Combined Use of Tc-99m MIBI Scan and MRI for Evaluation of Active Lesions in Multiple Myeloma

International Nuclear Information System (INIS)

Mititelu, R.; Marinescu, G.; Iriciuc, M.; Rimbu, A.; Ghita, S.; Mazilu, C.; Murgoci, P.; Codorean, I.

2006-01-01

Full text: Multiple Myeloma is a malignancy of plasma cells, in which neoplastic bone involvement is one of the leading symptoms. Many researchers have been trying to develop new imaging modalities and new methods for detecting the bone involvement, mainly because apart from the fact that bone marrow infiltration is one of the diagnostic criteria, typical radiographic findings can be found only in 60 70% of pts with first diagnosis of MM, and 10% of pts can present only osteoporosis-like changes. Purpose To evaluate the efficacy of 99mTc-MIBI whole-body scan in diagnosis of Multiple Myeloma, in correlation with other imaging modalities, and mainly with MRI. Material and Method: We performed a retrospective review of 29 cases of Multiple Myeloma Patients, all of them in active stage of the disease. All of them underwent 99mTc-MIBI whole body scan, MRI examination of the spine and a bone scan. Diagnosis and staging of the disease was made by using standard criteria. MRI was performed mainly for imaging spinal cord compression and for morphological characterization of lesions. We obtained saggital and transverse images which included T1-weighted spin-echo, T2-weighted turbo spin-echo and STIR sequences. We performed whole body MIBI scan in anterior and posterior views, 10 - 20 min after IV injection of 500-550 MBq of 99mTc-MIBI, using a dual head gamma-camera Philips- Axis. Results: We obtained pathologic changes in 25/29 pts that underwent whole-body MIBI scan(86.75%), and in 27/29(89.65%) for the MRI. Bone scan shown pathologic uptake of radiotracer in 18/29 pts(62.06%). In 4 pts that demonstrated pathologic increased uptake of MIBI we found photopenic lesions on the bone scan which were missed at the first interpretation of the bone scan; these lesions were reported only after comparative evaluation of bone scan and MIBI scan.We found three different patterns of pathologic MIBI uptake: focal increased uptake of MIBI in different sites (9 pts), diffuse increased

Generating finite element models of the knee: How accurately can we determine ligament attachment sites from MRI scans?

NARCIS (Netherlands)

Rachmat, H.H.; Janssen, D.; Zevenbergen, W.J.; Verkerke, Gijsbertus Jacob; Diercks, R.L.; Verdonschot, Nicolaas Jacobus Joseph

2014-01-01

In this study, we evaluated the intra- and inter-observer variability when determining the insertion and origin sites of knee ligaments on MRI scan images. We collected data of five observers with different backgrounds, who determined the ligament attachment sites in an MRI scan of a right knee of a

MRI and brain spect findings in patients with unilateral temporal lobe epilepsy and normal CT scan

Directory of Open Access Journals (Sweden)

P.G. Carrilho

1994-06-01

Full Text Available 26 patients with temporal lobe epilepsy clinically documented by several abnormal interictal surface EEGs with typical unitemporal epileptiform activity and a normal CT scan were studied. Interictal99mTC HMPAO brain SPECT and MRI were performed in all subjects. Abnormalities were shown in 61.5% of MRI (n=16 and 65.4% of SPECT (n=17. Hippocampal atrophy associated to a high signal on T2-weighted MRI slices suggesting mesial temporal sclerosis was the main finding (n=12; 75% of abnormal MRI. MRI correlated well to surface EEG in 50% (n=13. There was also a good correlation between MRI and SPECT in 30.7% (n=8. SPECT and EEG were in agreement in 57.7% (n=l5. MRI, SPECT and EEG were congruent in 26.9% (n=7. These results support the usefulness of interictal brain SPECT and MRI in detecting lateralized abnormalities in temporal lobe epilepsy. On the other hand, in two cases, interictal SPECT correlated poorly with surface EEG. This functional method should not be used isolately in the detection of temporal lobe foci. MRI is more useful than CT as a neuroimaging technique in temporal lobe epilepsy. It may detect small structural lesions and mesial temporal lobe sclerosis which are not easily seen with traditional CT scanning.

Concurrent tACS-fMRI Reveals Causal Influence of Power Synchronized Neural Activity on Resting State fMRI Connectivity.

Science.gov (United States)

Bächinger, Marc; Zerbi, Valerio; Moisa, Marius; Polania, Rafael; Liu, Quanying; Mantini, Dante; Ruff, Christian; Wenderoth, Nicole

2017-05-03

Resting state fMRI (rs-fMRI) is commonly used to study the brain's intrinsic neural coupling, which reveals specific spatiotemporal patterns in the form of resting state networks (RSNs). It has been hypothesized that slow rs-fMRI oscillations (5 Hz); however, causal evidence for this relationship is currently lacking. Here we measured rs-fMRI in humans while applying transcranial alternating current stimulation (tACS) to entrain brain rhythms in left and right sensorimotor cortices. The two driving tACS signals were tailored to the individual's α rhythm (8-12 Hz) and fluctuated in amplitude according to a 1 Hz power envelope. We entrained the left versus right hemisphere in accordance to two different coupling modes where either α oscillations were synchronized between hemispheres (phase-synchronized tACS) or the slower oscillating power envelopes (power-synchronized tACS). Power-synchronized tACS significantly increased rs-fMRI connectivity within the stimulated RSN compared with phase-synchronized or no tACS. This effect outlasted the stimulation period and tended to be more effective in individuals who exhibited a naturally weak interhemispheric coupling. Using this novel approach, our data provide causal evidence that synchronized power fluctuations contribute to the formation of fMRI-based RSNs. Moreover, our findings demonstrate that the brain's intrinsic coupling at rest can be selectively modulated by choosing appropriate tACS signals, which could lead to new interventions for patients with altered rs-fMRI connectivity. SIGNIFICANCE STATEMENT Resting state fMRI (rs-fMRI) has become an important tool to estimate brain connectivity. However, relatively little is known about how slow hemodynamic oscillations measured with fMRI relate to electrophysiological processes. It was suggested that slowly fluctuating power envelopes of electrophysiological signals synchronize across brain areas and that the topography of this activity is spatially correlated to

ICA-based artifact removal diminishes scan site differences in multi-center resting-state fMRI.

Directory of Open Access Journals (Sweden)

Rogier Alexander Feis

2015-10-01

Full Text Available Resting-state fMRI (R-fMRI has shown considerable promise in providing potential biomarkers for diagnosis, prognosis and drug response across a range of diseases. Incorporating R-fMRI into multi-center studies is becoming increasingly popular, imposing technical challenges on data acquisition and analysis, as fMRI data is particularly sensitive to structured noise resulting from hardware, software and environmental differences. Here, we investigated whether a novel clean up tool for structured noise was capable of reducing center-related R-fMRI differences between healthy subjects.We analyzed 3 Tesla R-fMRI data from 72 subjects, half of whom were scanned with eyes closed in a Philips Achieva system in The Netherlands, and half of whom were scanned with eyes open in a Siemens Trio system in the UK. After pre-statistical processing and individual Independent Component Analysis (ICA, FMRIB’s ICA-based X-noiseifier (FIX was used to remove noise components from the data. GICA and dual regression were run and non-parametric statistics were used to compare spatial maps between groups before and after applying FIX.Large significant differences were found in all resting-state networks between study sites before using FIX, most of which were reduced to non-significant after applying FIX. The between-center difference in the medial/primary visual network, presumably reflecting a between-center difference in protocol, remained statistically different.FIX helps facilitate multi-center R-fMRI research by diminishing structured noise from R-fMRI data. In doing so, it improves combination of existing data from different centers in new settings and comparison of rare diseases and risk genes for which adequate sample size remains a challenge.

Arm MRI scan

Science.gov (United States)

... MRI and ultrasound. In: Adam A, Dixon AK, Gillard JH, Schaefer-Prokop CM, eds. Grainger & Allison's Diagnostic ... Magnetic resonance imaging: In: Adam A, Dixon AK, Gillard JH, Schaefer-Prokop CM, eds. Grainger & Allison's Diagnostic ...

Sinus MRI scan

Science.gov (United States)

... CT, and MRI. In: Adam A, Dixon AK, Gillard JH, Schaefer-Prokop CM, eds. Grainger & Allison's Diagnostic ... Magnetic resonance imaging. In: Adam A, Dixon AK, Gillard JH, Schaefer-Prokop CM, eds. Grainger & Allison's Diagnostic ...

Leg MRI scan

Science.gov (United States)

... MRI and ultrasound. In: Adam A, Dixon AK, Gillard JH, Schaefer-Prokop CM, eds. Grainger & Allison's Diagnostic ... Magnetic resonance imaging: In: Adam A, Dixon AK, Gillard JH, Schaefer-Prokop CM, eds. Grainger & Allison's Diagnostic ...

Knee MRI scan

Science.gov (United States)

... MRI and ultrasound. In: Adam A, Dixon AK, Gillard JH, Schaefer-Prokop CM, eds. Grainger & Allison's Diagnostic ... Magnetic resonance imaging. In: Adam A, Dixon AK, Gillard JH, Schaefer-Prokop CM, eds. Grainger & Allison's Diagnostic ...

Accurate measurement of brain changes in longitudinal MRI scans using tensor-based morphometry.

Science.gov (United States)

Hua, Xue; Gutman, Boris; Boyle, Christina P; Rajagopalan, Priya; Leow, Alex D; Yanovsky, Igor; Kumar, Anand R; Toga, Arthur W; Jack, Clifford R; Schuff, Norbert; Alexander, Gene E; Chen, Kewei; Reiman, Eric M; Weiner, Michael W; Thompson, Paul M

2011-07-01

This paper responds to Thompson and Holland (2011), who challenged our tensor-based morphometry (TBM) method for estimating rates of brain changes in serial MRI from 431 subjects scanned every 6 months, for 2 years. Thompson and Holland noted an unexplained jump in our atrophy rate estimates: an offset between 0 and 6 months that may bias clinical trial power calculations. We identified why this jump occurs and propose a solution. By enforcing inverse-consistency in our TBM method, the offset dropped from 1.4% to 0.28%, giving plausible anatomical trajectories. Transitivity error accounted for the minimal remaining offset. Drug trial sample size estimates with the revised TBM-derived metrics are highly competitive with other methods, though higher than previously reported sample size estimates by a factor of 1.6 to 2.4. Importantly, estimates are far below those given in the critique. To demonstrate a 25% slowing of atrophic rates with 80% power, 62 AD and 129 MCI subjects would be required for a 2-year trial, and 91 AD and 192 MCI subjects for a 1-year trial. Copyright © 2011 Elsevier Inc. All rights reserved.

MO-FG-CAMPUS-JeP2-02: Audiovisual Biofeedback Guided Respiratory-Gated MRI: An Investigation of Tumor Definition and Scan Time for Lung Cancer

Energy Technology Data Exchange (ETDEWEB)

Lee, D; Pollock, S; Keall, P [University of Sydney, Sydney, NSW (Australia); Greer, P; Lapuz, C; Ludbrook, J [Calvary Mater Newcastle, Newcastle, NSW (Australia); Kim, T [Virginia Commonwealth University, Glen Allen, VA (United States)

2016-06-15

Purpose: Breathing consistency variations can cause respiratory-related motion blurring and artifacts and increase in MRI scan time due to inadequate respiratory-gating and discarding of breathing cycles. In a previous study the concept of audiovisual biofeedback (AV) guided respiratory-gated MRI was tested with healthy volunteers and it demonstrated image quality improvement on anatomical structures and scan time reduction. This study tests the applicability of AV-guided respiratorygated MRI for lung cancer in a prospective patient study. Methods: Image quality and scan time were investigated in thirteen lung cancer patients who underwent two 3T MRI sessions. In the first MRI session (pre-treatment), respiratory-gated MR images with free breathing (FB) and AV were acquired at inhalation and exhalation. An RF navigator placed on the liver dome was employed for the respiratory-gated MRI. This was repeated in the second MRI session (mid-treatment). Lung tumors were delineated on each dataset. FB and AV were compared in terms of (1) tumor definition assessed by lung tumor contours and (2) intra-patient scan time variation using the total image acquisition time of inhalation and exhalation datasets from the first and second MRI sessions across 13 lung cancer patients. Results: Compared to FB AV-guided respiratory-gated MRI improved image quality for contouring tumors with sharper boundaries and less blurring resulted in the improvement of tumor definition. Compared to FB the variation of intra-patient scan time with AV was reduced by 48% (p<0.001) from 54 s to 28 s. Conclusion: This study demonstrated that AV-guided respiratorygated MRI improved the quality of tumor images and fixed tumor definition for lung cancer. These results suggest that audiovisual biofeedback breathing guidance has the potential to control breathing for adequate respiratory-gating for lung cancer imaging and radiotherapy.

MO-FG-CAMPUS-JeP2-02: Audiovisual Biofeedback Guided Respiratory-Gated MRI: An Investigation of Tumor Definition and Scan Time for Lung Cancer

International Nuclear Information System (INIS)

Lee, D; Pollock, S; Keall, P; Greer, P; Lapuz, C; Ludbrook, J; Kim, T

2016-01-01

Purpose: Breathing consistency variations can cause respiratory-related motion blurring and artifacts and increase in MRI scan time due to inadequate respiratory-gating and discarding of breathing cycles. In a previous study the concept of audiovisual biofeedback (AV) guided respiratory-gated MRI was tested with healthy volunteers and it demonstrated image quality improvement on anatomical structures and scan time reduction. This study tests the applicability of AV-guided respiratorygated MRI for lung cancer in a prospective patient study. Methods: Image quality and scan time were investigated in thirteen lung cancer patients who underwent two 3T MRI sessions. In the first MRI session (pre-treatment), respiratory-gated MR images with free breathing (FB) and AV were acquired at inhalation and exhalation. An RF navigator placed on the liver dome was employed for the respiratory-gated MRI. This was repeated in the second MRI session (mid-treatment). Lung tumors were delineated on each dataset. FB and AV were compared in terms of (1) tumor definition assessed by lung tumor contours and (2) intra-patient scan time variation using the total image acquisition time of inhalation and exhalation datasets from the first and second MRI sessions across 13 lung cancer patients. Results: Compared to FB AV-guided respiratory-gated MRI improved image quality for contouring tumors with sharper boundaries and less blurring resulted in the improvement of tumor definition. Compared to FB the variation of intra-patient scan time with AV was reduced by 48% (p<0.001) from 54 s to 28 s. Conclusion: This study demonstrated that AV-guided respiratorygated MRI improved the quality of tumor images and fixed tumor definition for lung cancer. These results suggest that audiovisual biofeedback breathing guidance has the potential to control breathing for adequate respiratory-gating for lung cancer imaging and radiotherapy.

VISARTTM superconducting MRI system

International Nuclear Information System (INIS)

Usui, Yoshiyuki; Goro, Takehiko; Yamagata, Hitoshi.

1995-01-01

We have developed VISART TM , a 1.5 T high-field magnetic resonance imaging (MRI) system based on technology developed for both the FLEXART TM (0.5T) and MRT-200/GP (1.5T) systems as the first and second products, respectively, of a new series of MRI systems. VISART TM is a newly coined word combining VISion and state-of-the-ART. A higher power gradient system and new high-speed imaging techniques have been developed to meet the market demand for higher resolution images and shorter scan times. The product concepts of VISART TM are high image quality, high patient throughput, flexible clinical application, and ease of use, all of which are essential features for an MRI system in the high-field MRI market segment. (author)

Feasibility of geometric-intensity-based semi-automated delineation of the tentorium cerebelli from MRI scans.

Science.gov (United States)

Penumetcha, Neeraja; Kabadi, Suraj; Jedynak, Bruno; Walcutt, Charles; Gado, Mokhtar H; Wang, Lei; Ratnanather, J Tilak

2011-04-01

This paper describes a feasibility study of a method for delineating the tentorium cerebelli in magnetic resonance imaging (MRI) brain scans. The tentorium cerebelli is a thin sheet of dura matter covering the cerebellum and separating it from the posterior part of the temporal lobe and the occipital lobe of the cerebral hemispheres. Cortical structures such as the parahippocampal gyrus can be indistinguishable from tentorium in magnetized prepared rapid gradient echo and T1-weighted MRI scans. Similar intensities in these neighboring regions make it difficult to perform accurate cortical analysis in neuroimaging studies of schizophrenia and Alzheimer's disease. A semi-automated, geometric, intensity-based procedure for delineating the tentorium from a whole-brain scan is described. Initial and final curves are traced within the tentorium. A cost function, based on intensity and Euclidean distance, is computed between the two curves using the Fast Marching method. The initial curve is then evolved to the final curve based on the gradient of the computed costs, generating a series of intermediate curves. These curves are then used to generate a triangulated surface of the tentorium. For 3 scans, surfaces were found to be within 2 voxels from hand segmentations. Copyright © 2009 by the American Society of Neuroimaging.

Correlation of intra-articular osseous measurements with posterior cruciate ligament length on MRI scans.

LENUS (Irish Health Repository)

Orakzai, S H

2010-01-01

Six patients with a clinical diagnosis of chronic posterior cruciate ligament (PCL) rupture, based on a positive posterior drawer test, had a normal appearance of the PCL on an MRI scan. It is postulated that the PCL had been ruptured but healed in a lengthened state. 12 volunteers with no history of knee trauma underwent an MRI scan of the knee. In this control group (n = 12), there was a close correlation between the lateral femoral condylar width in the sagittal plane and the PCL length, with a ratio of 2:1 (95% confidence interval (CI) = 1.817-2.095). In the clinically abnormal group (n = 6), the ratio was 1.49:1 (95% CI = 1.206-1.782) (p< 0.0005). In conclusion, the ratio of the lateral femoral condylar width in the sagittal plane to the PCL length is a useful index for diagnosing PCL attenuation and lengthening in the presence of a normal morphological MR appearance.

