeletal muscle in 2 clinically normal young adult dogs and 10 dogs affected with either B-cell lymphoma (n = 7) or myelodysplastic syndrome (n = 3). Falciform fat and urinary bladder were evaluated to provide additional perspective regarding signal intensity from the pulse sequences. Dogs with nonfocal disease could be distinguished from normal dogs according to both the visual and ROI signal-intensity relationships. In normal dogs, liver signal intensity on the T2-weighted sequence was greater than that of skeletal muscle by using either the visual or ROI approach. However in affected dogs, T2-weighted liver signal intensity was less than that of skeletal muscle by using either the ROI approach (10 of 10 dogs) or the visual approach (9 of 10 dogs). These findings suggest that the comparison of relative signal intensity among organs may have merit as a research model for infiltrative parenchymal disease (ROI approach) or metabolic effects of disease; this comparison may have practical clinical applicability (visual comparison approach) as well.

Double-labeled donor probe can enhance the signal of fluorescence resonance energy transfer (FRET) in detection of nucleic acid hybridization

Science.gov (United States)

Okamura, Yukio; Kondo, Satoshi; Sase, Ichiro; Suga, Takayuki; Mise, Kazuyuki; Furusawa, Iwao; Kawakami, Shigeki; Watanabe, Yuichiro

2000-01-01

A set of fluorescently-labeled DNA probes that hybridize with the target RNA and produce fluorescence resonance energy transfer (FRET) signals can be utilized for the detection of specific RNA. We have developed probe sets to detect and discriminate single-strand RNA molecules of plant viral genome, and sought a method to improve the FRET signals to handle in vivo applications. Consequently, we found that a double-labeled donor probe labeled with Bodipy dye yielded a remarkable increase in fluorescence intensity compared to a single-labeled donor probe used in an ordinary FRET. This double-labeled donor system can be easily applied to improve various FRET probes since the dependence upon sequence and label position in enhancement is not as strict. Furthermore this method could be applied to other nucleic acid substances, such as oligo RNA and phosphorothioate oligonucleotides (S-oligos) to enhance FRET signal. Although the double-labeled donor probes labeled with a variety of fluorophores had unexpected properties (strange UV-visible absorption spectra, decrease of intensity and decay of donor fluorescence) compared with single-labeled ones, they had no relation to FRET enhancement. This signal amplification mechanism cannot be explained simply based on our current results and knowledge of FRET. Yet it is possible to utilize this double-labeled donor system in various applications of FRET as a simple signal-enhancement method. PMID:11121494

High signal intensity of the septum pellucidum at MR imaging; Significance in hydrocephalus

International Nuclear Information System (INIS)

Yoon, Jeong Hee; Kim, Eun Ha; Chung, Chun Phil; Kim, Chang Soo

1994-01-01

To evaluate the significance of high signal intensity of the septum pellucidum in hydrocephalus on proton density-weighted brain MR images. Authors reviewed the MR images of 418 cases of patients with normal (175 case), hydrocephalic(35 cases), atrophic(58 cases), and other groups(150 cases) retrospectively. We analyzed the signal intensity of the septum pellucidum in the normal group and the incidences of high signal intensities of periventricular area of frontal horn of lateral ventricle(area 1), periventricular area except area 1 (area 2), callososeptal area(area 3), and septum pellucidum(area 4) in the normal and abnormal groups. In the normal group, the septum pellucidum was isointense to the head of caudate nucleus on proton density-weighted image. High signal intensity of the septum pellucidum was seen in 31 cases (22 cases of hydrocephalus, 5 cases of brain atrophy, and 4 cases of others), and showed high specificity(91.4%) for hydrocephalus in spite of low sensitivity(62.9%), as compared with periventricular hyperintensities of other areas. High signal intensity of the septum pellucidum on proton density- weighted image may be caused by transependymal CSF migration in the patients with hydrocephalus, and considered as an additional finding of hydrocephalus in the cases of ventriculomegaly

Harmonic detection of magnetic resonance for sensitivity improvement of optical atomic magnetometers

Energy Technology Data Exchange (ETDEWEB)

Ranjbaran, M. [Laser and Plasma Research Institute, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Tehranchi, M.M., E-mail: teranchi@sbu.ac.ir [Laser and Plasma Research Institute, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Physics Department, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Hamidi, S.M. [Laser and Plasma Research Institute, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Khalkhali, S.M.H. [Physics Department, Kharazmi University, Tehran (Iran, Islamic Republic of)

2017-02-15

Highly sensitive atomic magnetometers use optically detected magnetic resonance of atomic spins to measure extremely weak magnetic field changes. The magnetometer sensitivity is directly proportional to the ratio of intensity to line-shape of the resonance signal. To obtain narrower resonance signal, we implemented harmonic detection of magnetic resonance method in M{sub x} configuration. The nonlinear spin polarization dynamics in detection of the higher harmonics were employed in phenomenological Bloch equations. The measured and simulated harmonic components of the resonance signals in frequency domain yielded significantly narrower line-width accompanying much improved sensitivity. Our results confirm the sensitivity improvement by a factor of two in optical atomic magnetometer via second harmonic signal which can open a new insight in the weak magnetic field measurement system design. - Highlights: • Highly sensitive atomic magnetometers have been used to measure weak magentic filed. • To obtain narrower resonance signal, we impalnted harmonic detection of magnetic resonance. • The nonlinear spin polarization dynamics in detetion of the higher harmonics were imployed.

Stochastic resonance in a stochastic bistable system with additive noises and square–wave signal

International Nuclear Information System (INIS)

Feng, Guo; Xiang-Dong, Luo; Shao-Fu, Li; Yu-Rong, Zhou

2010-01-01

This paper considers the stochastic resonance in a stochastic bistable system driven by a periodic square-wave signal and a static force as well as by additive white noise and dichotomous noise from the viewpoint of signal-to-noise ratio. It finds that the signal-to-noise ratio appears as stochastic resonance behaviour when it is plotted as a function of the noise strength of the white noise and dichotomous noise, as a function of the system parameters, or as a function of the static force. Moreover, the influence of the strength of the stochastic potential force and the correlation rate of the dichotomous noise on the signal-to-noise ratio is investigated. (general)

Magnetic resonance imaging of thoracic hydatid disease

International Nuclear Information System (INIS)

Sinner, W.N. von; Rifal, A.; Te Strake, L.; Sieck, J.; King Faisal Specialist Hospital and Research Centre, Riyadh; Michigan Univ., Ann Arbor

1990-01-01

Two patients with thoracic manifestations of hydatid disease (HD) are discussed; one patient had recurrent HD of the chest wall and the other, intrapulmonary HD after rupture and intrathoracic extension of an infradiaphragmatic cyst. At magnetic resonance (MR) imaging the manifestations of HD in the thorax are similar to previously reported MR findings in HD in the liver. The presence of a low signal intensity rim on T2 weighted images representing the cyst wall was confirmed. On T1 weighted images cysts with heterogeneous low and intermediate signal intensity contents and a relatively high signal intensity wall were seen. ''Folded parasitic membranes'' previously not described on MR were noted. Daughter cysts may have a low or high signal intensity depending on contents. Reactive changes in the lung may be quite marked compared with the liver, due to reaction to the parasite or simply because the lung is more easily compressed leading to secondary atelectasis. (orig.)

Small-signal model for the series resonant converter

Science.gov (United States)

King, R. J.; Stuart, T. A.

1985-01-01

The results of a previous discrete-time model of the series resonant dc-dc converter are reviewed and from these a small signal dynamic model is derived. This model is valid for low frequencies and is based on the modulation of the diode conduction angle for control. The basic converter is modeled separately from its output filter to facilitate the use of these results for design purposes. Experimental results are presented.

Magnetic resonance imaging appearance at 1. 5 tesla of cartilaginous tumors involving the epiphysis

Energy Technology Data Exchange (ETDEWEB)

Fobben, E.S.; Dalinka, M.K.; Schiebler, M.L.; Burk, D.L.; Kressel, H.Y.; Fallon, M.D.; Schmidt, R.G.

1987-11-01

Three cases of lytic, calcified epiphyseal lesions with plain film and computed tomography features suggestive of chondroblastoma were imaged by magnetic resonance imaging. Histopathologic correlation was obtained in each case. Two cases of chondroblastoma showed low signal intensity on both short (TR600/TE20ms) and long (TR2500/TE80ms) spin echo (SE) images. The third case, a clear cell chondrosarcoma, demonstrated increased signal intensity on moderately T2 weighted (TR2500/TE40ms) images. These findings suggest that magnetic resonance imaging may be helpful in distinguishing these lesions. (orig.)

Robust high-resolution quantification of time signals encoded by in vivo magnetic resonance spectroscopy

Science.gov (United States)

Belkić, Dževad; Belkić, Karen

2018-01-01

This paper on molecular imaging emphasizes improving specificity of magnetic resonance spectroscopy (MRS) for early cancer diagnostics by high-resolution data analysis. Sensitivity of magnetic resonance imaging (MRI) is excellent, but specificity is insufficient. Specificity is improved with MRS by going beyond morphology to assess the biochemical content of tissue. This is contingent upon accurate data quantification of diagnostically relevant biomolecules. Quantification is spectral analysis which reconstructs chemical shifts, amplitudes and relaxation times of metabolites. Chemical shifts inform on electronic shielding of resonating nuclei bound to different molecular compounds. Oscillation amplitudes in time signals retrieve the abundance of MR sensitive nuclei whose number is proportional to metabolite concentrations. Transverse relaxation times, the reciprocal of decay probabilities of resonances, arise from spin-spin coupling and reflect local field inhomogeneities. In MRS single voxels are used. For volumetric coverage, multi-voxels are employed within a hybrid of MRS and MRI called magnetic resonance spectroscopic imaging (MRSI). Common to MRS and MRSI is encoding of time signals and subsequent spectral analysis. Encoded data do not provide direct clinical information. Spectral analysis of time signals can yield the quantitative information, of which metabolite concentrations are the most clinically important. This information is equivocal with standard data analysis through the non-parametric, low-resolution fast Fourier transform and post-processing via fitting. By applying the fast Padé transform (FPT) with high-resolution, noise suppression and exact quantification via quantum mechanical signal processing, advances are made, presented herein, focusing on four areas of critical public health importance: brain, prostate, breast and ovarian cancers.

Pedicle marrow signal intensity changes in the lumbar spine: a manifestation of facet degenerative joint disease

International Nuclear Information System (INIS)

Morrison, J.L.; Kaplan, P.A.; Dussault, R.G.; Anderson, M.W.

2000-01-01

Objective. Signal intensity changes in lumbar pedicles, similar to those described in vertebral body endplates adjacent to degenerated discs, have been described as an ancillary sign of spondylolysis on MRI. The purpose of this study was to determine whether pedicle marrow signal intensity changes also occur in association with facet degenerative joint disease.Design. Eighty-nine lumbar spine MRI examinations without spondylolysis were reviewed for marrow signal intensity changes in pedicles and vertebral bodies as well as for facet degenerative joint disease.Results. Five percent (46/890) of lumbar pedicles in 23 patients had marrow signal intensity changes. Ninety-one percent (42/46) of the abnormal pedicles had adjacent degenerative joint disease of the facets, while only 21% (189/890) of normal pedicles had adjacent facet degenerative joint disease (p<0.001). Eighty-nine percent (41/46) of the pedicles with marrow signal intensity changes had adjacent degenerative disc disease.Conclusions. Pedicle marrow signal intensity changes are not a specific sign of spondylolysis; they are commonly seen with adjacent facet degenerative joint disease in the absence of spondylolysis. Pedicle marrow signal intensity changes are probably a response to abnormal stresses related to abnormal motion or loading caused by the degenerative changes in the spinal segment. (orig.)

Pedicle marrow signal intensity changes in the lumbar spine: a manifestation of facet degenerative joint disease

Energy Technology Data Exchange (ETDEWEB)

Morrison, J.L.; Kaplan, P.A.; Dussault, R.G.; Anderson, M.W. [Dept. of Radiology, Univ. of Virginia Health System, Charlottesville, VA (United States)

2000-12-01

Objective. Signal intensity changes in lumbar pedicles, similar to those described in vertebral body endplates adjacent to degenerated discs, have been described as an ancillary sign of spondylolysis on MRI. The purpose of this study was to determine whether pedicle marrow signal intensity changes also occur in association with facet degenerative joint disease.Design. Eighty-nine lumbar spine MRI examinations without spondylolysis were reviewed for marrow signal intensity changes in pedicles and vertebral bodies as well as for facet degenerative joint disease.Results. Five percent (46/890) of lumbar pedicles in 23 patients had marrow signal intensity changes. Ninety-one percent (42/46) of the abnormal pedicles had adjacent degenerative joint disease of the facets, while only 21% (189/890) of normal pedicles had adjacent facet degenerative joint disease (p<0.001). Eighty-nine percent (41/46) of the pedicles with marrow signal intensity changes had adjacent degenerative disc disease.Conclusions. Pedicle marrow signal intensity changes are not a specific sign of spondylolysis; they are commonly seen with adjacent facet degenerative joint disease in the absence of spondylolysis. Pedicle marrow signal intensity changes are probably a response to abnormal stresses related to abnormal motion or loading caused by the degenerative changes in the spinal segment. (orig.)

Investigation of Resonance Effect Caused by Local Exposure of Extremely Low Frequency Magnetic Field on Brain Signals: A Randomize Clinical Trial

Directory of Open Access Journals (Sweden)

Rasul Zadeh Tabataba’ei K

2011-03-01

Full Text Available Background and Objectives: Some studies have investigated the effects of extremely low frequency magnetic fields (ELF-MFs on brain signals, but only few of them have reported that humans exposed to magnetic fields exhibit changes in brain signals at the frequency of stimulation, i.e. resonance effect. In most investigations, researchers usually take advantage of a uniform field which encompasses the head. The aim of present study was to expose different parts of the brain to ELF-MFs locally and to investigate variation of brain signal and resonance effect.Methods: The subjects consisting of 19 male-students with the mean age of 25.6±1.6 years participated in this study. Local ELF-MFs with 3, 5, 10, 17 and 45Hz frequencies and 240 μT intensity was applied on five points (T3, T4, Cz, F3 and F4 of participants scalp Separately in 10-20 system. In the end, relative power over this points in common frequency bands and at the frequency of magnetic fields was evaluated by paired t-test.Results: Exposure of Central area by local magnetic field caused significant change (p<0.05 in the forehead alpha band. Reduction in the alpha band over central area was observed when temporal area was exposed to ELF MF.Conclusion: The results showed that resonance effect in the brain signals caused by local magnetic field exposure was not observed and change in every part of the relative power spectrum might occur. The changes in the EEG bands were not limited necessarily to the exposure point.

Linear all-optical signal processing using silicon micro-ring resonators

DEFF Research Database (Denmark)

Ding, Yunhong; Ou, Haiyan; Xu, Jing

2016-01-01

Silicon micro-ring resonators (MRRs) are compact and versatile devices whose periodic frequency response can be exploited for a wide range of applications. In this paper, we review our recent work on linear all-optical signal processing applications using silicon MRRs as passive filters. We focus...

Electron spin resonance signal from a tetra-interstitial defect in silicon

CERN Document Server

Mchedlidze, T

2003-01-01

The Si-B3 electron spin resonance (ESR) signal from agglomerates of self-interstitials was detected for the first time in hydrogen-doped float-zone-grown silicon samples subjected to annealing after electron irradiation. Previously this signal had been detected only in neutron- or proton-irradiated silicon samples. The absence of obscuring ESR peaks for the investigated samples at applied measurement conditions allowed an investigation of the hyperfine structure of the Si-B3 spectra. The analysis supports assignment of a tetra-interstitial defect as the origin of the signal.

Gadolinium-DTPA enhanced magnetic resonance imaging of bone cysts in patients with rheumatoid arthritis.

Science.gov (United States)

Gubler, F M; Algra, P R; Maas, M; Dijkstra, P F; Falke, T H

1993-01-01

OBJECTIVES--To examine the contents of intraosseous cysts in patients with rheumatoid arthritis (RA) through the signal intensity characteristics on gadolinium-DTPA (Gd-DTPA) enhanced magnetic resonance imaging. METHODS--The hand or foot joints of nine patients with the cystic form of RA (where the initial radiological abnormality consisted of intraosseous cysts without erosions) were imaged before and after intravenous administration of Gd-DTPA. A 0.6 unit, T1 weighted spin echo and T2* weighted gradient echo were used to obtain images in at least two perpendicular planes. RESULTS--Most cysts showed a low signal intensity on the non-enhanced T1 weighted (spin echo) images and a high signal intensity on the T2* weighted (gradient echo) images, consistent with a fluid content. No cyst showed an enhancement of signal intensity on the T1 weighted images after intravenous administration of Gd-DTPA, whereas synovium hyperplasia at the site of bony erosions did show an increased signal intensity after Gd-DTPA. Magnetic resonance imaging detected more cysts (as small as 2 mm) than plain films, and the cysts were located truly intraosseously. In six patients no other joint abnormalities were identified by magnetic resonance imaging; the three other patients also showed, after Gd-DTPA administration, an enhanced synovium at the site of bony erosions. CONCLUSIONS--It is suggested that intraosseous bone cysts in patients with RA do not contain hyperaemic synovial proliferation. The bone cysts in patients with the cystic form of RA may be the only joint abnormality. Images PMID:8257207

Unusual signal intensity of congenital pulmonary airway malformation on fetal magnetic resonance imaging

Energy Technology Data Exchange (ETDEWEB)

Owada, Keiho; Miyazaki, Osamu; Nosaka, Shunsuke [National Center for Child Health and Development, Department of Radiology, Tokyo (Japan); Matsuoka, Kentaro [National Center for Child Health and Development, Department of Pathology, Tokyo (Japan); Sago, Haruhiko [National Center for Child Health and Development, Department of Perinatal Medicine and Maternal Care, Tokyo (Japan)

2015-05-01

Congenital pulmonary airway malformation (CPAM) is classified into pathologically different types. These types are sometimes distinguishable by fetal lung MRI and are usually observed as higher-signal lesions on T2-weighted images than normal lung. We describe a case of unusual CPAM resembling neoplasms, with a lower signal than is found in normal lung. Histopathology showed a large number of mucogenic cells but found no evidence that could explain this feature on fetal MRI. An unusual low-signal mass associated with a pulmonary cyst in fetal lung on MRI may suggest an unusual type 1 CPAM. (orig.)

Unusual signal intensity of congenital pulmonary airway malformation on fetal magnetic resonance imaging

International Nuclear Information System (INIS)

Owada, Keiho; Miyazaki, Osamu; Nosaka, Shunsuke; Matsuoka, Kentaro; Sago, Haruhiko

2015-01-01

Congenital pulmonary airway malformation (CPAM) is classified into pathologically different types. These types are sometimes distinguishable by fetal lung MRI and are usually observed as higher-signal lesions on T2-weighted images than normal lung. We describe a case of unusual CPAM resembling neoplasms, with a lower signal than is found in normal lung. Histopathology showed a large number of mucogenic cells but found no evidence that could explain this feature on fetal MRI. An unusual low-signal mass associated with a pulmonary cyst in fetal lung on MRI may suggest an unusual type 1 CPAM. (orig.)

Proton magnetic resonance spectroscopy and perfusion magnetic resonance imaging in the evaluation of musculoskeletal tumors

International Nuclear Information System (INIS)

Costa, Flavia Martins; Setti, Marcela; Vianna, Evandro Miguelote; Domingues, Romulo Cortes; Meohas, Walter; Rezende, Jose Francisco; Gasparetto, Emerson Leandro

2009-01-01

Objective: To assess the role of proton magnetic resonance spectroscopy and dynamic contrast-enhanced magnetic resonance imaging in the differentiation between malignant and benign musculoskeletal tumors. Materials And Methods: Fifty-five patients with musculoskeletal tumors (27 malignant and 28 benign) were studied. The examinations were performed in a 1.5 T magnetic resonance scanner with standard protocol, and single voxel proton magnetic resonance spectroscopy with 135 msec echo time. The dynamic contrast study was performed using T1-weighted gradient-echo sequence after intravenous gadolinium injection. Time signal intensity curves and slope values were calculated. The statistical analysis was performed with the Levene's test, followed by a Student's t-test, besides the Pearson's chi-squared and Fischer's exact tests. Results: Proton magnetic resonance spectroscopy sensitivity, specificity and accuracy were, respectively, 87.5%, 92.3% and 90.9% (p < 0.0001). Statistically significant difference was observed in the slope (%/min) between benign (mean, 27.5%/min) and malignant (mean, 110.9%/min) lesions (p < 0.0001). Conclusion: The time-intensity curve and slope values using dynamic-enhanced perfusion magnetic resonance imaging in association with the presence of choline peak demonstrated by single voxel magnetic resonance spectroscopy study are useful in the differentiation between malignant and benign musculoskeletal tumors. (author)

Exploring on the Sensitivity Changes of the LC Resonance Magnetic Sensors Affected by Superposed Ringing Signals.

Science.gov (United States)

Lin, Tingting; Zhou, Kun; Yu, Sijia; Wang, Pengfei; Wan, Ling; Zhao, Jing

2018-04-25

LC resonance magnetic sensors are widely used in low-field nuclear magnetic resonance (LF-NMR) and surface nuclear magnetic resonance (SNMR) due to their high sensitivity, low cost and simple design. In magnetically shielded rooms, LC resonance magnetic sensors can exhibit sensitivities at the fT/√Hz level in the kHz range. However, since the equivalent magnetic field noise of this type of sensor is greatly affected by the environment, weak signals are often submerged in practical applications, resulting in relatively low signal-to-noise ratios (SNRs). To determine why noise increases in unshielded environments, we analysed the noise levels of an LC resonance magnetic sensor ( L ≠ 0) and a Hall sensor ( L ≈ 0) in different environments. The experiments and simulations indicated that the superposed ringing of the LC resonance magnetic sensors led to the observed increase in white noise level caused by environmental interference. Nevertheless, ringing is an inherent characteristic of LC resonance magnetic sensors. It cannot be eliminated when environmental interference exists. In response to this problem, we proposed a method that uses matching resistors with various values to adjust the quality factor Q of the LC resonance magnetic sensor in different measurement environments to obtain the best sensitivity. The LF-NMR experiment in the laboratory showed that the SNR is improved significantly when the LC resonance magnetic sensor with the best sensitivity is selected for signal acquisition in the light of the test environment. (When the matching resistance is 10 kΩ, the SNR is 3.46 times that of 510 Ω). This study improves LC resonance magnetic sensors for nuclear magnetic resonance (NMR) detection in a variety of environments.

The clinical study on high intensity zone of magnetic resonance imaging using Scolopendrid Aquacupuncture.

Directory of Open Access Journals (Sweden)

Jeong-a Lim

2006-12-01

Full Text Available Objective : This study was designed to find out the effect of scolopendrid aquacupuncture on low back pain with or without sciatica showing high intensity zone of magnetic resonance imaging. Methods : The 30 patients who had a diagnosis of high intensity zone by lumbar-MRI and admitted to Gwangju oriental medical hospital in wonkwang university from January 2005 to August 2004 were observed. The symptom of inpatients is low back pain with or without sciatica. We treated 30 patients by scolopendrid aquacupuncture besides the general conservative treatment of oriental medicine. Results and Conclusion : The scolopendrid aquacupuncture treatment led to improvement in the pain and symptom of disability as determined by all efficacy measures. After scolopendrid aquacupuncture treatment, there was improvement in VAS, ROM and SLRT. This results suggest that scolopendrid aquacupuncture is good method for treatment of low back pain with or without sciatica showing high intensity zone of magnetic resonance imaging.

Optimizing signal intensity correction during evaluation of hepatic parenchymal enhancement on gadoxetate disodium-enhanced MRI: Comparison of three methods

International Nuclear Information System (INIS)

Onoda, Minori; Hyodo, Tomoko; Murakami, Takamichi; Okada, Masahiro; Uto, Tatsuro; Hori, Masatoshi; Miyati, Tosiaki

2015-01-01

Highlights: •Signal intensity is often used to evaluate hepatic enhancement with Gd-EOB-DTPA in the hepatobiliary phase. •Comparison of uncorrected signal intensity with T 1 value revealed signal intensity instability. •Measurement of uncorrected liver SI or SNR often yields erroneous results on late-phase gadoxetate MRI due to shimming and other optimization techniques. •Signal intensity corrected by scale and rescale slope from DICOM data gave comparable results. -- Abstract: Objective: To compare signal intensity (SI) correction using scale and rescale slopes with SI correction using SIs of spleen and muscle for quantifying multiphase hepatic contrast enhancement with Gd-EOB-DTPA by assessing their correlation with T 1 values generated from Look-Locker turbo-field-echo (LL-TFE) sequence data (ER-T 1 ). Materials and methods: Thirty patients underwent Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) in this prospective clinical study. For each patient, breath-hold T 1 -weighted fat-suppressed three-dimensional (3D) gradient echo sequences (e-THRIVE) were acquired before and 2 (first phase), 10 (second phase), and 20 min (third phase) after intravenous Gd-EOB-DTPA. Look-Locker turbo-field-echo (LL-TFE) sequences were acquired before and 1.5 (first phase), 8 (second phase), and 18 min (third phase) postcontrast. The liver parenchyma enhancement ratios (ER) of each phase were calculated using the SI from e-THRIVE sequences (ER-SI) and the T 1 values generated from LL-TFE sequence data (ER-T 1 ) respectively. ER-SIs were calculated in three ways: (1) comparing with splenic SI (ER-SI-s), (2) comparing with muscle SI (ER-SI-m), (3) using scale and rescale slopes obtained from DICOM headers (ER-SI-c), to eliminate the effects of receiver gain and scaling. For each of the first, second and third phases, correlation and agreement were assessed between each ER-SI and ER-T 1 . Results: In the first phase, all ER-SIs correlated weakly with ER-T 1 . In the second

Development of a signal-extraction scheme for resonant sideband extraction

International Nuclear Information System (INIS)

Kokeyama, K; Kawazoe, F; Sugamoto, A; Somiya, K; Sato, S; Kawamura, S

2008-01-01

As a future plan, an advanced gravitational-wave detector will employ an optical configuration of resonant sideband extraction (RSE), achieved with an additional mirror at the signal-detection port of the power-recycled Fabry-Perot Michelson interferometer. To control the complex coupled cavity system, one of the most important design issues is how to extract the longitudinal control signals of the cavities. We have developed a new signal-extraction scheme which provides an appropriate sensing matrix. The new method uses two sets of sidebands: one of the sideband components satisfies the critical coupling condition for the RSE interferometer and reaches the signal-extraction port, and the other sideband is completely reflected by the Michelson interferometer. They provide a diagonalized sensing matrix and enable the RSE control to be robust

Localization of Coronary High-Intensity Signals on T1-Weighted MR Imaging: Relation to Plaque Morphology and Clinical Severity of Angina Pectoris.

Science.gov (United States)

Matsumoto, Kenji; Ehara, Shoichi; Hasegawa, Takao; Sakaguchi, Mikumo; Otsuka, Kenichiro; Yoshikawa, Junichi; Shimada, Kenei

2015-10-01

This study sought to investigate the relationship between localization of high-intensity signals (HISs) on T1-weighted imaging (T1WI) with the noncontrast magnetic resonance technique and plaque morphology detected on optical coherence tomography, and the clinical severity of angina pectoris. Since the introduction of the T1WI noncontrast magnetic resonance technique for plaque imaging, some groups have reported that HISs in the coronary artery on T1WI are associated with a vulnerable morphology and future cardiac events. However, the association between the localization of HISs, such as coronary intrawall or intraluminal, and plaque morphology has not been investigated. One hundred lesions with either stable or unstable angina were included and divided into 3 groups according to the following criteria using T1WI. First, the plaques with the ratio between the signal intensities of coronary plaque and cardiac muscle ≤1.0 were classified as non-HISs (n = 39). Then, HISs with the ratio between the signal intensities of coronary plaque and cardiac muscle >1.0 were classified into 2 types by using cross-sectional T1WI. Those localized within the coronary wall when the lumen was identified were defined as intrawall HISs (n = 37), whereas those occupying the lumen when the lumen was not, or even if only partly, identified, were defined as intraluminal HISs (n = 24). Multivariate analysis revealed that intrawall HISs were associated with macrophage accumulation and the absence of calcification assessed by using optical coherence tomography. In contrast, thrombus and intimal vasculature were independent factors associated with intraluminal HISs. Furthermore, 50% of patients with intraluminal HISs experienced rest angina, such as Braunwald class II or III. This study shows that intrawall and intraluminal HISs on T1WI in patients with angina are related to the different types of vulnerable plaque morphology and the clinical severity. Copyright © 2015 American College of

Internal additive noise effects in stochastic resonance using organic field effect transistor

Energy Technology Data Exchange (ETDEWEB)

Suzuki, Yoshiharu; Asakawa, Naoki [Division of Molecular Science, Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515 (Japan); Matsubara, Kiyohiko [KOOROGI LLC, 6-1585-1-B Sakaino-cho, Kiryu, Gunma 376-0002 (Japan)

2016-08-29

Stochastic resonance phenomenon was observed in organic field effect transistor using poly(3-hexylthiophene), which enhances performance of signal transmission with application of noise. The enhancement of correlation coefficient between the input and output signals was low, and the variation of correlation coefficient was not remarkable with respect to the intensity of external noise, which was due to the existence of internal additive noise following the nonlinear threshold response. In other words, internal additive noise plays a positive role on the capability of approximately constant signal transmission regardless of noise intensity, which can be said “homeostatic” behavior or “noise robustness” against external noise. Furthermore, internal additive noise causes emergence of the stochastic resonance effect even on the threshold unit without internal additive noise on which the correlation coefficient usually decreases monotonically.

Magnetic resonance imaging of acute spinal-cord injury

International Nuclear Information System (INIS)

Yamamoto, Hideki; Nakagawa, Hiroshi; Yamada, Takahisa; Iwata, Kinjiro; Okumura, Terufumi; Hoshino, Daisaku.

1992-01-01

Magnetic resonance imaging (MRI) provides a noninvasive and very important method of investigating spinal-cord injuries. By means of MRI we examined 36 patients with spinal injuries, 34 of them in the acute stage. 19 cases had complete spinal-cord injury with paraplegia, while 17 cases had incomplete spinal-cord injury. MRI showed the injured spinal-cord in the acute stage to be partially swollen, with a high signal intensity in the T 2 -weighted images. In the chronic stage, the injured cord may show atrophic changes with a post-traumatic cavity or myelomalacia, which appears as a high-signal-intensity lesion in the T 2 -weighted images and as a low-signal intensity in the T 1 -weighted images. The cases with complete spinal injuries showed a high signal intensity at the wide level, and these prognoses were poor. The cases with incomplete injuries showed normal findings or a high-signal-intensity spot. In the Gd-DTPA enhanced images, the injured cords were enhanced very well in the subchronic stage. MRI is thus found to be useful in the diagnosis of spinal injuries; it also demonstrates a potential for predicting the neurological prognosis. (author)

Intravenous injection of gadobutrol in an epidemiological study group did not lead to a difference in relative signal intensities of certain brain structures after 5 years

Energy Technology Data Exchange (ETDEWEB)

Kromrey, Marie-Luise; Liedtke, Kim Rouven; Langner, Soenke; Kirsch, Michael; Kuehn, Jens-Peter [University Medicine Greifswald, Institute of Diagnostic Radiology and Neuroradiology, Greifswald (Germany); Ittermann, Till [University Medicine Greifswald, Institute for Community Medicine, Greifswald (Germany); Weitschies, Werner [University Greifswald, Institute of Biopharmacy and Pharmaceutical Technology, Greifswald (Germany)

2017-02-15

To investigate if application of macrocyclic gadolinium-based contrast agents in volunteers is associated with neuronal deposition detected by magnetic resonance imaging in a 5-year longitudinal survey. Three hundred eighty-seven volunteers who participated in a population-based study were enrolled. Subjects underwent plain T1-weighted brain MRI at baseline and 5 years later with identical sequence parameters. At baseline, 271 participants additionally received intravenous injection of the macrocyclic contrast agent gadobutrol (1.5 mmol/kg). A control group including 116 subjects received no contrast agent. Relative signal intensities of thalamus, pallidum, pons and dentate nucleus were compared at baseline and follow-up. No difference in relative signal intensities was observed between contrast group (thalamus, p = 0.865; pallidum, p = 0.263; pons, p = 0.533; dentate nucleus, p = 0.396) and control group (thalamus, p = 0.683; pallidum; p = 0.970; pons, p = 0.773; dentate nucleus, p = 0.232) at both times. Comparison between both groups revealed no significant differences in relative signal intensities (thalamus, p = 0.413; pallidum, p = 0.653; pons, p = 0.460; dentate nucleus, p = 0.751). The study showed no significant change in globus pallidus-to-thalamus or dentate nucleus-to-pons ratios. Five years after administration of a 1.5-fold dose gadobutrol to normal subjects, signal intensity of thalamus, pallidum, pons and dentate nucleus did not differ from participants who had not received gadobutrol. (orig.)

MRI signal intensity as a maker of impairment in incomplete cervical spinal cord injuries

International Nuclear Information System (INIS)

Chiba, Hidefumi; Aoki, Haruhito; Hamabe, Masaki; Sasao, Yutaka; Miura, Takehiko

1998-01-01

Incomplete cervical spinal cord injuries such as central cord syndrome may result in prolonged spasticity of the limbs, especially disabilities of the upper extremities, even if the patient is able to walk. In this study, relationship between cord impairment and clinical outcome was investigated using MRI. Results showed that small foci of low signal intensity in T 1 -weighted imaging combined with foci of high signal intensity in T 2 -weighted imaging in follow-up MRI are closely related to the severity of sequelae. Small foci of low signal intensity in T 1 -weighted imaging are considered in the literature to indicate myelomalacia or cyst formation with gliosis. (author)

Categorization of aortic aneurysm thrombus morphology by magnetic resonance imaging

Energy Technology Data Exchange (ETDEWEB)

Motte, Louise de la, E-mail: louise.de.la.motte@rh.regionh.dk [Department of Vascular Surgery, Rigshospitalet and University of Copenhagen (Denmark); Pedersen, Mads Møller, E-mail: phd@medit.dk [Department of Radiology, Rigshospitalet and University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen (Denmark); Thomsen, Carsten, E-mail: carsten.thomsen@rh.regionh.dk [Department of Radiology, Rigshospitalet and University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen (Denmark); Vogt, Katja, E-mail: Vogt@dadlnet.dk [Department of Vascular Surgery, Rigshospitalet and University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen (Denmark); Schroeder, Torben V., E-mail: Torben.Veith.schroeder@rh.regionh.dk [Department of Vascular Surgery, Rigshospitalet and University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen (Denmark); Lonn, Lars, E-mail: lonn.lars@gmail.com [Department of Vascular Surgery and Department of Radiology, Rigshospitalet and University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen (Denmark)

2013-10-01

Background: Magnetic resonance imaging (MRI) has been proposed for qualitative categorization of intraluminal thrombus morphology. We aimed to correlate the qualitative MRI categorization previously described to quantitative measurements of signal intensity and to compare morphological characteristics of intraluminal thrombus specimens to the appearance on magnetic resonance imaging. Methods: Thirty-four patients undergoing open surgery for abdominal aortic aneurysm had a preoperative MRI obtained with a 1.5 T magnet. Qualitative categorization was performed (blinded and in consensus) and correlated to intraluminal thrombus to muscle signal-intensity ratios. Morphology of intraluminal thrombus specimens collected during surgery were compared to the magnetic resonance imaging categories and specimen weight was correlated to thrombus volume measured on preoperative computer tomography angiography. Results: Blinded MRI categorization resulted in agreement in 22 out of 34 intraluminal thrombi (Kappa value 0.3, p = 0.006). Medians (p = 0.004) and distribution (p = 0.002) of signal-intensity ratios varied significantly across the three MRI categories obtained by consensus. Heterogeneous and homogenous specimen appearance corresponded to similar appearances on MRI in 78% and 55% respectively, resulting in an overall Kappa = 0.4 (p = 0.04). Intraluminal thrombus volume and weight correlated well (r{sub s} 0.831, p < 0.001) with a mean difference of 60 g (95% CI 38–80 g), without proportional bias. Conclusion: Qualitative evaluation of intraluminal thrombus morphology based on MRI can be quantified by measuring signal-intensity ratios. Concurrently a fair agreement to blinded qualitative evaluation of thrombus specimens can be obtained. However, the evaluation is impaired by loss of a large proportion of thrombus during sampling.

Categorization of aortic aneurysm thrombus morphology by magnetic resonance imaging

International Nuclear Information System (INIS)

Motte, Louise de la; Pedersen, Mads Møller; Thomsen, Carsten; Vogt, Katja; Schroeder, Torben V.; Lonn, Lars

2013-01-01

Background: Magnetic resonance imaging (MRI) has been proposed for qualitative categorization of intraluminal thrombus morphology. We aimed to correlate the qualitative MRI categorization previously described to quantitative measurements of signal intensity and to compare morphological characteristics of intraluminal thrombus specimens to the appearance on magnetic resonance imaging. Methods: Thirty-four patients undergoing open surgery for abdominal aortic aneurysm had a preoperative MRI obtained with a 1.5 T magnet. Qualitative categorization was performed (blinded and in consensus) and correlated to intraluminal thrombus to muscle signal-intensity ratios. Morphology of intraluminal thrombus specimens collected during surgery were compared to the magnetic resonance imaging categories and specimen weight was correlated to thrombus volume measured on preoperative computer tomography angiography. Results: Blinded MRI categorization resulted in agreement in 22 out of 34 intraluminal thrombi (Kappa value 0.3, p = 0.006). Medians (p = 0.004) and distribution (p = 0.002) of signal-intensity ratios varied significantly across the three MRI categories obtained by consensus. Heterogeneous and homogenous specimen appearance corresponded to similar appearances on MRI in 78% and 55% respectively, resulting in an overall Kappa = 0.4 (p = 0.04). Intraluminal thrombus volume and weight correlated well (r s 0.831, p < 0.001) with a mean difference of 60 g (95% CI 38–80 g), without proportional bias. Conclusion: Qualitative evaluation of intraluminal thrombus morphology based on MRI can be quantified by measuring signal-intensity ratios. Concurrently a fair agreement to blinded qualitative evaluation of thrombus specimens can be obtained. However, the evaluation is impaired by loss of a large proportion of thrombus during sampling

All-optical 10 Gb/s AND logic gate in a silicon microring resonator

DEFF Research Database (Denmark)

Xiong, Meng; Lei, Lei; Ding, Yunhong

2013-01-01

An all-optical AND logic gate in a single silicon microring resonator is experimentally demonstrated at 10 Gb/s with 50% RZ-OOK signals. By setting the wavelengths of two intensity-modulated input pumps on the resonances of the microring resonator, field-enhanced four-wave mixing with a total inp...... power of only 8.5 dBm takes place in the ring, resulting in the generation of an idler whose intensity follows the logic operation between the pumps. Clear and open eye diagrams with a bit-error- ratio below 10−9 are achieved....

A method for quantifying intervertebral disc signal intensity on T2-weighted imaging

International Nuclear Information System (INIS)

Nagashima, Masaki; Abe, Hitoshi; Amaya, Kenji; Matsumoto, Hideo; Yanaihara, Hisashi; Nishiwaki, Yuji; Toyama, Yoshiaki; Matsumoto, Morio

2012-01-01

Background Quantification of intervertebral disc degeneration based on intensity of the nucleus pulposus in magnetic resonance imaging (MRI) often uses the mean intensity of the region of interest (ROI) within the nucleus pulposus. However, the location and size of ROI have varied in different reports, and none of the reported methods can be considered fully objective. Purpose To develop a more objective method of establishing ROIs for quantitative evaluation of signal intensity in the nucleus pulposus using T2-weighted MRI. Material and Methods A 1.5-T scanner was used to obtain T2-weighted mid-sagittal images. A total of 288 intervertebral discs from 48 patients (25 men, 23 women) were analyzed. Mean age was 47.4 years (range, 17-69 years). All discs were classified into five grades according to Pfirrmann et al. Discs in grades I and II were defined as bright discs, and discs in grades IV and V were defined as dark discs. Eight candidate methods of ROI determination were devised. The method offering the highest degree of discrimination between bright and dark discs was investigated among these eight methods. Results The method with the greatest degree of discrimination was as follows. The quadrangle formed by anterior and posterior edges of the upper and lower end plates in contact with the intervertebral disc to be measured was defined as the intervertebral area. A shape similar to the intervertebral area but with one-quarter the area was drawn. The geometrical center of the shape was matched to the center of intensity, and this shape was then used as the ROI. Satisfactory validity and reproducibility were obtained using this method. Conclusion The present method offers adequate discrimination and could be useful for longitudinal tracking of intervertebral disc degeneration with sufficient reproducibility

A method for quantifying intervertebral disc signal intensity on T2-weighted imaging

Energy Technology Data Exchange (ETDEWEB)

Nagashima, Masaki [Dept. of Orthopaedic Surgery, Keio Univ. School of Medicine, Tokyo (Japan); Dept. of Orthopaedic Surgery, Kitasato Univ. Kitasato Inst. Hospital, Tokyo (Japan); Abe, Hitoshi [Dept. of Orthopaedic Surgery, Kitasato Univ. Kitasato Inst. Hospital, Tokyo (Japan)], E-mail: hit-abe@insti.kitasato-u.ac.jp; Amaya, Kenji [Graduate School of Information Science and Engineering, Tokyo Inst. of Technology, Tokyo (Japan); Matsumoto, Hideo [Inst. for Integrated Sports Medicine, Keio Univ. School of Medicine, Tokyo (Japan); Yanaihara, Hisashi [Dept. of Diagnostic Radiology, Kitasato Univ. Kitasato Inst. Hospital, Tokyo (Japan); Nishiwaki, Yuji [Dept. of Environmental and Occupational Health, Toho Univ. School of Medicine, Tokyo (Japan); Toyama, Yoshiaki; Matsumoto, Morio [Dept. of Orthopaedic Surgery, Keio Univ. School of Medicine, Tokyo (Japan)

2012-11-15

Background Quantification of intervertebral disc degeneration based on intensity of the nucleus pulposus in magnetic resonance imaging (MRI) often uses the mean intensity of the region of interest (ROI) within the nucleus pulposus. However, the location and size of ROI have varied in different reports, and none of the reported methods can be considered fully objective. Purpose To develop a more objective method of establishing ROIs for quantitative evaluation of signal intensity in the nucleus pulposus using T2-weighted MRI. Material and Methods A 1.5-T scanner was used to obtain T2-weighted mid-sagittal images. A total of 288 intervertebral discs from 48 patients (25 men, 23 women) were analyzed. Mean age was 47.4 years (range, 17-69 years). All discs were classified into five grades according to Pfirrmann et al. Discs in grades I and II were defined as bright discs, and discs in grades IV and V were defined as dark discs. Eight candidate methods of ROI determination were devised. The method offering the highest degree of discrimination between bright and dark discs was investigated among these eight methods. Results The method with the greatest degree of discrimination was as follows. The quadrangle formed by anterior and posterior edges of the upper and lower end plates in contact with the intervertebral disc to be measured was defined as the intervertebral area. A shape similar to the intervertebral area but with one-quarter the area was drawn. The geometrical center of the shape was matched to the center of intensity, and this shape was then used as the ROI. Satisfactory validity and reproducibility were obtained using this method. Conclusion The present method offers adequate discrimination and could be useful for longitudinal tracking of intervertebral disc degeneration with sufficient reproducibility.

Intensity inhomogeneity correction for magnetic resonance imaging of human brain at 7T

International Nuclear Information System (INIS)

Uwano, Ikuko; Yamashita, Fumio; Higuchi, Satomi; Ito, Kenji; Sasaki, Makoto; Kudo, Kohsuke; Goodwin, Jonathan; Harada, Taisuke; Ogawa, Akira

2014-01-01

Purpose: To evaluate the performance and efficacy for intensity inhomogeneity correction of various sequences of the human brain in 7T MRI using the extended version of the unified segmentation algorithm. Materials: Ten healthy volunteers were scanned with four different sequences (2D spin echo [SE], 3D fast SE, 2D fast spoiled gradient echo, and 3D time-of-flight) by using a 7T MRI system. Intensity inhomogeneity correction was performed using the “New Segment” module in SPM8 with four different values (120, 90, 60, and 30 mm) of full width at half maximum (FWHM) in Gaussian smoothness. The uniformity in signals in the entire white matter was evaluated using the coefficient of variation (CV); mean signal intensities between the subcortical and deep white matter were compared, and contrast between subcortical white matter and gray matter was measured. The length of the lenticulostriate (LSA) was measured on maximum intensity projection (MIP) images in the original and corrected images. Results: In all sequences, the CV decreased as the FWHM value decreased. The differences of mean signal intensities between subcortical and deep white matter also decreased with smaller FWHM values. The contrast between white and gray matter was maintained at all FWHM values. LSA length was significantly greater in corrected MIP than in the original MIP images. Conclusions: Intensity inhomogeneity in 7T MRI can be successfully corrected using SPM8 for various scan sequences

Intensity inhomogeneity correction for magnetic resonance imaging of human brain at 7T.

Science.gov (United States)

Uwano, Ikuko; Kudo, Kohsuke; Yamashita, Fumio; Goodwin, Jonathan; Higuchi, Satomi; Ito, Kenji; Harada, Taisuke; Ogawa, Akira; Sasaki, Makoto

2014-02-01

To evaluate the performance and efficacy for intensity inhomogeneity correction of various sequences of the human brain in 7T MRI using the extended version of the unified segmentation algorithm. Ten healthy volunteers were scanned with four different sequences (2D spin echo [SE], 3D fast SE, 2D fast spoiled gradient echo, and 3D time-of-flight) by using a 7T MRI system. Intensity inhomogeneity correction was performed using the "New Segment" module in SPM8 with four different values (120, 90, 60, and 30 mm) of full width at half maximum (FWHM) in Gaussian smoothness. The uniformity in signals in the entire white matter was evaluated using the coefficient of variation (CV); mean signal intensities between the subcortical and deep white matter were compared, and contrast between subcortical white matter and gray matter was measured. The length of the lenticulostriate (LSA) was measured on maximum intensity projection (MIP) images in the original and corrected images. In all sequences, the CV decreased as the FWHM value decreased. The differences of mean signal intensities between subcortical and deep white matter also decreased with smaller FWHM values. The contrast between white and gray matter was maintained at all FWHM values. LSA length was significantly greater in corrected MIP than in the original MIP images. Intensity inhomogeneity in 7T MRI can be successfully corrected using SPM8 for various scan sequences.

Stochastic resonance in feedforward acupuncture networks

Science.gov (United States)

Qin, Ying-Mei; Wang, Jiang; Men, Cong; Deng, Bin; Wei, Xi-Le; Yu, Hai-Tao; Chan, Wai-Lok

2014-10-01

Effects of noises and some other network properties on the weak signal propagation are studied systematically in feedforward acupuncture networks (FFN) based on FitzHugh-Nagumo neuron model. It is found that noises with medium intensity can enhance signal propagation and this effect can be further increased by the feedforward network structure. Resonant properties in the noisy network can also be altered by several network parameters, such as heterogeneity, synapse features, and feedback connections. These results may also provide a novel potential explanation for the propagation of acupuncture signal.

Stochastic resonance and stability for a stochastic metapopulation system subjected to non-Gaussian noise and multiplicative periodic signal

International Nuclear Information System (INIS)

Kang-Kang, Wang; Xian-Bin, Liu; Yu, Zhou

2015-01-01

In this paper, the stability and stochastic resonance (SR) phenomenon induced by the multiplicative periodic signal for a metapopulation system driven by the additive Gaussian noise, multiplicative non-Gaussian noise and noise correlation time is investigated. By using the fast descent method, unified colored noise approximation and McNamara and Wiesenfeld’s SR theory, the analytical expressions of the stationary probability distribution function and signal-to-noise ratio (SNR) are derived in the adiabatic limit. Via numerical calculations, each effect of the addictive noise intensity, the multiplicative noise intensity and the correlation time upon the steady state probability distribution function and the SNR is discussed, respectively. It is shown that multiplicative, additive noises and the departure parameter from the Gaussian noise can all destroy the stability of the population system. However, the noise correlation time can consolidate the stability of the system. On the other hand, the correlation time always plays an important role in motivating the SR and enhancing the SNR. Under different parameter conditions of the system, the multiplicative, additive noises and the departure parameter can not only excite SR phenomenon, but also restrain the SR phenomenon, which demonstrates the complexity of different noises upon the nonlinear system. (paper)

The design of photoelectric signal processing system for a nuclear magnetic resonance gyroscope based on FPGA

Science.gov (United States)

Zhang, Xian; Zhou, Binquan; Li, Hong; Zhao, Xinghua; Mu, Weiwei; Wu, Wenfeng

2017-10-01

Navigation technology is crucial to the national defense and military, which can realize the measurement of orientation, positioning, attitude and speed for moving object. Inertial navigation is not only autonomous, real-time, continuous, hidden, undisturbed but also no time-limited and environment-limited. The gyroscope is the core component of the inertial navigation system, whose precision and size are the bottleneck of the performance. However, nuclear magnetic resonance gyroscope is characteristic of the advantage of high precision and small size. Nuclear magnetic resonance gyroscope can meet the urgent needs of high-tech weapons and equipment development of new generation. This paper mainly designs a set of photoelectric signal processing system for nuclear magnetic resonance gyroscope based on FPGA, which process and control the information of detecting laser .The photoelectric signal with high frequency carrier is demodulated by in-phase and quadrature demodulation method. Finally, the processing system of photoelectric signal can compensate the residual magnetism of the shielding barrel and provide the information of nuclear magnetic resonance gyroscope angular velocity.

Modeling the diffusion magnetic resonance imaging signal inside neurons

International Nuclear Information System (INIS)

Nguyen, D V; Li, J R; Grebenkov, D S; Le Bihan, D

2014-01-01

The Bloch-Torrey partial differential equation (PDE) describes the complex transverse water proton magnetization due to diffusion-encoding magnetic field gradient pulses. The integral of the solution of this PDE yields the diffusion magnetic resonance imaging (dMRI) signal. In a complex medium such as cerebral tissue, it is difficult to explicitly link the dMRI signal to biological parameters such as the cellular geometry or the cellular volume fraction. Studying the dMRI signal arising from a single neuron can provide insight into how the geometrical structure of neurons influences the measured signal. We formulate the Bloch-Torrey PDE inside a single neuron, under no water exchange condition with the extracellular space, and show how to reduce the 3D simulation in the full neuron to a 3D simulation around the soma and 1D simulations in the neurites. We show that this latter approach is computationally much faster than full 3D simulation and still gives accurate results over a wide range of diffusion times

Parametric roll resonance monitoring using signal-based detection

DEFF Research Database (Denmark)

Galeazzi, Roberto; Blanke, Mogens; Falkenberg, Thomas

2015-01-01

Extreme roll motion of ships can be caused by several phenomena, one of which is parametric roll resonance. Several incidents occurred unexpectedly around the millennium and caused vast fiscal losses on large container vessels. The phenomenon is now well understood and some consider parametric roll...... algorithms in real conditions, and to evaluate the frequency of parametric roll events on the selected vessels. Detection performance is scrutinised through the validation of the detected events using owners’ standard methods, and supported by available wave radar data. Further, a bivariate statistical...... analysis of the outcome of the signal-based detectors is performed to assess the real life false alarm probability. It is shown that detection robustness and very low false warning rates are obtained. The study concludes that small parametric roll events are occurring, and that the proposed signal...

Categorization of aortic aneurysm thrombus morphology by magnetic resonance imaging

DEFF Research Database (Denmark)

de la Motte, Louise; Pedersen, Mads Møller; Thomsen, Carsten

2013-01-01

Magnetic resonance imaging (MRI) has been proposed for qualitative categorization of intraluminal thrombus morphology. We aimed to correlate the qualitative MRI categorization previously described to quantitative measurements of signal intensity and to compare morphological characteristics...

Stochastic resonance for a metapopulation system driven by multiplicative and additive colored noises

International Nuclear Information System (INIS)

Wang Kang-Kang; Liu Xian-Bin

2014-01-01

We investigate the stochastic resonance (SR) phenomenon induced by the periodic signal in a metapopulation system with colored noises. The analytical expression of signal-to-noise is derived in the adiabatic limit. By numerical calculation, the effects of the addictive noise intensity, the multiplicative noise intensity and two noise self-correlation times on SNR are respectively discussed. It shows that: (i) in the case that the addictive noise intensity M takes a small value, a SR phenomenon for the curve of SNR appears; however, when M takes a large value, SNR turns into a monotonic function on the multiplicative noise intensity Q. (ii) The resonance peaks in the plots of the multiplicative noise intensity Q versus its self-correlation time τ 1 and the addictive noise intensity M versus its self-correlation time τ 2 translate in parallel. Meanwhile, a parallel translation also appears in the plots of τ 1 versus Q and τ 2 versus M. (iii) The interactive effects between self-correlation times τ 1 and τ 2 are opposite. (general)

Resonance Energy Transfer Molecular Imaging Application in Biomedicine

Directory of Open Access Journals (Sweden)

NIE Da-hong1,2;TANG Gang-hua1,3

2016-11-01

Full Text Available Resonance energy transfer molecular imaging (RETI can markedly improve signal intensity and tissue penetrating capacity of optical imaging, and have huge potential application in the deep-tissue optical imaging in vivo. Resonance energy transfer (RET is an energy transition from the donor to an acceptor that is in close proximity, including non-radiative resonance energy transfer and radiative resonance energy transfer. RETI is an optical imaging technology that is based on RET. RETI mainly contains fluorescence resonance energy transfer imaging (FRETI, bioluminescence resonance energy transfer imaging (BRETI, chemiluminescence resonance energy transfer imaging (CRETI, and radiative resonance energy transfer imaging (RRETI. RETI is the hot field of molecular imaging research and has been widely used in the fields of biology and medicine. This review mainly focuses on RETI principle and application in biomedicine.

Functional magnetic resonance imaging of higher brain activity

International Nuclear Information System (INIS)

Cui He; Wang Yunjiu; Chen Runsheng; Tang Xiaowei.

1996-01-01

Functional magnetic resonance images (fMRIs) exhibit small differences in the magnetic resonance signal intensity in positions corresponding to focal areas of brain activation. These signal are caused by variation in the oxygenation state of the venous vasculature. Using this non-invasive and dynamic method, it is possible to localize functional brain activation, in vivo, in normal individuals, with an accuracy of millimeters and a temporal resolution of seconds. Though a series of technical difficulties remain, fMRI is increasingly becoming a key method for visualizing the working brain, and uncovering the topographical organization of the human brain, and understanding the relationship between brain and the mind

Clinical significance of the globus pallidus signal intensity ratio in patients with liver cirrhosis

Energy Technology Data Exchange (ETDEWEB)

Iwasa, Motoh; Kawamura, Noriko; Hiranuma, Kiyohiko [Kuwana Municipal Hospital, Mie (Japan)] [and others

1996-11-01

The object of this study was to evaluate the clinical value of the globus pallidus signal intensity ratio for the subclinical detection of hepatic encephalopathy. This study comprised 25 patients with liver cirrhosis without overt hepatic encephalopathy. There was a high frequency (56%) of patients exhibiting increased signal in the globus pallidus. The pallidal signal was related to the severity of the liver disease. The auditory brain stem reaction was not correlated with the pallidal intensity and laboratory parameters. During the follow-up study, 3 out of 5 patients presenting overt hepatic encephalopathy showed strong pallidal signals. The results of this investigation suggest that abnormal globus pallidus signal may constitute a useful method for the subclinical detection of hepatic encepalopathy. (author)

Clinical significance of the globus pallidus signal intensity ratio in patients with liver cirrhosis

International Nuclear Information System (INIS)

Iwasa, Motoh; Kawamura, Noriko; Hiranuma, Kiyohiko

1996-01-01

The object of this study was to evaluate the clinical value of the globus pallidus signal intensity ratio for the subclinical detection of hepatic encephalopathy. This study comprised 25 patients with liver cirrhosis without overt hepatic encephalopathy. There was a high frequency (56%) of patients exhibiting increased signal in the globus pallidus. The pallidal signal was related to the severity of the liver disease. The auditory brain stem reaction was not correlated with the pallidal intensity and laboratory parameters. During the follow-up study, 3 out of 5 patients presenting overt hepatic encephalopathy showed strong pallidal signals. The results of this investigation suggest that abnormal globus pallidus signal may constitute a useful method for the subclinical detection of hepatic encepalopathy. (author)

Optimizing signal intensity correction during evaluation of hepatic parenchymal enhancement on gadoxetate disodium-enhanced MRI: Comparison of three methods

Energy Technology Data Exchange (ETDEWEB)

Onoda, Minori, E-mail: onoda@radt.med.kindai.ac.jp [Department of Radiological Technology, Kinki University Hospital, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511 (Japan); Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa 920-0942 (Japan); Hyodo, Tomoko, E-mail: neneth@m.ehime-u.ac.jp [Department of Radiology, Kinki University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511 (Japan); Murakami, Takamichi, E-mail: murakami@med.kindai.ac.jp [Department of Radiology, Kinki University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511 (Japan); Okada, Masahiro, E-mail: okada777@med.u-ryukyu.ac.jp [Department of Radiology, Kinki University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511 (Japan); Uto, Tatsuro, E-mail: chuho@med.kindai.ac.jp [Department of Radiological Technology, Kinki University Hospital, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511 (Japan); Hori, Masatoshi, E-mail: mhori@radiol.med.osaka-u.ac.jp [Department of Radiology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871 (Japan); Miyati, Tosiaki, E-mail: ramiyati@mhs.mp.kanazawa-u.ac.jp [Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa 920-0942 (Japan)

2015-03-15

Highlights: •Signal intensity is often used to evaluate hepatic enhancement with Gd-EOB-DTPA in the hepatobiliary phase. •Comparison of uncorrected signal intensity with T{sub 1} value revealed signal intensity instability. •Measurement of uncorrected liver SI or SNR often yields erroneous results on late-phase gadoxetate MRI due to shimming and other optimization techniques. •Signal intensity corrected by scale and rescale slope from DICOM data gave comparable results. -- Abstract: Objective: To compare signal intensity (SI) correction using scale and rescale slopes with SI correction using SIs of spleen and muscle for quantifying multiphase hepatic contrast enhancement with Gd-EOB-DTPA by assessing their correlation with T{sub 1} values generated from Look-Locker turbo-field-echo (LL-TFE) sequence data (ER-T{sub 1}). Materials and methods: Thirty patients underwent Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) in this prospective clinical study. For each patient, breath-hold T{sub 1}-weighted fat-suppressed three-dimensional (3D) gradient echo sequences (e-THRIVE) were acquired before and 2 (first phase), 10 (second phase), and 20 min (third phase) after intravenous Gd-EOB-DTPA. Look-Locker turbo-field-echo (LL-TFE) sequences were acquired before and 1.5 (first phase), 8 (second phase), and 18 min (third phase) postcontrast. The liver parenchyma enhancement ratios (ER) of each phase were calculated using the SI from e-THRIVE sequences (ER-SI) and the T{sub 1} values generated from LL-TFE sequence data (ER-T{sub 1}) respectively. ER-SIs were calculated in three ways: (1) comparing with splenic SI (ER-SI-s), (2) comparing with muscle SI (ER-SI-m), (3) using scale and rescale slopes obtained from DICOM headers (ER-SI-c), to eliminate the effects of receiver gain and scaling. For each of the first, second and third phases, correlation and agreement were assessed between each ER-SI and ER-T{sub 1}. Results: In the first phase, all ER-SIs correlated

Pump-to-Signal Intensity Modulation Transfer in Saturated- Gain Fiber Optical Parametric Amplifiers

DEFF Research Database (Denmark)

Lali-Dastjerdi, Zohreh; Lund-Hansen, Toke; Rottwitt, Karsten

2011-01-01

The pump-to-signal intensity modulation transfer in saturated degenerate FOPAs is numerically investigated over the whole gain bandwidth. The intensity modulation transfer decreases and the OSNR improves when the amplifier operates in the saturation regime....

Transmission Property of Directly Modulated Signals Enhanced by a Micro-ring Resonator

DEFF Research Database (Denmark)

An, Yi; Lorences Riesgo, Abel; Seoane, Jorge

2012-01-01

A silicon micro-ring resonator is used to enhance the modulation speed of a 10-Gbit/s directly modulated laser to 40 Gbit/s. The generated signal is transmitted error free over 4.5 km SSMF. Dispersion tolerance is also studied....

Analysis of Magnetic Resonance Image Signal Fluctuations Acquired During MR-Guided Radiotherapy.

Science.gov (United States)

Breto, Adrian L; Padgett, Kyle R; Ford, John C; Kwon, Deukwoo; Chang, Channing; Fuss, Martin; Stoyanova, Radka; Mellon, Eric A

2018-03-28

Magnetic resonance-guided radiotherapy (MRgRT) is a new and evolving treatment modality that allows unprecedented visualization of the tumor and surrounding anatomy. MRgRT includes daily 3D magnetic resonance imaging (MRI) for setup and rapidly repeated near real-time MRI scans during treatment for target tracking. One of the more exciting potential benefits of MRgRT is the ability to analyze serial MRIs to monitor treatment response or predict outcomes. A typical radiation treatment (RT) over the span of 10-15 minutes on the MRIdian system (ViewRay, Cleveland, OH) yields thousands of "cine" images, each acquired in 250 ms. This unique data allows for a glimpse in image intensity changes during RT delivery. In this report, we analyze cine images from a single fraction RT of a glioblastoma patient on the ViewRay platform in order to characterize the dynamic signal changes occurring during RT therapy. The individual frames in the cines were saved into DICOM format and read into an MIM image analysis platform (MIM Software, Cleveland, OH) as a time series. The three possible states of the three Cobalt-60 radiation sources-OFF, READY, and ON-were also recorded. An in-house Java plugin for MIM was created in order to perform principal component analysis (PCA) on each of the datasets. The analysis resulted in first PC, related to monotonous signal increase over the course of the treatment fraction. We found several distortion patterns in the data that we postulate result from the perturbation of the magnetic field due to the moving metal parts in the platform while treatment was being administered. The largest variations were detected when all Cobalt-60 sources were OFF. During this phase of the treatment, the gantry and multi-leaf collimators (MLCs) are moving. Conversely, when all Cobalt-60 sources were in the ON position, the image signal fluctuations were minimal, relating to very little mechanical motion. At this phase, the gantry, the MLCs, and sources are fixed

A Modified Adaptive Stochastic Resonance for Detecting Faint Signal in Sensors

Directory of Open Access Journals (Sweden)

Hengwei Li

2007-02-01

Full Text Available In this paper, an approach is presented to detect faint signals with strong noises in sensors by stochastic resonance (SR. We adopt the power spectrum as the evaluation tool of SR, which can be obtained by the fast Fourier transform (FFT. Furthermore, we introduce the adaptive filtering scheme to realize signal processing automatically. The key of the scheme is how to adjust the barrier height to satisfy the optimal condition of SR in the presence of any input. For the given input signal, we present an operable procedure to execute the adjustment scheme. An example utilizing one audio sensor to detect the fault information from the power supply is given. Simulation results show that th

Reflecting on mirror mechanisms: motor resonance effects during action observation only present with low-intensity transcranial magnetic stimulation.

Directory of Open Access Journals (Sweden)

Michela Loporto

Full Text Available Transcranial magnetic stimulation (TMS studies indicate that the observation of other people's actions influences the excitability of the observer's motor system. Motor evoked potential (MEP amplitudes typically increase in muscles which would be active during the execution of the observed action. This 'motor resonance' effect is thought to result from activity in mirror neuron regions, which enhance the excitability of the primary motor cortex (M1 via cortico-cortical pathways. The importance of TMS intensity has not yet been recognised in this area of research. Low-intensity TMS predominately activates corticospinal neurons indirectly, whereas high-intensity TMS can directly activate corticospinal axons. This indicates that motor resonance effects should be more prominent when using low-intensity TMS. A related issue is that TMS is typically applied over a single optimal scalp position (OSP to simultaneously elicit MEPs from several muscles. Whether this confounds results, due to differences in the manner that TMS activates spatially separate cortical representations, has not yet been explored. In the current study, MEP amplitudes, resulting from single-pulse TMS applied over M1, were recorded from the first dorsal interosseous (FDI and abductor digiti minimi (ADM muscles during the observation of simple finger abductions. We tested if the TMS intensity (110% vs. 130% resting motor threshold or stimulating position (FDI-OSP vs. ADM-OSP influenced the magnitude of the motor resonance effects. Results showed that the MEP facilitation recorded in the FDI muscle during the observation of index-finger abductions was only detected using low-intensity TMS. In contrast, changes in the OSP had a negligible effect on the presence of motor resonance effects in either the FDI or ADM muscles. These findings support the hypothesis that MN activity enhances M1 excitability via cortico-cortical pathways and highlight a methodological framework by which the

Clinical significance of pontine high signals identified on magnetic resonance imaging

Energy Technology Data Exchange (ETDEWEB)

Watanabe, Masaki; Takahashi, Akira (Nagoya Univ. (Japan). Faculty of Medicine); Arahata, Yutaka; Motegi, Yoshimasa; Furuse, Masahiro

1993-07-01

Spin-echo magnetic resonance imaging (MRI) was evaluated to 530 cases in order to investigate the clinical significance of pontine high signals. The subjects comprised 109 cases of pontine infarction with high signal on T[sub 2]-weighted image and low signal on T[sub 1]-weighted image (PI group), 145 of pontine high signal with high signal on T[sub 2]-weighted image but normal signal on T[sub 1]-weighted image (PH group) and 276 of age-matched control without abnormality either on T[sub 1] or T[sub 2]-weighted images (AC group). Subjective complaints such as vertigo-dizziness were more frequent in the PH group than in the PI group. In both PI and groups, periventricular hyperintensity as well as subcortical high signals in the supratentorium were more severe than in the AC group. These degrees were higher in the PI group than in the PH group. In conclusion, PH as well as PI may result from diffuse arteriosclerosis and PH is considered to be an early finding of pontine ischemia. (author).

Clinical significance of pontine high signals identified on magnetic resonance imaging

International Nuclear Information System (INIS)

Watanabe, Masaki; Takahashi, Akira; Arahata, Yutaka; Motegi, Yoshimasa; Furuse, Masahiro.

1993-01-01

Spin-echo magnetic resonance imaging (MRI) was evaluated to 530 cases in order to investigate the clinical significance of pontine high signals. The subjects comprised 109 cases of pontine infarction with high signal on T 2 -weighted image and low signal on T 1 -weighted image (PI group), 145 of pontine high signal with high signal on T 2 -weighted image but normal signal on T 1 -weighted image (PH group) and 276 of age-matched control without abnormality either on T 1 or T 2 -weighted images (AC group). Subjective complaints such as vertigo-dizziness were more frequent in the PH group than in the PI group. In both PI and groups, periventricular hyperintensity as well as subcortical high signals in the supratentorium were more severe than in the AC group. These degrees were higher in the PI group than in the PH group. In conclusion, PH as well as PI may result from diffuse arteriosclerosis and PH is considered to be an early finding of pontine ischemia. (author)

Stochastic Resonance-Like and Resonance Suppression-Like Phenomena in a Bistable System with Time Delay and Additive Noise

International Nuclear Information System (INIS)

Shu Chang-Zheng; Nie Lin-Ru; Zhou Zhong-Rao

2012-01-01

Stochastic resonance (SR)-like and resonance suppression (RS)-like phenomena in a time-delayed bistable system driven by additive white noise are investigated by means of stochastic simulations of the power spectrum, the quality factor of the power spectrum, and the mean first-passage time (MFPT) of the system. The calculative results indicate that: (i) as the system is driven by a small periodic signal, the quality factor as a function delay time exhibits a maximal value at smaller noise intensities, i.e., an SR-like phenomenon. With the increment in additive noise intensity, the extremum gradually disappears and the quality factor decreases monotonously with delay time. (ii) As the additive noise intensity is smaller, the curve of the MFPT with respect to delay time displays a peak, i.e., an RS-like phenomenon. At higher levels of noise, however, the non-monotonic behavior is lost. (general)

Effect of the luminol signal enhancer on the chemiluminescence intensity and kinetics

International Nuclear Information System (INIS)

Liang Yanli; Yu Fei; Yu Songcheng; Wu Yongjun; Zhang Hongquan; Qu Lingbo

2012-01-01

The novel p-phenol derivatives, 4-(1-imidazolyl)-phenol, 4-hydroxybiphenyl, 4-hydroxy-4′-iodobiphenyl were employed as highly potent signal enhancers of luminol-hydrogen peroxide (H 2 O 2 )-horseradish peroxidase (HRP) chemiluminescence (CL) system. The CL reaction conditions were optimized, and the enhancement characteristics of these enhancers were compared with each other. The employment of these molecules greatly affected important assay parameters. Practically, the use of a novel enhancer, even a slightly change of the structure (or concentration) of 4-substituted phenol derivative, could affect assay properties quite dramatically. Furthermore, the use of different enhancers in the luminol–H 2 O 2 –HRP system can affect not only the intensity of the CL signal, which is well known, but also its kinetics. The experiment data indicated that the stronger intensity was combined with a more rapid decrease of the CL signal. - Highlights: ► 4-IMP, 4-BIP and HIOP take on different signal enhancement and light kinetics. ► The employment of 4-BIP resulted in a significant improvement of the detection limit. ► The magnitude of the signal enhancement was about 2.5-fold in the same system.

Functional magnetic resonance imaging by visual stimulation

International Nuclear Information System (INIS)

Nishimura, Yukiko; Negoro, Kiyoshi; Morimatsu, Mitsunori; Hashida, Masahiro

1996-01-01

We evaluated functional magnetic resonance images obtained in 8 healthy subjects in response to visual stimulation using a conventional clinical magnetic resonance imaging system with multi-slice spin-echo echo planar imaging. Activation in the visual cortex was clearly demonstrated by the multi-slice experiment with a task-related change in signal intensity. In addition to the primary visual cortex, other areas were also activated by a complicated visual task. Multi-slice spin-echo echo planar imaging offers high temporal resolution and allows the three-dimensional analysis of brain function. Functional magnetic resonance imaging provides a useful noninvasive method of mapping brain function. (author)

Equal intensity double plasmon resonance of bimetallic quasi-nanocomposites based on sandwich geometry

Energy Technology Data Exchange (ETDEWEB)

Chakravadhanula, V S K; Elbahri, M; Schuermann, U; Takele, H; Greve, H; Zaporojtchenko, V; Faupel, F [Chair for Multicomponent Materials, Technical Faculty of the CAU Kiel, Kaiserstrasse 2, D-24143 Kiel (Germany)], E-mail: ff@tf.uni-kiel.de

2008-06-04

We report a strategy to achieve a material showing equal intensity double plasmon resonance (EIDPR) based on sandwich geometry. We studied the interaction between localized plasmon resonances associated with different metal clusters (Au/Ag) on Teflon AF (TAF) in sandwich geometry. Engineering the EIDPR was done by tailoring the amount of Au/Ag and changing the TAF thickness. The samples were investigated by transmission electron microscopy (TEM) and UV-visible spectroscopy. Interestingly, and in agreement with the dipole-surface interaction, the critical barrier thickness for an optimum EIDPR was observed at 3.3 nm. The results clearly show a plasmon sequence effect and visualize the role of plasmon decay.

Relative signal intensity changes of frontal and occipital white matters on T 2 weighted axial MR image : correlation with age

International Nuclear Information System (INIS)

Kim, You Me; Kim, Seung Cheol

1998-01-01

The purpose of this study is to assess relative signal intensity changes in frontal and occipital white matter with age, as seen on T 2 weighted axial MR images. Thirty eight normal adults (20-29 years old) and 114 children (0-11 years old) were investigated. All had nonspecific neurologic symptoms and their MR images, obtained using a 1.5 T system (Signa, GE Medical Systems, Milwaukee, U.S.A.), appeared to be normal. The signal intensities of frontal and occipital white matter were evaluated on T2 weighted axial images at the level of the foramen of Monro. When the signal intensity of white matter was higher than that of gray matter, grade 0 was assigned; when the opposite situation pertained, this was graded I - III. Grade I indicated that the signal intensity of occipital white matter was lower than that of frontal white matter; grade II, that the signal intensity of white matter of both lobes was similar. When the signal intensity of frontal white matter was lower than that of occipital age, and by one year after 2 years of age, and then determined grade according to age, age distribution according to grade, and the ages at which signal intensities were similar to those of adults. On T2-weighted MR images, the signal intensity of frontal white matter ultimately shows a lower signal intensity than that of occipital white matter. (author). 11 refs., 6 figs

VXIbus-based signal generator for resonant power supply system of the 3 GeV RCS

Energy Technology Data Exchange (ETDEWEB)

Zhang, Fengqing; Watanabe, Yasuhiro; Koseki, Shoichiro; Tani, Norio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Adachi, Toshikazu; Someya, Hirohiko [High Energy Accelerator Reseach Organization, Tsukuba, Ibaraki (Japan)

2002-03-01

The 3 GeV Proton RCS of the JAERI-KEK Joint Project is a 25 Hz separate-function rapid cycling synchrotron under design. Bending magnets (BM) and quadrupole magnets (QM) are excited separately. The 3 GeV RCS requests above 10 families of magnets excited independently, far beyond 3 families in practical RCS's. Difficulty of field tracking between BM and QM is significantly increased. Magnet strings are grouped into resonant networks and excited resonantly with power supplies driven by a waveform pattern, typically a DC-biased sinusoidal signal. To achieve a close tracking between many families, the driving signal of each power supply should be adjusted in phase and amplitude flexibly and dynamically. This report proposes a signal generator based on VXIbus. The VXIbus, an extension of VMEbus (VME eXtensions for Instrument), provides an open architecture with shared process bus and timing. The VXIbus-based signal generator facilitates the timing synchronization and is easy to extend to many channels needed by the 3 GeV RCS. Experimental results of the signal generator are reported. (author)

A low noise photoelectric signal acquisition system applying in nuclear magnetic resonance gyroscope

Science.gov (United States)

Lu, Qilin; Zhang, Xian; Zhao, Xinghua; Yang, Dan; Zhou, Binquan; Hu, Zhaohui

2017-10-01

The nuclear magnetic resonance gyroscope serves as a new generation of strong support for the development of high-tech weapons, it solves the core problem that limits the development of the long-playing seamless navigation and positioning. In the NMR gyroscope, the output signal with atomic precession frequency is detected by the probe light, the final crucial photoelectric signal of the probe light directly decides the quality of the gyro signal. But the output signal has high sensitivity, resolution and measurement accuracy for the photoelectric detection system. In order to detect the measured signal better, this paper proposed a weak photoelectric signal rapid acquisition system, which has high SNR and the frequency of responded signal is up to 100 KHz to let the weak output signal with high frequency of the NMR gyroscope can be detected better.

Creutzfeldt-Jakob Disease with a prion protein gene codon 180 mutation presenting asymmetric cortical high-intensity on magnetic resonance imaging.

Science.gov (United States)

Amano, Yuko; Kimura, Noriyuki; Hanaoka, Takuya; Aso, Yasuhiro; Hirano, Teruyuki; Murai, Hiroyuki; Satoh, Katsuya; Matsubara, Etsuro

2015-01-01

Here we report a genetically confirmed case of Creutzfeldt-Jakob disease with a prion protein gene codon 180 mutation presenting atypical magnetic resonance imaging findings. The present case exhibited an acute onset and lateralized neurologic signs, and progressive cognitive impairment. No myoclonus or periodic synchronous discharges on electroencephalography were observed. Diffusion-weighted images revealed areas of high signal intensity in the right frontal and temporal cortices at onset that extended to the whole cortex and basal ganglia of the right cerebral hemisphere at 3 months. Although the cerebrospinal fluid (CSF) was initially negative for neuron specific enolase, tau protein, 14-3-3 protein, and abnormal prion protein, the CSF was positive for these brain-derived proteins at 3 months after onset.

Contribution of magnetic resonance imaging to the diagnosis of eosinophilic granuloma in children

International Nuclear Information System (INIS)

Gaucher, H.; Arnould, V.; Leblan, I.; Mainard, L.; Chastagner, P.; Galloy, M.A.; Hoeffel, J.C.

1995-01-01

Magnetic resonance imaging (MRI) findings in 12 patients with biopsy-proven eosinophilic granuloma were studied retrospectively. Signal intensity was variable on T1 images and increased on T2 images and after gadolinium injection. Magnetic resonance imaging identified all the granulomas, as well as accompanying bone marrow and soft tissue changes. In all 12 cases, the lesion appeared larger on MRI displays than on plain roentgenograms. MRI findings had low specificity and consistently tended to overestimate tumor spread, especially when a long limb bone was affected. Chemotherapy was followed by changes in the size and shape of MRI lesions (loss of the high-intensity signal on T2 images and after gadolinium) suggestive of a favorable response to treatment. (authors). 12 refs., 16 figs

Diagnostic apparatus employing nuclear magnetic resonance

International Nuclear Information System (INIS)

Hoshino, K.; Yamada, N.; Yoshitome, E.; Matsuura, H.

1987-01-01

An NMR diagnostic apparatus is described comprising means for applying a primary magnetic field to a subject; means for applying RF pulses to the subject to give nuclear magnetic resonance to the nuclei of atoms in the subject; means for applying gradient magnetic fields to project an NMR signal of the nuclei at least in one direction; means for observing the NMR signal projected by the gradient magnetic fields applying means; and arithmetic means for constructing a distribution of information on resonance energy as an image from an output signal from the observing means; wherein the gradient magnetic fields applying means comprises means for applying the gradient magnetic fields at a predetermined time and for not applying the gradient magnetic fields at another predetermined time, during the time period of one view; and wherein the gradient magnetic fields applying means further comprises means for measuring the NMR signal during the predetermined time when the gradient magnetic fields are applied, and means for measuring the intensity of the primary magnetic field during the other predetermined time when no gradient magnetic fields are applied

Arterial spin-labeling assessment of normalized vascular intratumoral signal intensity as a predictor of histologic grade of astrocytic neoplasms.

Science.gov (United States)

Furtner, J; Schöpf, V; Schewzow, K; Kasprian, G; Weber, M; Woitek, R; Asenbaum, U; Preusser, M; Marosi, C; Hainfellner, J A; Widhalm, G; Wolfsberger, S; Prayer, D

2014-03-01

Pulsed arterial spin-labeling is a noninvasive MR imaging perfusion method performed with the use of water in the arterial blood as an endogenous contrast agent. The purpose of this study was to determine the inversion time with the largest difference in normalized intratumoral signal intensity between high-grade and low-grade astrocytomas. Thirty-three patients with gliomas, histologically classified as low-grade (n = 7) or high-grade astrocytomas (n = 26) according to the World Health Organization brain tumor classification, were included. A 3T MR scanner was used to perform pulsed arterial spin-labeling measurements at 8 different inversion times (370 ms, 614 ms, 864 ms, 1114 ms, 1364 ms, 1614 ms, 1864 ms, and 2114 ms). Normalized intratumoral signal intensity was calculated, which was defined by the signal intensity ratio of the tumor and the contralateral normal brain tissue for all fixed inversion times. A 3-way mixed ANOVA was used to reveal potential differences in the normalized vascular intratumoral signal intensity between high-grade and low-grade astrocytomas. The difference in normalized vascular intratumoral signal intensity between high-grade and low-grade astrocytomas obtained the most statistically significant results at 370 ms (P = .003, other P values ranged from .012-.955). The inversion time by which to differentiate high-grade and low-grade astrocytomas by use of normalized vascular intratumoral signal intensity was 370 ms in our study. The normalized vascular intratumoral signal intensity values at this inversion time mainly reflect the labeled intra-arterial blood bolus and therefore could be referred to as normalized vascular intratumoral signal intensity. Our data indicate that the use of normalized vascular intratumoral signal intensity values allows differentiation between low-grade and high-grade astrocytomas and thus may serve as a new, noninvasive marker for astrocytoma grading.

High intensity focused ultrasound treatment of adenomyosis: The relationship between the features of magnetic resonance imaging on T2 weighted images and the therapeutic efficacy

Energy Technology Data Exchange (ETDEWEB)

Gong, Chunmei [State Key Laboratory of Ultrasound Engineering in Medicine Co-founded by Chongqing and the Ministry of Science and Technology, Chongqing Key Laboratory of Ultrasound in Medicine and Engineering, Chongqing Haifu Hospital, College of Biomedical Engineering, Chongqing Medical University, Chongqing (China); Setzen, Raymond [Department of Obstetrics and Gynecology, Chris Hani Baragwanath Academic Hospital, Johannesburg (South Africa); Liu, Zhongqiong; Liu, Yunchang [State Key Laboratory of Ultrasound Engineering in Medicine Co-founded by Chongqing and the Ministry of Science and Technology, Chongqing Key Laboratory of Ultrasound in Medicine and Engineering, Chongqing Haifu Hospital, College of Biomedical Engineering, Chongqing Medical University, Chongqing (China); Xie, Bin [Department of Ultrasound, Huanggang Central Hospital, Huanggang City, Hubei 438000 (China); Aili, Aixingzi, E-mail: 1819483078@qq.com [Shanghai First Maternity and Infant Health Hospital, Shanghai (China); Zhang, Lian, E-mail: lianwzhang@yahoo.com [State Key Laboratory of Ultrasound Engineering in Medicine Co-founded by Chongqing and the Ministry of Science and Technology, Chongqing Key Laboratory of Ultrasound in Medicine and Engineering, Chongqing Haifu Hospital, College of Biomedical Engineering, Chongqing Medical University, Chongqing (China)

2017-04-15

Objectives: To investigate the relationship between the features of magnetic resonance imaging (MRI) on T2 weighted images (T2WI) and the therapeutic efficacy of high intensity focused ultrasound (HIFU) on adenomyosis. Materials and methods: From January 2011 to November 2015, four hundred and twenty-eight patients with symptomatic adenomyosis were treated with HIFU. Based on the signal intensity and the number of hyperintense foci in the adenomyotic lesions on T2WI, the patients were classified into groups. The day after HIFU ablation patients underwent contrast-enhanced MRI and a comparison was made of non-perfused volume (NPV) ratio, energy efficiency factor (EEF), treatment time, sonication time, and adverse effects. Results: No significant difference in terms of HIFU treatment settings and results was observed between the group of patients with hypointense adenomyotic lesions and the group with isointense adenomyotic lesions (P > 0.05). However, the sonication time and EEF were significantly higher in the group with multiple hyperintense foci compared to the group with few hyperintense foci. The NPV ratio achieved in the lesions with multiple hyperintenese foci was significantly lower than that in the lesions with few hyperintense foci (P < 0.05). No significant difference was observed in the rate of adverse effects between the two groups. Conclusions: Based on our results, the response of the adenomyotic lesions to HIFU treatment is not related to the signal intensity of adenomyotic lesions on T2WI. However, the number of the high signal intensity foci in the adenomyotic lesions on T2WI can be considered as a predictive factor to help select patients for HIFU treatment.