Comparison of MRI fast SPGR single slice scan and continuous dynamic scan in patients with obstructive sleep apnea-hypopnea syndrome

Energy Technology Data Exchange (ETDEWEB)

Zhang Xinyu [Department of Radiology, Medical School Hospital of Qingdao University, 16 Jiangsu Road, Qingdao 266003 (China)], E-mail: myginny2@sina.com; Yang Xue [Department of Radiology, Medical School Hospital of Qingdao University, 16 Jiangsu Road, Qingdao 266003 (China)], E-mail: yangxueqyfy@126.com; Hua Hui [Department of Otorhinolaryngology-Head and Neck Surgery, Medical School Hospital of Qingdao University, Qingdao (China)], E-mail: huahuisky@163.com; Chen Jingjing [Department of Radiology, Medical School Hospital of Qingdao University, 16 Jiangsu Road, Qingdao 266003 (China)], E-mail: chenjingjingsky@126.com

2009-07-15

Objective: To evaluate the application value of MRI fast SPGR single slice scan in patients with obstructive sleep apnea-hypopnea syndrome when comparing the images between fast SPGR single slice scan and continuous dynamic scan. Methods: Eighteen patients with obstructive sleep apnea-hypopnea syndrome were examined by fast SPGR single slice scan and continuous dynamic scan in turn. Fast SPGR single slice scans were conducted when the phases of apnea, inspiration and expiration appeared on the respiratory wave of the subjects. Fast SPGR continuous dynamic scans were conducted when the patients were awake and apneic. The scan planes were median sagittal plane and axial planes (the slice of middle part of palate, the slice of inferior part of palate, the slice of middle part of lingual root and the slice of 0.5 cm beneath the free margin of epiglottis). The obstructed sites and the cross-sectional areas of upper airway were compared between the two scan methods. Results: Seven cases showed complete obstruction at the narrowest sites of upper airway when apnea appeared; eleven cases showed marked decrease in cross-sectional areas at the narrowest sites compared with the areas when the patients were awake; two cases manifested multiple narrowness. The obstructed sites showed by the two scan methods were same. The difference of the cross-sectional areas of upper airway between the two scan methods was insignificant (P > 0.05). Conclusion: Fast SPGR single slice scan can accurately reflect the obstructed sites of upper airway when the breath breaks off and is the complementary method of continuous dynamic scan. Sometimes, single slice scan can replace continuous dynamic scan.

Automatic Segmentation of Abdominal Fat in MRI-Scans, Using Graph-Cuts and Image Derived Energies

DEFF Research Database (Denmark)

Christensen, Anders Nymark; Larsen, Christian Thode; Mandrup Jensen, Camilla Maria

2017-01-01

For many clinical studies changes in the abdominal distribution of fat is an important measure. However, the segmentation of abdominal fat in MRI scans is both difficult and time consuming using manual methods. We present here an automatic and flexible software package, that performs both bias fi...

Microcomputer-based image processing system for CT/MRI scans II

International Nuclear Information System (INIS)

Kwok, J.C.K.; Yu, P.K.N.; Cheng, A.Y.S.; Ho, W.C.

1991-01-01

This paper reports that a microcomputer-based image processing system is used to digitize and process serial sections of CT/MRI scan and reconstruct three-dimensional images of brain structures and brain lesions. The images grabbed also serve as templates and different vital regions with different risk values are also traced out for 3D reconstruction. A knowledge-based system employing rule-based programming has been built to help identifying brain lesions and to help planning trajectory for operations. The volumes of the lesions are also automatically determined. Such system is very useful for medical skills archival, tumor size monitoring, survival and outcome forecasting, and consistent neurosurgical planning

The experience of patients participating in a small randomised control trial that explored two different interventions to reduce anxiety prior to an MRI scan.

Science.gov (United States)

Tugwell-Allsup, J; Pritchard, A W

2018-05-01

This paper reports qualitative findings from within a larger randomised control trial where a video clip or telephone conversation with a radiographer was compared to routine appointment letter and information sheet to help alleviate anxiety prior to their MRI scan. Questionnaires consisting of three free-text response questions were administered to all of the 74 patients recruited to the MRI anxiety clinical trial. The questionnaire was designed to establish patients' experiences of the intervention they had received. These questionnaires were administered post-scan. Two participants from each trial arm were also interviewed. A thematic approach was utilised for identifying recurrent categories emerging from the qualitative data which are supported by direct quotations. Participants in the interventional groups commented positively about the provision of pre-MRI scan information they received and this was contrastable with the relatively indifferent responses observed among those who received the standard information letter. Many important themes were identified including the patients needs for clear and simplified information, the experience of anticipation when waiting for the scan, and also the informally acquired information about having an MRI scan i.e. the shared experiences of friends and family. All themes highlighted the need for an inclusive and individually tailored approach to pre-scan information provision. Qualitative data collected throughout the trial is supportive of the statistical findings, where it is asserted that the use of a short video clip or a radiographer having a short conversation with patients before their scan reduces pre-scan anxiety. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Scanning fast and slow: current limitations of 3 Tesla functional MRI and future potential

Directory of Open Access Journals (Sweden)

Roland N Boubela

2014-02-01

Full Text Available Functional MRI at 3T has become a workhorse for the neurosciences, e.g., neurology, psychology, and psychiatry, enabling non-invasive investigation of brain function and connectivity. However, BOLD-based fMRI is a rather indirect measure of brain function, confounded by fluctuation related signals, e.g. head or brain motion, brain pulsation, blood flow, intermixed with susceptibility differences close or distant to the region of neuronal activity. Even though a plethora of preprocessing strategies have been published to address these confounds, their efficiency is still under discussion. In particular, physiological signal fluctuations closely related to brain supply may mask BOLD signal changes related to true neuronal activation. Here we explore recent technical and methodological advancements aimed at disentangling the various components, employing fast multiband vs. standard EPI, in combination with fast temporal ICA.Our preliminary results indicate that fast (TR< 0.5s scanning may help to identify and eliminate physiologic components, increasing tSNR and functional contrast. In addition, biological variability can be studied and task performance better correlated to other measures. This should increase specificity and reliability in fMRI studies. Furthermore, physiological signal changes during scanning may then be recognized as a source of information rather than a nuisance. As we are currently still undersampling the complexity of the brain, even at a rather coarse macroscopic level, we should be very cautious in the interpretation of neuroscientific findings, in particular when comparing different groups (e.g., age, sex, medication, pathology, etc.. From a technical point of view our goal should be to sample brain activity at layer specific resolution with low TR, covering as much of the brain as possible without violating SAR limits. We hope to stimulate discussion towards a better understanding and a more quantitative use of fMRI.

SU-F-I-27: Measurement of SAR and Temperature Elevation During MRI Scans

Energy Technology Data Exchange (ETDEWEB)

Seo, Y [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

2016-06-15

Purpose: The poor reliability and repeatability of the manufacturer-reported SAR values on clinical MRI systems have been acknowledged. The purpose of this study is to not only measure SAR values, but also RF-induced temperature elevation at 1.5 and 3T MRI systems. Methods: SAR measurement experiment was performed at 1.5 and 3T. Three MRI RF sequences (T1w TSE, T1w inversion recovery, and T2w TSE) with imaging parameters were selected. A hydroxyl-ethylcelluose (HEC) gelled saline phantom mimicking human body tissue was made. Human torso phantom were constructed, based on Korean adult standard anthropometric reference data (Fig.1). FDTD method was utilized to calculate the SAR distribution using Sim4Life software. Based on the results of the simulation, 4 electrical field (E-field) sensors were located inside the phantom. 55 Fiber Bragg Grating (FBG) temperature sensors (27 sensors in upper and lower cover lids, and one sensor located in the center as a reference) were located inside the phantom to measure temperature change during MRI scan (Fig.2). Results: Simulation shows that SAR value is 0.4 W/kg in the periphery and 0.001 W/kg in the center (Fig.2). One 1.5T and one of two 3T MRI systems represent that the measured SAR values were lower than MRI scanner-reported SAR values. However, the other 3T MRI scanner shows that the averaged SAR values measured by probe 2, 3, and 4 are 6.83, 7.59, and 6.01 W/kg, compared to MRI scanner-reported whole body SAR value (<1.5 W/kg) for T2w TSE (Table 1). The temperature elevation measured by FBG sensors is 5.2°C in the lateral shoulder, 5.1°C in the underarm, 4.7°C in the anterior axilla, 4.8°C in the posterior axilla, and 4.8°C in the lateral waist for T2w TSE (Fig.3). Conclusion: It is essential to assess the safety of MRI system for patient by measuring accurate SAR deposited in the body during clinical MRI.

Audiovisual biofeedback improves image quality and reduces scan time for respiratory-gated 3D MRI

Science.gov (United States)

Lee, D.; Greer, P. B.; Arm, J.; Keall, P.; Kim, T.

2014-03-01

The purpose of this study was to test the hypothesis that audiovisual (AV) biofeedback can improve image quality and reduce scan time for respiratory-gated 3D thoracic MRI. For five healthy human subjects respiratory motion guidance in MR scans was provided using an AV biofeedback system, utilizing real-time respiratory motion signals. To investigate the improvement of respiratory-gated 3D MR images between free breathing (FB) and AV biofeedback (AV), each subject underwent two imaging sessions. Respiratory-related motion artifacts and imaging time were qualitatively evaluated in addition to the reproducibility of external (abdominal) motion. In the results, 3D MR images in AV biofeedback showed more anatomic information such as a clear distinction of diaphragm, lung lobes and sharper organ boundaries. The scan time was reduced from 401±215 s in FB to 334±94 s in AV (p-value 0.36). The root mean square variation of the displacement and period of the abdominal motion was reduced from 0.4±0.22 cm and 2.8±2.5 s in FB to 0.1±0.15 cm and 0.9±1.3 s in AV (p-value of displacement audiovisual biofeedback improves image quality and reduces scan time for respiratory-gated 3D MRI. These results suggest that AV biofeedback has the potential to be a useful motion management tool in medical imaging and radiation therapy procedures.

Experimental and clinical evaluation of acromioclavicular joint structures with new scan orientations in MRI

International Nuclear Information System (INIS)

Schaefer, Fritz K.; Schaefer, Philipp J.; Brossmann, Joachim; Hilgert, Ralf Erik; Heller, Martin; Jahnke, Thomas

2006-01-01

The objective of the study was to evaluate MRI for visualization of acromioclavicular (ac) joint structures in cadaveric shoulders, asymptomatic volunteers and symptomatic patients with trauma of the ac-joint. Three cadaveric shoulders were examined to find adequate planes and sequences for MRI. Afterwards, MR images were correlated to corresponding anatomical sections. Six asymptomatic volunteers and 13 patients were scanned in a 1.5 T Magnetom Vision with three sequences in the following planes: (1) parallel to the clavicle; (2) orthogonal to the ac joint, each time a fat-suppressed proton density-weighted + T2-sequence (TR/TE 4,000/15 ms) was performed; (3) parallel to the clavicle, T1-SE (TR/TE 817/20 ms). The parameters were: slice thickness 3 mm, field-of-view 180 mm, matrix 210 x 256 pixels. Standard of reference in the patients was clinical examination and conventional X-rays. Classification was by Rockwood grades I-VI. MRI allowed excellent visualization and diagnoses of ac-joint structures in volunteers and patients (n=6 normal, n=1 Rockwood I, n=5 Rockwood II, n=3 Rockwood III, n=4 Rockwood V). On MRI, in one lesion type II and III each, a lower lesion type was suspected clinically and by X-ray. In one patient additional information by MRI led to surgery. MRI allows excellent anatomical display of ac-joint structures and can give clinically relevant information on type and extension of ac-joint trauma, which may influence therapy. (orig.)

Experimental and clinical evaluation of acromioclavicular joint structures with new scan orientations in MRI

Energy Technology Data Exchange (ETDEWEB)

Schaefer, Fritz K.; Schaefer, Philipp J.; Brossmann, Joachim; Hilgert, Ralf Erik; Heller, Martin; Jahnke, Thomas [University Hospital of Schleswig-Holstein Campus Kiel, Department of Diagnostic Radiology, Kiel (Germany)

2006-07-15

The objective of the study was to evaluate MRI for visualization of acromioclavicular (ac) joint structures in cadaveric shoulders, asymptomatic volunteers and symptomatic patients with trauma of the ac-joint. Three cadaveric shoulders were examined to find adequate planes and sequences for MRI. Afterwards, MR images were correlated to corresponding anatomical sections. Six asymptomatic volunteers and 13 patients were scanned in a 1.5 T Magnetom Vision with three sequences in the following planes: (1) parallel to the clavicle; (2) orthogonal to the ac joint, each time a fat-suppressed proton density-weighted + T2-sequence (TR/TE 4,000/15 ms) was performed; (3) parallel to the clavicle, T1-SE (TR/TE 817/20 ms). The parameters were: slice thickness 3 mm, field-of-view 180 mm, matrix 210 x 256 pixels. Standard of reference in the patients was clinical examination and conventional X-rays. Classification was by Rockwood grades I-VI. MRI allowed excellent visualization and diagnoses of ac-joint structures in volunteers and patients (n=6 normal, n=1 Rockwood I, n=5 Rockwood II, n=3 Rockwood III, n=4 Rockwood V). On MRI, in one lesion type II and III each, a lower lesion type was suspected clinically and by X-ray. In one patient additional information by MRI led to surgery. MRI allows excellent anatomical display of ac-joint structures and can give clinically relevant information on type and extension of ac-joint trauma, which may influence therapy. (orig.)

SU-E-J-220: Assessment of MRI Geometric Distortion in Head and Neck Cancer Patients Scanned in Immobilized Radiation Treatment Position

Energy Technology Data Exchange (ETDEWEB)

Hansen, C; Mohamed, A; Weygand, J; Ding, Y; Fuller, C; Frank, S; Wang, J [MD Anderson Cancer Center, Houston, TX (United States)

2015-06-15

Purpose: Uncertainties about geometric distortion have somewhat hindered MRI simulation in radiation therapy. Most of the geometric distortion studies were performed with phantom measurements but another major aspect of MR distortion is patient related. We studied the geometric distortion in patient images by comparing their MRI scans with the corresponding CT, using CT as the non-distorted gold standard. Methods: Ten H&N cancer patients were imaged with MRI as part of a prospective IRB approved study. All patients had their treatment planning CT done on the same day or within one week of the MRI. MR Images were acquired with a T2 SE sequence (1×1×2.5mm voxel size) in the same immobilization position as in the CT scans. MRI to CT rigid registration was then done and geometric distortion comparison was done by measuring the corresponding anatomical landmarks on both the MRI and the CT images by two observers. Several skin to skin (9 landmarks), bone to bone (8 landmarks), and soft tissue (3 landmarks) were measured at specific levels in horizontal and vertical planes of both scans. Results: The mean distortion for all landmark measurements in all scans was 1.8±1.9mm. For each patient 11 measurements were done in the horizontal plane while 9 were done in the vertical plane. The measured geometric distortion were significantly lower in the horizontal axis compared to the vertical axis (1.3±0.16 mm vs 2.2±0.19 mm, respectively, P=0.003*). The magnitude of distortion was lower in the bone to bone landmarks compared to the combined soft tissue and skin to skin landmarks (1.2±0.19 mm vs 2.3±0.17 mm, P=0.0006*). The mean distortion measured by observer one was not significantly different compared toobserver 2 (2.3 vs 2.4 mm, P=0.4). Conclusion: MRI geometric distortions were quantified in H&N patients with mean error of less than 2 mm. JW received a corporate sponsored research grant from Elekta.

Audiovisual biofeedback improves image quality and reduces scan time for respiratory-gated 3D MRI

International Nuclear Information System (INIS)

Lee, D; Keall, P; Kim, T; Greer, P B; Arm, J

2014-01-01

The purpose of this study was to test the hypothesis that audiovisual (AV) biofeedback can improve image quality and reduce scan time for respiratory-gated 3D thoracic MRI. For five healthy human subjects respiratory motion guidance in MR scans was provided using an AV biofeedback system, utilizing real-time respiratory motion signals. To investigate the improvement of respiratory-gated 3D MR images between free breathing (FB) and AV biofeedback (AV), each subject underwent two imaging sessions. Respiratory-related motion artifacts and imaging time were qualitatively evaluated in addition to the reproducibility of external (abdominal) motion. In the results, 3D MR images in AV biofeedback showed more anatomic information such as a clear distinction of diaphragm, lung lobes and sharper organ boundaries. The scan time was reduced from 401±215 s in FB to 334±94 s in AV (p-value 0.36). The root mean square variation of the displacement and period of the abdominal motion was reduced from 0.4±0.22 cm and 2.8±2.5 s in FB to 0.1±0.15 cm and 0.9±1.3 s in AV (p-value of displacement <0.01 and p-value of period 0.12). This study demonstrated that audiovisual biofeedback improves image quality and reduces scan time for respiratory-gated 3D MRI. These results suggest that AV biofeedback has the potential to be a useful motion management tool in medical imaging and radiation therapy procedures.

FAST MRI breast screening revisited

International Nuclear Information System (INIS)

Jain, Manish; Jain, Arushi; Hyzy, Marek D.; Werth, Graziella

2017-01-01

Screening for breast cancer in high-risk women takes about 40 minutes to acquire an MRI scan and is time-intensive to report. There is recent interest in the performance of an abbreviated MRI protocol (FAST) in the screening setting. FAST scans have a reported negative predictive value of 99.8%. This study evaluates the false positive rates (FPR) and recall rates for FAST scans as compared to full diagnostic studies (FD). A database of all screening breast MRI scans performed at our institution between 30 June 2013 and 1 July 2014 (n = 591) was created by one of the researchers, who did not subsequently analyse the MRI scans. The T1W and first post-contrast and subtracted images from each of these scans (FAST protocol) were assessed by experienced breast MRI radiologists, blinded to the final diagnosis. The findings were then compared with the FD result. The recall rates were 6.6% for FAST scans and 5.8% for FD scans. FPR rates were 4.7% and 3.9% respectively. There is no statistically significant difference in the recall rates or FPR of FAST scans in comparison with full diagnostic studies. Given the absence of statistically significant difference in the FPR and recall rates in comparison with FD, FAST scans can replace FD for screening of breast cancer.

An MRI-Conditional External Cardiac Defibrillator for Resuscitation Within the MRI Scanner Bore

Science.gov (United States)

Schmidt, Ehud J.; Watkins, Ronald D.; Zviman, Menekhem M.; Guttman, Michael A.; Wang, Wei; Halperin, Henry A.

2016-01-01

Background Subjects undergoing cardiac arrest within an MRI scanner are currently removed from the bore and then from the MRI suite, prior to delivery of CPR and defibrillation, potentially increasing risk of mortality. This precludes many higher-risk (acute-ischemic, acute-stroke) patients from undergoing MRI imaging and MRI-guided intervention. An MRI-conditional cardiac defibrillator should enable scanning with defibrillation pads attached and the generator ON, enabling application of defibrillation within the MRI seconds after a cardiac event. An MRI-conditional external defibrillator may improve patient acceptance for MRI procedures. Methods and Results A commercial external defibrillator was rendered 1.5 Tesla MRI-conditional by addition of novel Radio-Frequency (RF) filters between the generator and commercial disposable surface-pads. The RF filters reduced emission into the MRI scanner, and prevented cable/surface-pad heating during imaging, while preserving all the defibrillator’s monitoring and delivery functions. Human volunteers were imaged using high Specific-Absorption-Rate sequences to validate MRI image quality (IQ) and lack of heating. Swine were electrically fibrillated (N=4) and thereafter defibrillated both outside and inside the MRI bore. MRI IQ was reduced by 0.8 or 1.6 dB, with the generator in monitoring mode and operating on battery or AC power, respectively. Commercial surface-pads did not create artifacts deeper than 6mm below the skin surface. RF heating was within FDA guidelines. Defibrillation was completely successful inside and outside the MRI bore. Conclusions A prototype MRI-conditional defibrillation system successfully defibrillated in the MRI without degrading image quality, or increasing the time needed for defibrillation. It can increase patient acceptance for MRI procedures. PMID:27729363

High success rates of sedation-free brain MRI scanning in young children using simple subject preparation protocols with and without a commercial mock scanner–the Diabetes Research in Children Network (DirecNet) experience

Science.gov (United States)

Barnea-Goraly, Naama; Weinzimer, Stuart A.; Mauras, Nelly; Beck, Roy W.; Marzelli, Matt J.; Mazaika, Paul K.; Aye, Tandy; White, Neil H.; Tsalikian, Eva; Fox, Larry; Kollman, Craig; Cheng, Peiyao; Reiss, Allan L.

2013-01-01

Background The ability to lie still in an MRI scanner is essential for obtaining usable image data. To reduce motion, young children are often sedated, adding significant cost and risk. Objective We assessed the feasibility of using a simple and affordable behavioral desensitization program to yield high-quality brain MRI scans in sedation-free children. Materials and methods 222 children (4–9.9 years), 147 with type 1 diabetes and 75 age-matched non-diabetic controls, participated in a multi-site study focused on effects of type 1 diabetes on the developing brain. T1-weighted and diffusion-weighted imaging (DWI) MRI scans were performed. All children underwent behavioral training and practice MRI sessions using either a commercial MRI simulator or an inexpensive mock scanner consisting of a toy tunnel, vibrating mat, and video player to simulate the sounds and feel of the MRI scanner. Results 205 children (92.3%), mean age 7±1.7 years had high-quality T1-W scans and 174 (78.4%) had high-quality diffusion-weighted scans after the first scan session. With a second scan session, success rates were 100% and 92.5% for T1-and diffusion-weighted scans, respectively. Success rates did not differ between children with type 1 diabetes and children without diabetes, or between centers using a commercial MRI scan simulator and those using the inexpensive mock scanner. Conclusion Behavioral training can lead to a high success rate for obtaining high-quality T1-and diffusion-weighted brain images from a young population without sedation. PMID:24096802

High success rates of sedation-free brain MRI scanning in young children using simple subject preparation protocols with and without a commercial mock scanner-the Diabetes Research in Children Network (DirecNet) experience

International Nuclear Information System (INIS)

Barnea-Goraly, Naama; Marzelli, Matt J.; Mazaika, Paul K.; Weinzimer, Stuart A.; Ruedy, Katrina J.; Beck, Roy W.; Kollman, Craig; Cheng, Peiyao; Mauras, Nelly; Fox, Larry; Aye, Tandy; White, Neil H.; Tsalikian, Eva; Reiss, Allan L.

2014-01-01

The ability to lie still in an MRI scanner is essential for obtaining usable image data. To reduce motion, young children are often sedated, adding significant cost and risk. We assessed the feasibility of using a simple and affordable behavioral desensitization program to yield high-quality brain MRI scans in sedation-free children. 222 children (4-9.9 years), 147 with type 1 diabetes and 75 age-matched non-diabetic controls, participated in a multi-site study focused on effects of type 1 diabetes on the developing brain. T1-weighted and diffusion-weighted imaging (DWI) MRI scans were performed. All children underwent behavioral training and practice MRI sessions using either a commercial MRI simulator or an inexpensive mock scanner consisting of a toy tunnel, vibrating mat, and video player to simulate the sounds and feel of the MRI scanner. 205 children (92.3%), mean age 7 ± 1.7 years had high-quality T1-W scans and 174 (78.4%) had high-quality diffusion-weighted scans after the first scan session. With a second scan session, success rates were 100% and 92.5% for T1-and diffusion-weighted scans, respectively. Success rates did not differ between children with type 1 diabetes and children without diabetes, or between centers using a commercial MRI scan simulator and those using the inexpensive mock scanner. Behavioral training can lead to a high success rate for obtaining high-quality T1-and diffusion-weighted brain images from a young population without sedation. (orig.)

High success rates of sedation-free brain MRI scanning in young children using simple subject preparation protocols with and without a commercial mock scanner-the Diabetes Research in Children Network (DirecNet) experience

Energy Technology Data Exchange (ETDEWEB)

Barnea-Goraly, Naama; Marzelli, Matt J.; Mazaika, Paul K. [Center for Interdisciplinary Brain Sciences Research, Department of Psychiatry and Behavioral Sciences, Stanford, CA (United States); Weinzimer, Stuart A. [Yale University, Pediatric Endocrinology, New Haven, CT (United States); Ruedy, Katrina J.; Beck, Roy W.; Kollman, Craig; Cheng, Peiyao [Jaeb Center for Health Research, Tampa, FL (United States); Mauras, Nelly; Fox, Larry [Nemours Children' s Clinic, Pediatric Endocrinology, Jacksonville, FL (United States); Aye, Tandy [Stanford University, Department of Pediatrics, Stanford, CA (United States); White, Neil H. [Washington University in St. Louis, Department of Pediatrics, St. Louis, MO (United States); Tsalikian, Eva [University of Iowa, Pediatric Endocrinology, Iowa City, IA (United States); Reiss, Allan L. [Center for Interdisciplinary Brain Sciences Research, Department of Psychiatry and Behavioral Sciences, Stanford, CA (United States); Stanford University, Department of Pediatrics, Stanford, CA (United States); Stanford University, Department of Radiology, Diabetes Research in Children Network (DirecNet), Stanford, CA (United States); Collaboration: on behalf of the Diabetes Research in Children Network (DirecNet)

2014-02-15

The ability to lie still in an MRI scanner is essential for obtaining usable image data. To reduce motion, young children are often sedated, adding significant cost and risk. We assessed the feasibility of using a simple and affordable behavioral desensitization program to yield high-quality brain MRI scans in sedation-free children. 222 children (4-9.9 years), 147 with type 1 diabetes and 75 age-matched non-diabetic controls, participated in a multi-site study focused on effects of type 1 diabetes on the developing brain. T1-weighted and diffusion-weighted imaging (DWI) MRI scans were performed. All children underwent behavioral training and practice MRI sessions using either a commercial MRI simulator or an inexpensive mock scanner consisting of a toy tunnel, vibrating mat, and video player to simulate the sounds and feel of the MRI scanner. 205 children (92.3%), mean age 7 ± 1.7 years had high-quality T1-W scans and 174 (78.4%) had high-quality diffusion-weighted scans after the first scan session. With a second scan session, success rates were 100% and 92.5% for T1-and diffusion-weighted scans, respectively. Success rates did not differ between children with type 1 diabetes and children without diabetes, or between centers using a commercial MRI scan simulator and those using the inexpensive mock scanner. Behavioral training can lead to a high success rate for obtaining high-quality T1-and diffusion-weighted brain images from a young population without sedation. (orig.)

Learning Computational Models of Video Memorability from fMRI Brain Imaging.

Science.gov (United States)

Han, Junwei; Chen, Changyuan; Shao, Ling; Hu, Xintao; Han, Jungong; Liu, Tianming

2015-08-01

Generally, various visual media are unequally memorable by the human brain. This paper looks into a new direction of modeling the memorability of video clips and automatically predicting how memorable they are by learning from brain functional magnetic resonance imaging (fMRI). We propose a novel computational framework by integrating the power of low-level audiovisual features and brain activity decoding via fMRI. Initially, a user study experiment is performed to create a ground truth database for measuring video memorability and a set of effective low-level audiovisual features is examined in this database. Then, human subjects' brain fMRI data are obtained when they are watching the video clips. The fMRI-derived features that convey the brain activity of memorizing videos are extracted using a universal brain reference system. Finally, due to the fact that fMRI scanning is expensive and time-consuming, a computational model is learned on our benchmark dataset with the objective of maximizing the correlation between the low-level audiovisual features and the fMRI-derived features using joint subspace learning. The learned model can then automatically predict the memorability of videos without fMRI scans. Evaluations on publically available image and video databases demonstrate the effectiveness of the proposed framework.

Safety of routine early MRI in preterm infants

International Nuclear Information System (INIS)

Plaisier, Annemarie; Feijen-Roon, Monique; Heemskerk, Anneriet M.; Dudink, Jeroen; Raets, Marlou M.A.; Govaert, Paul; Starre, Cynthia van der; Lequin, Maarten H.

2012-01-01

Cerebral MRI performed on preterm infants at term-equivalent 30 weeks' gestational age (GA) is increasingly performed as part of standard clinical care. We evaluated safety of these early MRI procedures. We retrospectively collected data on patient safety of preterm infants who underwent early MRI scans. Data were collected at fixed times before and after the MRI scan. MRI procedures were carried out according to a comprehensive guideline. A total of 52 infants underwent an MRI scan at 30 weeks' GA. Although no serious adverse events occurred and vital parameters remained stable during the procedure, minor adverse events were encountered in 26 infants (50%). The MRI was terminated in three infants (5.8%) because of respiratory instability. Increased respiratory support within 24 h after the MRI was necessary for 12 infants (23.1%) and was significantly associated with GA, birth weight and the mode of respiratory support. Hypothermia (core temperature < 36 C) occurred in nine infants (17.3%). Temperature dropped significantly after the MRI scan. Minor adverse events after MRI procedures at 30 weeks GA were common and should not be underestimated. A dedicated and comprehensive guideline for MRI procedures in preterm infants is essential. (orig.)

Safety of routine early MRI in preterm infants

Energy Technology Data Exchange (ETDEWEB)

Plaisier, Annemarie; Feijen-Roon, Monique; Heemskerk, Anneriet M.; Dudink, Jeroen [Erasmus Medical Centre - Sophia, Division of Neonatology, Department of Pediatrics, Rotterdam (Netherlands); Erasmus Medical Centre - Sophia, Division of Pediatric Radiology, Department of Radiology, Rotterdam (Netherlands); Raets, Marlou M.A.; Govaert, Paul [Erasmus Medical Centre - Sophia, Division of Neonatology, Department of Pediatrics, Rotterdam (Netherlands); Starre, Cynthia van der [Erasmus Medical Centre - Sophia, Division of Neonatology, Department of Pediatrics, Rotterdam (Netherlands); Erasmus Medical Centre - Sophia, Intensive Care, Department of Pediatrics and Pediatric Surgery, Rotterdam (Netherlands); Lequin, Maarten H. [Erasmus Medical Centre - Sophia, Division of Pediatric Radiology, Department of Radiology, Rotterdam (Netherlands)

2012-10-15

Cerebral MRI performed on preterm infants at term-equivalent 30 weeks' gestational age (GA) is increasingly performed as part of standard clinical care. We evaluated safety of these early MRI procedures. We retrospectively collected data on patient safety of preterm infants who underwent early MRI scans. Data were collected at fixed times before and after the MRI scan. MRI procedures were carried out according to a comprehensive guideline. A total of 52 infants underwent an MRI scan at 30 weeks' GA. Although no serious adverse events occurred and vital parameters remained stable during the procedure, minor adverse events were encountered in 26 infants (50%). The MRI was terminated in three infants (5.8%) because of respiratory instability. Increased respiratory support within 24 h after the MRI was necessary for 12 infants (23.1%) and was significantly associated with GA, birth weight and the mode of respiratory support. Hypothermia (core temperature < 36 C) occurred in nine infants (17.3%). Temperature dropped significantly after the MRI scan. Minor adverse events after MRI procedures at 30 weeks GA were common and should not be underestimated. A dedicated and comprehensive guideline for MRI procedures in preterm infants is essential. (orig.)

High-resolution whole-brain diffusion MRI at 7T using radiofrequency parallel transmission.

Science.gov (United States)

Wu, Xiaoping; Auerbach, Edward J; Vu, An T; Moeller, Steen; Lenglet, Christophe; Schmitter, Sebastian; Van de Moortele, Pierre-François; Yacoub, Essa; Uğurbil, Kâmil

2018-03-30

Investigating the utility of RF parallel transmission (pTx) for Human Connectome Project (HCP)-style whole-brain diffusion MRI (dMRI) data at 7 Tesla (7T). Healthy subjects were scanned in pTx and single-transmit (1Tx) modes. Multiband (MB), single-spoke pTx pulses were designed to image sagittal slices. HCP-style dMRI data (i.e., 1.05-mm resolutions, MB2, b-values = 1000/2000 s/mm 2 , 286 images and 40-min scan) and data with higher accelerations (MB3 and MB4) were acquired with pTx. pTx significantly improved flip-angle detected signal uniformity across the brain, yielding ∼19% increase in temporal SNR (tSNR) averaged over the brain relative to 1Tx. This allowed significantly enhanced estimation of multiple fiber orientations (with ∼21% decrease in dispersion) in HCP-style 7T dMRI datasets. Additionally, pTx pulses achieved substantially lower power deposition, permitting higher accelerations, enabling collection of the same data in 2/3 and 1/2 the scan time or of more data in the same scan time. pTx provides a solution to two major limitations for slice-accelerated high-resolution whole-brain dMRI at 7T; it improves flip-angle uniformity, and enables higher slice acceleration relative to current state-of-the-art. As such, pTx provides significant advantages for rapid acquisition of high-quality, high-resolution truly whole-brain dMRI data. © 2018 International Society for Magnetic Resonance in Medicine.

The relation between statistical power and inference in fMRI.

Directory of Open Access Journals (Sweden)

Henk R Cremers

Full Text Available Statistically underpowered studies can result in experimental failure even when all other experimental considerations have been addressed impeccably. In fMRI the combination of a large number of dependent variables, a relatively small number of observations (subjects, and a need to correct for multiple comparisons can decrease statistical power dramatically. This problem has been clearly addressed yet remains controversial-especially in regards to the expected effect sizes in fMRI, and especially for between-subjects effects such as group comparisons and brain-behavior correlations. We aimed to clarify the power problem by considering and contrasting two simulated scenarios of such possible brain-behavior correlations: weak diffuse effects and strong localized effects. Sampling from these scenarios shows that, particularly in the weak diffuse scenario, common sample sizes (n = 20-30 display extremely low statistical power, poorly represent the actual effects in the full sample, and show large variation on subsequent replications. Empirical data from the Human Connectome Project resembles the weak diffuse scenario much more than the localized strong scenario, which underscores the extent of the power problem for many studies. Possible solutions to the power problem include increasing the sample size, using less stringent thresholds, or focusing on a region-of-interest. However, these approaches are not always feasible and some have major drawbacks. The most prominent solutions that may help address the power problem include model-based (multivariate prediction methods and meta-analyses with related synthesis-oriented approaches.

MRI simulation: end-to-end testing for prostate radiation therapy using geometric pelvic MRI phantoms

International Nuclear Information System (INIS)

Sun, Jidi; Menk, Fred; Lambert, Jonathan; Martin, Jarad; Denham, James W; Greer, Peter B; Dowling, Jason; Rivest-Henault, David; Pichler, Peter; Parker, Joel; Arm, Jameen; Best, Leah

2015-01-01

To clinically implement MRI simulation or MRI-alone treatment planning requires comprehensive end-to-end testing to ensure an accurate process. The purpose of this study was to design and build a geometric phantom simulating a human male pelvis that is suitable for both CT and MRI scanning and use it to test geometric and dosimetric aspects of MRI simulation including treatment planning and digitally reconstructed radiograph (DRR) generation.A liquid filled pelvic shaped phantom with simulated pelvic organs was scanned in a 3T MRI simulator with dedicated radiotherapy couch-top, laser bridge and pelvic coil mounts. A second phantom with the same external shape but with an internal distortion grid was used to quantify the distortion of the MR image. Both phantoms were also CT scanned as the gold-standard for both geometry and dosimetry. Deformable image registration was used to quantify the MR distortion. Dose comparison was made using a seven-field IMRT plan developed on the CT scan with the fluences copied to the MR image and recalculated using bulk electron densities.Without correction the maximum distortion of the MR compared with the CT scan was 7.5 mm across the pelvis, while this was reduced to 2.6 and 1.7 mm by the vendor’s 2D and 3D correction algorithms, respectively. Within the locations of the internal organs of interest, the distortion was <1.5 and <1 mm with 2D and 3D correction algorithms, respectively. The dose at the prostate isocentre calculated on CT and MRI images differed by 0.01% (1.1 cGy). Positioning shifts were within 1 mm when setup was performed using MRI generated DRRs compared to setup using CT DRRs.The MRI pelvic phantom allows end-to-end testing of the MRI simulation workflow with comparison to the gold-standard CT based process. MRI simulation was found to be geometrically accurate with organ dimensions, dose distributions and DRR based setup within acceptable limits compared to CT. (paper)

Effect of pulse sequence parameter selection on signal strength in positive-contrast MRI markers for MRI-based prostate postimplant assessment

Energy Technology Data Exchange (ETDEWEB)

Lim, Tze Yee [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 and The University of Texas at Houston Graduate School of Biomedical Sciences, 6767 Bertner Avenue, Houston, Texas 77030 (United States); Kudchadker, Rajat J., E-mail: rkudchad@mdanderson.org; Wang, Jihong; Ibbott, Geoffrey S. [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States); Stafford, R. Jason [Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States); MacLellan, Christopher [Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 and The University of Texas at Houston Graduate School of Biomedical Sciences, 6767 Bertner Avenue, Houston, Texas 77030 (United States); Rao, Arvind [Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States); Frank, Steven J. [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States)

2016-07-15

Purpose: For postimplant dosimetric assessment, computed tomography (CT) is commonly used to identify prostate brachytherapy seeds, at the expense of accurate anatomical contouring. Magnetic resonance imaging (MRI) is superior to CT for anatomical delineation, but identification of the negative-contrast seeds is challenging. Positive-contrast MRI markers were proposed to replace spacers to assist seed localization on MRI images. Visualization of these markers under varying scan parameters was investigated. Methods: To simulate a clinical scenario, a prostate phantom was implanted with 66 markers and 86 seeds, and imaged on a 3.0T MRI scanner using a 3D fast radiofrequency-spoiled gradient recalled echo acquisition with various combinations of scan parameters. Scan parameters, including flip angle, number of excitations, bandwidth, field-of-view, slice thickness, and encoding steps were systematically varied to study their effects on signal, noise, scan time, image resolution, and artifacts. Results: The effects of pulse sequence parameter selection on the marker signal strength and image noise were characterized. The authors also examined the tradeoff between signal-to-noise ratio, scan time, and image artifacts, such as the wraparound artifact, susceptibility artifact, chemical shift artifact, and partial volume averaging artifact. Given reasonable scan time and managable artifacts, the authors recommended scan parameter combinations that can provide robust visualization of the MRI markers. Conclusions: The recommended MRI pulse sequence protocol allows for consistent visualization of the markers to assist seed localization, potentially enabling MRI-only prostate postimplant dosimetry.