High intensity focused ultrasound treatment of adenomyosis: The relationship between the features of magnetic resonance imaging on T2 weighted images and the therapeutic efficacy

International Nuclear Information System (INIS)

Gong, Chunmei; Setzen, Raymond; Liu, Zhongqiong; Liu, Yunchang; Xie, Bin; Aili, Aixingzi; Zhang, Lian

2017-01-01

Objectives: To investigate the relationship between the features of magnetic resonance imaging (MRI) on T2 weighted images (T2WI) and the therapeutic efficacy of high intensity focused ultrasound (HIFU) on adenomyosis. Materials and methods: From January 2011 to November 2015, four hundred and twenty-eight patients with symptomatic adenomyosis were treated with HIFU. Based on the signal intensity and the number of hyperintense foci in the adenomyotic lesions on T2WI, the patients were classified into groups. The day after HIFU ablation patients underwent contrast-enhanced MRI and a comparison was made of non-perfused volume (NPV) ratio, energy efficiency factor (EEF), treatment time, sonication time, and adverse effects. Results: No significant difference in terms of HIFU treatment settings and results was observed between the group of patients with hypointense adenomyotic lesions and the group with isointense adenomyotic lesions (P > 0.05). However, the sonication time and EEF were significantly higher in the group with multiple hyperintense foci compared to the group with few hyperintense foci. The NPV ratio achieved in the lesions with multiple hyperintenese foci was significantly lower than that in the lesions with few hyperintense foci (P < 0.05). No significant difference was observed in the rate of adverse effects between the two groups. Conclusions: Based on our results, the response of the adenomyotic lesions to HIFU treatment is not related to the signal intensity of adenomyotic lesions on T2WI. However, the number of the high signal intensity foci in the adenomyotic lesions on T2WI can be considered as a predictive factor to help select patients for HIFU treatment.

Histological evaluation of lung cancer with T2-weighted magnetic resonance images

International Nuclear Information System (INIS)

Ohta, Takashi; Matsuura, Yoshifumi; Shioya, Sumie; Ohta, Yasuyo

1995-01-01

We investigated the differences in signal intensity of lung cancer tissue and non-cancerous lung tissues on T 2 -weighted magnetic resonance (MR) images. MR images were obtained from patients with squamous cell carcinoma (n=6), adenocarcinoma (n=5), small cell carcinoma (n=5), and large cell carcinoma (n=1). To compare the MR signal intensity between tissues, we calculated the signal intensity ratios for tumor/skeletal muscle and lung/skeletal muscle. The MR signal intensity for each tissue was measured with a densitometer and T 2 -weighted MR images with a similar window and a center. The value of the signal intensity ratio for squamous cell carcinoma (3.26±0.76) was greater than those for adenocarcinoma (1.99±0.50, p<0.05), small cell carcinoma (2.35±0.60), large cell carcinoma (2.46), and non-cancerous lung tissues (1.70±0.68, p<0.02). The values of the MR signal intensity ratio for non-cancerous lung tissues were 2.00 for a collapsed lung, 0.93 for a fibrotic lung, and 2.18 for a fibrotic lung with obstructive pneumonia. The results suggest that the MR signal intensity ratio for pathologic tissues/normal skeletal muscle can be a useful indicator for qualitative and quantitative MR imaging diagnosis. (author)

Near resonant absorption by atoms in intense, fluctuating fields: [Progress report

International Nuclear Information System (INIS)

1989-01-01

During the present grant period preparations for photon echo studies of the role of phase fluctuations of an optical driving field resonant with the 1 S 0 - 3 P 1 transition in 174 Yb are moving forward. This experimental study emphasizes the role of fluctuations as a decorrelating mechanism on a phased array of excited atoms. Improvements in laser stabilization and in the quality of the fluctuation spectrum have been carried out and the first spectroscopic measurements will be carried out during this grant year. In response to an important recent theoretical study we have also applied the phase fluctuation synthesizing capability to the study of the atomic sodium resonance fluorescence line profile, driven by a phase fluctuating laser. The measured fluctuations in the fluorescence, characterized in terms of the standard deviation of the fluorescence intensity, have an unexpected and strong dependence on detuning of the driving laser

Intravenous injection of gadobutrol in an epidemiological study group did not lead to a difference in relative signal intensities of certain brain structures after 5 years.

Science.gov (United States)

Kromrey, Marie-Luise; Liedtke, Kim Rouven; Ittermann, Till; Langner, Sönke; Kirsch, Michael; Weitschies, Werner; Kühn, Jens-Peter

2017-02-01

To investigate if application of macrocyclic gadolinium-based contrast agents in volunteers is associated with neuronal deposition detected by magnetic resonance imaging in a 5-year longitudinal survey. Three hundred eighty-seven volunteers who participated in a population-based study were enrolled. Subjects underwent plain T1-weighted brain MRI at baseline and 5 years later with identical sequence parameters. At baseline, 271 participants additionally received intravenous injection of the macrocyclic contrast agent gadobutrol (0.15 mmol/kg). A control group including 116 subjects received no contrast agent. Relative signal intensities of thalamus, pallidum, pons and dentate nucleus were compared at baseline and follow-up. No difference in relative signal intensities was observed between contrast group (thalamus, p = 0.865; pallidum, p = 0.263; pons, p = 0.533; dentate nucleus, p = 0.396) and control group (thalamus, p = 0.683; pallidum; p = 0.970; pons, p = 0.773; dentate nucleus, p = 0.232) at both times. Comparison between both groups revealed no significant differences in relative signal intensities (thalamus, p = 0.413; pallidum, p = 0.653; pons, p = 0.460; dentate nucleus, p = 0.751). The study showed no significant change in globus pallidus-to-thalamus or dentate nucleus-to-pons ratios. Five years after administration of a 1.5-fold dose gadobutrol to normal subjects, signal intensity of thalamus, pallidum, pons and dentate nucleus did not differ from participants who had not received gadobutrol. • Gadobutrol does not lead to neuronal signal alterations after 5 years. • Neuronal deposition of macrocyclic contrast agent could not be confirmed. • Macrocyclic contrast agents in a proven dosage are safe.

Association between preoperative magnetic resonance imaging, pain intensity and quantitative sensory testing in patients awaiting lumbar diskectomy.

LENUS (Irish Health Repository)

Hegarty, Dominic

2011-02-01

Magnetic resonance imaging (MRI) offers important information regarding the morphology, location and size of a herniated disc, which influences the decision to offer lumbar diskectomy (LD). This study aims to examine the association between clinical neurophysiologic indices including pain intensity and quantitative sensory testing (QST), and the degree of lumbar nerve root compromise depicted on magnetic resonance (MR) in patients awaiting LD.

Histopathology of breast cancer after magnetic resonance-guided high-intensity focused ultrasound and radiofrequency ablation

NARCIS (Netherlands)

Knuttel, Floor; Waaijer, Laurien; Merckel, LG; van den Bosch, Maurice A A J; Witkamp, Arjen J.; Deckers, Roel; van Diest, Paul J.

AIMS: Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) ablation and radiofrequency ablation (RFA) are being researched as possible substitutes for surgery in breast cancer patients. The histopathological appearance of ablated tissue has not been studied in great detail. This

Benign compression fractures of the spine: signal patterns

International Nuclear Information System (INIS)

Ryu, Kyung Nam; Choi, Woo Suk; Lee, Sun Wha; Lim, Jae Hoon

1992-01-01

Fifteen patients with 38 compression fractures of the spine underwent magnetic resonance(MR) imaging. We retrospectively evaluated MR images in those benign compression fractures. MR images showed four patterns in T1-weighted images. MR imaging patterns were normal signal(21), band like low signal(8), low signal with preservation of peripheral portion of the body(8), and diffuse low signal through the vertebral body(1). The low signal portions were changed to high signal intensities in T2-weighted images. In 7 of 15 patients (11 compression fractures), there was a history of trauma, and the remaining 8 patients (27 compression fractures) had no history of trauma. Benign compression fractures of trauma, remained 8 patients (27 compression fractures) were non-traumatic. Benign compression fractures of the spine reveal variable signal intensities in MR imagings. These patterns of benign compression fractures may be useful in interpretation of MR imagings of the spine

Magnetic resonance sialography for investigating major salivary gland duct system after intensity-modulated radiotherapy of nasopharyngeal carcinoma

International Nuclear Information System (INIS)

Ou Dan; He Xiayun; Zhang Yunyan

2013-01-01

We investigated the value of magnetic resonance sialography for evaluating xerostomia induced by intensity-modulated radiotherapy for nasopharyngeal carcinoma. Fourteen patients with nasopharyngeal carcinoma were treated with intensity-modulated radiotherapy. Salivary function was assessed by magnetic resonance sialography and subjective evaluation criteria pre-treatment, 1 week and 1 year post-radiotherapy. A magnetic resonance sialography categorical scoring system was used to compare the visibility of salivary ducts. The average mean dose was 38.93 Gy to the parotid glands and 59.34 Gy to the submandibular glands. Before radiotherapy, the visibility scores of both the parotid and submandibular ducts increased after secretion stimulation. The scores decreased and the response to stimulation was attenuated 1 week post-radiotherapy. For most of the parotid ducts, the visibility score improved at 1 year post-radiotherapy both at rest and under stimulation, but not for the submandibular ducts. With a median follow-up of 12.3 months, 8/12 patients had grade 1 xerostomia and 4/12 had grade 2 xerostomia. Magnetic resonance sialography allows non-invasive evaluation of radiation-induced ductal changes in the major salivary glands and enables reliable prediction of radiation-induced xerostomia. (author)

Magnetic resonance imaging of the normal equine digit and metacarpophalangeal joint

International Nuclear Information System (INIS)

Park, R.D.; Nelson, T.R.; Hoopes, P.J.

1987-01-01

Magnetic resonance (MR) images were made in sagittal and transverse planes through the metacarpophalangeal joint and digit of a horse. The images accurately depicted gross anatomic structures in the leg. Soft tissue structures were defined as separate entities on the images. Histologic variation in tissues correlated with signal intensity differences on the MR images. Magnetic resonance imaging appears to be a promising imaging modality for evaluating musculoskeletal structures in equine limbs

Quantitation of magnetic resonance spectroscopy signals: the jMRUI software package

International Nuclear Information System (INIS)

Stefan, D; Andrasescu, A; Cesare, F Di; Popa, E; Lazariev, A; Graveron-Demilly, D; Vescovo, E; Williams, S; Strbak, O; Starcuk, Z; Cabanas, M; Van Ormondt, D

2009-01-01

The software package jMRUI with Java-based graphical user interface enables user-friendly time-domain analysis of magnetic resonance spectroscopy (MRS) and spectroscopic imaging (MRSI) and HRMAS-NMR signals. Version 3.x has been distributed in more than 1200 groups or hospitals worldwide. The new version 4.x is a plug-in platform enabling the users to add their own algorithms. Moreover, it offers new functionalities compared to versions 3.x. The quantum-mechanical simulator based on NMR-SCOPE, the quantitation algorithm QUEST and the main MRSI functionalities are described. Quantitation results of signals obtained in vivo from a mouse and a human brain are given

Resonance broadening of Hg lines as a density diagnostic in high intensity discharge lamps

International Nuclear Information System (INIS)

Lawler, J E

2004-01-01

The use of width measurements on resonance broadened lines of Hg as a density diagnostic in high intensity discharge (HID) lamps is reviewed and further developed in this paper. Optical depths of Hg I lines at 491.6 nm, 577.0 nm, and 1014 nm are computed as a function of temperature to confirm that these lines are optically thin in most HID lamps. The effect of quadratic and quartic radial temperature variation on the width of resonance broadened lines is computed for arc core temperatures from 4000 K to 7000 K. Such variations in temperature, and inverse variations in Hg density, are found to increase the line widths by less than 10% for 'side-on' emission measurements averaged over the arc radius. Theoretical profiles of resonance broadened spectral lines, both radially averaged and as a function of chord offset, are presented. Observations of resonance broadened lines in a metal-halide HID lamp are presented and analysed. It is concluded that the widths of resonance broadened lines provide a convenient and reliable diagnostic for the arc core Hg density but are generally not very sensitive to the radial temperature and Hg density gradient

Magnetic resonance imaging of transfusional hemosiderosis complicating thalassemia major

International Nuclear Information System (INIS)

Brasch, R.C.; Wesbey, G.E.; Gooding, C.A.; Koerper, M.A.

1984-01-01

Tissue deposits of hemosiderin, a paramagnetic iron-protein complex, resulted in marked abnormalities of magnetic resonance (MR) spin-echo signal intensity within the viscera of three children with transfusional hemosiderosis and thalassemia major. In all patients the liver and bone marrow demonstrated abnormally low spin-echo intensities and the kidneys and muscles had abnormally high intensities. These observations correlate with in vitro MR observation of ferric (Fe +3 ) solutions, in which concentrations of ferric salts greater than 20 mmol yielded higher intensities than did water alone. MR imaging is sensitive to the tissue deposition of hemosiderin, and MR intensity appears to provide a rough measure of the amount of iron deposited

Magnetic resonance imaging of lumbar intervertebral disks with its pathological cerrelation

Energy Technology Data Exchange (ETDEWEB)

Kakitsubata, Yousuke; Nabeshima, Kazuki; Kihara, Yasushi; Harada, Kuniko; Mori, Yukiko; Kakitsubata, Sachiko; Watanabe, Katsushi

1988-02-01

Three cadaver spines were examined by magnetic resonance imaging (MRI) with 0.1 tesla resistive magnet. Anatomic sections of lumbar intervertebral disks were compared with various MR images, saturation recovery (SR), inversion recovery (IR), T1 and T2 weighted spin echo (SE) images. And the signal intensity of degenerated disks on T2 weighted images were correlated with the histological studies. The disks were well delineated by SR and their degenerative changes were detected most sensitively by T2 weighted SE image. Two parts of disk were delineated on T2 weighted SE image. The central portion of disk showed high signal intensity and the periphery a low signal intensity. The central high signal intensity area corresponded to the combination of annulus fibrosus and nucleus pulposus, which cannot be differenciated by MR. And the peripheral low signal intensity area corresponded to the collagenous fibers of annulus fibrosus. Histologically, disks with decreased signal intensity had marked increase of collagen fibers. The intranuclear cleft were evident on T2 weighted image, and the corresponding structures thought to be caused by invagination of the lamellae of the annulus into the nucleus in the histological specimens. MRI were useful modality for evaluation of intervertebral disks, but biochemical analysis may be needed for precise interpretation of MR images of disks in addition to histological studies.

Muscle MRI STIR signal intensity and atrophy are correlated to focal lower limb neuropathy severity.

Science.gov (United States)

Deroide, N; Bousson, V; Mambre, L; Vicaut, E; Laredo, J D; Kubis, Nathalie

2015-03-01

The objective is to determine if muscle MRI is useful for assessing neuropathy severity. Clinical, MRI and electromyography (EMG) examinations were performed in 17 patients with focal lower limb neuropathies. MRI Short Tau Inversion Recovery (STIR) signal intensity, amyotrophy, and muscle fatty infiltration measured after T1-weighted image acquisition, EMG spontaneous activity (SA), and maximal voluntary contraction (MVC) were graded using semiquantitative scores and quantitative scores for STIR signal intensity and were correlated to the Medical Research Council (MRC) score for testing muscle strength. Within this population, subgroups were selected according to severity (mild versus severe), duration (subacute versus chronic), and topography (distal versus proximal) of the neuropathy. EMG SA and MVC MRI amyotrophy and quantitative scoring of muscle STIR intensity were correlated with the MRC score. Moreover, MRI amyotrophy was significantly increased in severe, chronic, and proximal neuropathies along with fatty infiltration in chronic lesions. Muscle MRI atrophy and quantitative evaluation of signal intensity were correlated to MRC score in our study. Semiquantitative evaluation of muscle STIR signal was sensitive enough for detection of topography of the nerve lesion but was not suitable to assess severity. Muscle MRI could support EMG in chronic and proximal neuropathy, which showed poor sensitivity in these patients.

Muscle MRI STIR signal intensity and atrophy are correlated to focal lower limb neuropathy severity

Energy Technology Data Exchange (ETDEWEB)

Deroide, N.; Mambre, L.; Kubis, Nathalie [Service de Physiologie Clinique-Explorations Fonctionnelles, AP-HP, Hopital Lariboisiere, Paris (France); Universite Paris Diderot, Sorbonne Paris Cite France, Paris (France); Bousson, V.; Laredo, J.D. [Universite Paris Diderot, Sorbonne Paris Cite France, Paris (France); Radiologie Osteo-articulaire, AP-HP, Hopital Lariboisiere, Paris (France); Vicaut, E. [Universite Paris Diderot, Sorbonne Paris Cite France, Paris (France); URC, AP-HP, Hopital Lariboisiere, Paris (France)

2014-09-26

The objective is to determine if muscle MRI is useful for assessing neuropathy severity. Clinical, MRI and electromyography (EMG) examinations were performed in 17 patients with focal lower limb neuropathies. MRI Short Tau Inversion Recovery (STIR) signal intensity, amyotrophy, and muscle fatty infiltration measured after T1-weighted image acquisition, EMG spontaneous activity (SA), and maximal voluntary contraction (MVC) were graded using semiquantitative scores and quantitative scores for STIR signal intensity and were correlated to the Medical Research Council (MRC) score for testing muscle strength. Within this population, subgroups were selected according to severity (mild versus severe), duration (subacute versus chronic), and topography (distal versus proximal) of the neuropathy. EMG SA and MVC MRI amyotrophy and quantitative scoring of muscle STIR intensity were correlated with the MRC score. Moreover, MRI amyotrophy was significantly increased in severe, chronic, and proximal neuropathies along with fatty infiltration in chronic lesions. Muscle MRI atrophy and quantitative evaluation of signal intensity were correlated to MRC score in our study. Semiquantitative evaluation of muscle STIR signal was sensitive enough for detection of topography of the nerve lesion but was not suitable to assess severity. Muscle MRI could support EMG in chronic and proximal neuropathy, which showed poor sensitivity in these patients. (orig.)

Compton harmonic resonances, stochastic instabilities, quasilinear diffusion, and collisionless damping with ultra-high intensity laser waves

International Nuclear Information System (INIS)

Rax, J.M.

1992-04-01

The dynamics of electrons in two-dimensional, linearly or circularly polarized, ultra-high intensity (above 10 18 W/cm 2 ) laser waves, is investigated. The Compton harmonic resonances are identified as the source of various stochastic instabilities. Both Arnold diffusion and resonance overlap are considered. The quasilinear kinetic equation, describing the evolution of the electron distribution function, is derived, and the associated collisionless damping coefficient is calculated. The implications of these new processes are considered and discussed

Near resonant absorption by atoms in intense fluctuating laser fields

International Nuclear Information System (INIS)

Smith, S.J.

1994-01-01

The objective of this program was to make quantitative measurements of the effects of higher-order phase/frequency correlations in a laser beam on nonlinear optical absorption processes in atoms. The success of this program was due in large part to a unique experimental capability for modulating the extracavity beam of a stabilized (approx-lt 200 kHz) continuous-wave laser with statistically-well-characterized stochastic phase (or frequency) fluctuations, in order to synthesize laser bandwidths to ∼20 MHz (depending on noise amplitude), with profiles variable between Gaussian and Lorentzian (depending on noise bandwidth). Laser driven processes investigated included the following: (1) the optical Autler-Towns effect in the 3S 1/2 (F = 2, M F = 2) → 3P 3/2 (F = 3, M F = 3) two- level Na resonance, using a weak probe to the 4D 5/2 level; (2) the variance and spectra of fluorescence intensity fluctuations in the two-level Na resonance; (3) the Hanle effect in the 1 S 0 - 3 P 1 , transition at λ = 555.6 nm in 174 Yb; (4) absorption (and gain) of a weak probe, when the probe is a time-delayed replica of the resonant (with the two-level Na transition) pump laser; and (5) four-wave-mixing in a phase-conjugate geometry, in a sodium cell, and, finally, in a diffuse atomic sodium beam. The experimental results from these several studies have provided important confirmation of advanced theoretical methods

A feasibility study evaluating the relationship between dose and focal liver reaction in stereotactic ablative radiotherapy for liver cancer based on intensity change of Gd-EOB-DTPA-enhanced magnetic resonance images

Energy Technology Data Exchange (ETDEWEB)

Jung, Sang Hoon; Yu, Jeong Il; Park, Hee Chul; Lim, Do Hoon; Han, Young Yih [Dept. of Radiation Oncology, amsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

2016-03-15

In order to evaluate the relationship between the dose to the liver parenchyma and focal liver reaction (FLR) after stereotactic ablative body radiotherapy (SABR), we suggest a novel method using a three-dimensional dose distribution and change in signal intensity of gadoxetate disodium-gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) hepatobiliary phase images. In our method, change of the signal intensity between the pretreatment and follow-up hepatobiliary phase images of Gd-EOB-DTPA-enhanced MRI was calculated and then threshold dose (TD) for developing FLR was obtained from correlation of dose with the change of the signal intensity. For validation of the method, TDs for six patients, who had been treated for liver cancer with SABR with 45-60 Gy in 3 fractions, were calculated using the method, and we evaluated concordance between volume enclosed by isodose of TD by the method and volume identified as FLR by a physician. The dose to normal liver was correlated with change in signal intensity between pretreatment and follow-up MRI with a median R{sup 2} of 0.935 (range, 0.748 to 0.985). The median TD by the method was 23.5 Gy (range, 18.3 to 39.4 Gy). The median value of concordance was 84.5% (range, 44.7% to 95.9%). Our method is capable of providing a quantitative evaluation of the relationship between dose and intensity changes on follow-up MRI, as well as determining individual TD for developing FLR. We expect our method to provide better information about the individual relationship between dose and FLR in radiotherapy for liver cancer.

A feasibility study evaluating the relationship between dose and focal liver reaction in stereotactic ablative radiotherapy for liver cancer based on intensity change of Gd-EOB-DTPA-enhanced magnetic resonance images

International Nuclear Information System (INIS)

Jung, Sang Hoon; Yu, Jeong Il; Park, Hee Chul; Lim, Do Hoon; Han, Young Yih

2016-01-01

In order to evaluate the relationship between the dose to the liver parenchyma and focal liver reaction (FLR) after stereotactic ablative body radiotherapy (SABR), we suggest a novel method using a three-dimensional dose distribution and change in signal intensity of gadoxetate disodium-gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) hepatobiliary phase images. In our method, change of the signal intensity between the pretreatment and follow-up hepatobiliary phase images of Gd-EOB-DTPA-enhanced MRI was calculated and then threshold dose (TD) for developing FLR was obtained from correlation of dose with the change of the signal intensity. For validation of the method, TDs for six patients, who had been treated for liver cancer with SABR with 45-60 Gy in 3 fractions, were calculated using the method, and we evaluated concordance between volume enclosed by isodose of TD by the method and volume identified as FLR by a physician. The dose to normal liver was correlated with change in signal intensity between pretreatment and follow-up MRI with a median R 2 of 0.935 (range, 0.748 to 0.985). The median TD by the method was 23.5 Gy (range, 18.3 to 39.4 Gy). The median value of concordance was 84.5% (range, 44.7% to 95.9%). Our method is capable of providing a quantitative evaluation of the relationship between dose and intensity changes on follow-up MRI, as well as determining individual TD for developing FLR. We expect our method to provide better information about the individual relationship between dose and FLR in radiotherapy for liver cancer

Numerical modelling of the pump-to-signal relative intensity noise ...

Indian Academy of Sciences (India)

An accurate numerical model to investigate the pump-to-signal relative intensity noise (RIN) transfer in two-pump fibre optical parametric amplifiers (2-P FOPAs) for low modulation frequencies is presented. Compared to other models in the field, this model takes into account the fibre loss, pump depletion as well as the gain ...

Multiparametric magnetic resonance imaging characteristics of prostate tuberculosis

Energy Technology Data Exchange (ETDEWEB)

Cheng, Yue; Huang, Lixiang; Zhang, Xiaodong; Ji, Qian; Shen, Wen [Dept. of Radiology, Tianjin First Central Hospital, Tianjin (China)

2015-08-15

To describe the multiparametric magnetic resonance imaging (MRI) appearance of prostate tuberculosis. Six patients with prostate tuberculosis were analyzed retrospectively. The mean age of the patients was 60.5 years (range, 48-67 years). The mean prostate specific antigen concentration was 6.62 ng/mL (range, 0.54-14.57 ng/mL). All patients underwent a multiparametric MRI examination. The histopathological results were obtained from biopsies in four men and from transurethral resection of the prostate in two men after the MRI examination. Nodular (33%, 2/6 patients) and diffuse lesions (67%, 4/6 patients) were seen on MRI. The nodular lesions were featured by extremely low signal intensity (similar to that of muscle) on T2-weighted imaging (T2WI). The T2WI signal intensity of the diffuse lesions was low but higher than that of muscle, which showed high signal intensity on diffusion weighted imaging and low signal intensity on an apparent diffusion coefficient map. MR spectroscopic imaging of this type showed a normal-like spectrum. Abscesses were found in one patient with the nodular type and in one with the diffuse type. The appearance of prostate tuberculosis on MRI can be separated into multiple nodular and diffuse types. Multiparametric MRI may offer useful information for diagnosing prostate tuberculosis.

Magnetic resonance imaging evaluation of traumatic muscle injuries

International Nuclear Information System (INIS)

Dias, Elisa Pompeu; Marchiori, Edson

2001-01-01

We evaluated 43 magnetic resonance scans of the leg or thigh of patients suffering from sports trauma. Strains were the most frequent lesions observed. These lesions presented iso- or hypointense signal on T1 and hyperintense signal on T2 images, and were classified according to the intensity of the injury of the fibers into grades 1, 2 and 3. The second most common lesions in these series were contusions that appeared iso- or hypointense on T1 and hyperintense on T2 images. Fibrosis was also observed as low signal lesions on T1 and T2 images. (author)

Endometrial cancer: magnetic resonance imaging.

Science.gov (United States)

Manfredi, R; Gui, B; Maresca, G; Fanfani, F; Bonomo, L

2005-01-01

Carcinoma of the endometrium is the most common invasive gynecologic malignancy of the female genital tract. Clinically, patients with endometrial carcinoma present with abnormal uterine bleeding. The role of magnetic resonance imaging (MRI) in endometrial carcinoma is disease staging and treatment planning. MRI has been shown to be the most valuable imaging mod-ality in this task, compared with endovaginal ultrasound and computed tomography, because of its intrinsic contrast resolution and multiplanar capability. MRI protocol includes axial T1-weighted images; axial, sagittal, and coronal T2-weighted images; and dynamic gadolinium-enhanced T1-weighted imaging. MR examination is usually performed in the supine position with a phased array multicoil using a four-coil configuration. Endometrial carcinoma is isointense with the normal endometrium and myometrium on noncontrast T1-weighted images and has a variable appearance on T2-weighted images demonstrating heterogeneous signal intensity. The appearance of noninvasive endometrial carcinoma on MRI is characterized by a normal or thickened endometrium, with an intact junctional zone and a sharp tumor-myometrium interface. Invasive endometrial carcinoma is characterized disruption or irregularity of the junctional zone by intermediate signal intensity mass on T2-weighted images. Invasion of the cervical stroma is diagnosed when the low signal intensity cervical stroma is disrupted by the higher signal intensity endometrial carcinoma. MRI in endometrial carcinoma performs better than other imaging modalities in disease staging and treatment planning. Further, the accuracy and the cost of MRI are equivalent to those of surgical staging.

Photoionization of resonantly driven atomic states by an extreme ultraviolet-free-electron laser: intensity dependence and renormalization of Rabi frequencies

International Nuclear Information System (INIS)

Kaiser, B; Brand, A; Glässl, M; Vagov, A; Axt, V M; Pietsch, U

2013-01-01

We analyze theoretically the high intensity photoionization dynamics of a system with two atomic states resonantly coupled by coherent extreme ultraviolet laser radiation that also gives rise to the ionization. The ground state occupation of such a system is shown to exhibit damped Rabi oscillations. The corresponding ionization, which is responsible for the damping, scales almost linearly with the field intensity when the pulse length exceeds the Rabi period. For shorter pulses a quadratic scaling is found. The Rabi frequency is shifted compared to its value for an isolated two-level system. The shift increases with excitation intensity and can acquire a high percentage of the unrenormalized frequency at high intensities. Analytical results obtained within a simplified solvable model demonstrate that the damping and the shift both result from the coupling of the discrete states to the ionization continuum and are therefore closely related. Numerical simulations for a two-electron system reveal at high intensities the importance of off-resonant ionization channels. (paper)

Nuclear resonance apparatus including means for rotating a magnetic field

International Nuclear Information System (INIS)

Sugimoto, H.

1983-01-01

A nuclear magnetic resonance apparatus including magnet apparatus for generating a homogeneous static magnetic field between its magnetic poles, shims of a magnetic substance mounted on the magnetic poles to apply a first gradient magnetic field intensity distribution in a direction orthogonal as to the direction of line of magnetic force of the static magnetic field, gradient magnetic field generating electromagnetic apparatus for generating a second gradient magnetic field having a gradient magnetic field intensity distribution in superimposition with the static magnetic field and for changing the magnetic field gradient of the first gradient magnetic field, an oscillator for generating an oscillating output having a frequency corresponding to the nuclear magnetic resonance condition of an atomic nucleus to be measured, a coil wound around a body to be examined for applying the output of said oscillator as electromagnetic waves upon the body, a receiver for detecting the nuclear magnetic resonance signals received by the coil, a gradient magnetic field controller making a magnetic field line equivalent to the combined gradient magnetic fields and for rotating the line along the section of the body to be examined by controlling said gradient magnetic field generating electromagnetic apparatus and devices for recording the nuclear magnetic resonance signals, for reconstructing the concentration distribution of the specific atomic nuclei in the section of the body, and a display unit for depicting the result of reconstruction

Magnetic resonance imaging and quantitative analysis of contents of epidermoid and dermoid cysts

Energy Technology Data Exchange (ETDEWEB)

Takeshita, Mikihiko; Kubo, Osami; Hiyama, Hirofumi; Tajika, Yasuhiko; Izawa, Masahiro; Kagawa, Mizuo; Takakura, Kintomo; Kobayashi, Naotoshi; Toyoda, Masako [Tokyo Women' s Medical Coll. (Japan)

1994-07-01

The intracapsular cholesterol protein, and calcium contents of epidermoid and dermoid cysts from seven patients were compared with the signal intensities on T[sub 1]-weighted spin-echo magnetic resonance (MR) images. All specimens had a paste-like consistency when resected. Epidermoid and dermoid cysts demonstrated a wide range of cholesterol and calcium contents, and epidermoid cysts were not always rich in cholesterol. Five patients had cysts with lower signal intensity than white matter, which contained more than 18.3 mg/g wet weight of protein. One of these patients had the highest cholesterol content of all seven patients (22.25 mg/g wet weight) and another had the highest calcium content (0.75 mg/g wet weight). Two patients had cysts with higher signal intensity than white matter, with protein contents of lower than 4.3 mg/g wet weight. High protein content (>18.3 mg/g wet weight) may decrease signal intensity on T[sub 1]-weighted MR images, while low protein content (<4.3 mg/g wet weight) may increase signal intensity in epidermoid and dermoid cysts with high viscosity (paste-like consistency) contents. (author).

Resonantly-enhanced, four-photon ionization of krypton at laser intensities exceeding 1013 W/cm2

International Nuclear Information System (INIS)

Perry, M.D.; Landen, O.L.; Campbell, E.M.

1987-12-01

The yield of singly- and multiply- charged ions of krypton and xenon is presented as a function of laser intensity and frequency. The measurements were performed using the second harmonic output of a well-characterized, tunable picosecond dye laser in the range 285 to 310 nm at laser intensities from 1 x 10 12 to 10 14 W/cm 2 . Enhancement of the Kr + yield by two orders of magnitude by three-photon resonant, four-photon ionization is observed in the vicinity of the 4d'[5/2] 3 and the 4d[3/2] 1 intermediate states. A model incorporating line shifts and widths scaling linearly with intensity is in good agreement with the experimental results

In vitro study of relationship between signal intensity and gadolinium-DTPA concentration at high magnetic field strength

International Nuclear Information System (INIS)

Shahbazi-Gahrouei, D.; Williams, M.; Allen, B.J.

2001-01-01

Although gadolinium-diethylene triamine pentaacetic acid (Gd-DTPA) has been used as a contrast material in MRI, it is known that the contrast enhancement effect is not uniform for high concentrations of Gd-DTPA. In order to evaluate the proper pulse sequences for dynamic MRI in aqueous solutions of Gd-DTPA, blood samples and melanoma cells, the signal intensity for several concentrations of Gd-DTPA were measured under inversion recovery T 1 -weighted) at high magnetic field strength (7.0 Tesla). For aqueous solutions of Gd-DTPA, signal intensity correlated linearly with the concentration of Gd-DTPA between 0 mmol/L and 4 mmol/L. Using blood and melanoma cells, signal intensity correlated non-linearly with the concentration of Gd-DTPA between 0 mmol/L and 1.5 mmol/L. For concentrations of more than 4 mmol/L in aqueous solutions of Gd-DTPA, 1 mmol/L in blood and 1.5 mmol/L in melanoma, signal intensity decreased with increased Gd-DTPA concentration. Copyright (2001) Blackwell Science Pty Ltd

Magnetic resonance imaging in brain-stem tumors

International Nuclear Information System (INIS)

Nomura, Mikio; Saito, Hisazumi; Akino, Minoru; Abe, Hiroshi.

1988-01-01

Four patients with brain-stem tumors underwent magnetic resonance imaging (MRI) before and after radiotherapy. The brain-stem tumors were seen as a low signal intensity on T1-weighted images and as a high signal intensity on T2-weighted images. A tumor and its anatomic involvement were more clearly visualized on MRI than on cuncurrently performed CT. Changes in tumor before and after radiotherapy could be determined by measuring the diameter of tumor on sagittal and coronal images. This allowed quantitative evaluation of the reduction of tumor in association with improvement of symptoms. The mean T1 value in the central part of tumors was shortened in all patients after radiotherapy. The results indicate that MRI may assist in determining the effect of radiotherapy for brain-stem tumors. (Namekawa, K)

Stochastic resonance in small-world neuronal networks with hybrid electrical–chemical synapses

International Nuclear Information System (INIS)

Wang, Jiang; Guo, Xinmeng; Yu, Haitao; Liu, Chen; Deng, Bin; Wei, Xile; Chen, Yingyuan

2014-01-01

Highlights: •We study stochastic resonance in small-world neural networks with hybrid synapses. •The resonance effect depends largely on the probability of chemical synapse. •An optimal chemical synapse probability exists to evoke network resonance. •Network topology affects the stochastic resonance in hybrid neuronal networks. - Abstract: The dependence of stochastic resonance in small-world neuronal networks with hybrid electrical–chemical synapses on the probability of chemical synapse and the rewiring probability is investigated. A subthreshold periodic signal is imposed on one single neuron within the neuronal network as a pacemaker. It is shown that, irrespective of the probability of chemical synapse, there exists a moderate intensity of external noise optimizing the response of neuronal networks to the pacemaker. Moreover, the effect of pacemaker driven stochastic resonance of the system depends largely on the probability of chemical synapse. A high probability of chemical synapse will need lower noise intensity to evoke the phenomenon of stochastic resonance in the networked neuronal systems. In addition, for fixed noise intensity, there is an optimal chemical synapse probability, which can promote the propagation of the localized subthreshold pacemaker across neural networks. And the optimal chemical synapses probability turns even larger as the coupling strength decreases. Furthermore, the small-world topology has a significant impact on the stochastic resonance in hybrid neuronal networks. It is found that increasing the rewiring probability can always enhance the stochastic resonance until it approaches the random network limit

Osteomas of the skull. Comparison of magnetic resonance imaging and histological findings

Energy Technology Data Exchange (ETDEWEB)

Shibata, Yasushi; Matsumura, Akira; Yoshii, Yoshihiko; Nose, Tadao [Tsukuba Univ., Ibaraki (Japan). Inst. of Clinical Medicine

1995-01-01

Magnetic resonance (MR) images of five patients with osteomas of the skull and six patients with other primary skull tumors were reviewed. All osteomas appeared as low-intensity areas on T{sub 1}-weighted images. T{sub 2}-weighted images showed homogeneous low-intensity areas in two dense osteomas, a high-intensity area in one spongy osteoma, and mixed intensity areas in two mixed spongy and dense osteomas, respectively. The signal intensities of osteomas on T{sub 2}-weighted MR images correlated well with the histological findings. Other skull tumors showed no specific MR imaging appearance. (author).

Line shapes of atomic-candle-type Rabi resonances

International Nuclear Information System (INIS)

Coffer, J.G.; Camparo, J.C.; Sickmiller, B.; Presser, A.

2002-01-01

When atoms interact with a phase-modulated field, the probability of finding the atom in the excited-state oscillates at the second harmonic of the modulation frequency, 2ω m . The amplitude of this oscillating probability is a resonant function of the Rabi frequency Ω, and this is termed a β Rabi resonance. In this work, we examine the line shape of the β Rabi resonance both theoretically and experimentally. We find that a small-signal theory of the β-Rabi-resonance condition captures much of the line shape's character, and, in particular, that the resonance's 'line Q' (i.e., 2δΩ 1/2 /Ω) is proportional to the modulation frequency. This result can be applied to the atomic candle, where β Rabi resonances are employed to stabilize field strength. Considering our results in the context of developing an optical atomic candle, we find that a free-running diode laser's intensity noise could be improved by orders of magnitude using the atomic candle concept

Selectivity in multiple quantum nuclear magnetic resonance

International Nuclear Information System (INIS)

Warren, W.S.

1980-11-01

The observation of multiple-quantum nuclear magnetic resonance transitions in isotropic or anisotropic liquids is shown to give readily interpretable information on molecular configurations, rates of motional processes, and intramolecular interactions. However, the observed intensity of high multiple-quantum transitions falls off dramatically as the number of coupled spins increases. The theory of multiple-quantum NMR is developed through the density matrix formalism, and exact intensities are derived for several cases (isotropic first-order systems and anisotropic systems with high symmetry) to shown that this intensity decrease is expected if standard multiple-quantum pulse sequences are used. New pulse sequences are developed which excite coherences and produce population inversions only between selected states, even though other transitions are simultaneously resonant. One type of selective excitation presented only allows molecules to absorb and emit photons in groups of n. Coherent averaging theory is extended to describe these selective sequences, and to design sequences which are selective to arbitrarily high order in the Magnus expansion. This theory and computer calculations both show that extremely good selectivity and large signal enhancements are possible

Selectivity in multiple quantum nuclear magnetic resonance

Energy Technology Data Exchange (ETDEWEB)

Warren, Warren Sloan [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division

1980-11-01

The observation of multiple-quantum nuclear magnetic resonance transitions in isotropic or anisotropic liquids is shown to give readily interpretable information on molecular configurations, rates of motional processes, and intramolecular interactions. However, the observed intensity of high multiple-quantum transitions falls off dramatically as the number of coupled spins increases. The theory of multiple-quantum NMR is developed through the density matrix formalism, and exact intensities are derived for several cases (isotropic first-order systems and anisotropic systems with high symmetry) to shown that this intensity decrease is expected if standard multiple-quantum pulse sequences are used. New pulse sequences are developed which excite coherences and produce population inversions only between selected states, even though other transitions are simultaneously resonant. One type of selective excitation presented only allows molecules to absorb and emit photons in groups of n. Coherent averaging theory is extended to describe these selective sequences, and to design sequences which are selective to arbitrarily high order in the Magnus expansion. This theory and computer calculations both show that extremely good selectivity and large signal enhancements are possible.

Magnetic resonance imaging of splenic iron overload

International Nuclear Information System (INIS)

Arrive, L.; Thurnher, S.; Hricak, H.; Price, D.C.

1990-01-01

The value of magnetic resonance (MR) imaging in assessing iron overload in the spleen was retrospectively investigated in 40 consecutive patients. MR appearance, mesaure of signal intensity and T1-and T2-relaxation times were correlated with the histologically determined level of iron in the spleen in each patient. Histologic examination revealed no iron overload in 19 patients, mild iron overload in seven, moderate iron overload in six, and severe iron overload in eight. All 19 patients with no splenic iron overload and 11 of the other 21 patients with splenic iron overload were correctly identified by MR imaging (sensitivity 52%, specificity 100%, accuracy 75%). Splenic iron overload was diagnosed when a decrease of signal intensity of the spleen compared with those of adipose tissue and renal cortex was demonstrated. MR images demonstrated all eight cases of severe, three of the six cases of moderate, and none of the seven cases of mild iron overload. Only spleens with severe iron overload had a significant mean decrease in signal intensity and T1- and T2-relaxation times. Although specific, MR imaging is poorly sensitive to splenic iron overload. (author). 15 refs.; 5 figs.; 3 tabs

MR signal of the solid portion of pilocytic astrocytoma on T2-weighted images: is it useful for differentiation from medulloblastoma?

International Nuclear Information System (INIS)

Arai, Kiyokazu; Yagi, Akiko; Taketomi-Takahashi, Ayako; Morita, Hideo; Koyama, Yoshinori; Endo, Keigo; Sato, Noriko; Aoki, Jun; Oba, Hiroshi; Ishiuchi, Shogo; Saito, Nobuhito

2006-01-01

Background and purpose: Although imaging features of cerebellar pilocytic astrocytoma and medulloblastoma have been described in many texts, original comparisons of magnetic resonance intensity between these two tumours are limited. In the present study the results of magnetic resonance imaging (MRI) were reviewed, focusing especially on the signal intensity of the solid portion of these neoplasms. Methods: MR images of ten cerebellar pilocytic astrocytomas and ten medulloblastomas were reviewed. The signal intensities of the solid components were graded on a scale of 1 to 5, with higher scores indicating a signal intensity closer to that of water. The degree of enhancement, tumour cysts and peripheral oedema were evaluated on MR images. When the solid portion was heterogeneous (i.e. mixed signal intensity or degree of enhancement), the dominant area was selected for evaluation. On T2-weighted images, the signal intensity of the solid portion was equal to that of cerebrospinal fluid (CSF) in 50% of pilocytic astrocytomas. No medulloblastomas showed such hyperintensity. Most medulloblastomas (80%) were isointense to grey matter. On T1-weighted images, the signal intensity varied widely in pilocytic astrocytomas; however, all medulloblastomas were iso- or hypointense to grey matter. The MR enhancement pattern, cystic component and peripheral oedema all varied in both tumour types and no specific features were identified. A signal intensity of the solid portion isointense to CSF on T2-weighted images was characteristic of cerebellar pilocytic astrocytomas; this was not observed in medulloblastomas. Attention to T2-weighted imaging of the solid portions of a tumour is easy and helpful in differentiating between cerebellar pilocytic astrocytoma and medulloblastoma. (orig.)