Analysis on the value of the multi-slice spiral CT and MRI scanning for applying to the identifying diagnosis of the new and old vertebral compresion fracture

International Nuclear Information System (INIS)

Huo Zhiyi; Gao Shuming; Li Dasheng; Pei Lijun; Qu Hui

2008-01-01

Objective: To analyze and explore the value of the mutislice spiral CT (MSCT) scanning, its reconstructive technology and MRI scanning for applying to the identifying diagnosis of new and old vertebral compresion fracture. Methods: One hundred and sixty-seven cases with the new and old vertebral compresion fracture who have 189 vertebrae in total were examined using the MSCT scanning, their imaging information were postprocessed with 2D and 3D reconstruction at the work station. Thirty-four patients with overall 43 vertebrae were carried out by MRI scanning and their images were compared with those of MSCT. Results: They had the highest proportion of vertebrae in L1 with accounting for 27.68% (31/112) and 35.06% (27/77) among the patients with new and old vertebral compresion fracture, respectively. The next was T12, L2 and T11. There were statistically significant differences between new and old cases in such appearance as fracture line clear and sharp (102 and 21), contusion and hemorrhage of spinal cord (15 and 0), parenchyma shadow beside vertebrae(103 and 11), appendant fracture(26 and 5), organ's lacerated wound around vertebral body (30 and 0), discus intervertebrales vacuum (10 and 36), derangement and hardening of vertebral bone trabecularism (29 and 51) (P 1 WI signal, 27 vertebrae with the T 2 WI fat-suppresion irregular high signal were demonstrated in MRI scanning among 27 vertebrae of 21 cases with new vertebral compresion fracture. While 16 vertebrae with the T 1 WI and T 2 WI signals were the same as those of the normal vertebrae, 16 vertebrae were the T 2 WI fat-suppresion low signal among 13 cases with old vertebral compresion fracture. Conclusions: The MSCT plays an important role in identifying diagnosis for the most of the patients with the new and old vertebral compresion fracture, while MRI scanning may reflect the pathophysiological characteristics in diagnosis of the spinal cord and the ligament lesion. Therefore, the MSCT and MRI scanning

Scanning fast and slow: current limitations of 3 Tesla functional MRI and future potential

Science.gov (United States)

Boubela, Roland N.; Kalcher, Klaudius; Nasel, Christian; Moser, Ewald

2014-02-01

Functional MRI at 3T has become a workhorse for the neurosciences, e.g., neurology, psychology, and psychiatry, enabling non-invasive investigation of brain function and connectivity. However, BOLD-based fMRI is a rather indirect measure of brain function, confounded by fluctuation related signals, e.g. head or brain motion, brain pulsation, blood flow, intermixed with susceptibility differences close or distant to the region of neuronal activity. Even though a plethora of preprocessing strategies have been published to address these confounds, their efficiency is still under discussion. In particular, physiological signal fluctuations closely related to brain supply may mask BOLD signal changes related to "true" neuronal activation. Here we explore recent technical and methodological advancements aimed at disentangling the various components, employing fast multiband vs. standard EPI, in combination with fast temporal ICA.Our preliminary results indicate that fast (TRstudied and task performance better correlated to other measures. This should increase specificity and reliability in fMRI studies. Furthermore, physiological signal changes during scanning may then be recognized as a source of information rather than a nuisance. As we are currently still undersampling the complexity of the brain, even at a rather coarse macroscopic level, we should be very cautious in the interpretation of neuroscientific findings, in particular when comparing different groups (e.g., age, sex, medication, pathology, etc.). From a technical point of view our goal should be to sample brain activity at layer specific resolution with low TR, covering as much of the brain as possible without violating SAR limits. We hope to stimulate discussion towards a better understanding and a more quantitative use of fMRI.

Centimeter-scale MEMS scanning mirrors for high power laser application

Science.gov (United States)

Senger, F.; Hofmann, U.; v. Wantoch, T.; Mallas, C.; Janes, J.; Benecke, W.; Herwig, Patrick; Gawlitza, P.; Ortega-Delgado, M.; Grune, C.; Hannweber, J.; Wetzig, A.

2015-02-01

A higher achievable scan speed and the capability to integrate two scan axes in a very compact device are fundamental advantages of MEMS scanning mirrors over conventional galvanometric scanners. There is a growing demand for biaxial high speed scanning systems complementing the rapid progress of high power lasers for enabling the development of new high throughput manufacturing processes. This paper presents concept, design, fabrication and test of biaxial large aperture MEMS scanning mirrors (LAMM) with aperture sizes up to 20 mm for use in high-power laser applications. To keep static and dynamic deformation of the mirror acceptably low all MEMS mirrors exhibit full substrate thickness of 725 μm. The LAMM-scanners are being vacuum packaged on wafer-level based on a stack of 4 wafers. Scanners with aperture sizes up to 12 mm are designed as a 4-DOF-oscillator with amplitude magnification applying electrostatic actuation for driving a motor-frame. As an example a 7-mm-scanner is presented that achieves an optical scan angle of 32 degrees at 3.2 kHz. LAMM-scanners with apertures sizes of 20 mm are designed as passive high-Q-resonators to be externally excited by low-cost electromagnetic or piezoelectric drives. Multi-layer dielectric coatings with a reflectivity higher than 99.9 % have enabled to apply cw-laser power loads of more than 600 W without damaging the MEMS mirror. Finally, a new excitation concept for resonant scanners is presented providing advantageous shaping of intensity profiles of projected laser patterns without modulating the laser. This is of interest in lighting applications such as automotive laser headlights.

Can unenhanced multiparametric MRI substitute gadolinium-enhanced MRI in the characterization of vertebral marrow infiltrative lesions?

Directory of Open Access Journals (Sweden)

Dalia Z. Zidan

2014-06-01

Conclusion: Unenhanced-multiparametric MRI is compatible with gadolinium-enhanced MRI in reliable characterization of marrow infiltrative lesions. The routine MRI protocol of cancer patients should be altered to accommodate the evolving MRI technology and cost effectively substitute the need for a gadolinium enhanced scan.

MRI features of meningeal metastasis from lung cancer

International Nuclear Information System (INIS)

Luo Xuemao; Long Wansheng; Jin Zhifa; Hu Maoqing; Mai Xuyu

2009-01-01

Objective: To investigate the pathway and MRI findings of meningeal metastasis original from lung cancer. Methods: 44 cases with cerebro-spinal meningeal metastasis original from lung cancer proven by clinical and pathology were retrospectively reviewed. All cases undergone plain MRI scan and Gd-DTPA enhanced MRI scan on brain and/or spine. Results: MRI plain scan indicated 28 cases with brain metastases, 3 cases with meningeal nodosity or irregularly patchy abnormal signal, 1 case with nodule in left cavernous sinus, 10 cases with abnormal signal in spine, 2 cases with abnormal signal in spinal dura mater. 34 cases with cerebro meningeal metastases were found in MRI enhancement scan. Among them, 11 cases displayed cerebral dura mater-arachnoid enhancement, 17 cases revealed cerebral pia mater-arachnoid enhancement and 6 cases with mixed typed enhancement. Osteoclasia in skull was found in 4 cases, spinal metastasis was revealed in 17 cases, and patchy abnormal enhancement in spinal dura mater was showed in 12 cases. Conclusion: Hematogenous metastasis is a main route of meningeal metastasis caused by lung cancer and enhanced MRI scan is of important diagnostic value. (authors)

Serial CT scans and MRI scans of Tay-Sachs disease

International Nuclear Information System (INIS)

Shimoizumi, Hideo; Miyao, Masutomo; Ichihashi, Koh; Sawa, Rituko; Yamamoto, Yoshifumi; Tanaka, Osamu; Yanagisawa, Masayoshi; Kamoshita, Shigehiko.

1986-01-01

Serial X-ray CT and MRI were performed on 2 cases of Tay-Sachs disease. Case 1 : a 3-year-10-month-old girl. Her developmental milestones were normal until the age of 6 months. At the age of 10 months, hypotonia and unduly sensitiveness to sounds were noticed. She had cherry red spots in both fundi, and the serum hexosaminidase A activity was low. Significant clinical features during the next 3 years included regression of developmental milestones to the level of one month, and myoclonic and generalised seizures. After 3 years she showed megalencephaly, unstable body temperature, and respiratory disorders. Case 2 : a 2-year-6-month-old boy. His developmental milestones were normal until the age of 5 months. Then he manifested hyperreaction to noises and further developments ceased. He started to deteriorate from the age of 1 year and 2 months, and had no head control at the age of 1 year and 6 months. Cherry red spots were detected and the serum hexsosaminidase A activity was low, too. X-ray CT at the early stage of cases 1 and 2 showed mild cerebral atrophy and high density areas in bilateral thalami and basal ganglia. At the late stage of Case 1, high density areas appeared in occipital and frontal white matters. MRI in both patients were strikingly similar. In their grey matters, linear light areas were demonstrated on IR images. Their white matters showed extensive dark (long T 1 ) areas on IR images, and extensive light (long T 2 ) areas on SE images. Bilateral thalami and basal ganglia were light on IR images and dark on SE images. The findings of MRI in our patients seemed to correlate well with pathological and biochemical changes in their brains. (author)

Is There a Role for MRI in Plantar Heel Pain.

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Fazal, Muhammad Ali; Tsekes, Demetris; Baloch, Irshad

2018-06-01

There is an increasing trend to investigate plantar heel pain with magnetic resonance imaging (MRI) scan though plantar fasciitis is the most common cause. The purpose of our study was to evaluate the role of MRI in patients presenting with plantar heel pain. Case notes and MRI scans of 141 patients with a clinical diagnosis of plantar fasciitis were reviewed retrospectively. There were 98 females and 43 males patients. Fourteen patients had bilateral symptoms. Average age for male patients was 51 years (range = 26-78 years), and for female patients the average age was 52 years (range = 29-76 years). A total of 121 feet had MRI features suggestive of plantar fasciitis. MRI was normal in 32 feet. There was one case of stress fracture of calcaneus and another of a heel fibroma diagnosed on MRI scan. In our study, MRI scan was normal in 20.7% of the cases; 1.3% had a diagnosis other than plantar fasciitis but no sinister pathology. We therefore conclude that MRI scan is not routinely indicated and key is careful clinical assessment. Therapeutic, Level IV: Retrospective, Case series.

Atlas-based deformable image registration for MRI-guided prostate radiation therapy

International Nuclear Information System (INIS)

Dowling, J.; Fripp, J.; Salvado, O.; Lambert, J.; Denham, J.W.; Capp, A.; Grer, P.B.; Parker, J.

2010-01-01

Full text: To develop atlas-based deformable image registration methods to automatically segment organs and map electron densities to pelvic MRI scans for MRI-guided radiation therapy. Methods An MRT pelvic atlas and corresponding CT atlas were developed based on whole pelvic T 2 MRI scans and CT scans for 39 patients. Expert manual segmentations on both MRI and CT scans were obtained. The atlas was deformably registered to the individual patient MRI scans for automatic prostate, rectum, bladder and bone segmentation. These were compared to the manual segmentations using the Dice overlap coefficient. The same deformation vectors were then applied to the CT-atlas to produce pseudo-CT scans that correspond to the patient MRI scan anatomy but are populated with Hounsfield units. The original patient plan was recalculated on the pseudo-CT and compared to the original CT plan and bulk density plans on the MRI scans. Results Dice coefficient results were high (>0.8) for bone and prostate but lower (<0.7) for bladder and rectum which exhibit greater changes in shape and volume. Doses calculated on pseudo-CT scans were within 3% of original patient plans. Two sources of discrepancy were found; MR anatomy differences from CT due to patient setup differences at the MR scanner. and Hounsfield unit differences for bone in the pseudo-CT from original CT. Patient setup will be adressed with a

High-resolution MRI of the labyrinth. Optimization of scan parameters with 3D-FSE

International Nuclear Information System (INIS)

Sakata, Motomichi; Harada, Kuniaki; Shirase, Ryuji; Kumagai, Akiko; Ogasawara, Masashi

2005-01-01

The aim of our study was to optimize the parameters of high-resolution MRI of the labyrinth with a 3D fast spin-echo (3D-FSE) sequence. We investigated repetition time (TR), echo time (TE), Matrix, field of view (FOV), and coil selection in terms of CNR (contrast-to-noise ratio) and SNR (signal-to-noise ratio) by comparing axial images and/or three-dimensional images. The optimal 3D-FSE sequence parameters were as follows: 1.5 Tesla MR unit (Signa LX, GE Medical Systems), 3D-FSE sequence, dual 3-inch surface coil, acquisition time=12.08 min, TR=5000 msec, TE=300 msec, 3 number of excitations (NEX), FOV=12 cm, matrix=256 x 256, slice thickness=0.5 mm/0.0 sp, echo train=64, bandwidth=±31.5 kHz. High-resolution MRI of the labyrinth using the optimized 3D-FSE sequence parameters permits visualization of important anatomic details (such as scala tympani and scala vestibuli), making it possible to determine inner ear anomalies and the patency of cochlear turns. To obtain excellent heavily T2-weighted axial and three-dimensional images in the labyrinth, high CNR, SNR, and spatial resolution are significant factors at the present time. Furthermore, it is important not only to optimize the scan parameters of 3D-FSE but also to select an appropriate coil for high-resolution MRI of the labyrinth. (author)

An audit comparing the reporting of staging MRI scans for rectal cancer with the London Cancer Alliance (LCA) guidelines.

Science.gov (United States)

Siddiqui, M R S; Shanmuganandan, A P; Rasheed, S; Tekkis, P; Brown, G; Abulafi, A M

2017-11-01

This article focuses on the audit and assessment of clinical practice before and after introduction of MRI reporting guidelines. Standardised proforma based reporting may improve quality of MRI reports. Uptake of the use may be facilitated by endorsement from regional and national cancer organisations. This audit was divided into 2 phases. MRI reports issued between April 2014 and June 2014 were included in the first part of our audit. Phase II included MRI reports issued between April 2015 and June 2015. 14 out of 15 hospitals that report MRI scans in the LCA responded to our audit proposal. The completion rate of key MRI metrics/metrics was better in proforma compared to prose reports both before (98% vs 73%; p < 0.05) and after introduction of the guidelines (98% vs 71%; p < 0.05). There was an approximate doubling of proforma reporting after the introduction of guidelines and workshop interventions (39% vs 65%; p < 0.05). Evaluation of locally advanced cancers (tumours extending to or beyond the circumferential resection margin) for beyond TME surgery was reported in 3% of prose reports vs. 42% in proformas. Incorporation of standardised reporting in official guidelines improved the uptake of proforma based reporting. Proforma based reporting captured more MRI reportable items compared to prose summaries, before and after the implementation of guidelines. MRI reporting of advanced cancers for beyond TME surgery falls short of acceptable standards but is more detailed in proforma based reports. Further work to improve completion especially in beyond TME reporting is required. Copyright © 2017 Elsevier Ltd, BASO ~ The Association for Cancer Surgery, and the European Society of Surgical Oncology. All rights reserved.

Patch-based generation of a pseudo CT from conventional MRI sequences for MRI-only radiotherapy of the brain

DEFF Research Database (Denmark)

Andreasen, Daniel; Van Leemput, Koen; Hansen, Rasmus H.

2015-01-01

scans. In this study, we investigate the potential of a patch-based method for creating a pCT based on conventional T1-weighted MRI scans without using deformable registrations. We compare this method against two state-of-the-art methods within the voxel-based and atlas-based categories. Methods...... based on water equivalent path lengths was carried out, comparing the upper hemisphere of the head in the pCT and the real CT. Finally, the dosimetric accuracy was tested and compared for a photon treatment plan. Results:The pCTs produced with the patch-based method had the best voxel-wise, geometric......Purpose: In radiotherapy (RT) based on magnetic resonance imaging (MRI) as the only modality, the information on electron density must be derived from the MRI scan by creating a so-called pseudo computed tomography (pCT). This is a nontrivial task, since the voxel-intensities in an MRI scan...

MRI of the Chest

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Full Text Available ... metallic items, which can distort MRI images removable dental work pens, pocket knives and eyeglasses body piercings ... tomography (CT) scans, MRI does not utilize ionizing radiation. Instead, radiofrequency pulses re-align hydrogen atoms that ...

MRI of the Chest

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Full Text Available ... other internal body structures. MRI does not use ionizing radiation (x-rays). Detailed MR images allow physicians ... computed tomography (CT) scans, MRI does not utilize ionizing radiation. Instead, radiofrequency pulses re-align hydrogen atoms ...

MRI of the Chest

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Full Text Available ... other internal body structures. MRI does not use ionizing radiation (x-rays). Detailed MR images allow physicians to ... computed tomography (CT) scans, MRI does not utilize ionizing radiation. Instead, radiofrequency pulses re-align hydrogen atoms that ...

Prospective Comparison of F-18 Choline PET/CT Scan Versus Axial MRI for Detecting Bone Metastasis in Biochemically Relapsed Prostate Cancer Patients

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Wouter Huysse

2017-10-01

Full Text Available We compared fluor-18 choline positron emission tomography/computed tomography (PET/CT and axial skeleton magnetic resonance imaging (MRI prospectively obtained for the detection of bone metastases in non-castrated patients with biochemically recurrent prostate cancer following primary treatment. PET/CT was performed 45 min post-injection of 3–4 MBq/kg F-18 methyl choline. MRI included T1- and fluid sensitive T2-weighted images of the spine and pelvis. Readers were initially blinded from other results and all scans underwent independent double reading. The best valuable comparator (BVC defined the metastatic status. On the basis of the BVC, 15 out of 64 patients presented with 24 bone metastases. On a patient level, the sensitivity and specificity of MRI and PET were not significantly different. On a lesion level, the sensitivity of MRI was significantly better compared to PET, and the specificity did not differ significantly. In conclusion, axial MRI is an interesting screening tool for the detection of bone metastases because of its low probability of false negative results. However, F-18 choline PET is a valuable addition as it can overrule false positive MRI results and detect non-axial metastases.

The cerebellar development in chinese children-a study by voxel-based volume measurement of reconstructed 3D MRI scan.

Science.gov (United States)

Wu, Kuan-Hsun; Chen, Chia-Yuan; Shen, Ein-Yiao

2011-01-01

Cerebellar disorder was frequently reported to have relation with structural brain volume alteration and/or morphology change. In dealing with such clinical situations, we need a convenient and noninvasive imaging tool to provide clinicians with a means of tracing developmental changes in the cerebellum. Herein, we present a new daily practice method for cerebellum imaging that uses a work station and a software program to process reconstructed 3D neuroimages after MRI scanning. In a 3-y period, 3D neuroimages reconstructed from MRI scans of 50 children aged 0.2-12.7 y were taken. The resulting images were then statistically analyzed against a growth curve. We observed a remarkable increase in the size of the cerebellum in the first 2 y of life. Furthermore, the unmyelinated cerebellum grew mainly between birth and 2 y of age in the postnatal stage. In contrast, the postnatal development of the brain mainly depended on the growth of myelinated cerebellum from birth through adolescence. This study presents basic data from a study of ethnic Chinese children's cerebellums using reconstructed 3D brain images. Based on the technique we introduce here, clinicians can evaluate the growth of the brain.

A multi-layer MRI description of Parkinson's disease

Science.gov (United States)

La Rocca, M.; Amoroso, N.; Lella, E.; Bellotti, R.; Tangaro, S.

2017-09-01

Magnetic resonance imaging (MRI) along with complex network is currently one of the most widely adopted techniques for detection of structural changes in neurological diseases, such as Parkinson's Disease (PD). In this paper, we present a digital image processing study, within the multi-layer network framework, combining more classifiers to evaluate the informative power of the MRI features, for the discrimination of normal controls (NC) and PD subjects. We define a network for each MRI scan; the nodes are the sub-volumes (patches) the images are divided into and the links are defined using the Pearson's pairwise correlation between patches. We obtain a multi-layer network whose important network features, obtained with different feature selection methods, are used to feed a supervised multi-level random forest classifier which exploits this base of knowledge for accurate classification. Method evaluation has been carried out using T1 MRI scans of 354 individuals, including 177 PD subjects and 177 NC from the Parkinson's Progression Markers Initiative (PPMI) database. The experimental results demonstrate that the features obtained from multiplex networks are able to accurately describe PD patterns. Besides, also if a privileged scale for studying PD disease exists, exploring the informative content of more scales leads to a significant improvement of the performances in the discrimination between disease and healthy subjects. In particular, this method gives a comprehensive overview of brain regions statistically affected by the disease, an additional value to the presented study.

Gyral high density on CT scan after head injury; [sup 123]I-IMP SPECT and MRI findings in three children

Energy Technology Data Exchange (ETDEWEB)

Abe, Takumi; Matsumoto, Kiyoshi (Showa Univ., Tokyo (Japan). School of Medicine); Sakamoto, Tetsuya; Aruga, Tohru

1994-02-01

The authors treated three children who had 'gyral high density' on plain CT scans after head injury with acute subdural hematoma. [sup 123]I-IMP SPECT (IMP) and MRI in the chronic stage were performed. All were males, about one year of age, with acute subdural hematoma. CT scan 48 hours after injury showed diffuse low density in the ipsilateral parenchyma with minimum midline shift, and IMP showed decreased activity in the same area. Plain CT scan 1 to 3 weeks after injury showed remarkably high density along the gyri in part of the same area. This area was markedly enhanced on CT with contrast medium and showed decreased blood flow on IMP. This high density area disappeared within 2 months after injury and the area concerned showed brain atrophy. In the chronic stage (after 6 months), only the high density area along the gyri seen in the CT scan showed MRI evidence of ishemia, but there was no definite evidence of hemorrhage. All three children had hemiplegia at the time of discharge. The gyral high density suggests ischemic brain, but the pathophysiological process might be different from that of so-called hemorrhagic infarction. Presumably, it is due to incomplete autoregulation, the incomplete blood-brain barrier and the sensitivity to stimulation of cerebral blood vessels in the brains of infants. The intensity and range of the gyral high density are considered to be important in estimating the future amount of atrophic change in the insulted brain and the resulting sequelae. (author).

An Automated and Intelligent Medical Decision Support System for Brain MRI Scans Classification.

Directory of Open Access Journals (Sweden)

Muhammad Faisal Siddiqui

Full Text Available A wide interest has been observed in the medical health care applications that interpret neuroimaging scans by machine learning systems. This research proposes an intelligent, automatic, accurate, and robust classification technique to classify the human brain magnetic resonance image (MRI as normal or abnormal, to cater down the human error during identifying the diseases in brain MRIs. In this study, fast discrete wavelet transform (DWT, principal component analysis (PCA, and least squares support vector machine (LS-SVM are used as basic components. Firstly, fast DWT is employed to extract the salient features of brain MRI, followed by PCA, which reduces the dimensions of the features. These reduced feature vectors also shrink the memory storage consumption by 99.5%. At last, an advanced classification technique based on LS-SVM is applied to brain MR image classification using reduced features. For improving the efficiency, LS-SVM is used with non-linear radial basis function (RBF kernel. The proposed algorithm intelligently determines the optimized values of the hyper-parameters of the RBF kernel and also applied k-fold stratified cross validation to enhance the generalization of the system. The method was tested by 340 patients' benchmark datasets of T1-weighted and T2-weighted scans. From the analysis of experimental results and performance comparisons, it is observed that the proposed medical decision support system outperformed all other modern classifiers and achieves 100% accuracy rate (specificity/sensitivity 100%/100%. Furthermore, in terms of computation time, the proposed technique is significantly faster than the recent well-known methods, and it improves the efficiency by 71%, 3%, and 4% on feature extraction stage, feature reduction stage, and classification stage, respectively. These results indicate that the proposed well-trained machine learning system has the potential to make accurate predictions about brain abnormalities

Combined bilateral idiopathic necrosis of the humerus and femur heads: Bone scan, X-ray, CT, and MRI findings

International Nuclear Information System (INIS)

Piepenburg, R.; Hahn, K.; Doll, G.; Grimm, J.

1992-01-01

Untreated aseptic bone necroses close to a joint commonly leads to severe secondary arthrosis and destruction of the joint within a short time. Therefore, only a diagnosis in an early stage of the disease offers the chance of a successful joint- preserving therapy. In cases of clinically suspected aseptic bone necrosis but still negative or doubtful X-ray findings, bone scans or MRI are reliable methods of verifying the diagnosis. (orig./MG) [de

Efficient and robust identification of cortical targets in concurrent TMS-fMRI experiments

Science.gov (United States)

Yau, Jeffrey M.; Hua, Jun; Liao, Diana A.; Desmond, John E.

2014-01-01

Transcranial magnetic stimulation (TMS) can be delivered during fMRI scans to evoke BOLD responses in distributed brain networks. While concurrent TMS-fMRI offers a potentially powerful tool for non-invasively investigating functional human neuroanatomy, the technique is currently limited by the lack of methods to rapidly and precisely localize targeted brain regions – a reliable procedure is necessary for validly relating stimulation targets to BOLD activation patterns, especially for cortical targets outside of motor and visual regions. Here we describe a convenient and practical method for visualizing coil position (in the scanner) and identifying the cortical location of TMS targets without requiring any calibration or any particular coil-mounting device. We quantified the precision and reliability of the target position estimates by testing the marker processing procedure on data from 9 scan sessions: Rigorous testing of the localization procedure revealed minimal variability in coil and target position estimates. We validated the marker processing procedure in concurrent TMS-fMRI experiments characterizing motor network connectivity. Together, these results indicate that our efficient method accurately and reliably identifies TMS targets in the MR scanner, which can be useful during scan sessions for optimizing coil placement and also for post-scan outlier identification. Notably, this method can be used generally to identify the position and orientation of MR-compatible hardware placed near the head in the MR scanner. PMID:23507384

Magnetic Resonance Imaging (MRI) -- Head

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Full Text Available ... metallic items, which can distort MRI images removable dental work pens, pocket knives and eyeglasses body piercings ... tomography (CT) scans, MRI does not utilize ionizing radiation. Instead, radiofrequency pulses re-align hydrogen atoms that ...

Magnetic Resonance Imaging (MRI) -- Head

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Full Text Available ... used in tattoos may contain iron and could heat up during an MRI scan, but this is ... imaging based on the electrical activity of the heart, such as electrocardiography (EKG). MRI generally is not ...

Actual imaging time in fetal MRI

International Nuclear Information System (INIS)

Brugger, Peter C.; Prayer, Daniela

2012-01-01

Objective: Safety issues in magnetic resonance imaging (MRI) are important, especially in fetal MRI. However, since basic data with respect of the effective exposure time in fetal MRI are not available, this study aimed to determine the actual imaging time during a fetal MRI study. Methods: 100 fetal MRI studies of singleton pregnancies performed on a 1.5 T system were analysed with respect to study duration (from starting the survey scan until the end of study), the number of sequences acquired, and the actual imaging time, which was calculated by adding up scan time of each sequence. Furthermore, each sequence type was analysed regarding the number of acquisitions, specific absorption rates (SAR), and duration. Results: Mean study duration was 34.6 min (range: 14–58 min; standard deviation (SD): 9.7 min), the average number of sequences acquired was 26.6 (range: 11–44, SD: 6.6). Actual scan time averaged 11.4 min (range: 4–19 min, SD: 4.0 min). Ultrafast T2-weighted and steady-state free-precession sequences accounted for 62.3% of actual scan time, and were distributed over the whole duration of the study. Conclusion: Actual imaging time only accounts for 33% of total study time and is not continuous. The remaining time is consumed by the preparation phases of the scanner, and is spent with planning sequences and the eventual repositioning of the coil and/or pregnant woman. These data may help to more accurately estimate the exposure to radiofrequency deposition and noise during fetal MRI studies.

Organizing Knowing in Interdisciplinary MRI Practice

DEFF Research Database (Denmark)

Yoshinaka, Yutaka

's CT-scan and X-ray machines, were to take on MRI scanning, on an albeit rotational basis. Opening up to a broader group of operators to the scanning practice was to allow for organizational flexibility and a broader basis for competence building among radiology staff, where different occupational......This paper addresses organizational knowledge practices pertaining to the interdisciplinary work of Magnetic Resonance Imaging (MRI) at a hospital radiology department. The setting occasions an interesting venue for exploring domestication of MRI as it unfolds in distributed settings of collective......, facilitating, and yet, in tension with, efforts at organizational transformation – its occasioning(s), mediations and contingent effects. The case study is based on direct observation and interviews, exploring and drawing upon the idea of different units of analysis as a methodological means to address...

Device localization and dynamic scan plane selection using a wireless MRI detector array

Science.gov (United States)

Riffe, Matthew J.; Yutzy, Stephen R.; Jiang, Yun; Twieg, Michael D.; Blumenthal, Colin J.; Hsu, Daniel P.; Pan, Li; Gilson, Wesley D.; Sunshine, Jeffrey L.; Flask, Christopher A.; Duerk, Jeffrey L.; Nakamoto, Dean; Gulani, Vikas; Griswold, Mark A.

2013-01-01

Purpose A prototype wireless guidance device using single sideband amplitude modulation (SSB) is presented for a 1.5T MRI system. Methods The device contained three fiducial markers each mounted to an independent receiver coil equipped with wireless SSB technology. Acquiring orthogonal projections of these markers determined the position and orientation of the device, which was used to define the scan plane for a subsequent image acquisition. Device localization and scan plane update required approximately 30 ms, so it could be interleaved with high temporal resolution imaging. Since the wireless device is used for localization and doesn’t require full imaging capability, the design of the SSB wireless system was simplified by allowing an asynchronous clock between the transmitter and receiver. Results When coupled to a high readout bandwidth, the error caused by the lack of a shared frequency reference was quantified to be less than one pixel (0.78 mm) in the projection acquisitions. Image-guidance with the prototype was demonstrated with a phantom where a needle was successfully guided to a target and contrast was delivered. Conclusion The feasibility of active tracking with a wireless detector array is demonstrated. Wireless arrays could be incorporated into devices to assist in image-guided procedures. PMID:23900921

MRI Primer

International Nuclear Information System (INIS)

Oldendorf, W.; Oldendorf, W. Jr.

1991-01-01

Designed for studies, radiologists, and clinicians at all levels of training, this book provides a basic introduction to the principles, physics, and instrumentation of magnetic resonance imaging. The fundamental concepts that are essential for the optimal clinical use of MRI are thoroughly explained in easily accessible terms. To facilitate the reader's comprehension, the material is presented nonmathematically, using no equations and a minimum of symbols and abbreviations. MRI Primer presents a clear account of the phenomenon of nuclear magnetic resonance and the use of gradient magnetic fields to create clinically useful images of cross-sectional slices. Close attention is given to the magnetization vector as a means of expressing nuclear behavior, the role of T 1 and T 2 weighing in imaging, the use of contrast agents, and the pulse sequences most often used in clinical practice, as well as to the relative capabilities and limitations of MRI and CT. The basic hardware components of an MRI scanner are described in detail. Sample MRI scans illustrate how MRI characterizes tissue. An appendix provides a brief introduction to quantum processes in MRI

Analog electro-optical readout of SiPMs for compact, low power ToF PET/MRI

International Nuclear Information System (INIS)

Bieniosek, Matthew F; Levin, Craig S

2014-01-01

The aim of this work is to demonstrate time of flight (ToF) performance from analog electro-optical transmission of SiPM-based PET detector signals. In electro-optical readout schemes, scintillation signals are converted to near-infrared light by a laser diode and transmitted out of the MRI bore with fiber-optics [], greatly reducing the PET system's footprint, power consumption, and mutual interference with the MRI.

Delayed enhanced MRI in intraparenchymal tumors

International Nuclear Information System (INIS)

Eguchi, Takahiko; Morimoto, Tetsuya; Takeshima, Toshikazu

1991-01-01

Delayed enhanced MRI was performed on 20 intraparenchymal tumors, and these findings were compared with those of early enhanced MRI. Using the spin-echo technique (SE: 400-500/20 msec), early scans were obtained 5 minutes, and delayed scans were obtained 60 minutes, after the intravenous injection of 0.1 nmol of gadolinium-DTPA/Kg. We discussed the changes in the delayed scan with regard to the change in the pattern of enhancement and the boundary of enhancement. In these twenty intraparenchymal tumors, there were three low-grade astrocytomas, two anaplastic astrocytomas, seven glioblastomas, and eight metastatic tumors. The changes in the enhanced pattern showed three types as follows: Type I: heterogeneous enhancement in both early and delayed scans; Type II: heterogeneous enhancement in early scan and homogeneous enhancement in delayed scan; Type III: homogeneous enhancement in both early and delayed scans. Most malignant tumors, such as glioblastomas (6/8), anaplastic astrocytomas (2/2), and metastatic tumors (7/8), revealed Type I, although low-grade astrocytomas showed Type II (3/2) and Type III (1/3). The heterogeneous enhancement in delayed scan was found in malignant tumors and in low-grade astrocytoma; even if the early scan revealed heterogeneous enhancement, the delayed scan showed homogeneous enhancement. In the delayed scan, most enhanced boundaries spread out of the boundaries in the early scan. Glioblastomas spread markedly in the delayed scan, although none of the low-grade astrocytomas, anaplastic astrocytomas, or metastases revealed marked spreading. We called these marked increases in the delayed scan a 'spreading sign' and thought that this sign was specific to glioblastomas. Recently some authors have emphasized the usefulness of serial scans. Delayed enhanced MRI 60 minutes after the administration of a contrast medium was here found also to be useful for the accurate diagnosis for brain tumors. (author)

Safety of a dedicated brain MRI protocol in patients with a vagus nerve stimulator.

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de Jonge, Jeroen C; Melis, Gerrit I; Gebbink, Tineke A; de Kort, Gérard A P; Leijten, Frans S S

2014-11-01

Although implanted metallic devices constitute a relative contraindication to magnetic resonance imaging (MRI) scanning, the safety of brain imaging in a patient with a vagus nerve stimulator (VNS) is classified as "conditional," provided that specific manufacturer guidelines are followed when a transmit and receive head coil is used at 1.5 or 3.0 Tesla. The aim of this study was to evaluate the safety of performing brain MRI scans in patients with the VNS. From September 2009 until November 2011, 101 scans were requested in 73 patients with the VNS in The Netherlands. Patients were scanned according to the manufacturer's guidelines. No patient reported any side effect, discomfort, or pain during or after the MRI scan. In one patient, a lead break was detected based on device diagnostics after the MRI-scan. However, because no system diagnostics had been performed prior to MR scanning in this patient, it is unclear whether MR scanning was responsible for the lead break. The indication for most scans was epilepsy related. Twenty-six scans (26%) were part of a (new) presurgical evaluation and could probably better have been performed prior to VNS implantation. Performing brain MRI scans in patients with an implanted VNS is safe when a modified MRI protocol is followed. Wiley Periodicals, Inc. © 2014 International League Against Epilepsy.

Scan-rescan reproducibility of segmental aortic wall shear stress as assessed by phase-specific segmentation with 4D flow MRI in healthy volunteers.

Science.gov (United States)

van der Palen, Roel L F; Roest, Arno A W; van den Boogaard, Pieter J; de Roos, Albert; Blom, Nico A; Westenberg, Jos J M

2018-05-26

The aim was to investigate scan-rescan reproducibility and observer variability of segmental aortic 3D systolic wall shear stress (WSS) by phase-specific segmentation with 4D flow MRI in healthy volunteers. Ten healthy volunteers (age 26.5 ± 2.6 years) underwent aortic 4D flow MRI twice. Maximum 3D systolic WSS (WSSmax) and mean 3D systolic WSS (WSSmean) for five thoracic aortic segments over five systolic cardiac phases by phase-specific segmentations were calculated. Scan-rescan analysis and observer reproducibility analysis were performed. Scan-rescan data showed overall good reproducibility for WSSmean (coefficient of variation, COV 10-15%) with moderate-to-strong intraclass correlation coefficient (ICC 0.63-0.89). The variability in WSSmax was high (COV 16-31%) with moderate-to-good ICC (0.55-0.79) for different aortic segments. Intra- and interobserver reproducibility was good-to-excellent for regional aortic WSSmax (ICC ≥ 0.78; COV ≤ 17%) and strong-to-excellent for WSSmean (ICC ≥ 0.86; COV ≤ 11%). In general, ascending aortic segments showed more WSSmax/WSSmean variability compared to aortic arch or descending aortic segments for scan-rescan, intraobserver and interobserver comparison. Scan-rescan reproducibility was good for WSSmean and moderate for WSSmax for all thoracic aortic segments over multiple systolic phases in healthy volunteers. Intra/interobserver reproducibility for segmental WSS assessment was good-to-excellent. Variability of WSSmax is higher and should be taken into account in case of individual follow-up or in comparative rest-stress studies to avoid misinterpretation.