Effects of magnetic resonance-guided high-intensity focused ultrasound ablation on bone mechanical properties and modeling

NARCIS (Netherlands)

Yeoh, S.Y.; Arias Moreno, A.J.; Rietbergen, van B.; Hoeve, ter N.D.; Diest, van P.J.; Grull, H.

2015-01-01

Background Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) is a promising technique for palliative treatment of bone pain. In this study, the effects of MR-HIFU ablation on bone mechanics and modeling were investigated. Methods A total of 12 healthy rat femurs were ablated

Theory of resonant multiphoton ionization of krypton by intense ultraviolet laser radiation

International Nuclear Information System (INIS)

Tang, X.; Lambropoulos, P.; L'Huillier, A.; Dixit, S.N.

1989-01-01

We present a theoretical interpretation of the experimental results on three-photon-resonant four-photon ionization of Kr reported by Landen, Perry, and Campbell [Phys. Rev. Lett. 59, 2558 (1987)] and Perry and Landen [Phys. Rev. A 38, 2815 (1988)]. Our calculations are based on multichannel quantum-defect theory combined with a density-matrix formalism describing the spatiotemporal development of the process. We obtain good agreement with the data, which even at intensities as high as 10 14 W/cm 2 show the imprint of the underlying atomic structure

MRI of symptomatic Rathke`s cleft cyst. MR intensity of cyst contents and clinical manifestations

Energy Technology Data Exchange (ETDEWEB)

Takeichi, Yasuhiro [Soseikai General Hospital, Kyoto (Japan); Nakasu, Yoko; Handa, Jyoji

1997-07-01

We have not known surgical indications for incidental Rathke`s cleft cysts, because of our lack of knowledge about their natural history. In this study, we investigated whether symptomatic Rathke`s cleft cysts have any characteristic features in magnetic resonance (MR) signal intensities, and analyzed their relation to clinical manifestations and to patterns of suprasellar expansion. MR signal intensities on T1-weighted (T1W) and T2-weighted (T2W) images were categorized into 3 types in 78 cases including our 9 cases; type I, low signal intensity on T1W images and hyperintensity on T2W images in 25 cases; type II, hyperintensity on both T1W and T2W images in 20; and type III, low intensity on T2W images, in other 33. Patients of type I signal intensities presented with significantly high percentage of large cysts compressing the third ventricle than patients with other types. The patients of type I signal intensities also frequently had visual disturbance. Patients in type II showed significantly less percentage of large cysts. Anterior pituitary dysfunction was observed more often in patients of type II and III than patients of type I. We conclude that Rathke`s cleft cysts with MR signal intensity like cerebrospinal fluid (CSF) are slowly growing, and are frequently diagnosed as large cysts associated with visual disturbance. The patients with other types of MR signal intensities may suffer pituitary dysfunction or other symptoms before the cysts compress the hypothalamic region. The assessment of MR signal intensities may contribute in predicting clinical progression in patients with Rathke`s cleft cysts. (author)

Regenerative feedback resonant circuit

Science.gov (United States)

Jones, A. Mark; Kelly, James F.; McCloy, John S.; McMakin, Douglas L.

2014-09-02

A regenerative feedback resonant circuit for measuring a transient response in a loop is disclosed. The circuit includes an amplifier for generating a signal in the loop. The circuit further includes a resonator having a resonant cavity and a material located within the cavity. The signal sent into the resonator produces a resonant frequency. A variation of the resonant frequency due to perturbations in electromagnetic properties of the material is measured.

Neurilemmoma of the glans penis: ultrasonography and magnetic resonance imaging findings.

Science.gov (United States)

Jung, Dae Chul; Hwang, Sung Il; Jung, Sung Il; Kim, Sun Ho; Kim, Seung Hyup

2006-01-01

Neurilemmoma of the glans penis is rare, and no imaging findings have been reported. A case of neurilemmoma of the glans penis is presented. Ultrasonography (US) and magnetic resonance imaging revealed a well-defined small mass in the glans penis. The mass appeared hypoechoic on gray-scale US and hypervascular on color Doppler US. Magnetic resonance imaging revealed high signal intensity of the mass on a T2-weighted image and strong enhancement on a contrast-enhanced T1-weighted image.

Magnetic resonance imaging signal reduction may precede volume loss in the pituitary gland of transfusion-dependent beta-thalassemic patients

Energy Technology Data Exchange (ETDEWEB)

Hekmatnia, Ali; Rahmani, Ali Asghar; Adibi, Atoosa (Image Processing and Signal Research Center, Dept. of Radiology, Isfahan Univ. of Medical Sciences, Isfahan (Iran)); Radmard, Amir Reza (Dept. of Radiology, Shariati Hospital, Tehran Univ. of Medical Sciences, Tehran (Iran)); Khademi, Hooman (Shariati Hospital, Tehran Univ. of Medical Sciences, Tehran (Iran)), e-mail: radmard@ams.ac.ir

2010-01-15

Background: Pituitary iron overload in patients with transfusion-dependent beta-thalassemia may lead to delayed puberty. Magnetic resonance imaging (MRI) has the potential to estimate tissue iron concentration by detecting its paramagnetic effect and hypophyseal damage by measuring its dimensions indirectly. Purpose: To investigate the association of pituitary MRI findings and pubertal status in thalassemic patients as well as to demonstrate any priority in appearance of them. Material and Methods: Twenty-seven beta-thalassemic patients, aged 15-25 years, were divided into 13 with (group A) and 14 without hypogonadism (group B), matched by age, gender, duration of transfusion, and chelation therapy. Thirty-eight age- and sex-adjusted healthy control individuals were also included (group C). All participants underwent pituitary MRI using a 1.5T unit. Pituitary-to-fat signal intensity ratios (SIR) were calculated from coronal T2-weighted images. Estimated pituitary volumes were measured using pituitary height, width, and length on T1-weighted images. Results: The mean values of pituitary-to-fat SIRs were significantly lower in group A as compared with group B (P <0.001), and likewise group B had statistically lower values than group C (P=0.03). The pituitary height and volume were significantly decreased in group A compared to group B (P = 0.006 and P = 0.002, respectively), while these differences did not demonstrate statistically significance between groups B and C. Conclusion: Pituitary MRI findings such as signal intensity reduction and decrease in volume can be useful markers in estimating pituitary dysfunction in beta-thalassemic patients. Compared to healthy controls, lower values of pituitary-to-fat SIRs in thalassemic patients experiencing normal puberty, without marked decrease in volume, indicate that signal reduction may precede volume loss and could be expected first on MRI

Lineshape estimation for magnetic resonance spectroscopy (MRS) signals: self-deconvolution revisited

International Nuclear Information System (INIS)

Sima, D M; Garcia, M I Osorio; Poullet, J; Van Huffel, S; Suvichakorn, A; Antoine, J-P; Van Ormondt, D

2009-01-01

Magnetic resonance spectroscopy (MRS) is an effective diagnostic technique for monitoring biochemical changes in an organism. The lineshape of MRS signals can deviate from the theoretical Lorentzian lineshape due to inhomogeneities of the magnetic field applied to patients and to tissue heterogeneity. We call this deviation a distortion and study the self-deconvolution method for automatic estimation of the unknown lineshape distortion. The method is embedded within a time-domain metabolite quantitation algorithm for short-echo-time MRS signals. Monte Carlo simulations are used to analyze whether estimation of the unknown lineshape can improve the overall quantitation result. We use a signal with eight metabolic components inspired by typical MRS signals from healthy human brain and allocate special attention to the step of denoising and spike removal in the self-deconvolution technique. To this end, we compare several modeling techniques, based on complex damped exponentials, splines and wavelets. Our results show that self-deconvolution performs well, provided that some unavoidable hyper-parameters of the denoising methods are well chosen. Comparison of the first and last iterations shows an improvement when considering iterations instead of a single step of self-deconvolution

Dependence of Moessbauer resonance intensities on vibrational lattice anisotropy in case of an axial electric field gradient

International Nuclear Information System (INIS)

Friedt, J.M.

1976-01-01

The change in the hyperfine line intensities is discussed for various Moessbauer transitions in cases involving axial vibrational lattice anisotropy and axial electric field gradient at the resonant nucleus. The change in the relative intensities of the spectral components has been calculed numerically for the different types of Moessbauer transitions. Polynomial expansions are given to describe the functional dependence of the relative intensities on the magnitude of the vibration anisotropy. They may be used to extract the relevant parameters from experimental data without requiring the numerical integrations implied in the description of the Goldanskii-Karyagin effect [fr

Stochastic Resonance in an Underdamped System with Pinning Potential for Weak Signal Detection

Directory of Open Access Journals (Sweden)

Haibin Zhang

2015-08-01

Full Text Available Stochastic resonance (SR has been proved to be an effective approach for weak sensor signal detection. This study presents a new weak signal detection method based on a SR in an underdamped system, which consists of a pinning potential model. The model was firstly discovered from magnetic domain wall (DW in ferromagnetic strips. We analyze the principle of the proposed underdamped pinning SR (UPSR system, the detailed numerical simulation and system performance. We also propose the strategy of selecting the proper damping factor and other system parameters to match a weak signal, input noise and to generate the highest output signal-to-noise ratio (SNR. Finally, we have verified its effectiveness with both simulated and experimental input signals. Results indicate that the UPSR performs better in weak signal detection than the conventional SR (CSR with merits of higher output SNR, better anti-noise and frequency response capability. Besides, the system can be designed accurately and efficiently owing to the sensibility of parameters and potential diversity. The features also weaken the limitation of small parameters on SR system.

Stochastic Resonance in an Underdamped System with Pinning Potential for Weak Signal Detection.

Science.gov (United States)

Zhang, Haibin; He, Qingbo; Kong, Fanrang

2015-08-28

Stochastic resonance (SR) has been proved to be an effective approach for weak sensor signal detection. This study presents a new weak signal detection method based on a SR in an underdamped system, which consists of a pinning potential model. The model was firstly discovered from magnetic domain wall (DW) in ferromagnetic strips. We analyze the principle of the proposed underdamped pinning SR (UPSR) system, the detailed numerical simulation and system performance. We also propose the strategy of selecting the proper damping factor and other system parameters to match a weak signal, input noise and to generate the highest output signal-to-noise ratio (SNR). Finally, we have verified its effectiveness with both simulated and experimental input signals. Results indicate that the UPSR performs better in weak signal detection than the conventional SR (CSR) with merits of higher output SNR, better anti-noise and frequency response capability. Besides, the system can be designed accurately and efficiently owing to the sensibility of parameters and potential diversity. The features also weaken the limitation of small parameters on SR system.

Quantification of in vivo 1H magnetic resonance spectroscopy signals with baseline and lineshape estimation

International Nuclear Information System (INIS)

Osorio-Garcia, M I; Sima, D M; Van Huffel, S; Nielsen, F U; Dresselaers, T; Himmelreich, U; Van Leuven, F

2011-01-01

The in vivo quantification of magnetic resonance spectroscopy (MRS) signals is a method to estimate metabolite concentrations of living tissue. Obtaining reliable concentrations is still a challenge due to the experimental conditions affecting spectral quality. Additionally, lipids and macromolecules overlap with the metabolites of interest, affecting their reliable estimation. In this study, we propose to combine the self-deconvolution lineshape estimation method, which accounts for spectral shape distortions, with two different approaches for taking into account the macromolecular baseline contribution: (a) based on macromolecules and lipids measured in vivo using an inversion recovery technique, and (b) based on the simulation of macromolecular resonances using prior knowledge from a database of inversion recovery signals. The ultimate goal is to measure macromolecular and lipid data only once as described in (a) to create macromolecular and lipid profiles. These profiles then can be used as described in (b) for data measured under the same conditions. The method is evaluated on in vivo 1 H MRS signals at 9.4 T from mouse hippocampus. Results show that better metabolite fits are obtained when lineshape and baseline estimations are simultaneously performed and that baseline estimation based on prior knowledge from macromolecular measured signals can be reliably used to replace time-consuming individual macromolecular and lipid acquisitions

Periodic modulation-based stochastic resonance algorithm applied to quantitative analysis for weak liquid chromatography-mass spectrometry signal of granisetron in plasma

Science.gov (United States)

Xiang, Suyun; Wang, Wei; Xiang, Bingren; Deng, Haishan; Xie, Shaofei

2007-05-01

The periodic modulation-based stochastic resonance algorithm (PSRA) was used to amplify and detect the weak liquid chromatography-mass spectrometry (LC-MS) signal of granisetron in plasma. In the algorithm, the stochastic resonance (SR) was achieved by introducing an external periodic force to the nonlinear system. The optimization of parameters was carried out in two steps to give attention to both the signal-to-noise ratio (S/N) and the peak shape of output signal. By applying PSRA with the optimized parameters, the signal-to-noise ratio of LC-MS peak was enhanced significantly and distorted peak shape that often appeared in the traditional stochastic resonance algorithm was corrected by the added periodic force. Using the signals enhanced by PSRA, this method extended the limit of detection (LOD) and limit of quantification (LOQ) of granisetron in plasma from 0.05 and 0.2 ng/mL, respectively, to 0.01 and 0.02 ng/mL, and exhibited good linearity, accuracy and precision, which ensure accurate determination of the target analyte.

Magnetic resonance imaging (MRI) of avascular necrosis of the femoral head

International Nuclear Information System (INIS)

Kokubo, Takashi; Yoshikawa, Kohki; Aoki, Shigeki

1987-01-01

Thirty-seven patients with the clinical diagnosis of or suspicious of avascular necrosis (AN) of the femoral head were examined by magnetic resonance imaging (MRI). In all patients with AN confirmed from clinical symptoms, past history and plain radiographs, MRI demonstrated abnormal low intensity area in the necrosed femoral head. The abnormal findings on MRI were divided into three patterns: low signal intensity occupying the greater part of the femoral head (type A), low signal intensity localized in the periphery (type B), ring-shaped or band-like low signal intensity (type C). No correlation was found among MRI patterns, radiographic findings and radionuclide bone scan images, except that the type C was not found in the stage IV determined radiographically. In the patients suspicious of AN, the positive rate of MRI was higher than that of radionuclide scan. Abnormal findings on only MRI may not necessarily indicate AN. However, such a patient must be kept under observation, because the possibility exists that only MRI detects early or asymptomatic AN of the femoral head. (author)

Magnetic resonance imaging (MRI) of avascular necrosis of the femoral head

Energy Technology Data Exchange (ETDEWEB)

Kokubo, Takashi; Yoshikawa, Kohki; Aoki, Shigeki

1987-05-01

Thirty-seven patients with the clinical diagnosis of or suspicious of avascular necrosis (AN) of the femoral head were examined by magnetic resonance imaging (MRI). In all patients with AN confirmed from clinical symptoms, past history and plain radiographs, MRI demonstrated abnormal low intensity area in the necrosed femoral head. The abnormal findings on MRI were divided into three patterns: low signal intensity occupying the greater part of the femoral head (type A), low signal intensity localized in the periphery (type B), ring-shaped or band-like low signal intensity (type C). No correlation was found among MRI patterns, radiographic findings and radionuclide bone scan images, except that the type C was not found in the stage IV determined radiographically. In the patients suspicious of AN, the positive rate of MRI was higher than that of radionuclide scan. Abnormal findings on only MRI may not necessarily indicate AN. However, such a patient must be kept under observation, because the possibility exists that only MRI detects early or asymptomatic AN of the femoral head.

The application of radiation-induced free radicals signals in retrospective dosimetry

International Nuclear Information System (INIS)

Liu Zhongchao; Zhang Wenyi; Jiao Ling

2013-01-01

For some materials and biological samples, free radicals can be induced after ionizing radiation. Electron spin resonance (ESR) spectroscopy can detect free radical signal and its intensity can reflect the dose of the ionizing radiation. It is a typical way to estimate the radiation dosimetry by using the ESR spectroscopy of teeth. In recent years, many researchers studied on ESR of easy-getting materials such as finger (toe) nail, hair, cell phone screen, in order to investigate the relationship between signal intensity and radiation dose. The aim of this paper is to survey the current literature about methodologies and the materials on background signal, linearity of dose-response relationship, minimum detection limit and post-irradiation signal stability, so that more data will be provided for nuclear accident dose estimation. (authors)

Magnetic resonance imaging and spectroscopy of combretastatin A4 prodrug-induced disruption of tumour perfusion and energetic status

OpenAIRE

1998-01-01

The effects of combretastatin A4 prodrug on perfusion and the levels of 31P metabolites in an implanted murine tumour were investigated for 3 h after drug treatment using nuclear magnetic resonance imaging (MRI) and spectroscopy (MRS). The area of regions of low signal intensity in spin-echo images of tumours increased slightly after treatment with the drug. These regions of low signal intensity corresponded to necrosis seen in histological sections, whereas the expanding regions surrounding ...

Computed Tomography and Magnetic Resonance Imaging of Myoepitheliloma in the Soft Palate: A Case Report

International Nuclear Information System (INIS)

Lim, Hun Cheol; Yu, In Kyu; Park, Mi Ja; Jang, Dong Sik

2011-01-01

We report the appearance of myoepithelioma arising from minor salivary glands in the soft palate observed on computed tomography (CT) and magnetic resonance imaging (MRI). CT, the tumor was round with a smooth and partial lobulating contour, and slightly marginal contrast enhancement. On T1-weighted images, the mass had heterogeneous iso-signal intensity compared to the pharyngeal muscle. Additionally, the tumor had heterogeneously high T2 signal intensity with heterogeneously strong enhancement on the Gd-enhanced T1-weighted image. Radiologists should consider myoepithelioma in the radiological differential diagnosis of soft palate tumors.

Stochastic resonance: noise-enhanced order

International Nuclear Information System (INIS)

Anishchenko, Vadim S; Neiman, Arkady B; Moss, F; Shimansky-Geier, L

1999-01-01

Stochastic resonance (SR) provides a glaring example of a noise-induced transition in a nonlinear system driven by an information signal and noise simultaneously. In the regime of SR some characteristics of the information signal (amplification factor, signal-to-noise ratio, the degrees of coherence and of order, etc.) at the output of the system are significantly improved at a certain optimal noise level. SR is realized only in nonlinear systems for which a noise-intensity-controlled characteristic time becomes available. In the present review the physical mechanism and methods of theoretical description of SR are briefly discussed. SR features determined by the structure of the information signal, noise statistics and properties of particular systems with SR are studied. A nontrivial phenomenon of stochastic synchronization defined as locking of the instantaneous phase and switching frequency of a bistable system by external periodic force is analyzed in detail. Stochastic synchronization is explored in single and coupled bistable oscillators, including ensembles. The effects of SR and stochastic synchronization of ensembles of stochastic resonators are studied both with and without coupling between the elements. SR is considered in dynamical and nondynamical (threshold) systems. The SR effect is analyzed from the viewpoint of information and entropy characteristics of the signal, which determine the degree of order or self-organization in the system. Applications of the SR concept to explaining the results of a series of biological experiments are discussed. (reviews of topical problems)

Stochastic resonance: noise-enhanced order

Energy Technology Data Exchange (ETDEWEB)

Anishchenko, Vadim S; Neiman, Arkady B [N.G. Chernyshevskii Saratov State University, Saratov (Russian Federation); Moss, F [Department of Physics and Astronomy, University of Missouri at St. Louis (United States); Shimansky-Geier, L [Humboldt University at Berlin (Germany)

1999-01-31

Stochastic resonance (SR) provides a glaring example of a noise-induced transition in a nonlinear system driven by an information signal and noise simultaneously. In the regime of SR some characteristics of the information signal (amplification factor, signal-to-noise ratio, the degrees of coherence and of order, etc.) at the output of the system are significantly improved at a certain optimal noise level. SR is realized only in nonlinear systems for which a noise-intensity-controlled characteristic time becomes available. In the present review the physical mechanism and methods of theoretical description of SR are briefly discussed. SR features determined by the structure of the information signal, noise statistics and properties of particular systems with SR are studied. A nontrivial phenomenon of stochastic synchronization defined as locking of the instantaneous phase and switching frequency of a bistable system by external periodic force is analyzed in detail. Stochastic synchronization is explored in single and coupled bistable oscillators, including ensembles. The effects of SR and stochastic synchronization of ensembles of stochastic resonators are studied both with and without coupling between the elements. SR is considered in dynamical and nondynamical (threshold) systems. The SR effect is analyzed from the viewpoint of information and entropy characteristics of the signal, which determine the degree of order or self-organization in the system. Applications of the SR concept to explaining the results of a series of biological experiments are discussed. (reviews of topical problems)

Vibronic Rabi resonances in harmonic and hard-wall ion traps for arbitrary laser intensity and detuning

International Nuclear Information System (INIS)

Lizuain, I.; Muga, J. G.

2007-01-01

We investigate laser-driven vibronic transitions of a single two-level atomic ion in harmonic and hard-wall traps. In the Lamb-Dicke regime, for tuned or detuned lasers with respect to the internal frequency of the ion, and weak or strong laser intensities, the vibronic transitions occur at well-isolated Rabi resonances, where the detuning-adapted Rabi frequency coincides with the transition frequency between vibrational modes. These vibronic resonances are characterized as avoided crossings of the dressed levels (eigenvalues of the full Hamiltonian). Their peculiarities due to symmetry constraints and trapping potential are also examined

Injection-controlled laser resonator

Science.gov (United States)

Chang, J.J.

1995-07-18

A new injection-controlled laser resonator incorporates self-filtering and self-imaging characteristics with an efficient injection scheme. A low-divergence laser signal is injected into the resonator, which enables the injection signal to be converted to the desired resonator modes before the main laser pulse starts. This injection technique and resonator design enable the laser cavity to improve the quality of the injection signal through self-filtering before the main laser pulse starts. The self-imaging property of the present resonator reduces the cavity induced diffraction effects and, in turn, improves the laser beam quality. 5 figs.

Magnetic resonance imaging of thoracic hydatid disease; Correlation with clinical findings, radiography, ultrasonography, CT and pathology

Energy Technology Data Exchange (ETDEWEB)

Sinner, W.N. von; Rifal, A.; Te Strake, L.; Sieck, J. (King Faisal Specialist Hospital and Research Centre, Riyadh (Saudi Arabia). Dept. of Radiology King Faisal Specialist Hospital and Research Centre, Riyadh (Saudi Arabia). Dept. of Medicine Michigan Univ., Ann Arbor (USA). Dept. of Radiology)

1990-01-01

Two patients with thoracic manifestations of hydatid disease (HD) are discussed; one patient had recurrent HD of the chest wall and the other, intrapulmonary HD after rupture and intrathoracic extension of an infradiaphragmatic cyst. At magnetic resonance (MR) imaging the manifestations of HD in the thorax are similar to previously reported MR findings in HD in the liver. The presence of a low signal intensity rim on T2 weighted images representing the cyst wall was confirmed. On T1 weighted images cysts with heterogeneous low and intermediate signal intensity contents and a relatively high signal intensity wall were seen. ''Folded parasitic membranes'' previously not described on MR were noted. Daughter cysts may have a low or high signal intensity depending on contents. Reactive changes in the lung may be quite marked compared with the liver, due to reaction to the parasite or simply because the lung is more easily compressed leading to secondary atelectasis. (orig.).

High intensity signal of the posterior pituitary. A study with horizontal direction of frequency-encoding and fat suppression MR techniques

International Nuclear Information System (INIS)

Arslan, A.

1999-01-01

Purpose: To evaluate the consistency of fat in the high intensity signals of the normal neurohypophysis and to differentiate the high signal of posterior pituitary from that of dorsum sella. Sagittal SE T1-weighted images with frequency encoding in the horizontal direction were used in order to differentiate the high signal of posterior pituitary and dorsum sella by the vertically-oriented chemical shift artifact. Material and methods: The sellae of 46 normal volunteers were imaged with a commercially available fat suppression technique and SE sequences with frequency encoding in vertical (25 cases) and horizontal (21 cases) axes. Results: The high signal intensity was absent in 9% of the normal volunteers with no predilection to any specific age group. None of the cases with posterior pituitary high intensity signals showed suppression of the signal with fat suppression technique. A fat suppression technique was helpful in documenting the hyperintensity in 7% of normal volunteers. Nineteen of the 21 (90%) cases with high signal intensity were detected by routine SE T1-weighted images, whereas 18 of the 19 (95%) cases were detected by imaging with frequency encoding in the horizontal direction. Conclusion: The high signal does not indicate the presence of fat. Fat suppression technique and a horizontal direction of frequency encoding help in differentiating the high signal of the neurohypophysis from that of dorsum sella. (orig.)

Propagation of spiking regularity and double coherence resonance in feedforward networks.

Science.gov (United States)

Men, Cong; Wang, Jiang; Qin, Ying-Mei; Deng, Bin; Tsang, Kai-Ming; Chan, Wai-Lok

2012-03-01

We investigate the propagation of spiking regularity in noisy feedforward networks (FFNs) based on FitzHugh-Nagumo neuron model systematically. It is found that noise could modulate the transmission of firing rate and spiking regularity. Noise-induced synchronization and synfire-enhanced coherence resonance are also observed when signals propagate in noisy multilayer networks. It is interesting that double coherence resonance (DCR) with the combination of synaptic input correlation and noise intensity is finally attained after the processing layer by layer in FFNs. Furthermore, inhibitory connections also play essential roles in shaping DCR phenomena. Several properties of the neuronal network such as noise intensity, correlation of synaptic inputs, and inhibitory connections can serve as control parameters in modulating both rate coding and the order of temporal coding.

Usefulness of perfusion weighted magnetic resonance imaging with signal-intensity curves analysis in the differential diagnosis of sellar and parasellar tumors: Preliminary report

Energy Technology Data Exchange (ETDEWEB)

Bladowska, Joanna, E-mail: asia.bladowska@gmail.com [Department of General Radiology, Interventional Radiology and Neuroradiology, Wroclaw Medical University, Borowska 213, 50-556 Wroclaw (Poland); Zimny, Anna, E-mail: abernac@wp.pl [Department of General Radiology, Interventional Radiology and Neuroradiology, Wroclaw Medical University, Borowska 213, 50-556 Wroclaw (Poland); Guziński, Maciej, E-mail: guziol@wp.pl [Department of General Radiology, Interventional Radiology and Neuroradiology, Wroclaw Medical University, Borowska 213, 50-556 Wroclaw (Poland); Hałoń, Agnieszka, E-mail: ahalon2@gmail.com [Department of Pathomorphology and Oncological Cytology, Wroclaw Medical University, Borowska 213, 50-556 Wroclaw (Poland); Tabakow, Paweł, E-mail: p.tabakov@wp.pl [Department of Neurosurgery, Wroclaw Medical University, Borowska 213, 50-556 Wroclaw (Poland); Czyż, Marcin, E-mail: mt.czyz@gmail.com [Department of Neurosurgery, Wroclaw Medical University, Borowska 213, 50-556 Wroclaw (Poland); Czapiga, Bogdan, E-mail: bogdanczapiga@op.pl [Department of Neurosurgery, Wroclaw Medical University, Borowska 213, 50-556 Wroclaw (Poland); Jarmundowicz, Włodzimierz, E-mail: jarmund@wp.pl [Department of Neurosurgery, Wroclaw Medical University, Borowska 213, 50-556 Wroclaw (Poland); Sąsiadek, Marek J., E-mail: marek.sasiadek@am.wroc.pl [Department of General Radiology, Interventional Radiology and Neuroradiology, Wroclaw Medical University, Borowska 213, 50-556 Wroclaw (Poland)

2013-08-15

Purpose: The most common pituitary tumors are adenomas, which however may be mimicked by other tumors that can show a very similar appearance in plain MRI. The aim of our study was to evaluate the usefulness of perfusion weighted MR imaging (PWI), including signal-intensity curves analysis in the differential diagnosis of sellar/parasellar tumors. Methods: Forty-one patients with sellar/parasellar tumors (23 macroadenomas, 10 meningiomas, 5 craniopharyngiomas, 1 intrasellar hemangioblastoma, 1 intrasellar prostate cancer metastasis, 1 suprasellar glioma), underwent plain MRI followed by PWI using a 1.5T unit. In each tumor, the mean and maximum values of relative cerebral blood volume (rCBV), as well as the relative peak height (rPH) and the relative percentage of signal intensity recovery (rPSR) were calculated. Results: The high perfusion tumors were: macroadenomas, meningiomas, squamous-papillary type of craniopharyngiomas, hemangioblastoma, glioma and metastasis. The low perfusion neoplasms included adamantinomatous type of craniopharyngiomas. By comparing adenomas and meningiomas, we found statistically significant differences in the mean and maximum rCBV values (p = 0.026 and p = 0.019, respectively), but not in rPH and rPSR. The maximum rCBV values >7.14 and the mean rCBV values >5.74 with the typical perfusion curve were very suggestive of the diagnosis of meningioma. There were differences between adenomas and other high perfusion tumors in rPH and rPSR values. Conclusions: PWI can provide additional information helpful in differential diagnosis of sellar/parasellar tumors. In our opinion PWI, as an easy to perform and fast technique should be incorporated into the MR protocol of all intracranial neoplasms including sellar/parasellar tumors.

Usefulness of perfusion weighted magnetic resonance imaging with signal-intensity curves analysis in the differential diagnosis of sellar and parasellar tumors: Preliminary report

International Nuclear Information System (INIS)

Bladowska, Joanna; Zimny, Anna; Guziński, Maciej; Hałoń, Agnieszka; Tabakow, Paweł; Czyż, Marcin; Czapiga, Bogdan; Jarmundowicz, Włodzimierz; Sąsiadek, Marek J.

2013-01-01

Purpose: The most common pituitary tumors are adenomas, which however may be mimicked by other tumors that can show a very similar appearance in plain MRI. The aim of our study was to evaluate the usefulness of perfusion weighted MR imaging (PWI), including signal-intensity curves analysis in the differential diagnosis of sellar/parasellar tumors. Methods: Forty-one patients with sellar/parasellar tumors (23 macroadenomas, 10 meningiomas, 5 craniopharyngiomas, 1 intrasellar hemangioblastoma, 1 intrasellar prostate cancer metastasis, 1 suprasellar glioma), underwent plain MRI followed by PWI using a 1.5T unit. In each tumor, the mean and maximum values of relative cerebral blood volume (rCBV), as well as the relative peak height (rPH) and the relative percentage of signal intensity recovery (rPSR) were calculated. Results: The high perfusion tumors were: macroadenomas, meningiomas, squamous-papillary type of craniopharyngiomas, hemangioblastoma, glioma and metastasis. The low perfusion neoplasms included adamantinomatous type of craniopharyngiomas. By comparing adenomas and meningiomas, we found statistically significant differences in the mean and maximum rCBV values (p = 0.026 and p = 0.019, respectively), but not in rPH and rPSR. The maximum rCBV values >7.14 and the mean rCBV values >5.74 with the typical perfusion curve were very suggestive of the diagnosis of meningioma. There were differences between adenomas and other high perfusion tumors in rPH and rPSR values. Conclusions: PWI can provide additional information helpful in differential diagnosis of sellar/parasellar tumors. In our opinion PWI, as an easy to perform and fast technique should be incorporated into the MR protocol of all intracranial neoplasms including sellar/parasellar tumors

Magnetic resonance imaging in hypertrophic cardiomyopathy

International Nuclear Information System (INIS)

Ichida, Fukiko; Hamamichi, Yuuji; Hashimoto, Ikuo; Tsubata, Shinichi; Miyazaki, Ayumi; Okada, Toshio; Futatsuya, Ryuusuke; Okada, Eikichi

1994-01-01

To evaluate the capability of magnetic resonance imaging (MRI) in the anatomical diagnosis and tissue characterization, 8 children with hypertrophic cardiomyopathy were studied comparing with echocardiography and 201 Tl myocardial imaging. The severity and distribution of hypertrophy were comparable on echocardiography and MRI. MRI was superior to echocardiography to demonstrate the apical hypertrophy. In 4 patients with severe hypertrophy, heterogenous high signal intensity was demonstrated in the site of hypertrophy, which was enhanced by T 2 weighted imaging. In the patient with decreased cardiac performance and progressed cardiac failure, the heterogeneity and high signal intensity progressed in one year interval. Simultaneously performed 201 Tl myocardial imaging showed patchy perfusion defect. Histological findings of the left ventricle demonstrated hypertrophy, degeneration and marked dysarray of the myocytes and fibrosis. MRI has the potential ability for the evaluation and sequential monitoring of myocardial tissue characterization as well as cardiac anatomy in childhood hypertrophic cardiomyopathy. (author)

Magnetic resonance imaging in hypertrophic cardiomyopathy

Energy Technology Data Exchange (ETDEWEB)

Ichida, Fukiko; Hamamichi, Yuuji; Hashimoto, Ikuo; Tsubata, Shinichi; Miyazaki, Ayumi; Okada, Toshio; Futatsuya, Ryuusuke; Okada, Eikichi [Toyama Medical and Pharmaceutical Univ. (Japan)

1994-02-01

To evaluate the capability of magnetic resonance imaging (MRI) in the anatomical diagnosis and tissue characterization, 8 children with hypertrophic cardiomyopathy were studied comparing with echocardiography and [sup 201]Tl myocardial imaging. The severity and distribution of hypertrophy were comparable on echocardiography and MRI. MRI was superior to echocardiography to demonstrate the apical hypertrophy. In 4 patients with severe hypertrophy, heterogenous high signal intensity was demonstrated in the site of hypertrophy, which was enhanced by T[sub 2] weighted imaging. In the patient with decreased cardiac performance and progressed cardiac failure, the heterogeneity and high signal intensity progressed in one year interval. Simultaneously performed [sup 201]Tl myocardial imaging showed patchy perfusion defect. Histological findings of the left ventricle demonstrated hypertrophy, degeneration and marked dysarray of the myocytes and fibrosis. MRI has the potential ability for the evaluation and sequential monitoring of myocardial tissue characterization as well as cardiac anatomy in childhood hypertrophic cardiomyopathy. (author).

Attenuation of spin resonance signals in media with the multi-component system of collectivized electrons

International Nuclear Information System (INIS)

Vojtenko, V.A.

1995-01-01

Universal relaxation theory of spectral line form at electron scattering light with spin flip at scattering of neutrons and at electron paramagnetic resonance, is plotted. Signals of spin resonances are shown to be subjected to strong attenuation caused by mutual transformations of various current carriers in multicomponent spin systems contained in intermetallic actinides with heavy fermions, in HTSC-crystals, in indirect highly alloyed semiconductors, solid solutions and superlattices. Physical reasons of observation of light strong scattering with spin flip in intermetallic actinides with semi-width independent of the wave vector are discussed. 19 refs

Resonant heating of a cluster plasma by intense laser light

International Nuclear Information System (INIS)

Antonsen, Thomas M. Jr.; Taguchi, Toshihiro; Gupta, Ayush; Palastro, John; Milchberg, Howard M.

2005-01-01

Gases of atomic clusters are interaction media for laser pulse propagation with properties useful for applications such as extreme ultraviolet (EUV) and x-ray microscopy, harmonic generation, EUV lithography, and laser plasma acceleration. To understand cluster heating and expansion, a series of two- and three-dimensional electrostatic particle in cell simulations of the explosion of argon clusters of diameter in the range 20 nm-53 nm have been preformed. The studies show that heating is dominated by a nonlinear, resonant absorption process that gives rise to a size-dependent intensity threshold for strong absorption and that controls the dielectric properties of the cluster. Electrons are first accelerated out from the cluster and then driven back into it by the combined effects of the laser field and the electrostatic field produced by the laser-driven charge separation. Above the intensity threshold for strong heating there is a dramatic increase in the production of energetic particles and harmonic radiation. The dielectric properties of a gas of clusters are determined by the ensemble average cluster polarizability. Individual electrons contribute to the polarizability differently depending on whether they are in the core of the cluster or in the outer edge. Consequently, there can be large fluctuations in polarizability during the heating of a cluster

Quantitative measurement of intervertebral disc signal using MRI

International Nuclear Information System (INIS)

Niemelaeinen, R.; Videman, T.; Dhillon, S.S.; Battie, M.C.

2008-01-01

Aim: To investigate the spinal cord as an alternative intra-body reference to cerebrospinal fluid (CSF) in evaluating thoracic disc signal intensity. Materials and methods: T2-weighted magnetic resonance imaging (MRI) images of T6-T12 were obtained using 1.5 T machines for a population-based sample of 523 men aged 35-70 years. Quantitative data on the signal intensities were acquired using an image analysis program (SpEx (copy right) ). A random sample of 30 subjects and intraclass correlation coeffcients (ICC) were used to examine the repeatability of the spinal cord measurements. The validity of using the spinal cord as a reference was examined by correlating cord and CSF samples. Finally, thoracic disc signal was validated by correlating it with age without adjustment and adjusting for either cord or CSF. Pearson's r was used for correlational analyses. Results: The repeatability of the spinal cord signal measurements was extremely high (≥0.99). The correlations between the signals of spinal cord and CSF by level were all above 0.9. The spinal cord-adjusted disc signal and age correlated similarly with CSF-adjusted disc signal and age (r = -0.30 to -0.40 versus r = -0.26 to -0.36). Conclusion: Adjacent spinal cord is a good alternative reference to the current reference standard, CSF, for quantitative measurements of disc signal intensity. Clearly fewer levels were excluded when using spinal cord as compared to CSF due to missing reference samples

Quantitative measurement of intervertebral disc signal using MRI

Energy Technology Data Exchange (ETDEWEB)

Niemelaeinen, R. [Faculty of Rehabilitation Medicine, University of Alberta, Edmonton (Canada)], E-mail: riikka.niemelainen@ualberta.ca; Videman, T. [Faculty of Rehabilitation Medicine, University of Alberta, Edmonton (Canada); Dhillon, S.S. [Department of Radiology and Diagnostic Imaging, University of Alberta, Edmonton (Canada); Battie, M.C. [Faculty of Rehabilitation Medicine, University of Alberta, Edmonton (Canada)

2008-03-15

Aim: To investigate the spinal cord as an alternative intra-body reference to cerebrospinal fluid (CSF) in evaluating thoracic disc signal intensity. Materials and methods: T2-weighted magnetic resonance imaging (MRI) images of T6-T12 were obtained using 1.5 T machines for a population-based sample of 523 men aged 35-70 years. Quantitative data on the signal intensities were acquired using an image analysis program (SpEx (copy right) ). A random sample of 30 subjects and intraclass correlation coeffcients (ICC) were used to examine the repeatability of the spinal cord measurements. The validity of using the spinal cord as a reference was examined by correlating cord and CSF samples. Finally, thoracic disc signal was validated by correlating it with age without adjustment and adjusting for either cord or CSF. Pearson's r was used for correlational analyses. Results: The repeatability of the spinal cord signal measurements was extremely high ({>=}0.99). The correlations between the signals of spinal cord and CSF by level were all above 0.9. The spinal cord-adjusted disc signal and age correlated similarly with CSF-adjusted disc signal and age (r = -0.30 to -0.40 versus r = -0.26 to -0.36). Conclusion: Adjacent spinal cord is a good alternative reference to the current reference standard, CSF, for quantitative measurements of disc signal intensity. Clearly fewer levels were excluded when using spinal cord as compared to CSF due to missing reference samples.

Electron spin resonance (ESR) studies on irradiated cocoa beans and niger seeds

International Nuclear Information System (INIS)

Mangaonkar, S.R.; Natarajan, V.; Sastry, M.D.; Desai, S.R.P.; Kulkarni, P.R.

1997-01-01

Electron spin resonance (ESR) spectra of irradiated (10kGy) and unirradiated cocoa beans and niger seeds have been compared. Unirradiated cocoa beans failed to give any ESR signal, whereas after irradiation (10kGy) an ESR signal at g = 2.0042 was observed. However, ESR signals are given by both irradiated and unirradiated niger seeds. The intensity of signal was found to be dose-dependent up to 10kGy for both seeds. The signals were stable up to 180 days in both cases. The results indicate the possibility of using ESR for distinguishing between irradiated and unirradiated cocoa beans but not for niger seeds

Gadolinium-DTPA enhanced magnetic resonance imaging of bone cysts in patients with rheumatoid arthritis

NARCIS (Netherlands)

Gubler, F. M.; Algra, P. R.; Maas, M.; Dijkstra, P. F.; Falke, T. H.

1993-01-01

To examine the contents of intraosseous cysts in patients with rheumatoid arthritis (RA) through the signal intensity characteristics on gadolinium-DTPA (Gd-DTPA) enhanced magnetic resonance imaging. The hand or foot joints of nine patients with the cystic form of RA (where the initial radiological

A Dynamical System Exhibits High Signal-to-noise Ratio Gain by Stochastic Resonance

Science.gov (United States)

Makra, Peter; Gingl, Zoltan

2003-05-01

On the basis of mixed-signal simulations, we demonstrate that signal-to-noise ratio (SNR) gains much greater than unity can be obtained in the double-well potential through stochastic resonance (SR) with a symmetric periodic pulse train as deterministic and Gaussian white noise as random excitation. We also show that significant SNR improvement is possible in this system even for a sub-threshold sinusoid input if, instead of the commonly used narrow-band SNR, we apply an equally simple but much more realistic wide-band SNR definition. Using the latter result as an argument, we draw attention to the fact that the choice of the measure to reflect signal quality is critical with regard to the extent of signal improvement observed, and urge reconsideration of the practice prevalent in SR studies that most often the narrow-band SNR is used to characterise SR. Finally, we pose some questions concerning the possibilities of applying SNR improvement in practical set-ups.