Visual, Auditory, and Cross Modal Sensory Processing in Adults with Autism: An EEG Power and BOLD fMRI Investigation

Science.gov (United States)

Hames, Elizabeth’ C.; Murphy, Brandi; Rajmohan, Ravi; Anderson, Ronald C.; Baker, Mary; Zupancic, Stephen; O’Boyle, Michael; Richman, David

2016-01-01

Electroencephalography (EEG) and blood oxygen level dependent functional magnetic resonance imagining (BOLD fMRI) assessed the neurocorrelates of sensory processing of visual and auditory stimuli in 11 adults with autism (ASD) and 10 neurotypical (NT) controls between the ages of 20–28. We hypothesized that ASD performance on combined audiovisual trials would be less accurate with observable decreased EEG power across frontal, temporal, and occipital channels and decreased BOLD fMRI activity in these same regions; reflecting deficits in key sensory processing areas. Analysis focused on EEG power, BOLD fMRI, and accuracy. Lower EEG beta power and lower left auditory cortex fMRI activity were seen in ASD compared to NT when they were presented with auditory stimuli as demonstrated by contrasting the activity from the second presentation of an auditory stimulus in an all auditory block vs. the second presentation of a visual stimulus in an all visual block (AA2-VV2).We conclude that in ASD, combined audiovisual processing is more similar than unimodal processing to NTs. PMID:27148020

Visual, Auditory, and Cross Modal Sensory Processing in Adults with Autism:An EEG Power and BOLD fMRI Investigation

Directory of Open Access Journals (Sweden)

Elizabeth C Hames

2016-04-01

Full Text Available Electroencephalography (EEG and Blood Oxygen Level Dependent Functional Magnetic Resonance Imagining (BOLD fMRI assessed the neurocorrelates of sensory processing of visual and auditory stimuli in 11 adults with autism (ASD and 10 neurotypical (NT controls between the ages of 20-28. We hypothesized that ASD performance on combined audiovisual trials would be less accurate with observable decreased EEG power across frontal, temporal, and occipital channels and decreased BOLD fMRI activity in these same regions; reflecting deficits in key sensory processing areas. Analysis focused on EEG power, BOLD fMRI, and accuracy. Lower EEG beta power and lower left auditory cortex fMRI activity were seen in ASD compared to NT when they were presented with auditory stimuli as demonstrated by contrasting the activity from the second presentation of an auditory stimulus in an all auditory block versus the second presentation of a visual stimulus in an all visual block (AA2­VV2. We conclude that in ASD, combined audiovisual processing is more similar than unimodal processing to NTs.

The propagation of high power CW scanning electron beam in air

International Nuclear Information System (INIS)

Korenev, Sergey; Korenev, Ivan

2002-01-01

The question of propagation of high power electron beam in air presents the scientific and applied interests. The high power (80 kW) CW electron accelerator 'Rhodotron' with kinetic energy of electrons 5 and 10 MeV was used in the experiments. The experimental results for propagation of scanning electron beams in air are presented and discussed

MRI of the prostate. Recommendations on patient preparation and scanning protocol

International Nuclear Information System (INIS)

Franiel, Tobias; Quentin, Michael; Schimmoeller, Lars; Mueller-Lisse, Ullrich Gerd; Asbach, Patrick; Roedel, Stefan; Willinek, Winfried; Hueper, Katja; Beyersdorff, Dirk; Roethke, Matthias

2017-01-01

The Working Group Uroradiology and Urogenital Diagnosis of the German Roentgen Society has developed uniform recommendations for the preparation and implementation of prostate MRI. In the first part detailed recommendations are given in tabular form regarding 1. anamnestic data before prostate MRI, 2. termination of examinations and preparation of examinations, 3. examination protocol and 4. MRI-guided in-bore biopsy. In the second part, the recommendations are discussed in detail and relevant background information is provided.

A proposal for PET/MRI attenuation correction with μ-values measured using a fixed-position radiation source and MRI segmentation

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Kawaguchi, Hiroshi, E-mail: kwgc@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Hirano, Yoshiyuki, E-mail: yhirano@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Yoshida, Eiji, E-mail: rush@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Kershaw, Jeff, E-mail: len@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Shiraishi, Takahiro, E-mail: tshira@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Suga, Mikio, E-mail: mikio.suga@faculty.chiba-u.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Graduate School of Engineering of Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Ikoma, Yoko, E-mail: ikoma@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Obata, Takayuki, E-mail: t_obata@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Ito, Hiroshi, E-mail: hito@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Yamaya, Taiga, E-mail: taiga@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan)

2014-01-11

Several MRI-based attenuation correction methods have been reported for PET/MRI; these methods are expected to make efficient use of high-quality anatomical MRIs and reduce the radiation dose for PET/MRI scanning. The accuracy of the attenuation map (μ-map) from an MRI depends on the accuracy of tissue segmentation and the attenuation coefficients to be assigned (μ-values). In this study, we proposed an MRI-based μ-value estimation method with a non-rotational radiation source to construct a suitable μ-map for PET/MRI. The proposed method uses an accurately segmented tissue map, the partial path length of each tissue, and detected intensities of attenuated radiation from a fixed-position (rather than a rotating) radiation source to obtain the μ-map. We estimated the partial path length from a virtual blank scan of fixed-point radiation with the same scanner geometry using the known tissue map from MRI. The μ-values of every tissue were estimated by inverting a linear relationship involving the partial path lengths and measured radioactivity intensity. Validation of the proposed method was performed by calculating a fixed- point data set based upon real a real transmission scan. The root-mean-square error between the μ-values derived from a conventional transmission scan and those obtained with our proposed method were 2.4±1.4%, 17.4±9.1% and 6.6±4.3% for brain, bone and soft tissue other than brain, respectively. Although the error estimates for bone and soft tissue are not insignificant, the method we propose is able to estimate the brain μ-value accurately and it is this factor that most strongly affects the quantitative value of PET images because of the large volumetric ratio of the brain. -- Highlights: • An MRI-derived µ-map for the attenuation correction of PET images is proposed. • Method relies on segmentation of MRI and a fixed-point source transmission scan. • Tissue segmentation reduces the number of unknown µ-values. • Method

A proposal for PET/MRI attenuation correction with μ-values measured using a fixed-position radiation source and MRI segmentation

International Nuclear Information System (INIS)

Kawaguchi, Hiroshi; Hirano, Yoshiyuki; Yoshida, Eiji; Kershaw, Jeff; Shiraishi, Takahiro; Suga, Mikio; Ikoma, Yoko; Obata, Takayuki; Ito, Hiroshi; Yamaya, Taiga

2014-01-01

Several MRI-based attenuation correction methods have been reported for PET/MRI; these methods are expected to make efficient use of high-quality anatomical MRIs and reduce the radiation dose for PET/MRI scanning. The accuracy of the attenuation map (μ-map) from an MRI depends on the accuracy of tissue segmentation and the attenuation coefficients to be assigned (μ-values). In this study, we proposed an MRI-based μ-value estimation method with a non-rotational radiation source to construct a suitable μ-map for PET/MRI. The proposed method uses an accurately segmented tissue map, the partial path length of each tissue, and detected intensities of attenuated radiation from a fixed-position (rather than a rotating) radiation source to obtain the μ-map. We estimated the partial path length from a virtual blank scan of fixed-point radiation with the same scanner geometry using the known tissue map from MRI. The μ-values of every tissue were estimated by inverting a linear relationship involving the partial path lengths and measured radioactivity intensity. Validation of the proposed method was performed by calculating a fixed- point data set based upon real a real transmission scan. The root-mean-square error between the μ-values derived from a conventional transmission scan and those obtained with our proposed method were 2.4±1.4%, 17.4±9.1% and 6.6±4.3% for brain, bone and soft tissue other than brain, respectively. Although the error estimates for bone and soft tissue are not insignificant, the method we propose is able to estimate the brain μ-value accurately and it is this factor that most strongly affects the quantitative value of PET images because of the large volumetric ratio of the brain. -- Highlights: • An MRI-derived µ-map for the attenuation correction of PET images is proposed. • Method relies on segmentation of MRI and a fixed-point source transmission scan. • Tissue segmentation reduces the number of unknown µ-values. • Method

Clinical and MRI evaluation of tuberculous meningitis

International Nuclear Information System (INIS)

Jiang Chunjing; Shu Jiner; Chen Jian; Sheng Sanlan; Lu Jinhua; Cai Xiaoxiao; Li Huimin

2010-01-01

Objective: To evaluate the relationship of clinical and magnetic resonance imaging (MRI) findings in patients with tuberculous meningitis (TBM), and to improve the understanding of TBM. Methods: The clinical and MRI findings in 42 patients with confirmed TBM were analyzed retrospectively. MRI examination was performed using a 1 Tesla system, including SE T 1 WI and T 2 WI. Intravenous contrast was injected in 29 patients, and follow-up scans were performed on 17 patients. Results: Of 24 patients with early TBM, MRI was abnormal in 5(21%) with slight Tl-hypointense meningeal (4) or ependymal thickening (1). MRI on 33/35 (94%) patients with late stage TBM was abnormal with T 1 hypointensity and T 2 hyperintensity including meningeal thickening (19), mild surrounding brain edema (10), nodules (11), tuberculoma (5) and abscess (2). There was significant plaque-like, nodular or rim enhancement with surrounding brain edema. Conclusion: Tuberculous meningitis has minimal clinical and MRI findings in the early phase and significant clinical and MRI findings in the late phase. The enhanced scan may help to detect the abnormality. (authors)

Temporal interpolation alters motion in fMRI scans: Magnitudes and consequences for artifact detection.

Directory of Open Access Journals (Sweden)

Jonathan D Power

Full Text Available Head motion can be estimated at any point of fMRI image processing. Processing steps involving temporal interpolation (e.g., slice time correction or outlier replacement often precede motion estimation in the literature. From first principles it can be anticipated that temporal interpolation will alter head motion in a scan. Here we demonstrate this effect and its consequences in five large fMRI datasets. Estimated head motion was reduced by 10-50% or more following temporal interpolation, and reductions were often visible to the naked eye. Such reductions make the data seem to be of improved quality. Such reductions also degrade the sensitivity of analyses aimed at detecting motion-related artifact and can cause a dataset with artifact to falsely appear artifact-free. These reduced motion estimates will be particularly problematic for studies needing estimates of motion in time, such as studies of dynamics. Based on these findings, it is sensible to obtain motion estimates prior to any image processing (regardless of subsequent processing steps and the actual timing of motion correction procedures, which need not be changed. We also find that outlier replacement procedures change signals almost entirely during times of motion and therefore have notable similarities to motion-targeting censoring strategies (which withhold or replace signals entirely during times of motion.

Neural correlates of social motivation: an fMRI study on power versus affiliation.

Science.gov (United States)

Quirin, Markus; Meyer, Frank; Heise, Nils; Kuhl, Julius; Küstermann, Ekkehard; Strüber, Daniel; Cacioppo, John T

2013-06-01

Power versus affiliation motivations refer to two different strivings relevant in the context of social relationships. We used functional magnetic resonance imaging (fMRI) to determine neural structures involved in power versus affiliation motivation based on an individual differences approach. Seventeen participants provided self-reports of power and affiliation motives and were presented with love, power-related, and control movie clips. The power motive predicted activity in four clusters within the left prefrontal cortex (PFC), while participants viewed power-related film clips. The affiliation motive predicted activity in the right putamen/pallidum while participants viewed love stories. The present findings extend previous research on social motivations to the level of neural functioning and suggest differential networks for power-related versus affiliation-related social motivations. Copyright © 2012 Elsevier B.V. All rights reserved.

MRI with cardiac pacing devices – Safety in clinical practice

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Kaasalainen, Touko, E-mail: touko.kaasalainen@hus.fi [HUS Medical Imaging Center, Helsinki University Central Hospital, POB 340 (Haartmaninkatu 4), 00290 Helsinki (Finland); Department of Physics, University of Helsinki (Finland); Pakarinen, Sami, E-mail: sami.pakarinen@hus.fi [HUS Department of Cardiology, Helsinki University Central Hospital, POB 340 (Haartmaninkatu 4), 00290 Helsinki (Finland); Kivistö, Sari, E-mail: sari.kivisto@hus.fi [HUS Medical Imaging Center, Helsinki University Central Hospital, POB 340 (Haartmaninkatu 4), 00290 Helsinki (Finland); Holmström, Miia, E-mail: miia.holmstrom@hus.fi [HUS Medical Imaging Center, Helsinki University Central Hospital, POB 340 (Haartmaninkatu 4), 00290 Helsinki (Finland); Hänninen, Helena, E-mail: helena.hanninen@hus.fi [HUS Department of Cardiology, Helsinki University Central Hospital, POB 340 (Haartmaninkatu 4), 00290 Helsinki (Finland); Peltonen, Juha, E-mail: juha.peltonen@hus.fi [HUS Medical Imaging Center, Helsinki University Central Hospital, POB 340 (Haartmaninkatu 4), 00290 Helsinki (Finland); Department of Biomedical Engineering and Computational Science, School of Science, Aalto University, Helsinki (Finland); Lauerma, Kirsi, E-mail: kirsi.lauerma@hus.fi [HUS Medical Imaging Center, Helsinki University Central Hospital, POB 340 (Haartmaninkatu 4), 00290 Helsinki (Finland); Sipilä, Outi, E-mail: outi.sipila@hus.fi [HUS Medical Imaging Center, Helsinki University Central Hospital, POB 340 (Haartmaninkatu 4), 00290 Helsinki (Finland)

2014-08-15

Objectives: The aim of this study was to introduce a single centre “real life” experience of performing MRI examinations in clinical practice on patients with cardiac pacemaker systems. Additionally, we aimed to evaluate the safety of using a dedicated safety protocol for these patients. Materials and methods: We used a 1.5 T MRI scanner to conduct 68 MRI scans of different body regions in patients with pacing systems. Of the cardiac devices, 32% were MR-conditional, whereas the remaining 68% were MR-unsafe. We recorded the functional parameters of the devices prior, immediately after, and approximately one month after the MRI scanning, and compared the device parameters to the baseline values. Results: All MRI examinations were completed safely, and each device could be interrogated normally following the MRI. We observed no changes in the programmed parameters of the devices. For most of the participants, the distributions of the immediate and one-month changes in the device parameters were within 20% of the baseline values, although some changes approached clinically important thresholds. Furthermore, we observed no differences in the variable changes between MR-conditional and MR-unsafe pacing systems, or between scans of the thorax area and other scanned areas. Conclusion: MRI in patients with MR-conditional pacing systems and selected MR-unsafe systems could be performed safely under strict conditions in this study.

AUTOMATIC RAILWAY POWER LINE EXTRACTION USING MOBILE LASER SCANNING DATA

Directory of Open Access Journals (Sweden)

S. Zhang

2016-06-01

Full Text Available Research on power line extraction technology using mobile laser point clouds has important practical significance on railway power lines patrol work. In this paper, we presents a new method for automatic extracting railway power line from MLS (Mobile Laser Scanning data. Firstly, according to the spatial structure characteristics of power-line and trajectory, the significant data is segmented piecewise. Then, use the self-adaptive space region growing method to extract power lines parallel with rails. Finally use PCA (Principal Components Analysis combine with information entropy theory method to judge a section of the power line whether is junction or not and which type of junction it belongs to. The least squares fitting algorithm is introduced to model the power line. An evaluation of the proposed method over a complicated railway point clouds acquired by a RIEGL VMX450 MLS system shows that the proposed method is promising.

A Novel Marker Based Method to Teeth Alignment in MRI

Science.gov (United States)

Luukinen, Jean-Marc; Aalto, Daniel; Malinen, Jarmo; Niikuni, Naoko; Saunavaara, Jani; Jääsaari, Päivi; Ojalammi, Antti; Parkkola, Riitta; Soukka, Tero; Happonen, Risto-Pekka

2018-04-01

Magnetic resonance imaging (MRI) can precisely capture the anatomy of the vocal tract. However, the crowns of teeth are not visible in standard MRI scans. In this study, a marker-based teeth alignment method is presented and evaluated. Ten patients undergoing orthognathic surgery were enrolled. Supraglottal airways were imaged preoperatively using structural MRI. MRI visible markers were developed, and they were attached to maxillary teeth and corresponding locations on the dental casts. Repeated measurements of intermarker distances in MRI and in a replica model was compared using linear regression analysis. Dental cast MRI and corresponding caliper measurements did not differ significantly. In contrast, the marker locations in vivo differed somewhat from the dental cast measurements likely due to marker placement inaccuracies. The markers were clearly visible in MRI and allowed for dental models to be aligned to head and neck MRI scans.

SU-F-J-166: Volumetric Spatial Distortions Comparison for 1.5 Tesla Versus 3 Tesla MRI for Gamma Knife Radiosurgery Scans Using Frame Marker Fusion and Co-Registration Modes

International Nuclear Information System (INIS)

Neyman, G

2016-01-01

Purpose: To compare typical volumetric spatial distortions for 1.5 Tesla versus 3 Tesla MRI Gamma Knife radiosurgery scans in the frame marker fusion and co-registration frame-less modes. Methods: Quasar phantom by Modus Medical Devices Inc. with GRID image distortion software was used for measurements of volumetric distortions. 3D volumetric T1 weighted scans of the phantom were produced on 1.5 T Avanto and 3 T Skyra MRI Siemens scanners. The analysis was done two ways: for scans with localizer markers from the Leksell frame and relatively to the phantom only (simulated co-registration technique). The phantom grid contained a total of 2002 vertices or control points that were used in the assessment of volumetric geometric distortion for all scans. Results: Volumetric mean absolute spatial deviations relatively to the frame localizer markers for 1.5 and 3 Tesla machine were: 1.39 ± 0.15 and 1.63 ± 0.28 mm with max errors of 1.86 and 2.65 mm correspondingly. Mean 2D errors from the Gamma Plan were 0.3 and 1.0 mm. For simulated co-registration technique the volumetric mean absolute spatial deviations relatively to the phantom for 1.5 and 3 Tesla machine were: 0.36 ± 0.08 and 0.62 ± 0.13 mm with max errors of 0.57 and 1.22 mm correspondingly. Conclusion: Volumetric spatial distortions are lower for 1.5 Tesla versus 3 Tesla MRI machines localized with markers on frames and significantly lower for co-registration techniques with no frame localization. The results show the advantage of using co-registration technique for minimizing MRI volumetric spatial distortions which can be especially important for steep dose gradient fields typically used in Gamma Knife radiosurgery. Consultant for Elekta AB

SU-F-J-166: Volumetric Spatial Distortions Comparison for 1.5 Tesla Versus 3 Tesla MRI for Gamma Knife Radiosurgery Scans Using Frame Marker Fusion and Co-Registration Modes

Energy Technology Data Exchange (ETDEWEB)

Neyman, G [The Cleveland Clinic Foundation, Cleveland, OH (United States)

2016-06-15

Purpose: To compare typical volumetric spatial distortions for 1.5 Tesla versus 3 Tesla MRI Gamma Knife radiosurgery scans in the frame marker fusion and co-registration frame-less modes. Methods: Quasar phantom by Modus Medical Devices Inc. with GRID image distortion software was used for measurements of volumetric distortions. 3D volumetric T1 weighted scans of the phantom were produced on 1.5 T Avanto and 3 T Skyra MRI Siemens scanners. The analysis was done two ways: for scans with localizer markers from the Leksell frame and relatively to the phantom only (simulated co-registration technique). The phantom grid contained a total of 2002 vertices or control points that were used in the assessment of volumetric geometric distortion for all scans. Results: Volumetric mean absolute spatial deviations relatively to the frame localizer markers for 1.5 and 3 Tesla machine were: 1.39 ± 0.15 and 1.63 ± 0.28 mm with max errors of 1.86 and 2.65 mm correspondingly. Mean 2D errors from the Gamma Plan were 0.3 and 1.0 mm. For simulated co-registration technique the volumetric mean absolute spatial deviations relatively to the phantom for 1.5 and 3 Tesla machine were: 0.36 ± 0.08 and 0.62 ± 0.13 mm with max errors of 0.57 and 1.22 mm correspondingly. Conclusion: Volumetric spatial distortions are lower for 1.5 Tesla versus 3 Tesla MRI machines localized with markers on frames and significantly lower for co-registration techniques with no frame localization. The results show the advantage of using co-registration technique for minimizing MRI volumetric spatial distortions which can be especially important for steep dose gradient fields typically used in Gamma Knife radiosurgery. Consultant for Elekta AB.

Location of core diagnostic information across various sequences in brain MRI and implications for efficiency of MRI scanner utilization.

Science.gov (United States)

Sharma, Aseem; Chatterjee, Arindam; Goyal, Manu; Parsons, Matthew S; Bartel, Seth

2015-04-01

Targeting redundancy within MRI can improve its cost-effective utilization. We sought to quantify potential redundancy in our brain MRI protocols. In this retrospective review, we aggregated 207 consecutive adults who underwent brain MRI and reviewed their medical records to document clinical indication, core diagnostic information provided by MRI, and its clinical impact. Contributory imaging abnormalities constituted positive core diagnostic information whereas absence of imaging abnormalities constituted negative core diagnostic information. The senior author selected core sequences deemed sufficient for extraction of core diagnostic information. For validating core sequences selection, four readers assessed the relative ease of extracting core diagnostic information from the core sequences. Potential redundancy was calculated by comparing the average number of core sequences to the average number of sequences obtained. Scanning had been performed using 9.4±2.8 sequences over 37.3±12.3 minutes. Core diagnostic information was deemed extractable from 2.1±1.1 core sequences, with an assumed scanning time of 8.6±4.8 minutes, reflecting a potential redundancy of 74.5%±19.1%. Potential redundancy was least in scans obtained for treatment planning (14.9%±25.7%) and highest in scans obtained for follow-up of benign diseases (81.4%±12.6%). In 97.4% of cases, all four readers considered core diagnostic information to be either easily extractable from core sequences or the ease to be equivalent to that from the entire study. With only one MRI lacking clinical impact (0.48%), overutilization did not seem to contribute to potential redundancy. High potential redundancy that can be targeted for more efficient scanner utilization exists in brain MRI protocols.

Predictive values of BI-RADS® magnetic resonance imaging (MRI) in the detection of breast ductal carcinoma in situ (DCIS)

International Nuclear Information System (INIS)

Badan, Gustavo Machado; Piato, Sebastião; Roveda, Décio; Faria Castro Fleury, Eduardo de

2016-01-01

Purpose: The purpose of this study was to evaluate BI-RADS indicators in the detection of DCIS by MRI. Materials and methods: Prospective observational study that started in 2014 and lasted 24 months. A total of 110 consecutive patients were evaluated, who presented with suspicious or highly suspicious microcalcifications on screening mammography (BI-RADS categories 4 and 5) and underwent stereotactic-guided breast biopsy, having had an MRI scan performed prior to biopsy. Results: Altogether, 38 cases were characterized as positive for malignancy, of which 25 were DCIS and 13 were invasive ductal carcinoma cases. MRI had a sensitivity of 96%; specificity of 75.67%; positive predictive value (PPV) for DCIS detection of 57.14%; negative predictive value (NPV) in the detection of DCIS of 98.24%; and an accuracy of 80.80%. Conclusion: BI-RADS as a tool for the detection of DCIS by MRI is a powerful instrument whose sensitivity was higher when compared to that observed for mammography in the literature. Likewise, the PPV obtained by MRI was higher than that observed in the present study for mammography, and the high NPV obtained on MRI scans can provide early evidence to discourage breast biopsy in selected cases.

Magnetic Resonance Imaging (MRI) -- Head

Science.gov (United States)

... News Physician Resources Professions Site Index A-Z Magnetic Resonance Imaging (MRI) - Head Magnetic resonance imaging (MRI) of the head uses a powerful ... the Head? What is MRI of the Head? Magnetic resonance imaging (MRI) is a noninvasive medical test that ...

Clinical efficacy of FDG-PET scan as preoperative diagnostic tool in cervical cancer stage Ib and IIa: comparison between the results of FDG-PET scan and operative findings

Energy Technology Data Exchange (ETDEWEB)

Kim, Jong Hoon

1999-12-01

This study was done to evaluate the clinical feasibility of FDG-PET scan for routine preoperative diagnostic methods in cervical carcinoma. PET-scans were performed from March, 1999 to November, 1999. There were 6 stage Ib and 7 IIa patients and all patients were performed radical hysterectomy and bilateral pelvic lymph node dissections and were evaluated by FDG-PET scan before operation. The mean age of the patients were 50.3 years old. Six cases had lymph node metastases by pelvis MRI, and three cases by FDG-PET scan. We could not find any lymph node metastases at surgery in 3 patients (50.0%) among 6 patients who were diagnosed by nodal metastases by pelvis MRI. And we found 1 patients with nodal metastases who had negative findings by pelvis MRI. By FDG-PET scan, we could find metastases in all positive patients. But we also found 2 additional metastatic cases in the patients with negative findings. In this study, the comparison was very difficult due to the individual differences in the comparison would be made by site-specific not person. The sensitivity of MRI and FDG-PET scan were 50.0% and 30.0%. The specificity were 94.1 % and 95.6%. The positive predictive value were 55.6 % and 50.0 %. In conclusion, we could find any superiority of FDG-PET scan in the diagnosis of lymph node metastases the pelvis MRI. So there are limitations to use the FDG-PET scan in the routine preoperative diagnostic tools in cervical cancer. But if we have more experiences to use the FDG-PET scan such as precise cut-off value of SUV and combination of other imaging technique, the FDG-PET scan are still promising diagnostic tools in cervical cancer.

MRI versus CT in the diagnosis of Nelson's syndrome

International Nuclear Information System (INIS)

Kasperlik-Zaluska, A.; Walecki, J.; Brzezinski, J.; Jeske, W.; Migdalska, B.; Bonicki, W.; Brzezinska, A.; Makowska, A.

1997-01-01

The purpose of the study was to evaluate the utility of MRI and CT in the diagnosis of Nelson's syndrome, i. e. pituitary tumours in patients bilaterally adrenalectomized for Cushing's disease. Thirteen patients, followed up for 5-29 years after adrenalectomy, were studied. In 6 of them CT and MRI revealed no changes in the pituitary gland. In the remaining 7 patients only three CT scans were suggestive of a pituitary adenoma. MRI studies with administration of gadodiamide confirmed the CT diagnosis of Nelson's tumour in 3 patients and disclosed microadenomas in a further 4 patients. Neurosurgical treatment in 4 patients confirmed the MRI findings. Additionally CT and MRI examinations were performed in 5 patients suspected of a recurrent Nelson's tumour 3-11 years after neurosurgery. MRI visualized recurrent adenomas in 3 patients that were not well seen by CT scans. In our experience MRI was more effective than CT in the diagnosis of Nelson's syndrome. (orig.). With 3 figs., 1 tab

Automatic delineation of brain regions on MRI and PET images from the pig

DEFF Research Database (Denmark)

Villadsen, Jonas; Hansen, Hanne D; Jørgensen, Louise M

2018-01-01

: Manual inter-modality spatial normalization to a MRI atlas is operator-dependent, time-consuming, and can be inaccurate with lack of cortical radiotracer binding or skull uptake. NEW METHOD: A parcellated PET template that allows for automatic spatial normalization to PET images of any radiotracer....... RESULTS: MRI and [11C]Cimbi-36 PET scans obtained in sixteen pigs made the basis for the atlas. The high resolution MRI scans allowed for creation of an accurately averaged MRI template. By aligning the within-subject PET scans to their MRI counterparts, an averaged PET template was created in the same...... the MRI template with individual MRI images and 0.92±0.26mm using the PET template with individual [11C]Cimbi-36 PET images. We tested the automatic procedure by assessing eleven PET radiotracers with different kinetics and spatial distributions by using perfusion-weighted images of early PET time frames...

Proton MRI in the evaluation of pulmonary sarcoidosis: Comparison to chest CT

International Nuclear Information System (INIS)

Chung, Jonathan H.; Little, Brent P.; Forssen, Anna V.; Yong, Jin; Nambu, Atsushi; Kazlouski, Demitry; Puderbach, Michael; Biederer, Juergen; Lynch, David A.

2013-01-01

Purpose: The purpose of this study was to determine the feasibility of proton MRI of the lung in sarcoidosis patients and the agreement between the imaging appearance of pulmonary sarcoidosis on MRI and CT. Materials and methods: Chest CT scans and dedicated pulmonary MRI scans (including HASTE, VIBE, and TrueFISP sequences) were performed within 90 days of each other in 29 patients. The scans were scored for gross parenchymal opacification, reticulation, nodules, and masses using a 3-point lobar scale. Total and subset scores for corresponding MRI and CT scans were compared using the Spearman correlation test, Bland–Altman plots, and Cohen's quadratic-weighted kappa analysis. MRI scores were compared to CT by lobe and disease category, using percentage agreement, Spearman rank correlation, and Cohen's quadratic-weighted kappa. Results: The mean (±s.d.) time between MRI and CT scans was 33 ± 32 days. There was substantial correlation and agreement between total disease scoring on MRI and CT with a Spearman correlation coefficient of 0.774 (p < 0.0001) and a Cohen's weighted kappa score of 0.646. Correlation and agreement were highest for gross parenchymal opacification (0.695, 0.528) and reticulation (0.609, 0.445), and lowest in the setting of nodules (0.501, 0.305). Agreement testing was not performed for mass scores due to low prevalence. Upper lobe scoring on MRI and CT demonstrated greater agreement compared to the lower lobes (average difference in Cohen's weighted kappa score of 0.112). Conclusion: There is substantial correlation and agreement between MRI and CT in the scoring of pulmonary sarcoidosis, though MRI evaluation in the upper lobes may be more accurate than in the lower lobes

Reliability of Early Magnetic Resonance Imaging (MRI) and Necessity of Repeating MRI in Noncooled and Cooled Infants With Neonatal Encephalopathy.

Science.gov (United States)

Chakkarapani, Elavazhagan; Poskitt, Kenneth J; Miller, Steven P; Zwicker, Jill G; Xu, Qi; Wong, Darren S T; Roland, Elke H; Hill, Alan; Chau, Vann

2016-04-01

In cooled newborns with encephalopathy, although late magnetic resonance imaging (MRI) scan (10-14 days of age) is reliable in predicting long-term outcome, it is unknown whether early scan (3-6 days of life) is. We compared the predominant pattern and extent of lesion between early and late MRI in 89 term neonates with neonatal encephalopathy. Forty-three neonates (48%) were cooled. The predominant pattern of lesions and the extent of lesion in the watershed region agreed near perfectly in noncooled (kappa = 0.94; k = 0.88) and cooled (k = 0.89; k = 0.87) infants respectively. There was perfect agreement in the extent of lesion in the basal nuclei in noncooled infants (k = 0.83) and excellent agreement in cooled infants (k = 0.67). Changes in extent of lesions on late MRI occurred in 19 of 89 infants, with higher risk in infants with hypoglycemia and moderate-severe lesions in basal nuclei. In most term neonates with neonatal encephalopathy, early MRI (relative to late scan) robustly predicts the predominant pattern and extent of injury. © The Author(s) 2015.

Optimization of scan time in MRI for total hip prostheses. SEMAC tailoring for prosthetic implants containing different types of metals

Energy Technology Data Exchange (ETDEWEB)

Deligianni, X. [University of Basel Hospital, Basel (Switzerland). Div. of Radiological Physics; Merian Iselin Klinik, Basel (Switzerland). Inst. of Radiology; Bieri, O. [University of Basel Hospital, Basel (Switzerland). Div. of Radiological Physics; Elke, R. [Orthomerian, Basel (Switzerland); Wischer, T.; Egelhof, T. [Merian Iselin Klinik, Basel (Switzerland). Inst. of Radiology

2015-12-15

Magnetic resonance imaging (MRI) of soft tissues after total hip arthroplasty is of clinical interest for the diagnosis of various pathologies that are usually invisible with other imaging modalities. As a result, considerable effort has been put into the development of metal artifact reduction MRI strategies, such as slice encoding for metal artifact correction (SEMAC). Generally, the degree of metal artifact reduction with SEMAC directly relates to the overall time spent for acquisition, but there is no specific consensus about the most efficient sequence setup depending on the implant material. The aim of this article is to suggest material-tailored SEMAC protocol settings. Five of the most common total hip prostheses (1. Revision prosthesis (S-Rom), 2. Titanium alloy, 3. Mueller type (CoNiCRMo alloy), 4. Old Charnley prosthesis (Exeter/Stryker), 5. MS-30 stem (stainless-steel)) were scanned on a 1.5 T MRI clinical scanner with a SEMAC sequence with a range of artifact-resolving slice encoding steps (SES: 2 - 23) along the slice direction (yielding a total variable scan time ranging from 1 to 10 min). The reduction of the artifact volume in comparison with maximal artifact suppression was evaluated both quantitatively and qualitatively in order to establish a recommended number of steps for each case. The number of SES that reduced the artifact volume below approximately 300 mm{sup 3} ranged from 3 to 13, depending on the material. Our results showed that although 3 SES steps can be sufficient for artifact reduction for titanium prostheses, at least 11 SES should be used for prostheses made of materials such as certain alloys of stainless steel. Tailoring SES to the implant material and to the desired degree of metal artifact reduction represents a simple tool for workflow optimization of SEMAC imaging near total hip arthroplasty in a clinical setting.

Optimization of scan time in MRI for total hip prostheses. SEMAC tailoring for prosthetic implants containing different types of metals

International Nuclear Information System (INIS)

Deligianni, X.; Wischer, T.; Egelhof, T.

2015-01-01

Magnetic resonance imaging (MRI) of soft tissues after total hip arthroplasty is of clinical interest for the diagnosis of various pathologies that are usually invisible with other imaging modalities. As a result, considerable effort has been put into the development of metal artifact reduction MRI strategies, such as slice encoding for metal artifact correction (SEMAC). Generally, the degree of metal artifact reduction with SEMAC directly relates to the overall time spent for acquisition, but there is no specific consensus about the most efficient sequence setup depending on the implant material. The aim of this article is to suggest material-tailored SEMAC protocol settings. Five of the most common total hip prostheses (1. Revision prosthesis (S-Rom), 2. Titanium alloy, 3. Mueller type (CoNiCRMo alloy), 4. Old Charnley prosthesis (Exeter/Stryker), 5. MS-30 stem (stainless-steel)) were scanned on a 1.5 T MRI clinical scanner with a SEMAC sequence with a range of artifact-resolving slice encoding steps (SES: 2 - 23) along the slice direction (yielding a total variable scan time ranging from 1 to 10 min). The reduction of the artifact volume in comparison with maximal artifact suppression was evaluated both quantitatively and qualitatively in order to establish a recommended number of steps for each case. The number of SES that reduced the artifact volume below approximately 300 mm 3 ranged from 3 to 13, depending on the material. Our results showed that although 3 SES steps can be sufficient for artifact reduction for titanium prostheses, at least 11 SES should be used for prostheses made of materials such as certain alloys of stainless steel. Tailoring SES to the implant material and to the desired degree of metal artifact reduction represents a simple tool for workflow optimization of SEMAC imaging near total hip arthroplasty in a clinical setting.

Magnetic Resonance Imaging (MRI) -- Head

Medline Plus

Full Text Available ... News Physician Resources Professions Site Index A-Z Magnetic Resonance Imaging (MRI) - Head Magnetic resonance imaging (MRI) of the head uses a powerful ... the Head? What is MRI of the Head? Magnetic resonance imaging (MRI) is a noninvasive medical test that ...

Postmortem MRI of bladder agenesis

Energy Technology Data Exchange (ETDEWEB)

Barber, Brendan R. [St George' s Hospital, Radiology Department, London (United Kingdom); Weber, Martin A. [Great Ormond Street Hospital for Children, Department of Histopathology, London (United Kingdom); Bockenhauer, Detlef [Great Ormond Street Hospital for Children, Department of Nephrology, London (United Kingdom); Hiorns, Melanie P.; McHugh, Kieran [Great Ormond Street Hospital for Children, Radiology Department, London (United Kingdom)

2011-01-15

We report a 35-week preterm neonate with bladder agenesis and bilateral dysplastic kidneys. A suprapubic catheter was inadvertently inserted into one of the larger inferior cysts of the left dysplastic kidney. A postmortem MRI scan was performed with the findings being confirmed on autopsy. We are unaware of another postmortem MRI study demonstrating bladder agenesis. (orig.)

Postmortem MRI of bladder agenesis

International Nuclear Information System (INIS)

Barber, Brendan R.; Weber, Martin A.; Bockenhauer, Detlef; Hiorns, Melanie P.; McHugh, Kieran

2011-01-01

We report a 35-week preterm neonate with bladder agenesis and bilateral dysplastic kidneys. A suprapubic catheter was inadvertently inserted into one of the larger inferior cysts of the left dysplastic kidney. A postmortem MRI scan was performed with the findings being confirmed on autopsy. We are unaware of another postmortem MRI study demonstrating bladder agenesis. (orig.)

Application of 3D documentation and geometric reconstruction methods in traffic accident analysis: with high resolution surface scanning, radiological MSCT/MRI scanning and real data based animation.