Identification of. gamma. -irradiated spices by electron spin resonance (ESR) spectrometry

Energy Technology Data Exchange (ETDEWEB)

Uchiyama, Sadao; Kawamura, Yoko; Saito, Yukio (National Inst. of Hygienic Sciences, Tokyo (Japan))

1990-12-01

The electron spin resonance (ESR) spectrometry spectra of white (WP), black (BP) and red (Capsicum annuum L. var. frutescerns L., RP) peppers each had a principal signal with a g-value of 2.0043, and the intensities of the principal signals were increased not only by {gamma}-irradiation but also by heating. Irradiated RP also showed a minor signal -30G from the principal one, and the intensity of the minor signal increased linearly with increasing dose from 10 to 50 kGy. Since the minor signal was observed in RP irradiated at 10 kGy and stored for one year, but did not appear either after heating or after exposure to this signal is unique to {gamma}-irradiated RP and should therefore be useful for the identification of {gamma}-irradiated spices of Capsicum genus, such as paprika and chili pepper. The computer simulation of the ESR spectra suggested that the minor signal should be assigned to methyl radical and the principal signal mainly to a combination of phenoxyl and peroxyl radicals. Such minor signals were found in {gamma}-irradiated allspice and cinnamon among 10 kinds of other spices. (author).

Identification of γ-irradiated spices by electron spin resonance (ESR) spectrometry

International Nuclear Information System (INIS)

Uchiyama, Sadao; Kawamura, Yoko; Saito, Yukio

1990-01-01

The electron spin resonance (ESR) spectrometry spectra of white (WP), black (BP) and red (Capsicum annuum L. var. frutescerns L., RP) peppers each had a principal signal with a g-value of 2.0043, and the intensities of the principal signals were increased not only by γ-irradiation but also by heating. Irradiated RP also showed a minor signal -30G from the principal one, and the intensity of the minor signal increased linearly with increasing dose from 10 to 50 kGy. Since the minor signal was observed in RP irradiated at 10 kGy and stored for one year, but did not appear either after heating or after exposure to this signal is unique to γ-irradiated RP and should therefore be useful for the identification of γ-irradiated spices of Capsicum genus, such as paprika and chili pepper. The computer simulation of the ESR spectra suggested that the minor signal should be assigned to methyl radical and the principal signal mainly to a combination of phenoxyl and peroxyl radicals. Such minor signals were found in γ-irradiated allspice and cinnamon among 10 kinds of other spices. (author)

Design of Meter-Scale Antenna and Signal Detection System for Underground Magnetic Resonance Sounding in Mines.

Science.gov (United States)

Yi, Xiaofeng; Zhang, Jian; Fan, Tiehu; Tian, Baofeng; Jiang, Chuandong

2018-03-13

Magnetic resonance sounding (MRS) is a novel geophysical method to detect groundwater directly. By applying this method to underground projects in mines and tunnels, warning information can be provided on water bodies that are hidden in front prior to excavation and thus reduce the risk of casualties and accidents. However, unlike its application to ground surfaces, the application of MRS to underground environments is constrained by the narrow space, quite weak MRS signal, and complex electromagnetic interferences with high intensities in mines. Focusing on the special requirements of underground MRS (UMRS) detection, this study proposes the use of an antenna with different turn numbers, which employs a separated transmitter and receiver. We designed a stationary coil with stable performance parameters and with a side length of 2 m, a matching circuit based on a Q-switch and a multi-stage broad/narrowband mixed filter that can cancel out most electromagnetic noise. In addition, noises in the pass-band are further eliminated by adopting statistical criteria and harmonic modeling and stacking, all of which together allow weak UMRS signals to be reliably detected. Finally, we conducted a field case study of the UMRS measurement in the Wujiagou Mine in Shanxi Province, China, with known water bodies. Our results show that the method proposed in this study can be used to obtain UMRS signals in narrow mine environments, and the inverted hydrological information generally agrees with the actual situation. Thus, we conclude that the UMRS method proposed in this study can be used for predicting hazardous water bodies at a distance of 7-9 m in front of the wall for underground mining projects.

Design of Meter-Scale Antenna and Signal Detection System for Underground Magnetic Resonance Sounding in Mines

Directory of Open Access Journals (Sweden)

Xiaofeng Yi

2018-03-01

Full Text Available Magnetic resonance sounding (MRS is a novel geophysical method to detect groundwater directly. By applying this method to underground projects in mines and tunnels, warning information can be provided on water bodies that are hidden in front prior to excavation and thus reduce the risk of casualties and accidents. However, unlike its application to ground surfaces, the application of MRS to underground environments is constrained by the narrow space, quite weak MRS signal, and complex electromagnetic interferences with high intensities in mines. Focusing on the special requirements of underground MRS (UMRS detection, this study proposes the use of an antenna with different turn numbers, which employs a separated transmitter and receiver. We designed a stationary coil with stable performance parameters and with a side length of 2 m, a matching circuit based on a Q-switch and a multi-stage broad/narrowband mixed filter that can cancel out most electromagnetic noise. In addition, noises in the pass-band are further eliminated by adopting statistical criteria and harmonic modeling and stacking, all of which together allow weak UMRS signals to be reliably detected. Finally, we conducted a field case study of the UMRS measurement in the Wujiagou Mine in Shanxi Province, China, with known water bodies. Our results show that the method proposed in this study can be used to obtain UMRS signals in narrow mine environments, and the inverted hydrological information generally agrees with the actual situation. Thus, we conclude that the UMRS method proposed in this study can be used for predicting hazardous water bodies at a distance of 7–9 m in front of the wall for underground mining projects.

Magnetic resonance imaging of the femoral head necrosis

Energy Technology Data Exchange (ETDEWEB)

Narita, Shinya; Asada, Kanji; Yoshida, Kenjiro and others

1986-06-01

Ten patients with avascular femoral head necrosis and four normal adults were examined by magnetic resonance imaging (MRI). In addition, the relationship between MRI and pathophysiology of three operated-on avascular femoral heads was evaluated. The medullary cavities of the normal femoral heads had a strong signal intensity on the saturation recovery (SR) image due to fat marrow, and the T/sub 1/ relaxation time was 160 +- 11 msec. In avascular femoral head necrosis, the necrotic area had a low signal intensity on the SR image and a prolonged T/sub 1/ relaxation time, while the reactive fibrous area had more prolonged T/sub 1/ relaxation time. For these reasons, MRI was found to show the pathological changes of avascular femoral head necrosis and can be expected to be useful for making early diagnoses and operation planning.

Magnetic resonance imaging of the femoral head necrosis

International Nuclear Information System (INIS)

Narita, Shinya; Asada, Kanji; Yoshida, Kenjiro

1986-01-01

Ten patients with avascular femoral head necrosis and four normal adults were examined by magnetic resonance imaging (MRI). In addition, the relationship between MRI and pathophysiology of three operated-on avascular femoral heads was evaluated. The medullary cavities of the normal femoral heads had a strong signal intensity on the saturation recovery (SR) image due to fat marrow, and the T 1 relaxation time was 160 ± 11 msec. In avascular femoral head necrosis, the necrotic area had a low signal intensity on the SR image and a prolonged T 1 relaxation time, while the reactive fibrous area had more prolonged T 1 relaxation time. For these reasons, MRI was found to show the pathological changes of avascular femoral head necrosis and can be expected to be useful for making early diagnoses and operation planning. (author)

Intense highly charged ion beam production and operation with a superconducting electron cyclotron resonance ion source

Science.gov (United States)

Zhao, H. W.; Sun, L. T.; Guo, J. W.; Lu, W.; Xie, D. Z.; Hitz, D.; Zhang, X. Z.; Yang, Y.

2017-09-01

The superconducting electron cyclotron resonance ion source with advanced design in Lanzhou (SECRAL) is a superconducting-magnet-based electron cyclotron resonance ion source (ECRIS) for the production of intense highly charged heavy ion beams. It is one of the best performing ECRISs worldwide and the first superconducting ECRIS built with an innovative magnet to generate a high strength minimum-B field for operation with heating microwaves up to 24-28 GHz. Since its commissioning in 2005, SECRAL has so far produced a good number of continuous wave intensity records of highly charged ion beams, in which recently the beam intensities of 40Ar+ and 129Xe26+ have, for the first time, exceeded 1 emA produced by an ion source. Routine operations commenced in 2007 with the Heavy Ion accelerator Research Facility in Lanzhou (HIRFL), China. Up to June 2017, SECRAL has been providing more than 28,000 hours of highly charged heavy ion beams to the accelerator demonstrating its great capability and reliability. The great achievement of SECRAL is accumulation of numerous technical advancements, such as an innovative magnetic system and an efficient double-frequency (24 +18 GHz ) heating with improved plasma stability. This article reviews the development of SECRAL and production of intense highly charged ion beams by SECRAL focusing on its unique magnet design, source commissioning, performance studies and enhancements, beam quality and long-term operation. SECRAL development and its performance studies representatively reflect the achievements and status of the present ECR ion source, as well as the ECRIS impacts on HIRFL.

Generation of a 640 Gbit/s NRZ OTDM signal using a silicon microring resonator

DEFF Research Database (Denmark)

Ding, Yunhong; Hu, Hao; Galili, Michael

2011-01-01

in a highly nonlinear fiber. Second, RZ-to-NRZ format conversion is achieved in a specially designed silicon microring resonator with FSR of 1280 GHz, Q value of 638, high extinction ratio and low coupling loss to optical fiber. A 640 Gbit/s NRZ OTDM signal with very clear eye-diagram and narrower bandwidth...

Contribution to the study of nuclear resonance in magnetic media (1963)

International Nuclear Information System (INIS)

Hartmann-Boutron, F.

1963-06-01

An attempt is made to interpret the results of nuclear magnetic resonance experiments made by various workers on ferro and ferrimagnetic compounds of the iron group. The problems encountered are the following: effects of the dipolar fields and the hyperfine structure anisotropy; signal intensity; frequency pulling due to the Suhl-Nakamura interaction between nuclear spins ; nuclear relaxation and ferrimagnetic resonance in single domain samples of impure YIG; nuclear relaxation in the Bloch walls of insulators. The results of our calculations are generally in good agreement with experiment. (author) [fr

Stochastic resonance is applied to quantitative analysis for weak chromatographic signal of glyburide in plasma

International Nuclear Information System (INIS)

Zhang Wei; Xiang Bingren; Wu Yanwei; Shang Erxin

2005-01-01

Based on the theory of stochastic resonance, a new method carried on the quantitive analysis to weak chromatographic signal of glyburide in plasma, which was embedded in the noise background and the signal-to-noise ratio (SNR) of HPLC-UV is enhanced remarkably. This method enhances the quantification limit to 1 ng ml -1 , which is the same as HPLC-MS, and makes it possible to detect the weak signal accurately by HPLC-UV, which was not suitable before. The results showed good recovery and linear range from 1 to 50 ng ml -1 of glyburide in plasma and the method can be used for quantitative analysis of glyburide

Stochastic resonance in a delayed triple-well potential driven by correlated noises.

Science.gov (United States)

Xu, Pengfei; Jin, Yanfei; Xiao, Shaomin

2017-11-01

In this paper, we investigate stochastic resonance (SR) in a delayed triple-well potential subject to correlated noises and a harmonic signal. The stationary probability density, together with the response amplitude of the system, is obtained by using the small time delay approximation. It is found that the time delay, noise intensities, and the cross-correlation between noises can induce the occurrence of the transition. Moreover, the appropriate choice of noise intensities and time delay can improve the output of the system, enhance the SR effect, and lead to the phenomenon of noise enhanced stability. Especially, the stochastic multi-resonance phenomenon is observed when the multiplicative and additive noises are correlated. Finally, the theoretical results are well verified through numerical simulations.

Effects of spike-time-dependent plasticity on the stochastic resonance of small-world neuronal networks

Energy Technology Data Exchange (ETDEWEB)

Yu, Haitao; Guo, Xinmeng; Wang, Jiang, E-mail: jiangwang@tju.edu.cn; Deng, Bin; Wei, Xile [School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072 (China)

2014-09-01

The phenomenon of stochastic resonance in Newman-Watts small-world neuronal networks is investigated when the strength of synaptic connections between neurons is adaptively adjusted by spike-time-dependent plasticity (STDP). It is shown that irrespective of the synaptic connectivity is fixed or adaptive, the phenomenon of stochastic resonance occurs. The efficiency of network stochastic resonance can be largely enhanced by STDP in the coupling process. Particularly, the resonance for adaptive coupling can reach a much larger value than that for fixed one when the noise intensity is small or intermediate. STDP with dominant depression and small temporal window ratio is more efficient for the transmission of weak external signal in small-world neuronal networks. In addition, we demonstrate that the effect of stochastic resonance can be further improved via fine-tuning of the average coupling strength of the adaptive network. Furthermore, the small-world topology can significantly affect stochastic resonance of excitable neuronal networks. It is found that there exists an optimal probability of adding links by which the noise-induced transmission of weak periodic signal peaks.

Effects of spike-time-dependent plasticity on the stochastic resonance of small-world neuronal networks

International Nuclear Information System (INIS)

Yu, Haitao; Guo, Xinmeng; Wang, Jiang; Deng, Bin; Wei, Xile

2014-01-01

The phenomenon of stochastic resonance in Newman-Watts small-world neuronal networks is investigated when the strength of synaptic connections between neurons is adaptively adjusted by spike-time-dependent plasticity (STDP). It is shown that irrespective of the synaptic connectivity is fixed or adaptive, the phenomenon of stochastic resonance occurs. The efficiency of network stochastic resonance can be largely enhanced by STDP in the coupling process. Particularly, the resonance for adaptive coupling can reach a much larger value than that for fixed one when the noise intensity is small or intermediate. STDP with dominant depression and small temporal window ratio is more efficient for the transmission of weak external signal in small-world neuronal networks. In addition, we demonstrate that the effect of stochastic resonance can be further improved via fine-tuning of the average coupling strength of the adaptive network. Furthermore, the small-world topology can significantly affect stochastic resonance of excitable neuronal networks. It is found that there exists an optimal probability of adding links by which the noise-induced transmission of weak periodic signal peaks

Double-wall carbon nanotubes doped with different Br2 doping levels: a resonance Raman study.

Science.gov (United States)

do Nascimento, Gustavo M; Hou, Taige; Kim, Yoong Ahm; Muramatsu, Hiroyuki; Hayashi, Takuya; Endo, Morinobu; Akuzawa, Noboru; Dresselhaus, Mildred S

2008-12-01

This report focuses on the effects of different Br2 doping levels on the radial breathing modes of "double-wall carbon nanotube (DWNT) buckypaper". The resonance Raman profile of the Br2 bands are shown for different DWNT configurations with different Br2 doping levels. Near the maximum intensity of the resonance Raman profile, mainly the Br2 molecules adsorbed on the DWNT surface contribute strongly to the observed omega(Br-Br) Raman signal.

High signal intensity of anterior pituitary gland on T1-weighted MR imaging in normal postpartum women

International Nuclear Information System (INIS)

Kim, Myung Soon; Yang, Hak Seok; Chung, In Bai

1995-01-01

The purpose of this study is to evaluate the signal intensity and size of anterior pituitary gland in postpartum women, and to compare with those of control group. In 34 postpartum women (18-43 years, mean: 27 years) and another 35 control nonpregnant women (20-29 years, mean: 24 years), midsagittal T1-weighted MR images were obtained. The signal intensity and height of the anterior pituitary gland were compared between the post-partum and normal control groups. In postpartum women, the signal intensity of the anterior pituitary gland relative to the pons was higher than that of the control group. Pituitary gland height of postpartum women was higher (5-11. 8mm, mean 8.18 ± 1.8mm) than that of control group (2-9mm, mean: 6.2 ± 1.7mm). It is concluded that the hyperintensity of the anterior pituitary gland on T1-weighted image is a normal finding in postpartum women, which is useful in differentiation from pituitary abnormality

High signal intensity of anterior pituitary gland on T1-weighted MR imaging in normal postpartum women

Energy Technology Data Exchange (ETDEWEB)

Kim, Myung Soon; Yang, Hak Seok; Chung, In Bai [Wonju College of Medicine, Yonsei University, Wonju (Korea, Republic of)

1995-01-15

The purpose of this study is to evaluate the signal intensity and size of anterior pituitary gland in postpartum women, and to compare with those of control group. In 34 postpartum women (18-43 years, mean: 27 years) and another 35 control nonpregnant women (20-29 years, mean: 24 years), midsagittal T1-weighted MR images were obtained. The signal intensity and height of the anterior pituitary gland were compared between the post-partum and normal control groups. In postpartum women, the signal intensity of the anterior pituitary gland relative to the pons was higher than that of the control group. Pituitary gland height of postpartum women was higher (5-11. 8mm, mean 8.18 {+-} 1.8mm) than that of control group (2-9mm, mean: 6.2 {+-} 1.7mm). It is concluded that the hyperintensity of the anterior pituitary gland on T1-weighted image is a normal finding in postpartum women, which is useful in differentiation from pituitary abnormality.

Ultra-low power transmitter for encoding non-MR signals in Magnetic Resonance (MR) recordings

DEFF Research Database (Denmark)

Petersen, Jan Raagaard; Pedersen, Jan Ole; Zhurbenko, Vitaliy

collection of data from non-MRI sensors. The transmitter consumes only 1.3mW while transmitting 2.7µW at 120MHz with high frequency stability. The presented design is useful in low power applications requiring high frequency stability and is intended for wireless transmission of non-MR signal recordings......Advancing Magnetic Resonance Imaging (MRI) technology requires integration of the MRI scanners with sensors and systems for monitoring various non-MRI signals. In this paper, we present design and integration of a low power AM radio transmitter into a 3T MRI scanner, which can be used for efficient...

Devise for measuring the nuclear quadrupole resonance weak signal relaxation at the ISSh-1-12 spectrometer with the SIGMA digital storage

International Nuclear Information System (INIS)

Chernyavskij, V.N.; Konstantinov, G.I.

1984-01-01

The device, consisting of an analog memory device and the Karr-Parsell pulse programming device (radio frequency pulse train is 90 deg - tau - 180 deg - 2 tau - 180 deg - 2 tau ..., where tau is the interval between 90 deg - and 180 deg - pulses), is described. The device is destined for measurement of the time T 2 of nuclear quadrupole resonance spin-spin relaxation weak signal with signal-to-noise ratio 0 - 10 4 ), pulse numbers in series are 2-1024, start output signal amplitude >= 22 V, duration is 1 μs. The device may be also used in pulsed nuclear magnetic and electron paramagnetic resonance spectroscopy

AD Leonis: Radial Velocity Signal of Stellar Rotation or Spin–Orbit Resonance?

Science.gov (United States)

Tuomi, Mikko; Jones, Hugh R. A.; Barnes, John R.; Anglada-Escudé, Guillem; Butler, R. Paul; Kiraga, Marcin; Vogt, Steven S.

2018-05-01

AD Leonis is a nearby magnetically active M dwarf. We find Doppler variability with a period of 2.23 days, as well as photometric signals: (1) a short-period signal, which is similar to the radial velocity signal, albeit with considerable variability; and (2) a long-term activity cycle of 4070 ± 120 days. We examine the short-term photometric signal in the available All-Sky Automated Survey and Microvariability and Oscillations of STars (MOST) photometry and find that the signal is not consistently present and varies considerably as a function of time. This signal undergoes a phase change of roughly 0.8 rad when considering the first and second halves of the MOST data set, which are separated in median time by 3.38 days. In contrast, the Doppler signal is stable in the combined High-Accuracy Radial velocity Planet Searcher and High Resolution Echelle Spectrometer radial velocities for over 4700 days and does not appear to vary in time in amplitude, phase, period, or as a function of extracted wavelength. We consider a variety of starspot scenarios and find it challenging to simultaneously explain the rapidly varying photometric signal and the stable radial velocity signal as being caused by starspots corotating on the stellar surface. This suggests that the origin of the Doppler periodicity might be the gravitational tug of a planet orbiting the star in spin–orbit resonance. For such a scenario and no spin–orbit misalignment, the measured v\\sin i indicates an inclination angle of 15.°5 ± 2.°5 and a planetary companion mass of 0.237 ± 0.047 M Jup.

Ionizing nightglow: sources, intensity, and spatial distribution

International Nuclear Information System (INIS)

Young, J.M.; Troy, B.E. Jr.; Johnson, C.Y.; Holmes, J.C.

1975-01-01

Photometers carried aboard an Aerobee rocket mapped the ultraviolet night sky at White Sands, New Mexico. Maps for five 300 A passbands in the wavelength range 170 to 1400 A reveal spatial radiation patterns unique to each spectral subregion. The major ultraviolet features seen in these maps are ascribed to a variety of sources: 1) solar Lyman α (1216 A) and Lyman β (1026 A), resonantly scattered by geocoronal hydrogen; 2) solar HeII (304 A) resonantly scattered by ionized helium in the Earth's plasmasphere; 3) solar HeI (584 A) resonantly scattered by neutral helium in the interstellar wind and Doppler shifted so that it penetrates the Earth's helium blanket; and 4) starlight in the 912 to 1400 A band, primarily from early-type stars in the Orion region. Not explained are the presence of small, but measurable, albedo signals observed near the peak of flight. Intensities vary from several kilorayleighs for Lyman α to a few rayleighs for HeII. (auth)

Integrated unaligned resonant modulator tuning

Energy Technology Data Exchange (ETDEWEB)

Zortman, William A.; Lentine, Anthony L.

2017-10-03

Methods and systems for tuning a resonant modulator are disclosed. One method includes receiving a carrier signal modulated by the resonant modulator with a stream of data having an approximately equal number of high and low bits, determining an average power of the modulated carrier signal, comparing the average power to a predetermined threshold, and operating a tuning device coupled to the resonant modulator based on the comparison of the average power and the predetermined threshold. One system includes an input structure, a plurality of processing elements, and a digital control element. The input structure is configured to receive, from the resonant modulator, a modulated carrier signal. The plurality of processing elements are configured to determine an average power of the modulated carrier signal. The digital control element is configured to operate a tuning device coupled to the resonant modulator based on the average power of the modulated carrier signal.

Electron magnetic resonance study of monovalent Na doping in Pr0.6Sr0.4−xNaxMnO3 manganites

International Nuclear Information System (INIS)

Thaljaoui, Rachid; Boujelben, Wahiba; Pękała, Marek; Szydłowska, Jadwiga; Cheikhrouhou, Abdelwaheb

2012-01-01

Highlights: ► New monovalent doped manganites Pr 0.6 Sr 0.4−x Na x MnO 3 (x = 0, 0.05). ► Comparison of electron magnetic resonance spectra in ferro- and paramagnetic phases. ► Double exchange interactions weakened by Na doping as indicated by activation energy. ► Magnetic susceptibility derived from resonance intensity obeys Curie–Weiss law. - Abstract: Effect of monovalent Na doping on the magnetic properties is studied in Pr 0.6 Sr 0.4−x Na x MnO 3 system (x = 0, 0.05) using X-band electron magnetic resonance and magnetization measurements. Temperature variation of magnetic resonance spectra of doped and undoped manganites is analyzed for paramagnetic and ferromagnetic states and compared to similar systems. In paramagnetic phase the magnetic susceptibility proportional to resonance signal intensity is found to obey the Curie–Weiss law. The effective magnetic moment becomes smaller in doped manganite. The paramagnetic Curie temperature derived from signal intensity equals to 312 and 306 K for the undoped and doped manganites, respectively, and is close to values obtained from magnetization variation in paramagnetic phase. The activation energy determined using the adiabatic small polaron hopping model is higher for the undoped than the doped manganite, which proves that the Na doping slightly reduces the Mn 3+ /Mn 4+ double exchange interactions.

Evaluation of the degree of arteriovenous shunting in intracranial arteriovenous malformations using pseudo-continuous arterial spin labeling magnetic resonance imaging

Energy Technology Data Exchange (ETDEWEB)

Sunwoo, Leonard; Park, Sun-Won [Seoul Metropolitan Government - Seoul National University Boramae Medical Center, Department of Radiology, Seoul (Korea, Republic of); Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Sohn, Chul-Ho; Yun, Tae Jin; Choi, Seung Hong; Cho, Young Dae; Kim, Ji-hoon; Han, Moon Hee [Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Seoul National University Hospital, Department of Radiology, Seoul (Korea, Republic of); Lee, Jong Young [Kangdong Sacred Heart Hospital, Department of Neurosurgery, Seoul (Korea, Republic of); Yi, Kyung Sik [Chungbuk National University Hospital, Department of Radiology, Cheongju (Korea, Republic of); Paek, Sun Ha; Kim, Yong Hwy; Kim, Jin Wook; Chung, Hyun-Tai; Kim, Dong Gyu [Seoul National University Hospital, Department of Neurosurgery, Seoul (Korea, Republic of)

2015-08-15

Intracranial arteriovenous malformations (AVMs) display venous signals on arterial spin labeling (ASL) magnetic resonance (MR) imaging due to the presence of arteriovenous shunting. Our aim was to quantitatively correlate AVM signal intensity on ASL with the degree of arteriovenous shunting estimated on digital subtraction angiography (DSA) in AVMs. MR imaging including pseudo-continuous ASL at 3 T and DSA were obtained on the same day in 40 patients with intracranial AVMs. Two reviewers assessed the nidus and venous signal intensities on ASL images to determine the presence of arteriovenous shunting. Interobserver agreement on ASL between the reviewers was determined. ASL signal intensity of the AVM lesion was correlated with AVM size and the time difference between normal and AVM venous transit times measured from the DSA images. Interobserver agreement between two reviewers for nidus and venous signal intensities was excellent (κ = 0.80 and 1.0, respectively). Interobserver agreement regarding the presence of arteriovenous shunting was perfect (κ = 1.0). AVM signal intensity showed a positive relationship with the time difference between normal and AVM venous transit times (r = 0.638, P < 0.001). AVM signal intensity also demonstrated a positive relationship with AVM size (r = 0.561, P < 0.001). AVM signal intensity on ASL in patients with AVM correlates well with the degree of early vein opacification on DSA, which corresponds to the degree of arteriovenous shunting. (orig.)

Electromagnetic design of a β=0.4 superconducting spoke resonator for a high intensity proton linac

International Nuclear Information System (INIS)

Pathak, Abhishek; Krishnagopal, Srinivas

2015-01-01

Here we present electromagnetic design simulations of a superconducting single-spoke resonator with a geometrical beta of 0.4 and operating at 325 MHz for a high intensity proton linac (HIPL). The spoke equatorial and base parameters were optimized to minimize the peak electric and peak magnetic fields and maximize the shunt impedance, while keeping the same resonant frequency. Variation of the surface magnetic fields was investigated as a function of the spoke base shape, and it was found that an elliptical profile is preferred over a circular or racecourse profile with E peak /E acc =4.71, E peak /E acc =4.33 (mT/(MV/m)) and R/Q=272 Ω. (author)

Gadolinium-enhanced magnetic resonance imaging in acute myocardial infarction

International Nuclear Information System (INIS)

Dijkman, P.R.M. van; Wall, E.E. van der; Roos, A. de; Doornbos, J.; Laarse, A. van der; Voorthuisen, A.E. van; Bruschke, A.V.G.; Rossum, A.C. van

1990-01-01

To evaluate he usefulness of the paramagnetic contrast agent Gadolinium-DTPA (diethylenetriaminepentaacetic acid) in Magnetic Resonance. Imaging of acute myocardial infarction, we studied a total of 45 patients with a first acute myocardial infarction by ECG-gated magnetic resonance imaging before and after intravenous administration of 0.1 mmol/kg Gadolinium-DTPA. All patients received thrombolytic treatment by intravenous streptokinase. The magnetic resonance imaging studies were preformed after a meam of 88 h (range 15-241) after the acute onset of acute myocardial infarction. Five patients without evidence of cardiac disease served as controls. Spin-echo measurements (TE 30 ms) were made using a Philips Gyroscan (0.5 Tesla) or a Teslacon II (0.6 Tesla). The 45 patients were divided into four groups of patients. In Group I( patients) Gadolinium-DTPA improved the detection of myocardial infarction by Gadolinium-DTPA. In Group II (20 patients) the magnetic resonance imaging procedure was repeated every 10 min for up to 40 min following administration of Gadolinium-DTPA. Optimal contrast enhancement was obtained 20-25 min after Gadolinium-DTPA. In Group III (27 patients) signal intensities were significantly higher in the patients who underwent the magnetic resonance imaging study more than 72 h (mean 120) after the acute event, suggesting increased acculumation of Gadolinium-DTPA in a more advanced stage of the infarction process. In Group IV (45 patients) Gadolinium-DTPA was administered in an attempt to distinguish between reperfused and nonreperfused myocardial areas after thrombolytic treatment for acute myocardial infarction. The signal intensities did not differ, but reperfused areas showed a more homogeneous aspect whereas nonreperfused areas were visualized as a more heterogeneous contrast enhancement. It is concluded that magnetic resonance imaging using the contrast agent Gadolinium-DTPA significantly improves the detection of infarcted myocardial areas

Excited-state structure and electronic dephasing time of Nile blue from absolute resonance Raman intensities

Science.gov (United States)

Lawless, Mary K.; Mathies, Richard A.

1992-06-01

Absolute resonance Raman cross sections are measured for Nile blue 690 perchlorate dissolved in ethylene glycol with excitation at 514, 531, and 568 nm. These values and the absorption spectrum are modeled using a time-dependent wave packet formalism. The excited-state equilibrium geometry changes are quantitated for 40 resonance Raman active modes, seven of which (590, 1141, 1351, 1429, 1492, 1544, and 1640 cm-1 ) carry 70% of the total resonance Raman intensity. This demonstrates that in addition to the prominent 590 and 1640 cm-1 modes, a large number of vibrational degrees of freedom are Franck-Condon coupled to the electronic transition. After exposure of the explicit vibrational progressions, the residual absorption linewidth is separated into its homogeneous [350 cm-1 half-width at half-maximum (HWHM)] and inhomogeneous (313 cm-1 HWHM) components through an analysis of the absolute Raman cross sections. The value of the electronic dephasing time derived from this study (25 fs) compares well to previously published results. These data should be valuable in multimode modeling of femtosecond experiments on Nile blue.

Intense highly charged ion beam production and operation with a superconducting electron cyclotron resonance ion source

Directory of Open Access Journals (Sweden)

H. W. Zhao

2017-09-01

Full Text Available The superconducting electron cyclotron resonance ion source with advanced design in Lanzhou (SECRAL is a superconducting-magnet-based electron cyclotron resonance ion source (ECRIS for the production of intense highly charged heavy ion beams. It is one of the best performing ECRISs worldwide and the first superconducting ECRIS built with an innovative magnet to generate a high strength minimum-B field for operation with heating microwaves up to 24–28 GHz. Since its commissioning in 2005, SECRAL has so far produced a good number of continuous wave intensity records of highly charged ion beams, in which recently the beam intensities of ^{40}Ar^{12+} and ^{129}Xe^{26+} have, for the first time, exceeded 1 emA produced by an ion source. Routine operations commenced in 2007 with the Heavy Ion accelerator Research Facility in Lanzhou (HIRFL, China. Up to June 2017, SECRAL has been providing more than 28,000 hours of highly charged heavy ion beams to the accelerator demonstrating its great capability and reliability. The great achievement of SECRAL is accumulation of numerous technical advancements, such as an innovative magnetic system and an efficient double-frequency (24+18  GHz heating with improved plasma stability. This article reviews the development of SECRAL and production of intense highly charged ion beams by SECRAL focusing on its unique magnet design, source commissioning, performance studies and enhancements, beam quality and long-term operation. SECRAL development and its performance studies representatively reflect the achievements and status of the present ECR ion source, as well as the ECRIS impacts on HIRFL.

Magnetic resonance imaging of Achilles tendon xanthomas in familial hypercholesterolemia

International Nuclear Information System (INIS)

Liem, M.S.L.; Bloem, J.L.; Schipper, J.

1992-01-01

The demonstration of tendon xanthomas is helpful in diagnosing heterozygous familial hypercholesterolemia. We investigated the possibility the lipid element with magnetic resonance (MR) imaging in seven patients with familial hypercholesterolemia and six controls. Although the mean relative signal intensities measured on long TR/TE spin echo sequences of the tendon were significantly higher in patients than in controls, the lack of such elevation does not rule out the presence of such lesions. MR imaging and US provide equal information on the anatomy of the Achilles tendon; as an abnormally increased signal intensity within the xanthoma on MRI was found in only a minority of our patients, the value of MRI in the demonstration of Achilles tendon xanthomas is limited when using conventional T1 and T2 spin echo sequences. (orig./DG)

Magnetic Resonance-Based Treatment Planning for Prostate Intensity-Modulated Radiotherapy: Creation of Digitally Reconstructed Radiographs

International Nuclear Information System (INIS)

Chen, Lili; Nguyen, Thai-Binh; Jones, Elan; Chen Zuoqun; Luo Wei; Wang Lu; Price, Robert A.; Pollack, Alan; Ma, C.-M. Charlie

2007-01-01

Purpose: To develop a technique to create magnetic resonance (MR)-based digitally reconstructed radiographs (DRR) for initial patient setup for routine clinical applications of MR-based treatment planning for prostate intensity-modulated radiotherapy. Methods and Materials: Twenty prostate cancer patients' computed tomography (CT) and MR images were used for the study. Computed tomography and MR images were fused. The pelvic bony structures, including femoral heads, pubic rami, ischium, and ischial tuberosity, that are relevant for routine clinical patient setup were manually contoured on axial MR images. The contoured bony structures were then assigned a bulk density of 2.0 g/cm 3 . The MR-based DRRs were generated. The accuracy of the MR-based DDRs was quantitatively evaluated by comparing MR-based DRRs with CT-based DRRs for these patients. For each patient, eight measuring points on both coronal and sagittal DRRs were used for quantitative evaluation. Results: The maximum difference in the mean values of these measurement points was 1.3 ± 1.6 mm, and the maximum difference in absolute positions was within 3 mm for the 20 patients investigated. Conclusions: Magnetic resonance-based DRRs are comparable to CT-based DRRs for prostate intensity-modulated radiotherapy and can be used for patient treatment setup when MR-based treatment planning is applied clinically

MRI investigation of normal fetal lung maturation using signal intensities on different imaging sequences

International Nuclear Information System (INIS)

Balassy, Csilla; Kasprian, Gregor; Weber, Michael; Hoermann, Marcus; Prayer, Daniela; Brugger, Peter C.; Csapo, Bence; Mittermayer, Christoph

2007-01-01

To purpose of this paper is to study the relation between normal lung maturation signal and changes in intensity ratios (SIR) and to determine which magnetic resonance imaging sequence provides the strongest correlation of normal lung SIs with gestational age. 126 normal singleton pregnancies (20-37 weeks) were examined with a 1.5 Tesla unit. Mean SIs for lungs, liver, and gastric fluid were assessed on six different sequences, and SIRs of lung/liver (LLSIR) and lung/gastric fluid (LGSIR) were correlated with gestational age for each sequence. To evaluate the feasibility of SIRs in the prediction of the state of the lung maturity, accuracy of the predicted SIRs (D*) was measured by calculating relative residuals (D*-D)/D for each sequence. LLSIRs showed significant changes in every sequence (p<0.05), while LGSIRs only on two sequences. Significant differences were shown for the mean of absolute residuals for both LLSIRs (p<0.001) and for LGSIRs (p=0.003). Relative residuals of LLSIRs were significantly smaller on T1-weighted sequence, whereas they were significantly higher for LGSIRs on FLAIR sequence. Fetal liver seems to be adequate reference for the investigation of lung maturation. T1-weighted sequence was the most accurate for the measurement of the lung SIs; thus, we propose to determine LLSIR on T1-weighted sequence when evaluating lung development. (orig.)

MRI investigation of normal fetal lung maturation using signal intensities on different imaging sequences

Energy Technology Data Exchange (ETDEWEB)

Balassy, Csilla; Kasprian, Gregor; Weber, Michael; Hoermann, Marcus; Prayer, Daniela [Medical University of Vienna, Department of Radiology, Vienna (Austria); Brugger, Peter C. [Medical University of Vienna, Center of Anatomy and Cell Biology, Vienna (Austria); Csapo, Bence [Medical University of Vienna, Department of Obstetrics and Gyneocology, Vienna (Austria); Mittermayer, Christoph [Medical University of Vienna, Department of Pediatrics, Vienna (Austria)

2007-03-15

To purpose of this paper is to study the relation between normal lung maturation signal and changes in intensity ratios (SIR) and to determine which magnetic resonance imaging sequence provides the strongest correlation of normal lung SIs with gestational age. 126 normal singleton pregnancies (20-37 weeks) were examined with a 1.5 Tesla unit. Mean SIs for lungs, liver, and gastric fluid were assessed on six different sequences, and SIRs of lung/liver (LLSIR) and lung/gastric fluid (LGSIR) were correlated with gestational age for each sequence. To evaluate the feasibility of SIRs in the prediction of the state of the lung maturity, accuracy of the predicted SIRs (D*) was measured by calculating relative residuals (D*-D)/D for each sequence. LLSIRs showed significant changes in every sequence (p<0.05), while LGSIRs only on two sequences. Significant differences were shown for the mean of absolute residuals for both LLSIRs (p<0.001) and for LGSIRs (p=0.003). Relative residuals of LLSIRs were significantly smaller on T1-weighted sequence, whereas they were significantly higher for LGSIRs on FLAIR sequence. Fetal liver seems to be adequate reference for the investigation of lung maturation. T1-weighted sequence was the most accurate for the measurement of the lung SIs; thus, we propose to determine LLSIR on T1-weighted sequence when evaluating lung development. (orig.)

Novel 19F MRS/I nanoprobe based on pH-responsive PEGylated nanogel. pH-dependent 19F magnetic resonance studies

International Nuclear Information System (INIS)

Oishi, Motoi; Sumitani, Shogo; Nagasaki, Yukio; Bronich, Tatiana K.; Kabanov, Alexander V.; Boska, Michael D.

2009-01-01

The pH-responsive PEGylated nanogels composed of the cross-linked poly[2-(N,N-diethylamino)ethyl methacrylate]-co-poly(2,2,2-trifluoroethyl methacrylate) gel core showed a remarkable on-off regulation of 19 F magnetic resonance signal intensity (T 2 values) as well as signal-to-noise ratios in response to extracellular pH 6.5 of tumor environment under 19 F magnetic resonance spectroscopic imaging (MRS/I), demonstrating the utility of the PEGylated nanogels as solid tumor-specific 19 F MRI/S nanoprobes. (author)

T2-weighted high-intensity signals in the basal ganglia as an interesting image finding in Unverricht-Lundborg disease.

Science.gov (United States)

Korja, Miikka; Ferlazzo, Edoardo; Soilu-Hänninen, Merja; Magaudda, Adriana; Marttila, Reijo; Genton, Pierre; Parkkola, Riitta

2010-01-01

We conducted a search for white matter changes (WMCs) in 13 Unverricht-Lundborg disease patients and compared the prevalence of WMCs in these patients to age-matched long-term epileptics and healthy controls. ULD patients had significantly more T2-weighted high-intensity signals on MRI than control subjects, due to the increased prevalence of these signals in the basal ganglia. Interestingly, ULD patients with the basal ganglia changes were overweight. Basal ganglia T2-weighted high-intensity signals are novel findings in ULD. 2009 Elsevier B.V. All rights reserved.

Integration of Resonant Coil for Wireless Power Transfer and Implantable Antenna for Signal Transfer

Directory of Open Access Journals (Sweden)

Dong-Wook Seo

2016-01-01

Full Text Available We propose the integration of the resonant coil for wireless power transfer (WPT and the implantable antenna for physiological signal transfer. The integration allows for a compact biomedical implantable system such as electrocardiogram (ECG recorder and pacemaker. While the resonant coils resonate at the frequency of 13.56 MHz for the WPT, the implantable antenna works in the medical implant communications service (MICS band of 402–405 MHz for wireless communications. They share the narrow substrate area of a bar-type shape; the coil has the current path on the outer part of the substrate and the meandered planar inverted-F antenna (PIFA occupies the inside of the coil. To verify the potentials of the proposed structure, a prototype is fabricated and tested in vitro. The power transfer efficiency (PTE of about 20% is obtained at a distance of 15 mm and the antenna gain of roughly −40 dBi is achieved.

Biomechanics of the Peacock's Display: How Feather Structure and Resonance Influence Multimodal Signaling.

Science.gov (United States)

Dakin, Roslyn; McCrossan, Owen; Hare, James F; Montgomerie, Robert; Amador Kane, Suzanne

2016-01-01

Courtship displays may serve as signals of the quality of motor performance, but little is known about the underlying biomechanics that determines both their signal content and costs. Peacocks (Pavo cristatus) perform a complex, multimodal "train-rattling" display in which they court females by vibrating the iridescent feathers in their elaborate train ornament. Here we study how feather biomechanics influences the performance of this display using a combination of field recordings and laboratory experiments. Using high-speed video, we find that train-rattling peacocks stridulate their tail feathers against the train at 25.6 Hz, on average, generating a broadband, pulsating mechanical sound at that frequency. Laboratory measurements demonstrate that arrays of peacock tail and train feathers have a broad resonant peak in their vibrational spectra at the range of frequencies used for train-rattling during the display, and the motion of feathers is just as expected for feathers shaking near resonance. This indicates that peacocks are able to drive feather vibrations energetically efficiently over a relatively broad range of frequencies, enabling them to modulate the feather vibration frequency of their displays. Using our field data, we show that peacocks with longer trains use slightly higher vibration frequencies on average, even though longer train feathers are heavier and have lower resonant frequencies. Based on these results, we propose hypotheses for future studies of the function and energetics of this display that ask why its dynamic elements might attract and maintain female attention. Finally, we demonstrate how the mechanical structure of the train feathers affects the peacock's visual display by allowing the colorful iridescent eyespots-which strongly influence female mate choice-to remain nearly stationary against a dynamic iridescent background.

Stochastic resonance in an asymmetric bistable system driven by multiplicative colored noise and additive white noise

International Nuclear Information System (INIS)

Zhou Bingchang; Xu Wei

2008-01-01

The phenomenon of stochastic resonance (SR) in a bistable system driven by multiplicative colored and additive white noises and a periodic rectangular signal with a constant component is studied by using the unified colored noise approximation and the theory of signal-to-noise (SNR) in the adiabatic limit. The analytic expression of the SNR is obtained for arbitrary signal amplitude without being restricted to small amplitudes. The SNR is a non-monotonic function of intensities of multiplicative colored and additive white noises and correlation time of multiplicative colored noise, so SR exhibits in the bistable system. The effects of potential asymmetry r and correlation time τ of multiplicative colored noise on SNR are opposite. Moreover, It is more sensitive to control SR through adjusting the additive white noise intensity D than adjusting the multiplicative colored noise intensity Q

Hallervorden Spatz syndrome: magnetic resonance findings. Case report

International Nuclear Information System (INIS)

Farage, Luciano; Castro, Mario Augusto Padula; Macedo, Tulio Augusto Alves; Assis, Marcelo Cardoso de; Souza, Lincoln Pereira de; Freitas, Luiz Oliveira de

2004-01-01

Hallervorden-Spatz syndrome is a neuro degenerative disease, autosomic recessive with two clinical features: early and late onset. Psychiatric, pyramidal and extrapyramidal signs are present in the late subtype. We report the case of a 41-old woman with extrapyramidal signs. Magnetic resonance imaging (MRI) showed the eye-of-the-tiger sign in the medial globus pallidus. This is due to a gliosis (increased signal) and accumulation of surrounding iron (decreased signal intensity) in long T R sequences. There is a strong relationship between MRI findings and the gene mutation responsible for this disease. It makes the MRI sensible for diagnosing this syndrome. (author)

Diffusion-weighted magnetic resonance imaging - a new instrument in the diagnosis of Creutzfeldt-Jacob's disease

International Nuclear Information System (INIS)

Romi, Fredrik; Smivoll, Alf Inge; Moerk, Sverre; Tysnes, Ole-Bjoern

2000-01-01

Creutzfeldt-Jacob's disease (CID) is characterised by rapidly progressive dementia, ataxia, myoclonus and several other neurological deficits. It generally affects older adults and occurs in sporadic, genetic and iatrogenic forms. Death occurs usually within one year after onset of the disease. The diagnosis is based on clinical criteria, neuro physiological and radiological findings and confirmed by post mortal histopathology. During the last two years several cases of CID have been reported with diffusion-weighted magnetic resonance imaging (MR) abnormalities represented by increased signal intensity indicating reduced diffusion in basal ganglia and/or cortex cerebric. These abnormalities seem to be characteristic of CID. We report a case of CID in a 54 year old woman who developed vertigo, nystagmus, ataxia, myoclonus and dementia over a period of eight months. Diffusion-weighted magnetic resonance imaging showed increased signal intensity in corpus striatum and gyrus conguli. The diagnosis was post mortally confirmed with histopathology. (Author) 7 figs., 15 refs

Assessment of the signal intensity distribution pattern within the unruptured cerebral aneurysms using color-coded 3D MR angiography

International Nuclear Information System (INIS)

Satoh, Toru; Omi, Megumi; Ohsako, Chika

2005-01-01

To evaluate the interaction between the MR signal intensity distribution pattern and bleb formation/deformation of the aneurysmal dome, fifty cases of the unruptured cerebral aneurysms were investigated with the color-coded 3D MR angiography. Patterns were categorized into central-type, neck-type and peripheral-type according to the distribution of MR signals with low-, moderate- and high signal intensity areas. Imaging analysis revealed the significant relationship (P<0.02) of the peripheral-type aneurysms to the bleb formation and deformation of the dome, compared with those of central- and neck-type. Additionally, peripheral-type signal intensity distribution pattern was shown with aneurysms harboring relatively large dome size and lateral-type growth including internal carotid aneurysms. Prospective analysis of intraaneurysmal flow pattern with the color-coded 3D MR angiography may provide patient-specific analysis of intraaneurysmal flow status in relation to the morphological change of the corresponding aneurysmal dome in the management of unruptured cerebral aneurysms. (author)

Work in progress: nuclear magnetic resonance imaging of the gallbladder

International Nuclear Information System (INIS)

Hricak, H.; Filly, R.A.; Margulis, A.R.; Moon, K.L.; Crooks, L.E.; Kaufman, L.

1983-01-01

A preliminary study of the relation between food intake and intensity of gallbladder bile on nuclear magnetic resonance (NMR) images was made. Twelve subjects (seven volunteers, five patients) were imaged following a minimum of 14 hours of fasting. Six of seven volunteers were reimaged one hour after stimulation by either a fatty meal or an alcoholic beverage. An additional seven patients were imaged two hours after a hospital breakfast. It was found that concentrated bile emits a high-intensity spin echo signal (SE), while hepatic bile in the gallbladder produces a low-intensity SE signal. Following ingestion of cholecystogogue, dilute hepatic bile settles on top of the concentrated bile, each emitting SE signals of different intensity. The average T1 value of concentrated bile was 594 msec, while the T1 vaue of dilute hepatic bile was 2,646 msec. The average T2 values were 104 msec for concentrated bile and 126 msec for dilute bile. The most likely cause for the different SE intensities of bile is the higher water content, and therefore longer T1 or T2 relaxation times, of hepatic bile. It is suggested that NMR imaging has the ability to provide physiological information about the gallbladder and that it may prove to be a simple and safe clinical test of gallbladder function

Sequential changes of sodium magnetic resonance images after cerebral hemorrhage

International Nuclear Information System (INIS)

Shimizu, T.; Naritomi, H.; Kuriyama, Y.; Sawada, T.

1992-01-01

Four patients with cerebral hemorrhage were examined serially from the acute to chronic phase by 1 H magnetic resonance imaging (MRI), 23 Na MRI and computed tomography (CT). At 1-2 days after bleeding, the 23 Na image revealed no visible signal change in the area of hemorrhage, although CT and 1 H images clearly demonstrated the existence of a hematoma in the thalamus or putamen. At 4-7 days after the hemorrhage, the 23 Na images began to exhibit a small increase in signal intensity at the hematoma site, while at 2-3 weeks, a marked increase in 23 Na signal intensity was observed. These findings suggest that the hematoma consisted mainly of a corpuscular component, with a low Na + concentration, with little serum component. 23 Na MRI appears to provide important information for understanding the evoluation of cerebral hemorrhage and for estimating the viability of cells, although its value for diagnosis may not be great. (orig./GDG)

Demonstration of evolution of hemispherical spondysclerosis by contrast enhanced Gd-DTPA magnetic resonance imaging

International Nuclear Information System (INIS)

Jevtic, V.; Majcen, N.

2004-01-01

Background. The purpose of the study was to estimate the value of Gd-DTPA magnetic resonance imaging (MRI) in demonstrating the evolution of hemispherical spondylosclerosis (HSS). Patients and methods. In eighteen patients with chronic low back pain and typical radiographic findings of HSS seen on plain films, Gd-DTPA MRI of the lumbar spine was performed. MRI morphological and signal intensity appearances of HSS were analysed and compared with radiographic changes. Results. On the basis of MRI features, three distinct groups of cases were identifiable. Within the first group the region of dome-shaped osteosclerosis demonstrated low signal intensity on T1-weighted precontrast spin-echo images, high signal intensity on T2-weighted images and diffuse contrast enhancement on T1-weighted postcontrast images, findings compatible with bone marrow oedema and hyperaemia. The second group showed high signal intensity vertebral body corners surrounded by low signal intensity area, which indicated the combination of fat accumulation and the sclerotic bone. In the third intermediate group anterior disco-vertebral junctions revealed a mixture of MRI appearances characteristic of the first and the second group. Conclusions. Gd-DTPA MRI is capable of demonstrating a spectrum of features which reflect the evolution of HSS. These typical appearances showed by MRI could be of eventual clinical relevance in following the progression of HSS. (author)

Clinical role of secretin loading magnetic resonance cholangiopancreatography in the patients undergoing pancreatic resection

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Shimada, Ken; Takahashi, Tsuyoshi; Yoshida, Muneki; Kakita, Akira [Kitasato Univ., Sagamihara, Kanagawa (Japan). School of Medicine

2002-01-01

We determined factors contributing to increased signal intensity in the reconstructed jejunal loop in patients undergoing pancreatic resection, frequently observed on magnetic resonance cholangiopancreatography following intravenous injection of secretin (S/MRCP). We also evaluated the possible roles of S/MRCP in assessing the patency of pancreatojejunal anastomosis and the secretory function of the remnant pancreas. Subject were 44 patients undergoing several types of pancreatic resection. Baseline output and response to secretin of the remnant pancreas were measured after surgery. S/MRCP and pancreatic function diagnostant (PFD) tests were conducted preoperatively, and in early and late periods after surgery. Baseline pancreatic output was 1.2{+-}0.7 ml/10-min, and increased after secretin load to a maximum 9.0{+-}6.6 ml/10-min in 10 min. Signal intensity of the jejunal loop increased in 2 patients versus 40 patients (95%) during the early versus late postoperative periods. During the late period, PFD was significantly higher in patients with increased signal intensity than in those without. PFD correlated well with cumulative pancreatic output following secretin loading (r=0.820). A major factor responsible for increased signal intensity in S/MRCP of the jejunal loop was increased pancreatic output. The increase in signal intensity was a definitive sign of patent pancreatojejunal anastomosis. S/MRCP thus seems to have a potential for evaluating the secretory function of the remnant pancreas. (author)

Clinical role of secretin loading magnetic resonance cholangiopancreatography in the patients undergoing pancreatic resection

International Nuclear Information System (INIS)

Shimada, Ken; Takahashi, Tsuyoshi; Yoshida, Muneki; Kakita, Akira

2002-01-01

We determined factors contributing to increased signal intensity in the reconstructed jejunal loop in patients undergoing pancreatic resection, frequently observed on magnetic resonance cholangiopancreatography following intravenous injection of secretin (S/MRCP). We also evaluated the possible roles of S/MRCP in assessing the patency of pancreatojejunal anastomosis and the secretory function of the remnant pancreas. Subject were 44 patients undergoing several types of pancreatic resection. Baseline output and response to secretin of the remnant pancreas were measured after surgery. S/MRCP and pancreatic function diagnostant (PFD) tests were conducted preoperatively, and in early and late periods after surgery. Baseline pancreatic output was 1.2±0.7 ml/10-min, and increased after secretin load to a maximum 9.0±6.6 ml/10-min in 10 min. Signal intensity of the jejunal loop increased in 2 patients versus 40 patients (95%) during the early versus late postoperative periods. During the late period, PFD was significantly higher in patients with increased signal intensity than in those without. PFD correlated well with cumulative pancreatic output following secretin loading (r=0.820). A major factor responsible for increased signal intensity in S/MRCP of the jejunal loop was increased pancreatic output. The increase in signal intensity was a definitive sign of patent pancreatojejunal anastomosis. S/MRCP thus seems to have a potential for evaluating the secretory function of the remnant pancreas. (author)

Complex on the base of the ISKRA 226.6 personal computer for nuclear quadrupole resonance signal processing

International Nuclear Information System (INIS)

Morgunov, V.G.; Kravchenko, Eh.A.

1988-01-01

Complex, designed to conduct investigations by means of nuclear quadrupole resonance (NQR) method, which includes radiospectrometer, multichannel spectrum analyzer and ISKRA 226.6 personal computer, is developed. Analog-to-digital converter (ADC) with buffer storage device, interface and microcomputer are used to process NQR-signals. ADS conversion time is no more, than 50 ns, linearity - 1%. Programs on Fourier analysis of NQR-signals and calculation of relaxation times are developed

Improving the Molecular Ion Signal Intensity for In Situ Liquid SIMS Analysis.

Science.gov (United States)

Zhou, Yufan; Yao, Juan; Ding, Yuanzhao; Yu, Jiachao; Hua, Xin; Evans, James E; Yu, Xiaofei; Lao, David B; Heldebrant, David J; Nune, Satish K; Cao, Bin; Bowden, Mark E; Yu, Xiao-Ying; Wang, Xue-Lin; Zhu, Zihua

2016-12-01

In situ liquid secondary ion mass spectrometry (SIMS) enabled by system for analysis at the liquid vacuum interface (SALVI) has proven to be a promising new tool to provide molecular information at solid-liquid and liquid-vacuum interfaces. However, the initial data showed that useful signals in positive ion spectra are too weak to be meaningful in most cases. In addition, it is difficult to obtain strong negative molecular ion signals when m/z>200. These two drawbacks have been the biggest obstacle towards practical use of this new analytical approach. In this study, we report that strong and reliable positive and negative molecular signals are achievable after optimizing the SIMS experimental conditions. Four model systems, including a 1,8-diazabicycloundec-7-ene (DBU)-base switchable ionic liquid, a live Shewanella oneidensis biofilm, a hydrated mammalian epithelia cell, and an electrolyte popularly used in Li ion batteries were studied. A signal enhancement of about two orders of magnitude was obtained in comparison with non-optimized conditions. Therefore, molecular ion signal intensity has become very acceptable for use of in situ liquid SIMS to study solid-liquid and liquid-vacuum interfaces. Graphical Abstract ᅟ.

Stochastic resonance in a piecewise nonlinear model driven by multiplicative non-Gaussian noise and additive white noise

Science.gov (United States)

Guo, Yongfeng; Shen, Yajun; Tan, Jianguo

2016-09-01

The phenomenon of stochastic resonance (SR) in a piecewise nonlinear model driven by a periodic signal and correlated noises for the cases of a multiplicative non-Gaussian noise and an additive Gaussian white noise is investigated. Applying the path integral approach, the unified colored noise approximation and the two-state model theory, the analytical expression of the signal-to-noise ratio (SNR) is derived. It is found that conventional stochastic resonance exists in this system. From numerical computations we obtain that: (i) As a function of the non-Gaussian noise intensity, the SNR is increased when the non-Gaussian noise deviation parameter q is increased. (ii) As a function of the Gaussian noise intensity, the SNR is decreased when q is increased. This demonstrates that the effect of the non-Gaussian noise on SNR is different from that of the Gaussian noise in this system. Moreover, we further discuss the effect of the correlation time of the non-Gaussian noise, cross-correlation strength, the amplitude and frequency of the periodic signal on SR.

Partly Duffing Oscillator Stochastic Resonance Method and Its Application on Mechanical Fault Diagnosis

Directory of Open Access Journals (Sweden)

Jian Dang

2016-01-01

Full Text Available Due to the fact that the slight fault signals in early failure of mechanical system are usually submerged in heavy background noise, it is unfeasible to extract the weak fault feature via the traditional vibration analysis. Stochastic resonance (SR, as a method of utilizing noise to amplify weak signals in nonlinear dynamical systems, can detect weak signals overwhelmed in the noise. However, based on the analysis of the impact of noise intensity on SR effect, it is concluded that the detection results are dramatically limited by the noise intensity of measured signals, especially for incipient fault feature of mechanical system with poor working environment. Therefore, this paper proposes a partly Duffing oscillator SR method to extract the fault feature of mechanical system. In this method, to locate the appearance of weak fault feature and decrease noise intensity, the permutation entropy index is constructed to select the measured signals for the input of Duffing oscillator system. Then, according to the regulation of system parameters, a reasonable match between the selected signals and Duffing oscillator model is achieved to produce a SR phenomenon and realize the fault diagnosis of mechanical system. Experiment results demonstrate that the proposed method achieves a better effect on the fault diagnosis of mechanical system.

New method of isolation and perfusion of rat pancreas for phosphorus nucletic resonance study

Energy Technology Data Exchange (ETDEWEB)

Matsumoto, Takehisa; Kanno, Tomio; Murakami, Masataka; Watari, Hiroshi; Seo, Yoshiteru

1988-02-01

Phosphorus nuclear magnetic resonance (/sup 31/P-NMR) was applied to measure phosphorus metabolites in the pancreas. Rat pancreatic gland was isolated and perfused with a modified Krebs-Henseleit solution at room temperature (25 deg C). Removal of the duodenum from the pancreas made it possible to record /sup 31/P-NMR spectra only from the pancreatic tissue. /sup 31/P signals of creatine phosphate (PCr), ATP and inorganic phosphate (Pi) were observed in all the glands. In different individual glands, the Signal intensity of PCr varied, but those of ATP were almost the same. The initial levels of all the phosphorus metabolites in individual glands remained almost unchanged during perfusion with the standard solution for 2 hours. When the perfusion was stopped, signal intensity of ATP and PCr decreased while Pi resonance increased and shifted to a higher magnetic field, indicating tissue acidification. On re-perfusion, each resonance and tissue pH were restored to the respective initial resting levels. Continuous stimulation with 0.3 ..mu..M acetylcholine (ACh) or 0.1 nM CCK-8 caused a markedly larger increase in pancreatic exocrine secretion than that observed in the perfused pancreas which was prepared by the previous method. Continuous stimulation with 0.1 ..mu..M ACh caused a marked and sustained increase in pancreatic exocrine secretion. During the stimulation, the resonances of phosphorus energy metabolites and tissue pH remained almost unchanged. These results indicate that the isolated perfused rat pancreas which is prepared by our new method is a useful preparation for analysis of secretion-metabolism coupling in the exocrine pancreas.

Prospects of high-resolution resonant X-ray inelastic scattering studies on solid materials, liquids and gases at diffraction-limited storage rings

International Nuclear Information System (INIS)

Schmitt, Thorsten; Groot, Frank M. F. de; Rubensson, Jan-Erik

2014-01-01

Diffraction-limited storage rings will allow for pushing the achievable energy resolution, signal intensity and the sampled spot size in resonant inelastic X-ray scattering (RIXS) experiments to new limits. In this article the types of improved soft X-ray RIXS studies that will become possible with these instrumental improvements are envisioned. The spectroscopic technique of resonant inelastic X-ray scattering (RIXS) will particularly profit from immensely improved brilliance of diffraction-limited storage rings (DLSRs). In RIXS one measures the intensities of excitations as a function of energy and momentum transfer. DLSRs will allow for pushing the achievable energy resolution, signal intensity and the sampled spot size to new limits. With RIXS one nowadays probes a broad range of electronic systems reaching from simple molecules to complex materials displaying phenomena like peculiar magnetism, two-dimensional electron gases, superconductivity, photovoltaic energy conversion and heterogeneous catalysis. In this article the types of improved RIXS studies that will become possible with X-ray beams from DLSRs are envisioned

Estimation of gadolinium-induced T1-shortening with measurement of simple signal intensity ratio between the cochlea and brain parenchyma on 3D-FLAIR. Correlation with T1 measurement by TI scout sequence

International Nuclear Information System (INIS)

Naganawa, Shinji; Ishihara, Shunichi; Iwano, Shingo; Kawai, Hisashi; Sone, Michihiko; Nakashima, Tsutomu

2010-01-01

The purpose of this study was to T 1 -shortening of labyrinthine fluid on 3-dimensional fluid-attenuated inversion recovery (3D-FLAIR) has been reported in many inner ear disorders. Although semi-quantitative assessment by simple signal intensity ratio between cochlear fluid and brain tissue has been tried, its feasibility using a multi-channel phased-array head coil with an inherently inhomogenous sensitivity distribution has not been fully evaluated. We evaluated the feasibility of measuring simple signal intensity ratio by correlating rapid T 1 measurements using an inversion time (TI) scout sequence. We evaluated 10 patients with Meniere's disease and 4 patients with sudden deafness. Nine of the patients with Meniere's disease received a unilateral intratympanic injection of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA); the tenth patient received bilateral injections. The 4 patients with sudden deafness received a double-dose intravenous injection. Magnetic resonance (MR) images were obtained 24 hours after intratympanic injections and 4 hours after intravenous injections at 3 tesla using a 32-channel head coil. We measured the ratio (CM ratio) between the signal intensity of the perilymph in the cochlea (C) and that of the medulla oblongata (M) and correlated it with the null-point inversion time (TI null ) obtained with the TI scout sequence. The TI scout consisted of 85 images obtained with TI values between 132.5 and 3087.5 ms at increments of 37.5 ms. The correlation coefficient between TI null and the natural logarithm of the CM ratio was -0.88 (P<0.01). There was significant negative linear correlation. Measurement of the simple signal intensity ratio between the cochlea and the medulla can be used for semi-quantitative analysis of 3D-FLAIR. The results of this study may facilitate clinical research of inner-ear disease using 3D-FLAIR. (author)

Time-frequency peak filtering for random noise attenuation of magnetic resonance sounding signal

Science.gov (United States)

Lin, Tingting; Zhang, Yang; Yi, Xiaofeng; Fan, Tiehu; Wan, Ling

2018-05-01

When measuring in a geomagnetic field, the method of magnetic resonance sounding (MRS) is often limited because of the notably low signal-to-noise ratio (SNR). Most current studies focus on discarding spiky noise and power-line harmonic noise cancellation. However, the effects of random noise should not be underestimated. The common method for random noise attenuation is stacking, but collecting multiple recordings merely to suppress random noise is time-consuming. Moreover, stacking is insufficient to suppress high-level random noise. Here, we propose the use of time-frequency peak filtering for random noise attenuation, which is performed after the traditional de-spiking and power-line harmonic removal method. By encoding the noisy signal with frequency modulation and estimating the instantaneous frequency using the peak of the time-frequency representation of the encoded signal, the desired MRS signal can be acquired from only one stack. The performance of the proposed method is tested on synthetic envelope signals and field data from different surveys. Good estimations of the signal parameters are obtained at different SNRs. Moreover, an attempt to use the proposed method to handle a single recording provides better results compared to 16 stacks. Our results suggest that the number of stacks can be appropriately reduced to shorten the measurement time and improve the measurement efficiency.

Soliton-induced nonlocal resonances observed through high-intensity tunable spectrally compressed second-harmonic peaks

DEFF Research Database (Denmark)

Zhou, Binbin; Guo, Hairun; Bache, Morten

2014-01-01

Experimental data of femtosecond thick-crystal second-harmonic generation show that when tuning away from phase matching, a dominating narrow spectral peak appears in the second harmonic that can be tuned over hundreds of nanometers by changing the phase-mismatch parameter. Traditional theory...... and the nonlocal theory indirectly proves that we have observed a soliton-induced nonlocal resonance. The soliton exists in the self-defocusing regime of the cascaded nonlinear interaction and in the normal dispersion regime of the crystal, and needs high input intensities to become excited....

Magnetic resonance beacon to detect intracellular microRNA during neurogenesis.

Science.gov (United States)

Lee, Jonghwan; Jin, Yeon A; Ko, Hae Young; Lee, Yong Seung; Heo, Hyejung; Cho, Sujeong; Kim, Soonhag

2015-02-01

Magnetic resonance imaging (MRI) offers great spatial resolution for viewing deep tissues and anatomy. We developed a self-assembling signal-on magnetic fluorescence nanoparticle to visualize intracellular microRNAs (miRNAs or miRs) during neurogenesis using MRI. The self-assembling nanoparticle (miR124a MR beacon) was aggregated by the incubation of three different oligonucleotides: a 3' adaptor, a 5' adaptor, and a linker containing miR124a-binding sequences. The T2-weighted magnetic resonance (MR) signal of the self-assembled nanoparticle was quenched when miR124a was absent from test tubes or was minimally expressed in cells and tissues. When miR124a was present in test tubes or highly expressed in vitro and in vivo during P19 cell neurogenesis, it hybridized with the miR124a MR beacon, causing the linker to detach, resulting in increased signal-on MRI intensity. This MR beacon can be used as a new imaging probe to monitor the miRNA-mediated regulation of cellular processes. Copyright © 2014 Elsevier Ltd. All rights reserved.

Magnetic resonance imaging in osteomalacic insufficiency fractures of the pelvis

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Kanberoglu, K. [Department of Radiology, Cerrahpasa Medical Faculty, Istanbul University, Istanbul (Turkey)]. E-mail: zkanber@istanbul.edu.tr; Kantarci, F. [Department of Radiology, Cerrahpasa Medical Faculty, Istanbul University, Istanbul (Turkey); Cebi, D. [Department of Radiology, Cerrahpasa Medical Faculty, Istanbul University, Istanbul (Turkey); Yilmaz, M.H. [Department of Radiology, Cerrahpasa Medical Faculty, Istanbul University, Istanbul (Turkey); Kurugoglu, S. [Department of Radiology, Cerrahpasa Medical Faculty, Istanbul University, Istanbul (Turkey); Bilici, A. [Department of Internal Medicine, Cerrahpasa Medical Faculty, Istanbul University, Istanbul (Turkey); Koyuncu, H. [Department of Physical Medicine and Rehabilitation, Cerrahpasa Medical Faculty, Istanbul University, Istanbul (Turkey)

2005-01-01

AIMS: To report the magnetic resonance imaging (MRI) findings of osteomalacic insufficiency fractures of the pelvis. MATERIALS AND METHODS: In all, 12 persons presenting with chronic pelvic pain and with a definitive diagnosis of osteomalacia (OM) were enrolled in this study. Radiological work-up included direct radiographs (n=12), computed tomography (n=5), scintigraphy n=12) and MRI (n=12). The location of the insufficiency fractures and corresponding MRI appearances were evaluated. Depending on the presence or absence of signal intensity around the fractures, the lesions were grouped into active and chronic forms. RESULTS: A total of 34 insufficiency fractures were depicted on imaging studies. MRI demonstrated 33 of the lesions. All the insufficiency fractures were seen as a hypointense lines or fissures on T1- and T2-weighted and STIR MR images. There was a high frequency of insufficiency fractures at the sacrum and iliac bone (16/34, 47%). Overall, 11 chronic-type (no abnormal signal intensity around the fissure) and 22 active-type (abnormal signal intensity around the fissure) insufficiency fractures were detected by MRI. Follow-up MR examinations of 2 subjects showed that abnormal signal intensity had disappeared after appropriate treatment. CONCLUSION: The results of this study showed that the iliac and sacral bones are frequently involved in patients with OM. MRI can determine the clinical activity of the disease, and can monitor the response to treatment of the active type of insufficiency fractures.

Magnetic resonance imaging in osteomalacic insufficiency fractures of the pelvis

International Nuclear Information System (INIS)

Kanberoglu, K.; Kantarci, F.; Cebi, D.; Yilmaz, M.H.; Kurugoglu, S.; Bilici, A.; Koyuncu, H.

2005-01-01

AIMS: To report the magnetic resonance imaging (MRI) findings of osteomalacic insufficiency fractures of the pelvis. MATERIALS AND METHODS: In all, 12 persons presenting with chronic pelvic pain and with a definitive diagnosis of osteomalacia (OM) were enrolled in this study. Radiological work-up included direct radiographs (n=12), computed tomography (n=5), scintigraphy n=12) and MRI (n=12). The location of the insufficiency fractures and corresponding MRI appearances were evaluated. Depending on the presence or absence of signal intensity around the fractures, the lesions were grouped into active and chronic forms. RESULTS: A total of 34 insufficiency fractures were depicted on imaging studies. MRI demonstrated 33 of the lesions. All the insufficiency fractures were seen as a hypointense lines or fissures on T1- and T2-weighted and STIR MR images. There was a high frequency of insufficiency fractures at the sacrum and iliac bone (16/34, 47%). Overall, 11 chronic-type (no abnormal signal intensity around the fissure) and 22 active-type (abnormal signal intensity around the fissure) insufficiency fractures were detected by MRI. Follow-up MR examinations of 2 subjects showed that abnormal signal intensity had disappeared after appropriate treatment. CONCLUSION: The results of this study showed that the iliac and sacral bones are frequently involved in patients with OM. MRI can determine the clinical activity of the disease, and can monitor the response to treatment of the active type of insufficiency fractures

Biomechanics of the Peacock's Display: How Feather Structure and Resonance Influence Multimodal Signaling.

Directory of Open Access Journals (Sweden)

Roslyn Dakin

Full Text Available Courtship displays may serve as signals of the quality of motor performance, but little is known about the underlying biomechanics that determines both their signal content and costs. Peacocks (Pavo cristatus perform a complex, multimodal "train-rattling" display in which they court females by vibrating the iridescent feathers in their elaborate train ornament. Here we study how feather biomechanics influences the performance of this display using a combination of field recordings and laboratory experiments. Using high-speed video, we find that train-rattling peacocks stridulate their tail feathers against the train at 25.6 Hz, on average, generating a broadband, pulsating mechanical sound at that frequency. Laboratory measurements demonstrate that arrays of peacock tail and train feathers have a broad resonant peak in their vibrational spectra at the range of frequencies used for train-rattling during the display, and the motion of feathers is just as expected for feathers shaking near resonance. This indicates that peacocks are able to drive feather vibrations energetically efficiently over a relatively broad range of frequencies, enabling them to modulate the feather vibration frequency of their displays. Using our field data, we show that peacocks with longer trains use slightly higher vibration frequencies on average, even though longer train feathers are heavier and have lower resonant frequencies. Based on these results, we propose hypotheses for future studies of the function and energetics of this display that ask why its dynamic elements might attract and maintain female attention. Finally, we demonstrate how the mechanical structure of the train feathers affects the peacock's visual display by allowing the colorful iridescent eyespots-which strongly influence female mate choice-to remain nearly stationary against a dynamic iridescent background.

New Approach For Detection Of Irradiated Spices Using Electron Spin Resonance (ESR)

International Nuclear Information System (INIS)

FARAG, S.A.; SHAMS EL DIEEN, N.M.M.

2010-01-01

Black pepper and anise samples were irradiated with different doses of gamma rays (5, 10 and 20 kGy) then the irradiated samples were stored at room temperature (20 0 C, 70-75 % RH) for one year. The measurements of free radicals were carried out by electron spin resonance (ESR) at different intervals (3, 6, 9 and 12 months). A series of signals tentatively described as cellulose-like and complex radical observed at G values were 2.01027 for black pepper and 2.01019 for anise. The ESR signals of irradiated spices showed a directly proportional relationship for increasing dose with increasing intensity of signal. A relationship was noticed as polynomial regression analysis resulted between signals of ESR intensity and applied doses with significant values of correlation coefficient (R 2 ). All combination treatments of thermal and irradiation beside long storage caused significant reduction of ESR intensity of irradiated black pepper and anise. Upon using low doses as 1, 2 and 3 kGy for re-irradiation, the irradiated samples (10 and 20 kGy) increased the power of ESR intensity. The enhancement effect was markedly increased. For example, the irradiated black pepper (10 kGy) increased the ESR intensity with high percentages as 49.19%, 69.23% and 89.68% while the high dose (20 kGy) caused increase by 39.96%, 69.05% and 96.90% for irradiated black pepper samples. This approach with that technique can be used easily to overcome the main disadvantages of ESR signals fading especially at the end of storage period.

T2-weighted signal intensity-selected volumetry for prediction of pathological complete response after preoperative chemoradiotherapy in locally advanced rectal cancer.

Science.gov (United States)

Kim, Sungwon; Han, Kyunghwa; Seo, Nieun; Kim, Hye Jin; Kim, Myeong-Jin; Koom, Woong Sub; Ahn, Joong Bae; Lim, Joon Seok

2018-06-01

To evaluate the diagnostic value of signal intensity (SI)-selected volumetry findings in T2-weighted magnetic resonance imaging (MRI) as a potential biomarker for predicting pathological complete response (pCR) to preoperative chemoradiotherapy (CRT) in patients with rectal cancer. Forty consecutive patients with pCR after preoperative CRT were compared with 80 age- and sex-matched non-pCR patients in a case-control study. SI-selected tumor volume was measured on post-CRT T2-weighted MRI, which included voxels of the treated tumor exceeding the SI (obturator internus muscle SI + [ischiorectal fossa fat SI - obturator internus muscle SI] × 0.2). Three blinded readers independently rated five-point pCR confidence scores and compared the diagnostic outcome with SI-selected volumetry findings. The SI-selected volumetry protocol was validated in 30 additional rectal cancer patients. The area under the receiver-operating characteristic curve (AUC) of SI-selected volumetry for pCR prediction was 0.831, with an optimal cutoff value of 649.6 mm 3 (sensitivity 0.850, specificity 0.725). The AUC of the SI-selected tumor volume was significantly greater than the pooled AUC of readers (0.707, p volumetry in post-CRT T2-weighted MRI can help predict pCR after preoperative CRT in patients with rectal cancer. • Fibrosis and viable tumor MRI signal intensities (SIs) are difficult to distinguish. • T2 SI-selected volumetry yields high diagnostic performance for assessing pathological complete response. • T2 SI-selected volumetry is significantly more accurate than readers and non-SI-selected volumetry. • Post-chemoradiation therapy T2-weighted MRI SI-selected volumetry facilitates prediction of pathological complete response.

Medulloblastoma: correlation among findings of conventional magnetic resonance imaging, diffusion-weighted imaging and proton magnetic resonance spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Fonte, Mariana Vieira de Melo da; Otaduy, Maria Concepcion Garcia; Lucato, Leandro Tavares; Reed, Umbertina Conti; Leite, Claudia da Costa [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Hospital das Clinicas. Inst. de Radiologia]. E-mail: mvmfonte@uol.com.br; Costa, Maria Olivia Rodrigues; Amaral, Raquel Portugal Guimaraes [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Faculdade de Medicina. Dept. de Radiologia; Reed, Umbertina Conti [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Faculdade de Medicina. Dept. de Neurologia; Rosemberg, Sergio [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Hospital das Clinicas. Dept. de Patologia

2008-11-15

To correlate imaging findings of medulloblastomas at conventional magnetic resonance imaging, diffusion-weighted imaging and proton magnetic resonance spectroscopy, comparing them with data in the literature. Preoperative magnetic resonance imaging studies of nine pediatric patients with histologically confirmed medulloblastomas (eight desmoplastic medulloblastoma, and one giant cell medulloblastoma) were retrospectively reviewed, considering demographics as well as tumors characteristics such as localization, morphology, signal intensity, contrast-enhancement, dissemination, and diffusion-weighted imaging and spectroscopy findings. In most of cases the tumors were centered in the cerebellar vermis (77.8%), predominantly solid (88.9%), hypointense on T 1-weighted images and intermediate/hyperintense on T 2-FLAIR-weighted images, with heterogeneous enhancement (100%), tumor dissemination/extension (77.8%) and limited water molecule mobility (100%). Proton spectroscopy acquired with STEAM technique (n = 6) demonstrated decreased Na a / Cr ratio (83.3%) and increased Co/Cr (100%) and ml/Cr (66.7%) ratios; and with PRESS technique (n = 7) demonstrated lactate peak (57.1%). Macroscopic magnetic resonance imaging findings in association with biochemical features of medulloblastomas have been useful in the differentiation among the most frequent posterior fossa tumors. (author)

Medulloblastoma: correlation among findings of conventional magnetic resonance imaging, diffusion-weighted imaging and proton magnetic resonance spectroscopy

International Nuclear Information System (INIS)

Fonte, Mariana Vieira de Melo da; Otaduy, Maria Concepcion Garcia; Lucato, Leandro Tavares; Reed, Umbertina Conti; Leite, Claudia da Costa; Costa, Maria Olivia Rodrigues; Amaral, Raquel Portugal Guimaraes; Reed, Umbertina Conti; Rosemberg, Sergio

2008-01-01

To correlate imaging findings of medulloblastomas at conventional magnetic resonance imaging, diffusion-weighted imaging and proton magnetic resonance spectroscopy, comparing them with data in the literature. Preoperative magnetic resonance imaging studies of nine pediatric patients with histologically confirmed medulloblastomas (eight desmoplastic medulloblastoma, and one giant cell medulloblastoma) were retrospectively reviewed, considering demographics as well as tumors characteristics such as localization, morphology, signal intensity, contrast-enhancement, dissemination, and diffusion-weighted imaging and spectroscopy findings. In most of cases the tumors were centered in the cerebellar vermis (77.8%), predominantly solid (88.9%), hypointense on T 1-weighted images and intermediate/hyperintense on T 2-FLAIR-weighted images, with heterogeneous enhancement (100%), tumor dissemination/extension (77.8%) and limited water molecule mobility (100%). Proton spectroscopy acquired with STEAM technique (n = 6) demonstrated decreased Na a / Cr ratio (83.3%) and increased Co/Cr (100%) and ml/Cr (66.7%) ratios; and with PRESS technique (n = 7) demonstrated lactate peak (57.1%). Macroscopic magnetic resonance imaging findings in association with biochemical features of medulloblastomas have been useful in the differentiation among the most frequent posterior fossa tumors. (author)

Contribution of magnetic resonance imaging to the diagnosis of eosinophilic granuloma in children; Interet de l`IRM dans le granulome eosinophile de l`enfant

Energy Technology Data Exchange (ETDEWEB)

Gaucher, H.; Arnould, V.; Leblan, I.; Mainard, L.; Chastagner, P.; Galloy, M.A.; Hoeffel, J.C. [Hopital d`Enfants, 54 - Vandoeuvre-les-Nancy (France)

1995-05-01

Magnetic resonance imaging (MRI) findings in 12 patients with biopsy-proven eosinophilic granuloma were studied retrospectively. Signal intensity was variable on T1 images and increased on T2 images and after gadolinium injection. Magnetic resonance imaging identified all the granulomas, as well as accompanying bone marrow and soft tissue changes. In all 12 cases, the lesion appeared larger on MRI displays than on plain roentgenograms. MRI findings had low specificity and consistently tended to overestimate tumor spread, especially when a long limb bone was affected. Chemotherapy was followed by changes in the size and shape of MRI lesions (loss of the high-intensity signal on T2 images and after gadolinium) suggestive of a favorable response to treatment. (authors). 12 refs., 16 figs.

The use of sugar pellets in ESR [electron spin resonance] dosimetry

International Nuclear Information System (INIS)

Tchen, A.; Greenstock, C.L.; Trivedi, A.

1993-01-01

Table sugar (sucrose) is a convenient, common, tissue-equivalent material suitable for electron spin resonance (ESR) dosimetry of ionising radiation. The simple free radical signal in irradiated sugar is stabilised if the sugar is made into pellets using an inert silicone elastomer (Dow Corning 732). Such pellets, which offer greater convenience and signal stability and reproducibility, have been prepared and tested for their radiation response, sensitivity and post-irradiation stability. Irradiated sugar is detectable at ≥0.1 Gy, the signal intensity is linear with dose, and the fading of the signal, post-irradiation, is minimal for samples kept under ambient conditions. These pellets themselves, given sufficient post-irradiation signal stability, may be useful for environmental monitoring to determine long-term exposures in remote areas or at strategic locations. (Author)

Magnetic resonance imaging apparatus

International Nuclear Information System (INIS)

Ehnholm, G.J.

1991-01-01

This patent describes an electron spin resonance enhanced magnetic resonance (MR) imaging (ESREMRI) apparatus able to generate a primary magnetic field during periods of nuclear spin transition excitation and magnetic resonance signal detection. This allows the generation of ESREMRI images of a subject. A primary magnetic field of a second and higher value generated during periods of nuclear spin transition excitation and magnetic resonance signal detection can be used to generate conventional MR images of a subject. The ESREMRI and native MR images so generated may be combined, (or superimposed). (author)

Amplification of weak signals via the non-adiabatic regime of stochastic resonance in a bistable dynamical system with time delay

International Nuclear Information System (INIS)

Du Luchun; Mei Dongcheng

2011-01-01

The non-adiabatic regime of stochastic resonance (SR) in a bistable system with time delay, an additive white noise and a periodic signal was investigated. The signal power amplification η was employed to characterize the SR of the system. The simulation results indicate that (i) in the case of intermediate frequency Ω of the periodic signal, the typical behavior of SR is lowered monotonically by increasing the delay time τ; in the case of large Ω, τ weakens the SR behavior and then enhances it, with a non-monotonic behavior as a function of time delay; (ii) time delay induces SR when A is above the threshold, whereas no such resonance exists in the absence of time delay; (iii) time delay induces a transition from bimodal to unimodal configuration of η; (iv) varying the particular form of time delay results in different phenomena.

Hemorrhagic brain metastases with high signal intensity on diffusion-weighted MR images. A case report

Energy Technology Data Exchange (ETDEWEB)

Mori, H.; Abe, O.; Aoki, S.; Masumoto, T.; Yoshikawa, T.; Kunimatsu, A; Hayashi, N.; Ohtomo, K. [Graduate School of Medicine, Univ. of Tokyo (Japan). Dept. of Radiology

2002-11-01

Diffusion-weighted MR imaging has been applicable to the differential diagnosis of abscesses and necrotic or cystic brain tumors. However, restricted water diffusion is not necessarily specific for brain abscess. We describe ring-enhancing metastases of lung carcinoma characterized by high signal intensity on diffusion-weighted MR images. The signal pattern probably reflected intralesional hemorrhage. The present report adds to the growing literature regarding the differential diagnosis of ring-enhancing brain lesions.

Diagnosing aneurysmal and unicameral bone cysts with magnetic resonance imaging.

Science.gov (United States)

Sullivan, R J; Meyer, J S; Dormans, J P; Davidson, R S

1999-09-01

The differential between aneurysmal bone cysts and unicameral bone cysts usually is clear clinically and radiographically. Occasionally there are cases in which the diagnosis is not clear. Because natural history and treatment are different, the ability to distinguish between these two entities before surgery is important. The authors reviewed, in a blinded fashion, the preoperative magnetic resonance images to investigate criteria that could be used to differentiate between the two lesions. All patients had operative or pathologic confirmation of an aneurysmal bone cyst or unicameral bone cyst. The authors analyzed the preoperative magnetic resonance images of 14 patients with diagnostically difficult bone cysts (eight children with unicameral bone cysts and six children with aneurysmal bone cysts) and correlated these findings with diagnosis after biopsy or cyst aspiration and contrast injection. The presence of a double density fluid level within the lesion strongly indicated that the lesion was an aneurysmal bone cyst, rather than a unicameral bone cyst. Other criteria that suggested the lesion was an aneurysmal bone cyst were the presence of septations within the lesion and signal characteristics of low intensity on T1 images and high intensity on T2 images. The authors identified a way of helping to differentiate between aneurysmal bone cysts and unicameral bone cysts on magnetic resonance images. Double density fluid level, septation, and low signal on T1 images and high signal on T2 images strongly suggest the bone cyst in question is an aneurysmal bone cyst, rather than a unicameral bone cyst. This may be helpful before surgery for the child who has a cystic lesion for which radiographic features do not allow a clear differentiation of unicameral bone cyst from aneurysmal bone cyst.

Multiphase contrast-enhanced magnetic resonance imaging features of Bacillus Calmette-Guerin-induced granulomatous prostatitis in five patients

Energy Technology Data Exchange (ETDEWEB)

Kawada, Hiroshi; Kanematsu, Masayuki; Goshima, Satoshi; Kondo, Hiroshi; Watanabe, Haruo; Noda, Yoshifumi; Tanahashi, Yukichi; Kawai, Nobuyuki; Hoshi, Hiroaki [Gifu University Hospital, Gifu (Japan)

2015-04-15

To evaluate the multiphase contrast-enhanced magnetic resonance (MR) imaging features of Bacillus Calmette-Guerin (BCG)-induced granulomatous prostatitis (GP). Magnetic resonance images obtained from five patients with histopathologically proven BCG-induced GP were retrospectively analyzed for tumor location, size, signal intensity on T2-weighted images (T2WI) and diffusion-weighted images (DWI), apparent diffusion coefficient (ADC) value, and appearance on gadolinium-enhanced multiphase images. MR imaging findings were compared with histopathological findings. Bacillus Calmette-Guerin-induced GP (size range, 9-40 mm; mean, 21.2 mm) were identified in the peripheral zone in all patients. The T2WI showed lower signal intensity compared with the normal peripheral zone. The DWIs demonstrated high signal intensity and low ADC values (range, 0.44-0.68 x 10(-3) mm2/sec; mean, 0.56 x 10(-3) mm2/sec), which corresponded to GP. Gadolinium-enhanced multiphase MR imaging performed in five patients showed early and prolonged ring enhancement in all cases of GP. Granulomatous tissues with central caseation necrosis were identified histologically, which corresponded to ring enhancement and a central low intensity area on gadolinium-enhanced MR imaging. The findings on T2WI, DWI, and gadolinium-enhanced images became gradually obscured with time. Bacillus Calmette-Guerin-induced GP demonstrates early and prolonged ring enhancement on gadolinium-enhanced MR imaging which might be a key finding to differentiate it from prostate cancer.

Resonance contributions to Hanbury-Brown endash Twiss correlation radii

International Nuclear Information System (INIS)

Wiedemann, U.A.; Heinz, U.

1997-01-01

We study the effect of resonance decays on intensity interferometry for heavy ion collisions. Collective expansion of the source leads to a dependence of the two-particle correlation function on the pair momentum K. This opens the possibility to reconstruct the dynamics of the source from the K dependence of the measured Hanburg-Brown endash Twiss (HBT) radii. Here we address the question to what extent resonance decays can fake such a flow signal. Within a simple parametrization for the emission function we present a comprehensive analysis of the interplay of flow and resonance decays on the one- and two-particle spectra. We discuss in detail the non-Gaussian features of the correlation function introduced by long-lived resonances and the resulting problems in extracting meaningful HBT radii. We propose to define them in terms of the second-order q moments of the correlator C(q,K). We show that this yields a more reliable characterisation of the correlator in terms of its width and the correlation strength λ than other commonly used fit procedures. The normalized fourth-order q moments (kurtosis) provide a quantitative measure for the non-Gaussian features of the correlator. At least for the class of models studied here, the kurtosis helps separating effects from expansion flow and resonance decays, and provides the cleanest signal to distinguish between scenarios with and without transverse flow. copyright 1997 The American Physical Society

New model for gain control of signal intensity to object distance in echolocating bats

DEFF Research Database (Denmark)

Nørum, Ulrik; Brinkløv, Signe; Surlykke, Annemarie

2012-01-01

Echolocating bats emit ultrasonic calls and listen for the returning echoes to orient and localize prey in darkness. The emitted source level, SL (estimated signal intensity 10 cm from the mouth), is adjusted dynamically from call to call in response to sensory feedback as bats approach objects. ...

Direct UV written Michelson interferometer for RZ signal generation using phase-to-intensity modulation conversion

DEFF Research Database (Denmark)

Peucheret, Christophe; Geng, Yan; Zsigri, Beata

2005-01-01

An integrated Michelson delay interferometer structure making use of waveguide gratings as reflective elements is proposed and fabricated by direct ultraviolet writing. Successful return-to-zero alternate-mark-inversion signal generation using phase-to-intensity modulation conversion...

Identification of irradiated chicken meat using electron spin resonance spectroscopy

International Nuclear Information System (INIS)

Chawla, S.P.; Thomas, Paul

2004-01-01

Studies were carried out on detection of irradiation treatment in chicken using electron spin resonance (ESR) spectroscopy. The effect of gamma- irradiation treatment on radiation induced signal in different types of chicken namely, broiler, deshi and layers was studied. Irradiation treatment induced a characteristic ESR signal that was not detected in non-irradiated samples. The shape of the signal was not affected by type of the bone. The intensity of radiation induced ESR signal was affected by factors such as absorbed radiation dose, bone type irradiation temperature, post-irradiation storage, post-irradiation cooking and age of the bird. Deep-frying resulted in the formation of a symmetric signal that had a different shape and was weaker than the radiation induced signal. This technique can be effectively used to detect irradiation treatment in bone-in chicken meat even if stored and/or subjected to various traditional cooking procedures. (author)

Can magnetic resonance imaging predict the success of parturition in oxytocin-induced pregnant women?

International Nuclear Information System (INIS)

Sabir, N.; Akkemik, B.; Dicle, O.; Yurdakul, B.

2000-01-01

The aim of this study was to assess whether magnetic resonance imaging could predict the outcome of attempted vaginal delivery in a group of pregnant women whose parturition had to be induced by oxytocin. The signal intensity and morphology alterations in the cervix of 21 full-term pregnant women were analyzed before the induction of parturition. T2-weighted gradient echo sequences were utilized and signal intensity in the cervix was measured from the anterior and posterior lips of the cervix. An index indicating the brightness range of the cervix was formulated to overcome the effects of the individual intensity changes. Imaging features including the signal intensity and the evidence of effacement were correlated with the actual type of delivery performed. Images were also assessed visually by two independent radiologists. Statistical analysis of brightness indexes that were considered to have a predictive value as an indicator for possible delivery was not significant. However, visually assessed signal intensity of the cervix correlated strongly with the type of delivery. Effacement itself was the most reliable parameter in predicting the progress of the delivery. In conclusion, MR imaging seems to be useful for predicting normal parturition in full-term pregnant women who need oxytocin induction. However, the presence of effacement seems to be a more reliable and practical parameter that will be preferred in that prediction. (orig.)

Magnetic resonance imaging and computed radiography in Achilles tendon rupture

International Nuclear Information System (INIS)

Korenaga, Tateo; Hachiya, Junichi; Miyasaka, Yasuo

1988-01-01

Magnetic Resonance Imaging (MRI) and Computed Radiography (CR) were performed in 15 patients with complete Achilles tendon rupture who were treated conservatively without surgery. MRI was obtained using Toshiba MRT 50 A superconductive machine, operaing at 0.5 Tesla. CR was performed by CR-101, Fuji Medical System. In fresh cases, ruptured tendons showed intermediate signal intensity on T1-weighted images and high intensity on T2-weighted images. Thickening of the tendon was observed in all cases except in very acute stage. Configuration of thickend tendons tends to be dumbbell shape in subacute stage and fusiform in chronic stage of more than six months after the initial trauma. In cases which showed high signal intensity at the ruptured area both on T1 and T2 weighted images, migration of fat into the sapces between the ruptured tendons was considered to be the major source of increased signal intensity. Computed radiography showed thickening of the tendon, blurring of anterior margin of the tendon, and decreased translucency of pre-Achilles fat pad. However, MRI better demonstrated the details of ruptured tendons when compared to CR, and thought to be an usefull way of following up the healing process of the ruptured tendon to facilitate more reasonable judgement of the time of removing plaster casts and stating exercise. (author)

Investigation of EPR signals on tooth enamel

Energy Technology Data Exchange (ETDEWEB)

Pavlenko, A; Mironova-Ulmane, N; Polakov, M; Riekstina, D [Institute of Solid State Physics, University of Latvia, Riga (Latvia)

2007-12-15

Calcified tissues are involved in continues metabolic process in human organism exchanging a number of chemical elements with environment. The rate of biochemical reactions is tissue dependent and the slowest one at the tooth enamel, the most mineralized tissue of human organism. The long time stability and unique chemical composition make tooth enamel suitable for number of application. The assessment of individual radiation dose by Electron Paramagnetic Resonance (EPR) and evaluations of elemental composition by Instrumentation Neutron Activation Analysis (INAA) are the well known procedures where properties of tooth enamel intensively used. The current work is focused on investigation of EPR signals and determination of chemical composition on several teeth samples having different origin. The EPR spectra and INAA element content of milk tooth, caries tooth, and paradantose tooth have been compared to each other. The results showed that the intensity of EPR signal is much higher for the caries tooth than the for paradantose tooth that is in agreement with depleted Ca content.

Decrease in the cortical intensity on T2-weighted magnetic resonance imaging with aging in normal subjects

International Nuclear Information System (INIS)

Imon, Yukari; Murata, Yoshio; Kajima, Toshio; Nakamura, Shigenobu; Yamaguchi, Shinya

1997-01-01

We reported previously that Low T 2 intensity areas (LIAs) are more common in patients with central nervous system (CNS) diseases than in those with no such diseases, and that the occurrence of LIAs increases with aging. To determine a relationship between the intensity changes and aging, we investigated the intensity of the cerebral cortex in 26 normal Japanese individuals. Measurements of brain MRIs were performed with a Signa Advantage apparatus at 1.5 tesla. T 2 -weighted images were obtained using the spin-echo pulse sequences. On our laboratory console, we measured signal intensities in the regions of interest in the prefrontal, motor, sensory, parietal, temporal, or occipital cortex, and in the frontal white matter. To remove the effect of the system gain settings on signal intensity, that of cerebrospinal fluid was used as reference according to the method of Pujol et al. The average intensity in the temporal and prefrontal cortices was the highest, followed in order by the parietal, sensory, motor, and occipital cortices. The intensity in the temporal and parietal cortices decreased significantly with aging, and that in the motor and sensory cortices had a tendency to decrease with aging. The intensity in the motor and sensory cortices of the elderly subjects and that in the occipital cortex throughout all ages were lower than that in the prefrontal white matter, which would result in the appearance of LIAs. The average intensity of each cerebral cortex was inversely related to the non-heme iron content previously reported. It is likely that the difference in intensity among the cortices reflects variations of the non-heme iron content, and that the change in intensity with aging could be due to the increase in such cortical senile changes as that of microglia, astroglia, and senile plaques, which contain iron or iron-related proteins. The temporal cortex is most susceptible to senile changes. (K.H.)

A study of the magnetic resonance in a single-crystal Ni50.47Mn28.17Ga21.36 alloy

International Nuclear Information System (INIS)

Gavriljuk, V G; Dobrinsky, A; Shanina, B D; Kolesnik, S P

2006-01-01

The single-crystal non-stoichiometric magnetic shape memory alloy Ni 1-x-y Mn x Ga y with x = 0.2817, y = 0.2136 is studied using magnetic resonance spectroscopy: ferromagnetic resonance (FMR) and conduction electron spin resonance (CESR). The temperature dependence of the integral intensity, the resonance field and the line-width are measured across the wide temperature interval from 4.2 to 570 K. Three phase transformations are found in this alloy: paramagnetic ↔ ferromagnetic with a Curie temperature of 360 K, austenite-to-martensite (direct with T ms = 312 K and reverse with T as = 313 K), and a transformation at T = 45 K, suggestive of the spin-glass state. The angular dependence of the FMR signals is measured in the martensitic and austenitic states before and after the martensite-to-austenite transition. The experimental data are used for determination of the magnetization M m and anisotropy parameters K 1 and K 2 in the martensitic state. The obtained coefficient K 2 is determined to be not small and, moreover, it is comparable with K 1 . The temperature dependence of the resonance signals is also investigated at temperatures significantly higher than T C , where FMR was transformed to CESR. In the paramagnetic austenitic state (above T C ) the alloy reveals an extremely intensive signal of CESR, which suggests a high concentration of conduction electrons and correlates with the large value of the magnetic-field-induced strain observed in the alloys of such composition. The temperature dependence of the skin layer depth is found from the sharp decay of the CESR signal with temperature, which is related to the disappearing large magnetic resistance after transformation to the paramagnetic state

Measurement of the profile and intensity of the solar He I lambda 584-A resonance line

Science.gov (United States)

Maloy, J. O.; Hartmann, U. G.; Judge, D. L.; Carlson, R. W.

1978-01-01

The intensity and profile of the helium resonance line at 584 A from the entire disk of the sun was investigated by using a rocket-borne helium-filled spectrometer and a curve-of-growth technique. The line profile was found to be accurately represented by a Gaussian profile with full width at half maximum of 122 + or - 10 mA, while the integrated intensity was measured to be 2.6 + or - 1.3 billion photons/s per sq cm at solar activity levels of F(10.7) = 90.8 x 10 to the -22nd per sq m/Hz and Rz = 27. The measured line width is in good agreement with previous spectrographic measurements, but the integrated intensity is larger than most previous photoelectric measurements. However, the derived line center flux of 20 + or - 10 billion photons/s per sq cm/A is in good agreement with values inferred from airglow measurements.

High signal intensity lesion in basal ganglia on MR imaging: correlation with portal-systemic encephalopathy in liver cirrhosis

Energy Technology Data Exchange (ETDEWEB)

Kim, Yun Ju; Choi, Sun Jeong; Kim, Chang Soo; Kim, Sun Hee; Chung, Chun Phil; Kim, Yang Sook [Maryknoll Hospital, Pusan (Korea, Republic of)

1993-01-15

To evaluate of the relationship between basal ganglia lesion and portal-systemic encephalopathy, eleven patients who had clinically proved liver cirrhosis with superior mesenteric vein larger than 10mm in diameter on ultrasonogram underwent brain MR imaging. No evidence of clinical or neuropsychiatric disturbance was observed in any patient at the time of the MR examination. Brain MR imaging revealed basal ganglia lesion characterized by bilateral, symmetric, high signal intensity without edema or mass effect on spin echo T1-weighted images in nine patients which included three patients with the past history of portal-systemic encephalopathy. It was concluded that excepted in the circumstances of other causes of the high signal intensity in basal ganglia on T1-weighted images such as fat, methemoglobin, melanin, neurofibromatosis, dense calcification, and parenteral nutrition, bilateral and symmetric high signal intensity lesion in basal ganglia would be a useful MR finding of subclinical portal-systemic encephalopathy in liver cirrhosis patients with no clinical or neuropsychiatric symptoms and larger than 10mm in diameter of superior mesenteric vein in ultrasonography.

High signal intensity lesion in basal ganglia on MR imaging: correlation with portal-systemic encephalopathy in liver cirrhosis

International Nuclear Information System (INIS)

Kim, Yun Ju; Choi, Sun Jeong; Kim, Chang Soo; Kim, Sun Hee; Chung, Chun Phil; Kim, Yang Sook

1993-01-01

To evaluate of the relationship between basal ganglia lesion and portal-systemic encephalopathy, eleven patients who had clinically proved liver cirrhosis with superior mesenteric vein larger than 10mm in diameter on ultrasonogram underwent brain MR imaging. No evidence of clinical or neuropsychiatric disturbance was observed in any patient at the time of the MR examination. Brain MR imaging revealed basal ganglia lesion characterized by bilateral, symmetric, high signal intensity without edema or mass effect on spin echo T1-weighted images in nine patients which included three patients with the past history of portal-systemic encephalopathy. It was concluded that excepted in the circumstances of other causes of the high signal intensity in basal ganglia on T1-weighted images such as fat, methemoglobin, melanin, neurofibromatosis, dense calcification, and parenteral nutrition, bilateral and symmetric high signal intensity lesion in basal ganglia would be a useful MR finding of subclinical portal-systemic encephalopathy in liver cirrhosis patients with no clinical or neuropsychiatric symptoms and larger than 10mm in diameter of superior mesenteric vein in ultrasonography

Resonant freak microwaves

International Nuclear Information System (INIS)

Aguiar, F.M. de

2011-01-01

The Helmholtz equation describing transverse magnetic modes in a closed flat microwave resonator with 60 randomly distributed discs is numerically solved. At lower frequencies, the calculated wave intensity spatially distributed obeys the universal Porter-Thomas form if localized modes are excluded. A superposition of resonant modes is shown to lead to rare events of extreme intensities (freak waves) at localized 'hot spots'. The temporally distributed intensity of such a superposition at the center of a hot spot also follows the Porter-Thomas form. Branched modes are found at higher frequencies. The results bear resemblance to recent experiments reported in an open cavity.

Ferromagnetic nuclear resonance investigation of the surface magnetization in iron sheets

International Nuclear Information System (INIS)

Varga, L.; Tompa, K.

1977-09-01

The role of the domain structure and domain properties in ferromagnetic nuclear resonance (FNR) experiments is reconsidered. Using the FNR signal intensity as a measure of surface domain wall volume, it is found that the behaviour of the surface magnetization differs from that of the bulk magnetization of iron sheets. Namely, a critical field below which the FNR signal remains unchanqed is observed in the surface magnetization. This lag of surface domain wall annihilation is sensitive to the given surface conditions and in particular to the rolling deformation. Considering the small skin depth, FNR as a surface testing method is discussed. (D.P.)

Magnetic resonance tomography in syringomyelia

International Nuclear Information System (INIS)

Koehler, D.; Treisch, J.; Hertel, G.; Schoerner, W.; Fiegler, W.; Staedtisches Rudolf-Virchow Krankenhaus, Berlin

1985-01-01

Thirteen patients with a clinical diagnosis of syringomyelia were examined by nuclear tomography (0.35 T magnet) in the spin-echo mode. In all thirteen patients, the T1 images (Se 400/35) showed a longitudinal cavity with a signal intensity of CSF. The shape and extent of the syrinx could be adequately demonstrated in 12 of the 13 examinations. Downward displacement of the cerebellar tonsils was seen in eight cases. The examination took between half and one hour. Advantages of magnetic resonance tomography (nuclear tomography) include the absence of artifacts, images in the line of the lesion and its non-invasiveness. (orig.) [de

Effects of Colored Noise on Stochastic Resonance in Sensory Neurons

International Nuclear Information System (INIS)

Nozaki, D.; Mar, D.J.; Collins, J.J.; Grigg, P.

1999-01-01

Noise can assist neurons in the detection of weak signals via a mechanism known as stochastic resonance (SR). We demonstrate experimentally that SR-type effects can be obtained in rat sensory neurons with white noise, 1/f noise, or 1/f 2 noise. For low-frequency input noise, we show that the optimal noise intensity is the lowest and the output signal-to-noise ratio the highest for conventional white noise. We also show that under certain circumstances, 1/f noise can be better than white noise for enhancing the response of a neuron to a weak signal. We present a theory to account for these results and discuss the biological implications of 1/f noise. copyright 1999 The American Physical Society

14 GHz longitudinally detected electron spin resonance using microHall sensors

Science.gov (United States)

Bouterfas, M.; Mouaziz, S.; Popovic, R. S.

2017-09-01

In this work we developed a home-made LOngitudinally Detected Electron Spin Resonance (LODESR) spectrometer based on a microsize Hall sensor. A coplanar waveguide (CPW)-resonator is used to induce microwave-excitation on the sample at 14 GHz. We used InSb cross-shaped Hall devices with active areas of (10 μm × 10 μm) and (5 μm × 5 μm) . Signal intensities of the longitudinal magnetization component of DPPH and YIG samples of volumes about (10 μm) 3 and (5 μm) 3 , are measured under amplitude and frequency modulated microwave magnetic field generated by the CPW-resonator. At room temperature, 109spins /G √Hz sensitivity is achieved for 0.2mT linewidth, a result which is still better than most of inductive detected LODESR sensitivities.

Influence of the position of the foot on MRI signal in the deep digital flexor tendon and collateral ligaments of the distal interphalangeal joint in the standing horse.

Science.gov (United States)

Spriet, M; Zwingenberger, A

2009-05-01

Hyperintense signal is sometimes observed in ligaments and tendons of the equine foot on standing magnetic resonance examination without associated changes in size and shape. In such cases, the presence of a true lesion or an artifact should be considered. A change in position of a ligament or tendon relative to the magnetic field can induce increased signal intensity due to the magic angle effect. To assess if positional rotation of the foot in the solar plane could be responsible for artifactual changes in signal intensity in the collateral ligaments of the distal interphalangeal joint and in the deep digital flexor tendon. Six isolated equine feet were imaged with a standing equine magnetic resonance system in 9 different positions with different degrees of rotation in the solar plane. Rotation of the limb induced a linear hyperintense signal on all feet at the palmar aspect of one of the lobes of the deep digital flexor tendon and at the dorsal aspect of the other lobe. Changes in signal intensity in the collateral ligaments of the distal interphalangeal joint occurred with rotation of the limb only in those feet where mediolateral hoof imbalance was present. The position and conformation of the foot influence the signal intensity in the deep digital flexor tendon and in the collateral ligaments of the distal interphalangeal joint. The significance of increased signal intensity in the deep digital flexor tendon and in the collateral ligaments of the distal interphalangeal joint should be interpreted with regard to the position and the conformation of the foot.

Factors Affecting Detection Of Irradiated Bone Meat By Using Electron Spine Resonance

International Nuclear Information System (INIS)

FARAG, S.A.; ATIA, A.I.; HASSAN, G.M.

2009-01-01

Different types of bone meats were purchased locally such as camel, cow and sheep. The bones were removed, cleaned and irradiated with gamma rays at different doses (5, 10 and 20 kGy). The bone samples were stored in a refrigerator for five months for studying their stability of radiation-induced free radicals using electron spin resonance (ESR) technique. The effect of thermal treatment at 50 o C at intervals was studied besides effect of storage period and re-irradiation process on ESR signal intensity. The ESR spectrum for radical species in irradiated samples was characterized by signal with spectroscopic splitting factor (g factor) of g1=2.0025 and g2=1.9973 for camel, cow and sheep bones, respectively. The signal at g = 2.0025 was ascribed to free radical rotation CO -2 that was derived from radiation-induced hydroxyapatite. Generally, the results proved that all above mentioned factors under investigation can affect ESR signal intensity but not prevent the recognize of irradiated bones, therefore, it must be taken in mind when calculating the absorbed dose.

NIST mixed stain study 3: signal intensity balance in commercial short tandem repeat multiplexes.

Science.gov (United States)

Duewer, David L; Kline, Margaret C; Redman, Janette W; Butler, John M

2004-12-01

Short-tandem repeat (STR) allelic intensities were collected from more than 60 forensic laboratories for a suite of seven samples as part of the National Institute of Standards and Technology-coordinated 2001 Mixed Stain Study 3 (MSS3). These interlaboratory challenge data illuminate the relative importance of intrinsic and user-determined factors affecting the locus-to-locus balance of signal intensities for currently used STR multiplexes. To varying degrees, seven of the eight commercially produced multiplexes used by MSS3 participants displayed very similar patterns of intensity differences among the different loci probed by the multiplexes for all samples, in the hands of multiple analysts, with a variety of supplies and instruments. These systematic differences reflect intrinsic properties of the individual multiplexes, not user-controllable measurement practices. To the extent that quality systems specify minimum and maximum absolute intensities for data acceptability and data interpretation schema require among-locus balance, these intrinsic intensity differences may decrease the utility of multiplex results and surely increase the cost of analysis.

{sup 1}H and {sup 31}P magnetic resonance spectroscopic imaging of white matter signal hyperintensity areas in elderly subjects

Energy Technology Data Exchange (ETDEWEB)

Constans, J M [Department of Veterans Affairs Medical Center and University of California Magnetic Resonance Unit, San Francisco, CA (United States); [California Univ., San Francisco, CA (United States). Dept. of Radiology; Meyerhoff, D J [Department of Veterans Affairs Medical Center and University of California Magnetic Resonance Unit, San Francisco, CA (United States); [California Univ., San Francisco, CA (United States). Dept. of Radiology; Norman, D [California Univ., San Francisco, CA (United States). Dept. of Radiology; Fein, G [Department of Veterans Affairs Psychiatry Service, University of California, San Francisco, California (United States); [University of California, San Francisco, CA (United States). Dept. of Psychiatry; Weiner, M W [Department of Veterans Affairs Medical Center and University of California Magnetic Resonance Unit, San Francisco, CA (United States); [California Univ., San Francisco, CA (United States). Dept. of Radiology; [California Univ., San Francisco, CA (United States). Dept. of Medicine; [DVA Medical Center, Magnetic Resonance Spectroscopy Unit, San Francisco, CA (United States)

1995-11-01

White matter signal hyperintensities (WMSH) are commonly seen on MRI of elderly subjects. The purpose of this study was to characterize metabolic changes in the white matter of elderly subjects with extensive WMSH. We used water-suppressed proton ({sup 1}H) magnetic resonance spectroscopic imaging (MRSI) to compare six subjects with extensive WMSH with eight age-matched elderly subjects with minimal or absent WMSH, and phosphorus ({sup 31}P) MRSI to compare nine subjects with extensive WMSH and seven age-matched elderly subjects without extensive WMSH. Relative to region-matched tissue in elderly controls, extensive WMSH were associated with increased signal from choline-containing metabolites, no significant change of signal from N-acetylaspartate, and a trend to a decreased phosphomonoester (PME) resonance. These findings suggest that WMSH may be associated with an alteration of brain myelin phospholipids in the absence of axonal damage. There were no differences in energy phosphates, consistent with lack of ongoing brain ischemia. Within the group with extensive WMSH, PME resonance measures were significantly lower in WMSH than in contralateral normal-appearing white matter. These results provide information on pathophysiology of WMSH and a basis for comparison with WMSH in Alzheimer`s disease, vascular dementia, multiple sclerosis, and other diseases. (orig.). With 4 figs., 4 tabs.

Functional magnetic resonance imaging of the frontal eye fields during saccadic eye movements

International Nuclear Information System (INIS)

Miki, Atsushi; Takagi, Mineo; Abe, Haruki; Nakajima, Takashi; Miyauchi, Satoru.

1996-01-01

We evaluated activity-induced signal intensity changes in the human cerebral cortex during horizontal saccadic eye movements using functional magnetic resonance imaging (fMRI) based on the blood-oxygenation-level-dependent (BOLD) contrast method. Compared with central fixation, significant signal increases were observed bilaterally in the middle frontal gyrus (Brodmann area 8) during saccadic conditions. The location of the activated area was consistent with that of previously reported frontal eye fields (FEF). These results suggest that fMRI has potential merit for the study of cortical control of eye movements in humans. (author)

Novel diffusion-weighted magnetic resonance imaging findings in leptomeningeal carcinomatosis: a case report

Energy Technology Data Exchange (ETDEWEB)

Hu, Y.F.; Chang, F.C.; Hu, H.H.; Hsu, L.C. [Taipei Veterans General Hospital, Taiwan (China). Depts. of Internal Medicine and Radiology, and Neurological Inst.

2006-12-15

This report presents a rare case of leptomeningeal carcinomatosis initially presenting with mental impairment and rapidly progressing to coma without any history of malignancy. In addition to highlighting the diagnostic difficulties, the linear high signal intensity along the cortex on the diffusion-weighted imaging (DWI) sequence of magnetic resonance (MR) imaging was identified accidentally. High signal change in the corresponding areas was also noted on unenhanced fluid-attenuated inversion recovery (FLAIR) MR imaging, which may be a novel method of diagnosing leptomeningeal carcinomatosis, which should be studied further.

Observations of a free-energy source for intense electrostatic waves. [in upper atmosphere near upper hybrid resonance frequency

Science.gov (United States)

Kurth, W. S.; Frank, L. A.; Gurnett, D. A.; Burek, B. G.; Ashour-Abdalla, M.

1980-01-01

Significant progress has been made in understanding intense electrostatic waves near the upper hybrid resonance frequency in terms of the theory of multiharmonic cyclotron emission using a classical loss-cone distribution function as a model. Recent observations by Hawkeye 1 and GEOS 1 have verified the existence of loss-cone distributions in association with the intense electrostatic wave events, however, other observations by Hawkeye and ISEE have indicated that loss cones are not always observable during the wave events, and in fact other forms of free energy may also be responsible for the instability. Now, for the first time, a positively sloped feature in the perpendicular distribution function has been uniquely identified with intense electrostatic wave activity. Correspondingly, we suggest that the theory is flexible under substantial modifications of the model distribution function.

Magnetic resonance colonography without bowel cleansing using oral and rectal stool softeners (fecal cracking) - a feasibility study

International Nuclear Information System (INIS)

Ajaj, Waleed; Lauenstein, Thomas C.; Kuehle, Christiane; Herborn, Christoph U.; Goehde, Susanne C.; Schneemann, Hubert; Ruehm, Stefan G.; Goyen, Mathias

2005-01-01

The aim of our study was to assess the effect of oral and rectal stool softeners on dark-lumen magnetic resonance (MR) colonography without bowel cleansing. Ten volunteers underwent MR colonography without colonic cleansing. A baseline examination was performed without oral or rectal administration of stool softeners. In a second set, volunteers ingested 60 ml of lactulose 24 h prior to MR examination. In a third examination, water as a rectal enema was replaced by a solution of 0.5%-docusate sodium (DS). A fourth MR examination was performed, in conjunction with both oral administration of lactulose and rectal application of DS. A T1-weighted data set was acquired at scanning times of 0, 5 and 10 min after colonic filling. A fourth data set was acquired 75 s after i.v. injection of contrast agent. Signal intensity of stool was calculated for all colonic segments. Without oral ingestion of lactulose or rectal enema with DS stool signal intensity was high and did not decrease over time. However, lactulose and DS caused a decrease in stool signal intensity. Both substances together led to a decreasing signal intensity of feces. Combination of lactulose and DS provided the lowest signal intensity of stool. Thus, feces could hardly be distinguished from dark rectal enema allowing for the assessment of the colonic wall. (orig.)

Nonlinear dynamics in micromechanical and nanomechanical resonators and oscillators

Science.gov (United States)

Dunn, Tyler

In recent years, the study of nonlinear dynamics in microelectromechanical and nanoelectromechanical systems (MEMS and NEMS) has attracted considerable attention, motivated by both fundamental and practical interests. One example is the phenomenon of stochastic resonance. Previous measurements have established the presence of this counterintuitive effect in NEMS, showing that certain amounts of white noise can effectively amplify weak switching signals in nanomechanical memory elements and switches. However, other types of noise, particularly noises with 1/falpha spectra, also bear relevance in these and many other systems. At a more fundamental level, the role which noise color plays in stochastic resonance remains an open question in the field. To these ends, this work presents systematic measurements of stochastic resonance in a nanomechanical resonator using 1/f alpha and Ornstein-Uhlenbeck noise types. All of the studied noise spectra induce stochastic resonance, proving that colored noise can also be beneficial; however, stronger noise correlations suppress the effect, decreasing the maximum signal-to-noise ratio and increasing the optimal noise intensity. Evidence suggests that 1/falpha noise spectra with increasing noise color lead to increasingly asymmetric switching, reducing the achievable amplification. Another manifestly nonlinear effect anticipated in these systems is modal coupling. Measurements presented here demonstrate interactions between various mode types on a wide scale, providing the first reported observations of coupling in bulk longitudinal modes of MEMS. As a result of anharmonic elastic effects, each mode shifts in frequency by an amount proportional to the squared displacement (or energy) of a coupled mode. Since all resonator modes couple in this manner, these effects enable nonlinear measurement of energy and mechanical nonlinear signal processing across a wide range of frequencies. Finally, while these experiments address nonlinear

Electron spin resonance studies of iron-group impurities in beryllium fluoride glasses

Energy Technology Data Exchange (ETDEWEB)

Griscom, D L; Stapelbroek, M [Naval Research Lab., Washington, DC (USA); Weber, M J [California Univ., Livermore (USA). Lawrence Livermore National Lab.

1980-11-01

Electron spin resonance investigations have been carried out on unirradiated BeF/sub 2/ glasses. Two relatively intense resonances were observed in a water-free distilled glass known to contain 49 ppM Ni, 13 ppM Mn, and < 20 ppM Fe. One of these was the paramagnetic resonance spectrum of Mn/sup 2 +/. Analysis of the observed /sup 19/F superhyperfine structure demonstrated this manganese to occupy distorted octahedral sites in the glass network. The second resonance was shown by temperature and frequency dependence studies, coupled with computer line shape analysis, to be a ferromagnetic resonance signal due to precipitated ferrite phases. The data suggest that these ferrites are somewhat heterogeneous and most likely comprize magnetite-like phases similar to NiFe/sub 2/O/sub 4/. An optical extinction curve rising into the ultraviolet with an approximate lambda/sup -4/ dependence is tentatively ascribed to light scattering by ferrite particles approximately 1000 Angstroems in diameter.

GeneChip microarrays-signal intensities, RNA concentrations and probe sequences

International Nuclear Information System (INIS)

Binder, Hans; Preibisch, Stephan

2006-01-01

GeneChip microarrays consist of hundreds of thousands of oligonucleotide probes. The transformation of their signal intensities into RNA transcript concentrations requires the knowledge of the response function of the measuring device. We analysed the 'apparatus' function of perfect match (PM) and mismatched (MM) oligonucleotide probes of GeneChip microarrays after changes of the target concentration using the results of a spiked-in experiment. In agreement with previous studies we found that a competitive two-species Langmuir-adsorption model describes the probe intensities well. Each PM and MM probe is characterized by two hybridization constants which specify the propensity of the probe to bind specific and non-specific transcripts. The affinity for non-specific hybridization is on average equal for PM and MM. The purine-pyrimidine asymmetry of base pair interaction strengths, however, causes a characteristic PM-MM intensity difference, the sign of which depends on the middle base of the probe. The affinity for specific hybridization of the PM exceeds that of the MM on average by nearly one order of magnitude because the central mismatched base only weakly contributes to the stability of the probe/target duplexes. For the first time we differentiate between the free energy parameters related to the 64 possible middle-triples of DNA/RNA oligomer duplexes with a central Watson-Crick pairing and a central mismatched pairing. Both the PM and MM probes respond to the concentration of specific transcripts, which can be estimated from the PM and MM probe intensities using the Langmuir-model. The analysis of the PM-MM intensity difference provides at least no loss of accuracy and precision of the estimated concentration compared with the PM-only estimates which in turn outperform the MM-only estimates. The results show that the processing of the PM-MM intensity difference requires the consideration of a background term due to non-specific hybridization, which is

Pump-To-Signal Intensity Modulation Transfer Characteristics in FOPAs: Modulation Frequency and Saturation Effect

DEFF Research Database (Denmark)

Lali-Dastjerdi, Zohreh; Cristofori, Valentina; Lund-Hansen, Toke

2012-01-01

This paper reports a comprehensive study of pump- to-signal intensity modulation transfer (IMT) in single-pump fiber optic parametric amplifiers (FOPAs). In particular, the IMT is studied for the first time for high-frequency fluctuations of the pump as well as in the saturated gain regime. The IMT...... cut-off frequency in typical single-pump FOPAs is around 100–200 GHz. The possibilities to shift this frequency based on dispersion and nonlinearities involved in the parametric gain are discussed. The severe IMT to the signal at low modulation frequencies can be suppressed by more than 50...

Nuclear magnetic resonance imaging

International Nuclear Information System (INIS)

Young, I.R.

1984-01-01

In a method of imaging a body in which nuclear magnetic resonance is excited in a region including part of the body, and the free induction decay signal is measured, a known quantity of a material of known nuclear magnetic resonance properties, for example a bag of water, is included in the region so as to enhance the measured free induction decay signal. This then reduces the generation of noise during subsequent processing of the signal. (author)

Magnetic resonance imaging of aneurysmal subarachnoid hemorrhage

International Nuclear Information System (INIS)

Ogawa, Toshihide; Shimosegawa, Eku; Inugami, Atsushi; Shishido, Fumio; Fujita, Hideaki; Ito, Hiroshi; Uemura, Kazuo; Yasui, Nobuyuki

1991-01-01

Magnetic resonance imaging of subarachnoid hemorrhage (SAH) due to aneurysm rupture was evaluated in relation to CT findings in nine patients. Six patients were studied within 3 days and the other three patients were studied 4 to 6 days from the ictus of SAH using a 0.5 Tesla superconducting unit. In all of the patients, hematoma in the subarachnoid space and ventricles was demonstrated by the proton density-weighted spin echo sequence, which showed that bloody cerebrospinal fluid (CSF) had a higher signal intensity than brain tissue or normal CSF. Magnetic resonance imaging was more sensitive in detecting SAH and more informative as to the site of the ruptured aneurysm than CT. Despite some limitations in applying it to patients with acute SAH, magnetic resonace imaging has clear advantages in the diagnosis of SAH. (author)

Magnetic resonance imaging of aneurysmal subarachnoid hemorrhage

Energy Technology Data Exchange (ETDEWEB)

Ogawa, Toshihide; Shimosegawa, Eku; Inugami, Atsushi; Shishido, Fumio; Fujita, Hideaki; Ito, Hiroshi; Uemura, Kazuo; Yasui, Nobuyuki (Research Inst. of Brain and Blood Vessels, Akita (Japan))

1991-11-01

Magnetic resonance imaging of subarachnoid hemorrhage (SAH) due to aneurysm rupture was evaluated in relation to CT findings in nine patients. Six patients were studied within 3 days and the other three patients were studied 4 to 6 days from the ictus of SAH using a 0.5 Tesla superconducting unit. In all of the patients, hematoma in the subarachnoid space and ventricles was demonstrated by the proton density-weighted spin echo sequence, which showed that bloody cerebrospinal fluid (CSF) had a higher signal intensity than brain tissue or normal CSF. Magnetic resonance imaging was more sensitive in detecting SAH and more informative as to the site of the ruptured aneurysm than CT. Despite some limitations in applying it to patients with acute SAH, magnetic resonace imaging has clear advantages in the diagnosis of SAH. (author).

Progressive and resonant wave helices application to electron paramagnetic resonance; Helices a ondes progressives et resonnantes application a la resonance paramagnetique electronique

Energy Technology Data Exchange (ETDEWEB)

Volino, F [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1969-07-01

We show that helices can be used as resonant systems. Their properties are theoretically and experimentally studied. We describe resonant helices for electron paramagnetic resonance in X-band and develop a comparison between their sensitivity and the sensitivity of a normal resonant cavity. For cylindrical samples less than 3 mm diameter, the helix is more sensitive and can produce more intense microwave magnetic fields. (author) [French] Il est montre que les helices peuvent etre utilisees comme systeme resonnant. Leurs proprietes sont discutees theoriquement et experimentalement. Des helices resonnantes en bande X pour la resonance paramagnetique electronique sont decrites et leur sensibilite est comparee a celle des cavites resonnantes. Pour des echantillons cylindriques de moins de 3 mm de diametre, l'helice est plus sensible et peut produire des champs magnetiques hyper fins plus intenses. (auteur)

ESR signal features of 60Co γ-ray irradiated bone tissue and its dose response relationship

International Nuclear Information System (INIS)

Wu Ke; Sun Zunpu; Shi Yuanming

1993-01-01

Electron spin resonance (ESR) technique was used to study the radiation-induced ESR signal features of different paramagnetic species of 60 Co γ-ray irradiated bone tissue. The results showed that the intensity of an ESR signal at that the intensity of an ESR signal at g 2.0022 of human bones exposed to a dose range of 0-50 Gy had linear dose response relationships. The lower limit of detectable dose was about 2 Gy and the detecting error was about 10%. The signal was stable at room temperature during 60 days, and the effect of radiation dose rate of 0.5-8.0 Gy/min could be neglected. This signal was insensitive to microwave power and temperature, which was suitable for rapid and direct detection with ESR technique. These features suggest that human bones could be used for radiation accident dose evaluation by ESR

Biomechanics of the Peacock’s Display: How Feather Structure and Resonance Influence Multimodal Signaling

Science.gov (United States)

Dakin, Roslyn; McCrossan, Owen; Hare, James F.; Montgomerie, Robert; Amador Kane, Suzanne

2016-01-01

Courtship displays may serve as signals of the quality of motor performance, but little is known about the underlying biomechanics that determines both their signal content and costs. Peacocks (Pavo cristatus) perform a complex, multimodal “train-rattling” display in which they court females by vibrating the iridescent feathers in their elaborate train ornament. Here we study how feather biomechanics influences the performance of this display using a combination of field recordings and laboratory experiments. Using high-speed video, we find that train-rattling peacocks stridulate their tail feathers against the train at 25.6 Hz, on average, generating a broadband, pulsating mechanical sound at that frequency. Laboratory measurements demonstrate that arrays of peacock tail and train feathers have a broad resonant peak in their vibrational spectra at the range of frequencies used for train-rattling during the display, and the motion of feathers is just as expected for feathers shaking near resonance. This indicates that peacocks are able to drive feather vibrations energetically efficiently over a relatively broad range of frequencies, enabling them to modulate the feather vibration frequency of their displays. Using our field data, we show that peacocks with longer trains use slightly higher vibration frequencies on average, even though longer train feathers are heavier and have lower resonant frequencies. Based on these results, we propose hypotheses for future studies of the function and energetics of this display that ask why its dynamic elements might attract and maintain female attention. Finally, we demonstrate how the mechanical structure of the train feathers affects the peacock’s visual display by allowing the colorful iridescent eyespots–which strongly influence female mate choice–to remain nearly stationary against a dynamic iridescent background. PMID:27119380

Observation of the M1 giant resonance by resonance averaging in 106Pd

International Nuclear Information System (INIS)

Kopecky, J.

1987-01-01

An investigation of capture of 2 keV and 24 keV neutrons in a 105 Pd target resulted in resonance-averaged intensities of primary gamma rays with energies between 5.2 and 9.5 MeV. From these intensities the gamma ray strength functions have been evaluated for E1, M1 and E2 radiation and compared with predictions of the giant resonance theory. The inclusion of an energy dependent spreading width for the E1 giant resonance is necessary. The energy distribution of M1 reduced strength is consistent with an interpretation of a broad resonance around 8.8 MeV. E2 data agrees satisfactorily with the giant extrapolation. (orig.)

Low intensity areas observed T2-weighted magnetic resonance imaging of the cerebral cortex in various neurological diseases

Energy Technology Data Exchange (ETDEWEB)

Imon, Yukari [Hiroshima Univ. (Japan). School of Medicine

1996-02-01

We retrospectively studied magnetic resonance images of the brain in 158 patients (8 cases of amyotrophic lateral sclerosis, 16 cases of Alzheimer`s disease, 8 cases of Parkinson`s disease, 53 cases of multiple cerebral infarct, 20 cases of other central nervous system (CNS) diseases, and 53 cases without any CNS disease) to examine the appearance of T2-weighted low signal intensity areas (LIA) in the cerebral cortex. The age of subjects ranged from 36 to 85 years with the mean 65.0 and SD 9.9 years. LIA in the motor and sensory cortices, and brain atrophy were evaluated visually on axial images of the spin-echo sequence obtained with a 1.5 tesla system. The incidence of LIA in the motor cortex was significantly higher in all CNS diseases than in cases without any CNS disease, but not significantly different among CNS diseases. LIA in the motor cortex showed a correlation with age, temporal and parietal atrophy. The appearance of LIA in the sensory cortex correlated with that of LIA in the motor cortex, and parietal atrophy. These results suggest that LIA may appear according to age and be associated with the accumulation of nonheme iron in the cortex, especially in patients with CNS diseases. (author)

Contraction-induced changes in skeletal muscle Na(+), K(+) pump mRNA expression - importance of exercise intensity and Ca(2+)-mediated signalling

DEFF Research Database (Denmark)

Nordsborg, Nikolai Baastrup; Kusuhara, K; Hellsten, Ylva

2010-01-01

Abstract Aim: To investigate if exercise intensity and Ca(2+) signalling regulate Na(+), K(+) pump mRNA expression in skeletal muscle. Methods: The importance of exercise intensity was evaluated by having trained and untrained humans perform intense intermittent and prolonged exercise. The import...

Can intrinsic noise induce various resonant peaks?

Energy Technology Data Exchange (ETDEWEB)

Torres, J J; Marro, J; Mejias, J F, E-mail: jtorres@ugr.es [Institute Carlos I for Theoretical and Computational Physics and Departamento de Electromagnetismo y Fisica de la Materia, University of Granada, Granada (Spain)

2011-05-15

We theoretically describe how weak signals may be efficiently transmitted throughout more than one frequency range in noisy excitable media by a sort of stochastic multiresonance. This helps us to reinterpret recent experiments in neuroscience and to suggest that many other systems in nature might be able to exhibit several resonances. In fact, the observed behavior happens in our model as a result of competition between (i) changes in the transmitted signals as if the units were varying their activation threshold, and (ii) adaptive noise realized in the model as rapid activity-dependent fluctuations of the connection intensities. These two conditions are indeed known to characterize heterogeneously networked systems of excitable units, e.g. sets of neurons and synapses in the brain. Our results may find application also in the design of detector devices.

Can intrinsic noise induce various resonant peaks?

International Nuclear Information System (INIS)

Torres, J J; Marro, J; Mejias, J F

2011-01-01

We theoretically describe how weak signals may be efficiently transmitted throughout more than one frequency range in noisy excitable media by a sort of stochastic multiresonance. This helps us to reinterpret recent experiments in neuroscience and to suggest that many other systems in nature might be able to exhibit several resonances. In fact, the observed behavior happens in our model as a result of competition between (i) changes in the transmitted signals as if the units were varying their activation threshold, and (ii) adaptive noise realized in the model as rapid activity-dependent fluctuations of the connection intensities. These two conditions are indeed known to characterize heterogeneously networked systems of excitable units, e.g. sets of neurons and synapses in the brain. Our results may find application also in the design of detector devices.

Hemodynamic and metabolic characterization of orthotopic rat prostate carcinomas using dynamic MRI and proton magnetic resonance spectroscopy

International Nuclear Information System (INIS)

Kiessling, F.; Lichy, M.; Kauczor, H.U.; Schlemmer, H.P.; Grobholz, R.; Heilmann, M.; Meding, J.; Huber, P.E.; Peschke, P.

2003-01-01

The aim of this study was the noninvasive characterization of prostate carcinoma orthotopically implanted in rats using Gd-DTPA-assisted dynamic MRI (dMRI) and proton magnetic resonance spectroscopy ( 1 H-MRS). After surgical exposure of the prostate, Dunning R3327 orthotopic prostate carcinoma was induced by injecting cells of the MAT-LyLu subline. Six rats were examined 5 and 14 days after tumor induction with dMRI and 1 H-MRS at 1.5 T. Six tumor-free rats served as controls. Using an open two-compartment model, the parameters A (amplitude) and k ep (exchange rate constants) were calculated from the signal time curves of the dMRI. The relative signal intensities (Cho/Cr) of the resonances of choline (Cho) and the creatine-phosphocreatine complex (Cr) were computed from the MR spectra. Already after 5 days, the tumors in the prostate could be clearly identified based on the decrease in signal intensity to T2w and increase of A and k ep . High Cho/Cr levels and resonances of two lipid fractions (Lip 1 at 0.8-1.5 ppm and Lip 2 at 2.0-2.2 ppm) were observed by MRS in the highly necrotic tumors. The orthotopic rat prostate carcinoma model resembles human prostate carcinoma in regard to MR morphology, dMRI, and 1 H-MRS. The noninvasive characterization of perfusion and metabolism makes a comparative examination of different treatment modalities possible. (orig.) [de

Developmental patterns of fetal fat and corresponding signal on T1-weighted magnetic resonance imaging

International Nuclear Information System (INIS)

Blondiaux, Eleonore; Chougar, Lydia; Ducou le Pointe, Hubert; Garel, Catherine; Gelot, Antoinette; Valence, Stephanie; Audureau, Etienne; Jouannic, Jean-Marie; Dhombres, Ferdinand

2018-01-01

Evaluation of subcutaneous fetal fat layer thickness on T1-weighted sequences can be used to predict birth weight. Little is known about normal MR signal patterns of subcutaneous tissue throughout pregnancy. To establish developmental patterns of subcutaneous fetal fat signal on T1-weighted sequences during the 2nd and 3rd trimesters. We retrospectively examined T1-weighted images of 110 fetal MRI scans. We measured signal intensity of subcutaneous fat on thighs, buttocks, trunk, nuchal region, chin and scalp. We then calculated the ratios of the obtained values with fetal muscle, amnios and maternal fat signal, and compared the results with those of immunohistochemical examination of adipose tissue extracted from the abdominal wall of fetuses as part of standard autopsy protocol. We included 60 MRI scans in fetuses without intra-uterine growth restriction or macrosomia of non-diabetic mothers (range 23-37 weeks of gestation). Fat T1 intensity of all anatomical regions was low in all fetuses before 26 weeks of gestation. It became more hyperintense with increasing gestational age, in the following order: chin and nuchal region, then buttocks, thighs and trunk, and eventually the scalp at 33 weeks of gestation. After 33 weeks of gestation, all fetal subcutaneous tissues demonstrated overall hyperintense signal. This progression followed the conversion at immunohistochemistry of fetal adipose tissue composition from predominant brown to white adipose cells in 19 fetuses (19-41 weeks of gestation). Between 26 weeks and 33 weeks of gestation, subcutaneous fetal fat signal changed in an orderly pattern from chin to buttocks and scalp. This may reflect the conversion from predominant brown to white adipose tissues in subcutaneous fetal fat. (orig.)

A Robust Dynamic Heart-Rate Detection Algorithm Framework During Intense Physical Activities Using Photoplethysmographic Signals

Directory of Open Access Journals (Sweden)

Jiajia Song

2017-10-01

Full Text Available Dynamic accurate heart-rate (HR estimation using a photoplethysmogram (PPG during intense physical activities is always challenging due to corruption by motion artifacts (MAs. It is difficult to reconstruct a clean signal and extract HR from contaminated PPG. This paper proposes a robust HR-estimation algorithm framework that uses one-channel PPG and tri-axis acceleration data to reconstruct the PPG and calculate the HR based on features of the PPG and spectral analysis. Firstly, the signal is judged by the presence of MAs. Then, the spectral peaks corresponding to acceleration data are filtered from the periodogram of the PPG when MAs exist. Different signal-processing methods are applied based on the amount of remaining PPG spectral peaks. The main MA-removal algorithm (NFEEMD includes the repeated single-notch filter and ensemble empirical mode decomposition. Finally, HR calibration is designed to ensure the accuracy of HR tracking. The NFEEMD algorithm was performed on the 23 datasets from the 2015 IEEE Signal Processing Cup Database. The average estimation errors were 1.12 BPM (12 training datasets, 2.63 BPM (10 testing datasets and 1.87 BPM (all 23 datasets, respectively. The Pearson correlation was 0.992. The experiment results illustrate that the proposed algorithm is not only suitable for HR estimation during continuous activities, like slow running (13 training datasets, but also for intense physical activities with acceleration, like arm exercise (10 testing datasets.

Low-profile wireless passive resonators for sensing

Energy Technology Data Exchange (ETDEWEB)

Gong, Xun; An, Linan

2017-04-04

A resonator for sensing a physical or an environmental parameter includes a support having a top surface that provides a ground plane, and a polymer-derived ceramic (PDC) element positioned on the top surface including a PDC layer, and a metal patch on the PDC layer. The metal patch is electrically isolated from all surrounding structure, and the resonator has a resonant frequency that changes as a function of the physical or environmental parameter. A system for wirelessly sensing a physical or environmental parameter includes at least one resonator and a wireless RF reader located remotely from the resonator for transmitting a wide-band RF interrogation signal that excites the resonator. The wireless RF reader detects a sensing signal retransmitted by the resonator and includes a processor for determining the physical or environmental parameter at the location of the resonator from the sensing signal.

Magnetic resonance imaging and neurolupus

International Nuclear Information System (INIS)

Schott, A.M.; Colson, F.; Tebib, J.; Noel, E.; Bouvier, M.

1990-01-01

Magnetic resonance imaging (MRI) was assessed in the management of neuropsychiatric manifestations occurring in 6 SLE patients. The MRI scans were normal in 3 cases and was associated with remission of the symptoms except for a patient who experienced a chorea at the time of the examination. Abnormal MRI scans always revealed more lesions than CT scan. 2 different patterns of abnormalities seem to correspond to 2 specific disorders. In 2 patients with clinical presentation suggesting a cortical ischemia by vascular thrombosis, both MRI scans showed areas of abnormal high signal intensities located in the subcortical white matter. In one last patient, MRI scan revealed multiple focal areas of high signal intensities (on T 1 weighter scans) disseminated not only in the deep white matter but also in the gray one. These lesions could be depend upon demyelinisation which may occur by a local vascular process. This serie confirms the interest of MRI in the management of SLE brain involvement as well as it points out some problem of interpretation. This suggest further comparative studies especially at the real onset and during the course of neuro-psychiatric manifestations. At last, the coronal sections may be more informative for the diagnosis and patholophysiology than the horizontal ones [fr

Evaluation of potential practical oral contrast agents for pediatric magnetic resonance imaging

International Nuclear Information System (INIS)

Bisset, G.S. III; Cincinnati Univ., OH; Children's Hospital Medical Center, Cincinnati, OH

1989-01-01

Development of a practical oral contrast agent for magnetic resonance imaging is necessary to improve differentiation of bowel from adjacent structures. In order to find a readily available, inexpensive, non-toxic, palatable solution for use in the pediatric population, several formulas, milk products and a common oral sedative were evaluated in vitro. T1, T2 and signal intensity measurements were performed on a 1.5 T system. Similac with standard iron proved to be a useful high signal intensity agent on multiple pulse sequences. Early in vivo experience in four normal volunteers indicates that this agent provides excellent delineation of the stomach and duodenum from contiguous viscera. Distal small bowel visualization is less predictabel. Further clinical trials should confirm the utility of this solution, which contains a combination of iron salts and paramagnetic metallic ions. (orig.)

Stochastic resonance in a bistable system subject to multi-time-delayed feedback and aperiodic signal

International Nuclear Information System (INIS)

Li Jianlong; Zeng Lingzao

2010-01-01

We discuss in detail the effects of the multi-time-delayed feedback driven by an aperiodic signal on the output of a stochastic resonance (SR) system. The effective potential function and dynamical probability density function (PDF) are derived. To measure the performance of the SR system in the presence of a binary random signal, the bit error rate (BER) defined by the dynamical PDF is employed, as is commonly used in digital communications. We find that the delay time, strength of the feedback, and number of time-delayed terms can change the effective potential function and the effective amplitude of the signal, and then affect the BER of the SR system. The numerical simulations strongly support the theoretical results. The goal of this investigation is to explore the effects of the multi-time-delayed feedback on SR and give a guidance to nonlinear systems in the application of information processing.

Paradoxical signal pattern of mediastinal cysts on T2-weighted MR imaging: phantom and clinical study

Energy Technology Data Exchange (ETDEWEB)

Ueda, Ken, E-mail: k-ueda@radiol.med.osaka-u.ac.jp [Department of Radiology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita-city, Osaka 565-0871 (Japan); Yanagawa, Masahiro [Department of Radiology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita-city, Osaka 565-0871 (Japan); Ueguchi, Takashi [Department of Medical Physics and Engineering, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita-city, Osaka 565-0871 (Japan); Satoh, Yukihisa; Kawai, Misa; Gyobu, Tomoko; Sumikawa, Hiromitsu; Honda, Osamu; Tomiyama, Noriyuki [Department of Radiology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita-city, Osaka 565-0871 (Japan)

2014-06-15

Purpose: To evaluate the intracystic MRI (magnetic resonance imaging) signal intensity of mediastinal cystic masses on T2-weighted images. Materials and methods: A phantom study was performed to evaluate the signal intensity of a mediastinal cystic mass phantom (rubber balloon containing water) adjacent to a cardiac phantom pulsing at the rate of 60/min. T2-weighted images (sequence, fast spin echo [FSE] and single shot fast spin echo [SSFSE]) were acquired for the mediastinal cystic mass phantom. Further, a clinical study was performed in 33 patients (16 men, 17 women; age range, 19-85 years; mean, 65years) with thymic cysts or pericardial cysts. In all patients, T2-weighted images (FSE and SSFSE) were acquired. The signal intensity of cystic lesion was evaluated and was compared with that of muscle. A region of interest (ROI) was positioned on the standard MR console, and signal intensity of the cystic mass (cSI), that of the muscle (mSI), and the rate of absolute value of cSI–mSI to standard deviation (SD) of background noise (|cSI–mSI|/SD = CNR [contrast-to-noise ratio]) were measured. Results: The phantom study demonstrated that the rate phantom-ROI/saline-ROI was higher in SSFSE (0.36) than in FSE (0.19). In clinical cases, the degree of the signal intensity was higher in SSFSE than in FSE. The CNR was significantly higher in SSFSE (mean ± standard deviation, 111.0 ± 47.6) than in FSE (72.8 ± 36.6) (p < 0.001, Wilcoxon signed-rank test). Conclusions: Anterior mediastinal cysts often show lower signal intensity than the original signal intensity of water on T2-weighted images. SSFSE sequence reduces this paradoxical signal pattern on T2-weighted images, which may otherwise cause misinterpretation when assessing cystic lesions.

Paradoxical signal pattern of mediastinal cysts on T2-weighted MR imaging: phantom and clinical study

International Nuclear Information System (INIS)

Ueda, Ken; Yanagawa, Masahiro; Ueguchi, Takashi; Satoh, Yukihisa; Kawai, Misa; Gyobu, Tomoko; Sumikawa, Hiromitsu; Honda, Osamu; Tomiyama, Noriyuki

2014-01-01

Purpose: To evaluate the intracystic MRI (magnetic resonance imaging) signal intensity of mediastinal cystic masses on T2-weighted images. Materials and methods: A phantom study was performed to evaluate the signal intensity of a mediastinal cystic mass phantom (rubber balloon containing water) adjacent to a cardiac phantom pulsing at the rate of 60/min. T2-weighted images (sequence, fast spin echo [FSE] and single shot fast spin echo [SSFSE]) were acquired for the mediastinal cystic mass phantom. Further, a clinical study was performed in 33 patients (16 men, 17 women; age range, 19-85 years; mean, 65years) with thymic cysts or pericardial cysts. In all patients, T2-weighted images (FSE and SSFSE) were acquired. The signal intensity of cystic lesion was evaluated and was compared with that of muscle. A region of interest (ROI) was positioned on the standard MR console, and signal intensity of the cystic mass (cSI), that of the muscle (mSI), and the rate of absolute value of cSI–mSI to standard deviation (SD) of background noise (|cSI–mSI|/SD = CNR [contrast-to-noise ratio]) were measured. Results: The phantom study demonstrated that the rate phantom-ROI/saline-ROI was higher in SSFSE (0.36) than in FSE (0.19). In clinical cases, the degree of the signal intensity was higher in SSFSE than in FSE. The CNR was significantly higher in SSFSE (mean ± standard deviation, 111.0 ± 47.6) than in FSE (72.8 ± 36.6) (p < 0.001, Wilcoxon signed-rank test). Conclusions: Anterior mediastinal cysts often show lower signal intensity than the original signal intensity of water on T2-weighted images. SSFSE sequence reduces this paradoxical signal pattern on T2-weighted images, which may otherwise cause misinterpretation when assessing cystic lesions

Stochastic Resonance in Neuronal Network Motifs with Ornstein-Uhlenbeck Colored Noise

Directory of Open Access Journals (Sweden)

Xuyang Lou

2014-01-01

Full Text Available We consider here the effect of the Ornstein-Uhlenbeck colored noise on the stochastic resonance of the feed-forward-loop (FFL network motif. The FFL motif is modeled through the FitzHugh-Nagumo neuron model as well as the chemical coupling. Our results show that the noise intensity and the correlation time of the noise process serve as the control parameters, which have great impacts on the stochastic dynamics of the FFL motif. We find that, with a proper choice of noise intensities and the correlation time of the noise process, the signal-to-noise ratio (SNR can display more than one peak.

Signal intensity changes of normal brain at varying high b-value diffusion-weighted images using 3.0T MR scanner

International Nuclear Information System (INIS)

Lee, Jin Hee; Sohn, Chul Ho; Choi, Jin Soo

2003-01-01

Using diffusion-weighted MR imaging (DWI), to evaluate the signal intensity characteristics of normal adult brain as diffusion gradient strength (b value) increases from 1,000 to 3,000 s/mm 2 . Twenty-one healthy volunteers with neither neurologic symptoms nor pathologic findings at axial and sagittal T2-weighted MR imaging were involved in this study. All images were obtained with a 3.0T MR scanner. Six sets of spin-echo echo-planar images were acquired in the axial plane using progressively increasing strengths of diffusion-sensitizing gradients (corresponding to b values of 0, 1,000, 1,500, 2,000, 2,500, and 3,000 s/mm 2 ). All imaging parameters other than TE remained constant. Changes in normal white-gray matter signal intensity observed at variable b-value DWI were qualitatively analysed, and the signal-to-noise ratios (SNRs) in six anatomic regions (frontal and parietal white matter, genu and splenium corporis callosi, the posterior limb of the internal capsule, and the thalamus) quantitatively, and the ratios were averaged and compared with the average SNR of 1,000 s/mm DWI. As gradient strength increased from 1,000 to 3,000 s/mm 2 , both gray-and white-matter structures diminished in signal intensity, and images obtained at a b value of 3,000 s/mm 2 appeared very noisy. White matter became progressively hyperintense to gray matter as the diffusion sensitizing gradient increased, especially at the centrum semiovale, the posterior limb of the internal capsule, and the splenium corporis callosi, but the genu corporis callosi; showed exceptional intermediate low signal intensity. At quantitative assessment, the signal-to-noise ratio decreased as the diffusion sensitizing gradient increased. Relative to the images obtained at a b value of 1,000 s/mm 2 , average SNRs were 0.71 (b=1,500 s/mm 2 ), 0.52 (b=2,000 s/mm 2 ), 0.41 (b=2,500 s/mm 2 ), 0.33 (b=3,000 s/mm 2 ). As the diffusion sensitizing gradient increased, the signal-to-noise ratio of brain structures

Progressive and resonant wave helices application to electron paramagnetic resonance; Helices a ondes progressives et resonnantes application a la resonance paramagnetique electronique

Energy Technology Data Exchange (ETDEWEB)

Volino, F. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1969-07-01

We show that helices can be used as resonant systems. Their properties are theoretically and experimentally studied. We describe resonant helices for electron paramagnetic resonance in X-band and develop a comparison between their sensitivity and the sensitivity of a normal resonant cavity. For cylindrical samples less than 3 mm diameter, the helix is more sensitive and can produce more intense microwave magnetic fields. (author) [French] Il est montre que les helices peuvent etre utilisees comme systeme resonnant. Leurs proprietes sont discutees theoriquement et experimentalement. Des helices resonnantes en bande X pour la resonance paramagnetique electronique sont decrites et leur sensibilite est comparee a celle des cavites resonnantes. Pour des echantillons cylindriques de moins de 3 mm de diametre, l'helice est plus sensible et peut produire des champs magnetiques hyper fins plus intenses. (auteur)

As-grown graphene/copper nanoparticles hybrid nanostructures for enhanced intensity and stability of surface plasmon resonance

Science.gov (United States)

Li, Yun-Fei; Dong, Feng-Xi; Chen, Yang; Zhang, Xu-Lin; Wang, Lei; Bi, Yan-Gang; Tian, Zhen-Nan; Liu, Yue-Feng; Feng, Jing; Sun, Hong-Bo

2016-11-01

The transfer-free fabrication of the high quality graphene on the metallic nanostructures, which is highly desirable for device applications, remains a challenge. Here, we develop the transfer-free method by direct chemical vapor deposition of the graphene layers on copper (Cu) nanoparticles (NPs) to realize the hybrid nanostructures. The graphene as-grown on the Cu NPs permits full electric contact and strong interactions, which results in a strong localization of the field at the graphene/copper interface. An enhanced intensity of the localized surface plasmon resonances (LSPRs) supported by the hybrid nanostructures can be obtained, which induces a much enhanced fluorescent intensity from the dye coated hybrid nanostructures. Moreover, the graphene sheets covering completely and uniformly on the Cu NPs act as a passivation layer to protect the underlying metal surface from air oxidation. As a result, the stability of the LSPRs for the hybrid nanostructures is much enhanced compared to that of the bare Cu NPs. The transfer-free hybrid nanostructures with enhanced intensity and stability of the LSPRs will enable their much broader applications in photonics and optoelectronics.

Sterilization of proteinaceous food additives by irradiation. Temperature dependent changes in intensity of ESR signals generated by electron beam irradiation

International Nuclear Information System (INIS)

Sakaue, Kazushi; Murata, Yoshiyuki; Higashimura, Yutaka; Hayashi, Toru; Todoriki, Setsuko; Tada, Mikiro

1999-01-01

Thaumatin, egg white and soybean protein were selected as samples of proteinous food additives, and changes in the intensity of signals appearing in them after they had been irradiated with electron beams were measured by ESR. It was found by such measurement that the positions of signals of thaumatin and soy proteins are nearly the same. Changes in the intensity of radicals in thaumatin calculated on the basis of the coefficients of the respective approximations obtained by using thaumatin which had been irradiated and then stored at 4degC, 25degC, 37degC and 60degC showed that there is a temperature range to determine the remaining of such radicals (inner: 19.7degC, outer: 15.23degC) and that such radicals tend to decrease straight line-wise. It was confirmed that the intensity of signals in the protein powder such thaumatin and soy protein would not be affected at the storage condition below 15degC. (author)

Sterilization of proteinaceous food additives by irradiation. Temperature dependent changes in intensity of ESR signals generated by electron beam irradiation

Energy Technology Data Exchange (ETDEWEB)

Sakaue, Kazushi; Murata, Yoshiyuki [Graduate School of Natural Science and Technology, Okayama Univ., Okayama (Japan); Higashimura, Yutaka [San-Ei Gen F.F.I., Inc., Osaka (Japan); Hayashi, Toru; Todoriki, Setsuko [National Food Research Institute, Ministry of Agriculture, Tsukuba, Ibaraki (Japan); Tada, Mikiro [Okayama Univ. (Japan). Faculty of Agriculture

1999-09-01

Thaumatin, egg white and soybean protein were selected as samples of proteinous food additives, and changes in the intensity of signals appearing in them after they had been irradiated with electron beams were measured by ESR. It was found by such measurement that the positions of signals of thaumatin and soy proteins are nearly the same. Changes in the intensity of radicals in thaumatin calculated on the basis of the coefficients of the respective approximations obtained by using thaumatin which had been irradiated and then stored at 4degC, 25degC, 37degC and 60degC showed that there is a temperature range to determine the remaining of such radicals (inner: 19.7degC, outer: 15.23degC) and that such radicals tend to decrease straight line-wise. It was confirmed that the intensity of signals in the protein powder such thaumatin and soy protein would not be affected at the storage condition below 15degC. (author)

Evaluation of adriamycin nephropathy by an in vivo electron paramagnetic resonance

International Nuclear Information System (INIS)

Oteki, Takaaki; Nagase, Sohji; Yokoyama, Hidekatsu; Ohya, Hiroaki; Akatsuka, Takao; Tada, Mika; Ueda, Atsushi; Hirayama, Aki; koyama, Akio

2005-01-01

A rat model for human minimal change nephropathy was obtained by the intravenous injection of adriamycin (ADR) at 5 mg/kg. By using an in vivo electron paramagnetic resonance (EPR) spectrometer operating at 700 MHz, the temporal changes in signal intensities of a nitroxide radical, 4-hydroxyl-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL), in the kidneys of rats with ADR nephropathy were investigated. The decay rate of the EPR signal intensity obtained in the kidney is indicative of the renal reducing ability. It was found that the reducing ability in the kidney declined on the 7th day after ADR administration and recovered after the 14th day. Impairment of the reducing ability occurred before the appearance of continuous urinary protein. The in vitro EPR study showed that this impairment of in vivo renal reducing ability is related to impairment of the reducing ability in the mitochondria

Prevalence and signal characteristics of late gadolinium enhancement on contrast-enhanced magnetic resonance imaging in patients with takotsubo cardiomyopathy

International Nuclear Information System (INIS)

Nakamori, Shiro; Matsuoka, Koji; Onishi, Katsuya

2012-01-01

The background of this study was to determine the prevalence and signal intensity (SI) characteristics of late gadolinium enhancement (LGE) on magnetic resonance imaging (MRI) in takotsubo cardiomyopathy (TC). Cine, black-blood T2-weighted and LGE MR images were acquired in 23 patients with TC within 72h of onset. Wall motion abnormality (WMA), edema and LGE were evaluated with a 16-segment model. The SI characteristics of LGE were analyzed using SI distribution in remote normal segments as reference. Follow-up MRI was performed 3 months later. Retrospective analysis of LGE MRI was also performed in 10 patients with acute myocardial infarction (AMI) to compare the SI characteristics between TC and AMI. In acute phase, WMA and edema were observed in 236 (64%) and 205 (56%) of 368 segments. LGE was observed in 10 (2.7%) of 368 segments and in 5 (22%) of 23 patients. All LGE lesions in TC exhibited transmural enhancement. The contrast-to-noise ratio (CNR) in TC was significantly lower than that of AMI (3.1±0.3 standard deviations (SD) vs. 6.1±1.2 SD, P<0.01), and CNR value of 4 was useful for distinguishing TC from AMI. Both LGE and WMA disappeared within 12 months. Grey myocardial signal on LGE MRI may be observed in patients with TC. However, the extent of LGE is substantially less than that of WMA and edema, and disappears within 12 months. (author)

Incidence and Evaluation of Incidental Abnormal Bone Marrow Signal on Magnetic Resonance Imaging

Directory of Open Access Journals (Sweden)

Gunjan L. Shah

2014-01-01

Full Text Available Purpose. The increased use of magnetic resonance imaging (MRI has resulted in reports of incidental abnormal bone marrow (BM signal. Our goal was to determine the evaluation of an incidental abnormal BM signal on MRI and the prevalence of a subsequent oncologic diagnosis. Methods. We conducted a retrospective cohort study of patients over age 18 undergoing MRI between May 2005 and October 2010 at Tufts Medical Center (TMC with follow-up through November 2013. The electronic medical record was queried to determine imaging site, reason for scan, evaluation following radiology report, and final diagnosis. Results. 49,678 MRIs were done with 110 patients meeting inclusion criteria. Twenty two percent underwent some evaluation, most commonly a complete blood count, serum protein electrophoresis, or bone scan. With median follow-up of 41 months, 6% of patients were diagnosed with malignancies including multiple myeloma, non-Hodgkins lymphoma, metastatic non-small cell lung cancer, and metastatic adenocarcinoma. One patient who had not undergone evaluation developed breast cancer 24 months after the MRI. Conclusions. Incidentally noted abnormal or heterogeneous bone marrow signal on MRI was not inconsequential and should prompt further evaluation.

Resonant ultrasound spectrometer

Science.gov (United States)

Migliori, Albert; Visscher, William M.; Fisk, Zachary

1990-01-01

An ultrasound resonant spectrometer determines the resonant frequency spectrum of a rectangular parallelepiped sample of a high dissipation material over an expected resonant response frequency range. A sample holder structure grips corners of the sample between piezoelectric drive and receive transducers. Each transducer is mounted on a membrane for only weakly coupling the transducer to the holder structure and operatively contacts a material effective to remove system resonant responses at the transducer from the expected response range. i.e., either a material such as diamond to move the response frequencies above the range or a damping powder to preclude response within the range. A square-law detector amplifier receives the response signal and retransmits the signal on an isolated shield of connecting cabling to remove cabling capacitive effects. The amplifier also provides a substantially frequency independently voltage divider with the receive transducer. The spectrometer is extremely sensitive to enable low amplitude resonance to be detected for use in calculating the elastic constants of the high dissipation sample.

Diagnosing ulnar neuropathy at the elbow using magnetic resonance neurography

Energy Technology Data Exchange (ETDEWEB)

Keen, Nayela N.; Chin, Cynthia T.; Saloner, David; Steinbach, Lynne S. [University of California San Francisco, Dept of Radiology and Biomedical Imaging, San Francisco, CA (United States); Engstrom, John W. [University of California San Francisco, Department of Neurology, San Francisco, CA (United States)

2012-04-15

Early diagnosis of ulnar neuropathy at the elbow is important. Magnetic resonance neurography (MRN) images peripheral nerves. We evaluated the usefulness of elbow MRN in diagnosing ulnar neuropathy at the elbow. The MR neurograms of 21 patients with ulnar neuropathy were reviewed retrospectively. MRN was performed prospectively on 10 normal volunteers. The MR neurograms included axial T1 and axial T2 fat-saturated and/or axial STIR sequences. The sensitivity and specificity of MRN in detecting ulnar neuropathy were determined. The mean ulnar nerve size in the symptomatic and normal groups was 0.12 and 0.06 cm{sup 2} (P < 0.001). The mean relative signal intensity in the symptomatic and normal groups was 2.7 and 1.4 (P < 0.01). When using a size of 0.08 cm{sup 2}, sensitivity was 95% and specificity was 80%. Ulnar nerve size and signal intensity were greater in patients with ulnar neuropathy. MRN is a useful test in evaluating ulnar neuropathy at the elbow. (orig.)

Evaluation of the use of blueberry juice in magnetic resonance cholangiopancreatography

International Nuclear Information System (INIS)

Tanaka, Yasunori; Fujita, Osamu; Yuuki, Masako; Matsuoka, Takae; Yamamoto, Kazuhiro; Shimizu, Tadahumi; Narabayashi, Isamu; Nishio, Seiichi

1998-01-01

We evaluated the use of blueberry juice (BJ), which is rich in manganese, as an oral negative contrast agent for magnetic resonance cholangiopancreatography (MRCP) and compared the findings thus obtained with corresponding findings for ferric ammonium citrate solution (FerriSeltz; FS). The optimum concentrations for the two oral contrast agents were determined by a phantom examination. Precontrast and postcontrast MRCP images were obtained in 26 patients and 4 volunteers using BJ and in 30 patients using FS. The pulse sequence applied for MRCP was a single shot fast spin-echo (ssfse) with an echo time of 950 to 1300 ms. In several cases, multislice ssfse with 90 ms echo time was conducted using both BJ and FS. Additionally, 8 volunteers who had recently consumed food or liquids underwent precontrast and postcontrast MRCP using BJ. BJ and FS eliminated the high signal intensity of gastrointestinal fluids which degrade MRCP images. In the multislice ssfse images with 90 ms. Echo time, BJ reduced the intragastrointestinal high intensity signal, but FS did not. In all volunteers whose stomachs were filled with food and/or water, intragastrointestinal high intensity signal was eliminated with use of BJ. We concluded that BJ is very useful as an MRCP negative contrast agent. (author)

Magnetic resonance imaging evaluation of traumatic muscle injuries; Avaliacao por ressonancia magnetica das injurias musculares traumaticas

Energy Technology Data Exchange (ETDEWEB)

Dias, Elisa Pompeu [Santa Casa de Misericordia do Rio de Janeiro, RJ (Brazil); Marchiori, Edson [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Dept. de Radiologia; Coutinho Junior, Antonio Carlos; Domingues, Romulo Cortes; Domingues, Romeu Cortes [Centro Medico Barrashopping, Rio de Janeiro, RJ (Brazil). Clinica de Diagnostico por Imagem (CDPI)

2001-12-01

We evaluated 43 magnetic resonance scans of the leg or thigh of patients suffering from sports trauma. Strains were the most frequent lesions observed. These lesions presented iso- or hypointense signal on T1 and hyperintense signal on T2 images, and were classified according to the intensity of the injury of the fibers into grades 1, 2 and 3. The second most common lesions in these series were contusions that appeared iso- or hypointense on T1 and hyperintense on T2 images. Fibrosis was also observed as low signal lesions on T1 and T2 images. (author)

(1+1) resonant enhanced multiphoton ionization via the A 2Σ+ state of NO: Ionic rotational branching ratios and their intensity dependence

International Nuclear Information System (INIS)

Rudolph, H.; Dixit, S.N.; McKoy, V.; Huo, W.M.

1988-01-01

Recent high resolution photoelectron spectroscopic studies of the (1+1) resonant enhanced multiphoton ionization (REMPI) of NO via the 0--0 transition of the A--X band (γ band) have shown a pronounced ΔN = 0 signal (ΔNequivalentN/sub +/-N/sub i/) and smaller, but measurable, ΔN = +- 2 peaks. The authors [K. S. Viswanathan et al., J. Phys. Chem. 90, 5078 (1986)] assign the excitation to be via an R(21.5) line, with no further specification. We have performed ab initio calculations of the rotational branching ratios for the four possible ''R(21.5)'' transitions, namely, the rotationally ''clean'' R 21 and R 22 , and the ''mixed'' R 12 +Q 22 and R 11 +Q 21 branches. We find the mixed R 12 +Q 22 (21.5) branch to agree best with the observed photoelectron spectrum collected parallel to the polarization vector of the light. The discrepancy is larger for detection perpendicular to the polarization. To understand this difference, we have assessed the influence of laser intensity and polarization ''contamination'' on the branching ratios and photoelectron angular distributions

The state of development of an intense resonance electron-ion accelerator based on Doppler effect

Energy Technology Data Exchange (ETDEWEB)

Egorov, A M; Ivanov, B I; Butenko, V I; Ognivenko, V V; Onishchenko, I N; Prishchepov, V P [Kharkov Inst. of Physics and Technology (Ukraine)

1997-12-31

An intense ion accelerator has been proposed and now is being developed in which accelerating and focusing electric fields in a slow wave structure are excited by an intense electron beam using the anomalous and the normal Doppler effects. The results of theoretical studies and computer simulations show the advantage of this acceleration method that will make it possible to obtain acceleration rates of the order of 10 - 100 MeV/m, and ion beam energies and currents of the order of 10-100 MeV, 1-10 A. The project and technical documentation of an experimental accelerating installation were worked out. Currently, the 5 MeV accelerator-injector URAL-5 is in operation; preliminary experiments on a small installation have been carried out; experimental investigations of an accelerating RF resonator model (in 1/2 scaling) are being performed; the accelerating test installation is being manufactured. (author). 1 tab. 12 fig., 6 refs.

The state of development of an intense resonance electron-ion accelerator based on Doppler effect

International Nuclear Information System (INIS)

Egorov, A.M.; Ivanov, B.I.; Butenko, V.I.; Ognivenko, V.V.; Onishchenko, I.N.; Prishchepov, V.P.

1996-01-01

An intense ion accelerator has been proposed and now is being developed in which accelerating and focusing electric fields in a slow wave structure are excited by an intense electron beam using the anomalous and the normal Doppler effects. The results of theoretical studies and computer simulations show the advantage of this acceleration method that will make it possible to obtain acceleration rates of the order of 10 - 100 MeV/m, and ion beam energies and currents of the order of 10-100 MeV, 1-10 A. The project and technical documentation of an experimental accelerating installation were worked out. Currently, the 5 MeV accelerator-injector URAL-5 is in operation; preliminary experiments on a small installation have been carried out; experimental investigations of an accelerating RF resonator model (in 1/2 scaling) are being performed; the accelerating test installation is being manufactured. (author). 1 tab. 12 fig., 6 refs

Diffusion-Weighted Magnetic Resonance Imaging of Urinary Epithelial Cancer with Upper Urinary Tract Obstruction: Preliminary Results

International Nuclear Information System (INIS)

Takeuchi, M.; Matsuzaki, K.; Kubo, H.; Nishitani, H.

2008-01-01

Background: Various malignant tumors of the body show high signal intensity on diffusion-weighted magnetic resonance imaging (DWI). In the genitourinary region, DWI is expected to have a role in detecting urinary epithelial cancer noninvasively. Purpose: To demonstrate the feasibility of DWI for the diagnosis of urinary epithelial cancer with upper urinary tract obstruction. Material and Methods: Twenty upper urinary tract cancers in 16 patients were evaluated by high-b-value DWI (b=800s/mm2). The signal intensity was visually evaluated, and the apparent diffusion coefficients (ADCs) were measured. Results: All urinary epithelial cancers showed high signal intensity on DWI. The ADC in cancerous lesions was 1.31±0.27 x 10 -3 mm 2 /s, which was significantly lower than that of the lumens of the ureter or renal pelvis (3.32±0.44 x 10 -3 mm 2 /s; P<0.001). Maximum intensity projection images of DWI in combination with static-fluid MR urography provided three-dimensional entire urinary tract imaging with the extension of tumors. Conclusion: DWI is useful in the tumor detection and in evaluating the tumor extension of urinary epithelial cancer in patients with upper urinary tract obstruction

Nanopolyaniline as immobilization template for signal enhancement of surface plasmon resonance biosensor - A preliminary study

Science.gov (United States)

Kamarun, Dzaraini; Abdul Azem, Nor Hazirah Kamel; Sarijo, Siti Halimah; Mohd, Ahmad Faiza; Abdullah @ Mohd Noor, Mashita

2012-07-01

A technique for the enhancement of Surface Plasmon Resonance (SPR) signal for sensing biomolecular interactions is described. Polyaniline (PANI) of particle size in the range of 1 to 15 nm was synthesized and used as the template for the immobilization of protein molecules. Biomolecular interactions of unbound and PANI-bound proteins with antibody molecules were SPR-monitored using a model system comprising of Bovine Serum Albumin (BSA) and anti BSA. A 7-fold increased in the signal was recorded from interactions of the PANI-bound BSA with anti BSA compared to the interactions of its unbound counterpart. This preliminary observation provides new avenue in immunosensor technology for improving the detection sensitivity of SPR biosensor; and thereby increasing the lower detection limit of biomolecules.

Short-term effect of short, intensive speech therapy on articulation and resonance in Ugandan patients with cleft (lip and) palate

NARCIS (Netherlands)

Anke Luyten; H. Vermeersch; A. Hodges; K. Bettens; K. van Lierde; G. Galiwango

2016-01-01

Objectives: The purpose of the current study was to assess the short-term effectiveness of short and intensive speech therapy provided to patients with cleft (lip and) palate (C(L)P) in terms of articulation and resonance. Methods: Five Ugandan patients (age: 7.3-19.6 years) with non-syndromic C(L)P

Clinical diagnostic study by means of magnetic resonance imaging for lesions of the major salivary gland region

International Nuclear Information System (INIS)

Iihama, Tsuyoshi; Mataga, Izumi; Kato, Joji

1994-01-01

The diagnostic value of magnetic resonance imaging (MRI) for lesions situated in the major salivary glands was clinically discussed in this study. A total of 46 patients with salivary gland disorders treated in our department over the past five years were assessed by mean of MRI, and in 11 patients the findings were compared with the histopathological features of lesions sectioned at the same level postoperatively. In addition, preliminary investigations to introduce a new qualitative diagnostic procedure for estimation of salivary gland function in geriatric patients were attempted. In this investigation, T 1 and T 2 values, and signal intensity ratios of the submandibular gland were measured in elderly patients complaining of dry mouth and in healthy controls. Likewise, salivary gland function was examined by taste stimulation induced by applying citric acid to the tongue surface just before starting MRI. MRI clearly demonstrated lesions in the salivary glands. The histopathological diagnosis could not be accurately predicted by signal intensity. However, benign tumors showed higher intensity signals than did malignant tumors on T 2 -weighted images. Cystic lesions could be differentiated from tumors by signal intensity. Histopathological features of salivary gland tumors corresponded to the MRI signal intensity. Relaxation times of T 1 and T 2 values and signal intensity in each major salivary gland were diminished in elderly patients in a resting condition. Only T 1 values in healthy subjects remarkably responded to taste stimulation. These results suggest that MRI is useful and beneficial not only in the qualitative diagnosis of tumors arising from salivary glands but also in the estimation of salivary gland function. MRI should therefore be included in routine diagnostic examinations for salivary gland disorders. (author)