Science.gov (United States)

Buck, Ursula; Naether, Silvio; Braun, Marcel; Bolliger, Stephan; Friederich, Hans; Jackowski, Christian; Aghayev, Emin; Christe, Andreas; Vock, Peter; Dirnhofer, Richard; Thali, Michael J

2007-07-20

The examination of traffic accidents is daily routine in forensic medicine. An important question in the analysis of the victims of traffic accidents, for example in collisions between motor vehicles and pedestrians or cyclists, is the situation of the impact. Apart from forensic medical examinations (external examination and autopsy), three-dimensional technologies and methods are gaining importance in forensic investigations. Besides the post-mortem multi-slice computed tomography (MSCT) and magnetic resonance imaging (MRI) for the documentation and analysis of internal findings, highly precise 3D surface scanning is employed for the documentation of the external body findings and of injury-inflicting instruments. The correlation of injuries of the body to the injury-inflicting object and the accident mechanism are of great importance. The applied methods include documentation of the external and internal body and the involved vehicles and inflicting tools as well as the analysis of the acquired data. The body surface and the accident vehicles with their damages were digitized by 3D surface scanning. For the internal findings of the body, post-mortem MSCT and MRI were used. The analysis included the processing of the obtained data to 3D models, determination of the driving direction of the vehicle, correlation of injuries to the vehicle damages, geometric determination of the impact situation and evaluation of further findings of the accident. In the following article, the benefits of the 3D documentation and computer-assisted, drawn-to-scale 3D comparisons of the relevant injuries with the damages to the vehicle in the analysis of the course of accidents, especially with regard to the impact situation, are shown on two examined cases.

An exploration of GPs' use of MRI: a critical incident study.

Science.gov (United States)

Robling, M; Kinnersley, P; Houston, H; Hourihan, M; Cohen, D; Hale, J

1998-06-01

Direct access to Magnetic Resonance Imaging (MRI) is becoming available to GPs in the UK, offering major benefits for the improved diagnosis and management of certain clinical conditions. Variations in usage of this service may be large, and effective locally produced guidelines are not currently available. The Department of General Practice is conducting a research programme to develop and evaluate methods to optimize MRI use by GPs. We aimed to describe the current use of MRI by GPs in South Glamorgan; to summarize their reasons for requesting MRI; and to produce criteria to assess the appropriateness of magnetic resonance (MR) scan requests. Using the critical incident technique, 25 GPs were interviewed about recent scans requested for patients with knee and lumbar spine complaints. A local panel of primary and secondary care doctors was convened to develop criteria for assessing MR scan requests. Sixty-two scan requests were discussed. Doctors' reasons for requesting MR scans were identified and classified. Reasons for requests included personal, contextual and biomedical variables. Fifteen patients (24%) were managed in primary care following MRI when otherwise they would have been referred. When referrals were made, GPs felt able to reinforce the request and occasionally to direct the patient somewhere more appropriate. The panel reviewed the interview data to produce objective criteria to assess scan requests. The criteria reflect the relative importance of non-biomedical variables in the decision to request MRI. The study identified those reasons which are important to GPs when requesting MR scans and the impact of this new technology upon patient management. Interview data have been used to inform locally developed consensus criteria, which will be made available as practice guidelines as the research programme progresses.

Evaluation of an internet-based animated preparatory video for children undergoing non-sedated MRI.

Science.gov (United States)

McGlashan, Hannah L; Dineen, Rob A; Szeszak, Sofia; Whitehouse, William P; Chow, Gabriel; Love, Andrew; Langmack, Gill; Wharrad, Heather

2018-05-10

We evaluate the value of an internet-based educational animated video designed to prepare children for MRI scans, and whether this video reduces scan-related anxiety in children with a neurological disorder, and healthy controls. Participants completed a pre- and post-scan questionnaire evaluating participant online viewing behaviour, understanding of the MRI procedure, anxiety regarding the MRI, impact of animation in preparing the child and whether the child's expectation of the MRI scan matched their experience. 21 children were recruited (12 healthy controls) ranging in age from 6.5 to 11.5 years. The animation was successfully accessed by participants on a range of digital devices and had high levels of approval. Children who viewed the animation had a good understanding of the MRI procedure and low anxiety levels prior to the scan, and reported that their expectations broadly matched the real-life MRI experience. Children reported that the animation positively impacted on their preparation with similar ratings before and after the scan, and the impact on preparation was rated greater by younger children. There were no group differences between healthy children and those with the neurological disorder for ratings of anxiety, impact on preparation and expectation of the experience. This evaluation demonstrates accessibility, acceptability and relevance of internet-based educational animation for typically developing children, and children with a neurodisability aged 6 to 11 years, with positive impact on preparation for MRI. Advances in knowledge: The internet-based educational animation provides a widely accessible tool to support preparation of children for non-sedated MRI.

Achilles tendon (TA) size and power Doppler ultrasound (PD) changes compared to MRI: A preliminary observational study

International Nuclear Information System (INIS)

Richards, P.J.; Dheer, A.K.; McCall, I.M.

2001-01-01

AIM: To assess whether abnormal Achilles tendon (TA) magnetic resonance imaging (MRI) and spectral ultrasound (US) features have associated development of microvascular power Doppler (PD) flow. MATERIALS AND METHODS: In a prospective, controlled and blinded study six patients with TA symptoms were compared to five with other ankle abnormalities. Two radiologists independently measured the mean maximal anteroposterior diameter on MRI and conventional US (categorized as normal 1.6 cm), assessed morphology and studied the vessels using power Doppler. They formed a consensus over discrepancies. Sonography of the contralateral side within 24 h was used as a control. RESULTS: Twenty-one tendons in six women and five men, aged 45-77 years (mean 57.6 years), were examined, 12 tendons were of normal US morphology and size ( 0.74). Of the 12 tendons studied by MRI five were normal, seven tendons were enlarged, five of which had a proportionate increase in PD flow at the margin on the deep surface and four also had vessels in the centre of the tendon. All five of these tendons had high signal on T2-weighting (T2W). Of the two mildly enlarged tendons of intermediate signal on T1 and T2W, one showed PD flow and the other did not. CONCLUSIONS: In patients with TA disease power Doppler ultrasound shows proliferation of vessels in enlarged, abnormal tendons demonstrated on MRI and standard ultrasound, in the absence of definite tears. Richards, P.J. Dheer, A.K. and McCall, I.M. (2001)

Predictive values of BI-RADS{sup ®} magnetic resonance imaging (MRI) in the detection of breast ductal carcinoma in situ (DCIS)

Energy Technology Data Exchange (ETDEWEB)

Badan, Gustavo Machado, E-mail: gustavobadan@hotmail.com [Breast Imaging Service of Radiology Depatment—Irmandade da Santa Casa de Misericórdia de São Paulo, São Paulo, SP (Brazil); Piato, Sebastião [Mastology Division—Gynecology and Obstetrics Department (Brazil); Roveda, Décio; Faria Castro Fleury, Eduardo de [Breast Imaging Service of Radiology Depatment—Irmandade da Santa Casa de Misericórdia de São Paulo, São Paulo, SP (Brazil)

2016-10-15

Purpose: The purpose of this study was to evaluate BI-RADS indicators in the detection of DCIS by MRI. Materials and methods: Prospective observational study that started in 2014 and lasted 24 months. A total of 110 consecutive patients were evaluated, who presented with suspicious or highly suspicious microcalcifications on screening mammography (BI-RADS categories 4 and 5) and underwent stereotactic-guided breast biopsy, having had an MRI scan performed prior to biopsy. Results: Altogether, 38 cases were characterized as positive for malignancy, of which 25 were DCIS and 13 were invasive ductal carcinoma cases. MRI had a sensitivity of 96%; specificity of 75.67%; positive predictive value (PPV) for DCIS detection of 57.14%; negative predictive value (NPV) in the detection of DCIS of 98.24%; and an accuracy of 80.80%. Conclusion: BI-RADS as a tool for the detection of DCIS by MRI is a powerful instrument whose sensitivity was higher when compared to that observed for mammography in the literature. Likewise, the PPV obtained by MRI was higher than that observed in the present study for mammography, and the high NPV obtained on MRI scans can provide early evidence to discourage breast biopsy in selected cases.

Thyroid Scan and Uptake

Medline Plus

Full Text Available ... the gamma camera and single-photon emission-computed tomography (SPECT). The gamma camera, also called a scintillation ... high as with other imaging techniques, such as CT or MRI. However, nuclear medicine scans are more ...

Optimising EEG-fMRI for Localisation of Focal Epilepsy in Children.

Directory of Open Access Journals (Sweden)

Maria Centeno

Full Text Available Early surgical intervention in children with drug resistant epilepsy has benefits but requires using tolerable and minimally invasive tests. EEG-fMRI studies have demonstrated good sensitivity for the localization of epileptic focus but a poor yield although the reasons for this have not been systematically addressed. While adults EEG-fMRI studies are performed in the "resting state"; children are commonly sedated however, this has associated risks and potential confounds. In this study, we assessed the impact of the following factors on the tolerability and results of EEG-fMRI in children: viewing a movie inside the scanner; movement; occurrence of interictal epileptiform discharges (IED; scan duration and design efficiency. This work's motivation is to optimize EEG-fMRI parameters to make this test widely available to paediatric population.Forty-six children with focal epilepsy and 20 controls (6-18 underwent EEG-fMRI. For two 10 minutes sessions subjects were told to lie still with eyes closed, as it is classically performed in adult studies ("rest sessions", for another two sessions, subjects watched a child friendly stimulation i.e. movie ("movie sessions". IED were mapped with EEG-fMRI for each session and across sessions. The resulting maps were classified as concordant/discordant with the presumed epileptogenic focus for each subject.Movement increased with scan duration, but the movie reduced movement by ~40% when played within the first 20 minutes. There was no effect of movie on the occurrence of IED, nor in the concordance of the test. Ability of EEG-fMRI to map the epileptogenic region was similar for the 20 and 40 minute scan durations. Design efficiency was predictive of concordance.A child friendly natural stimulus improves the tolerability of EEG-fMRI and reduces in-scanner movement without having an effect on IED occurrence and quality of EEG-fMRI maps. This allowed us to scan children as young as 6 and obtain localising

MRI after operative reduction with femoral osteotomy in developmental dysplasia of the hip

Energy Technology Data Exchange (ETDEWEB)

Ranawat, Vijai [Great Ormond Street Hospital for Children NHS Trust, Orthopaedic Department, London (United Kingdom); London (United Kingdom); Rosendahl, Karen [Great Ormond Street Hospital for Children NHS Trust, Radiology Department, London (United Kingdom); Jones, David [Great Ormond Street Hospital for Children NHS Trust, Orthopaedic Department, London (United Kingdom)

2009-02-15

The use of MRI scanning has been described after open reduction of the hip in developmental dysplasia of the hip (DDH) to check hip position, but has not previously been reported after open reduction with femoral osteotomy and the use of metalwork. We report a prospective study to determine whether MRI scanning can be used to confirm satisfactory reduction of the hip following surgery for DDH, even in the presence of metalwork in the proximal femur. MRI scans were performed in 12 consecutive children, and all gave diagnostic information indicating satisfactory reduction. Sedation was not required and the mean scanning time was 3 min 45 s. Satisfactory images, the lack of need for sedation, comparable time and cost to CT scanning and most importantly the lack of exposure of the child to ionizing radiation make MRI a most appealing method for imaging. We therefore recommend it as the investigation of choice in this patient group. (orig.)

MRI after operative reduction with femoral osteotomy in developmental dysplasia of the hip

International Nuclear Information System (INIS)

Ranawat, Vijai; Rosendahl, Karen; Jones, David

2009-01-01

The use of MRI scanning has been described after open reduction of the hip in developmental dysplasia of the hip (DDH) to check hip position, but has not previously been reported after open reduction with femoral osteotomy and the use of metalwork. We report a prospective study to determine whether MRI scanning can be used to confirm satisfactory reduction of the hip following surgery for DDH, even in the presence of metalwork in the proximal femur. MRI scans were performed in 12 consecutive children, and all gave diagnostic information indicating satisfactory reduction. Sedation was not required and the mean scanning time was 3 min 45 s. Satisfactory images, the lack of need for sedation, comparable time and cost to CT scanning and most importantly the lack of exposure of the child to ionizing radiation make MRI a most appealing method for imaging. We therefore recommend it as the investigation of choice in this patient group. (orig.)

Practical MRI atlas of neonatal brain development

International Nuclear Information System (INIS)

Barkovich, A.J.; Truwit, C.L.

1990-01-01

This book is an anatomical reference for cranial magnetic resonance imaging (MRI) studies in neonates and infants. It contains 122 clear, sharp MRI scans and drawings showing changes in the normal appearance of the brain and skull during development. Sections of the atlas depict the major processes of maturation: brain myelination, development of the corpus callosum, development of the cranial bone marrow, and iron deposition in the brain. High-quality scans illustrate how these changes appear on magnetic resonance images during various stages of development

The application of MRI in gluteal muscle contracture

International Nuclear Information System (INIS)

Zhao Tao; You Yuhua; Sun Jing; Cheng Kebin; Liu Wei; Qu Hui

2003-01-01

Objective: To evaluate the MRI findings and its diagnostic value in gluteal muscle contracture (GMC). Methods: Eleven clinic or operation confirmed GMC patients were examined by plain X-ray and MRI. Conventional T 1 WI and T 2 WI MR imaging were performed and FFE-T 2 WI (fast field echo-T 2 WI) was also scanned. CT scan was conducted in 5 cases. Results: 11 GMC patients were all diagnosed by MRI. Conventional T 1 WI and T 2 WI could only show the atrophy of gluteal muscles, while FFE-T 2 WI could directly show the fibrous band of gluteal muscle and its fascia, and the fibrous band appeared as low signal intensity on FFE-T 2 WI sequence. Conclusions: MRI is the efficient modality in imaging the fibrous band for GMC patients, and FFE-T 2 WI is the most valuable sequence. MRI is very helpful in the diagnosis and treatment of GMC

Interactive scan control for kinematic study in open MRI

International Nuclear Information System (INIS)

Goto, Tomohiro; Hamada, Kiyomi; Ito, Taeko; Nagao, Hisako; Takahashi, Tetsuhiko; Hayashida, Yoshiko; Hiai, Yasuhiro; Yamashita, Yasuyuki

2007-01-01

A tool to support the subject is generally used for kinematic joint imaging with an open MRI apparatus because of difficulty setting the image plane correctly. However, use of a support tool requires a complicated procedure to position the subject, and setting the image plane when the joint angle changes is time consuming. Allowing the subject to move freely enables better diagnoses when kinematic joint imaging is performed. We therefore developed an interactive scan control (ISC) to facilitate the easy, quick, and accurate setting of the image plane even when a support tool is not used. We used a 0.4T magnetic resonance (MR) imaging system open in the horizontal direction. The ISC determines the image plane interactively on the basis of fluoroscopy images displayed on a user interface. The imaging pulse is a balanced steady-state acquisition with rewound gradient echo (SARGE) sequence with update time less than 2 s. Without using a tool to support the knee, we positioned the knee of a healthy volunteer at 4 different joint angles and set the image plane through the patella and femur at each of the angles. Lumbar imaging is also demonstrated with ISC. Setting the image plane was easy and quick at all knee angles, and images obtained clearly showed the patella and femur. Total imaging time was less than 10 min, a fourth of the time needed when a support tool is used. We also used our ISC in kinematic imaging of the lumbar. The ISC shortens total time for kinematic joint imaging, and because a support tool is not needed, imaging can be done more freely in an open MR imaging apparatus. (author)

Time-division polynomial pre-distorter for linearisation of 1.5 T MRI power amplifier

Directory of Open Access Journals (Sweden)

Ming Hui

2017-06-01

Full Text Available A time-division polynomial (TDP model is proposed for modelling and linearising a 1.5 T magnetic resonance imaging (MRI power amplifier (PA with strong non-linearity in high input signal dynamic range. In order to demonstrate the merit of this non-linear model, a 64 dBm 1.5 T MRI PA (63.89 MHz and two different Sinc-pulse signals are used in modelling and linearisation measurements. The TDP is compared with the conventional non-memory polynomial (NMP and no digital pre-distortion for the 1.5 T MRI PA, which is driven by test signal with 2 ms time length and 2% duty cycle. The proposed TDP leads to up to 9 dB improvement in the normalised mean square error compared with the NMP in two different test signals. More importantly, TDP illustrates significantly better reduction in amplitude modulation/amplitude modulation (AM/AM and amplitude modulation/phase modulation (AM/PM conversion compared with the NMP.

Conventional Supine MRI With a Lumbar Pillow-An Alternative to Weight-bearing MRI for Diagnosing Spinal Stenosis?

DEFF Research Database (Denmark)

Hansen, Bjarke Brandt; Hansen, Philip; Grindsted, Jacob

2017-01-01

to conventional MRI were included to an additional positional MRI scan (0.25T G-Scan) performed in: (1) conventional supine, (2) standing, (3) supine with a lumbar pillow in the lower back. LSS was evaluated for each position in consensus on a 0 to 3 semi-quantitative grading scale. Independently, L2-S1 lordosis...... included. The lordosis angle increased significantly from supine to standing (3.2° CI: 1.2-5.2) and with the lumbar pillow (12.8° CI: 10.3-15.3). One-way analysis of variance (ANOVA) showed significant differences between positions (P 

Portable MRI

Energy Technology Data Exchange (ETDEWEB)

Espy, Michelle A. [Los Alamos National Laboratory

2012-06-29

This project proposes to: (1) provide the power of MRI to situations where it presently isn't available; (2) perform the engineering required to move from lab to a functional prototype; and (3) leverage significant existing infrastructure and capability in ultra-low field MRI. The reasons for doing this: (1) MRI is the most powerful tool for imaging soft-tissue (e.g. brain); (2) Billions don't have access due to cost or safety issues; (3) metal will heat/move in high magnetic fields; (4) Millions of cases of traumatic brain injury in US alone; (5) even more of non-traumatic brain injury; (6) (e.g. stroke, infection, chemical exposure); (7) Need for early diagnostic; (8) 'Signature' wound of recent conflicts; (9) 22% of injuries; (10) Implications for post-traumatic stress disorder; and (11) chronic traumatic encephalopathy.

Portable MRI

International Nuclear Information System (INIS)

Espy, Michelle A.

2012-01-01

This project proposes to: (1) provide the power of MRI to situations where it presently isn't available; (2) perform the engineering required to move from lab to a functional prototype; and (3) leverage significant existing infrastructure and capability in ultra-low field MRI. The reasons for doing this: (1) MRI is the most powerful tool for imaging soft-tissue (e.g. brain); (2) Billions don't have access due to cost or safety issues; (3) metal will heat/move in high magnetic fields; (4) Millions of cases of traumatic brain injury in US alone; (5) even more of non-traumatic brain injury; (6) (e.g. stroke, infection, chemical exposure); (7) Need for early diagnostic; (8) 'Signature' wound of recent conflicts; (9) 22% of injuries; (10) Implications for post-traumatic stress disorder; and (11) chronic traumatic encephalopathy.

Spatial Distortion in MRI-Guided Stereotactic Procedures: Evaluation in 1.5-, 3- and 7-Tesla MRI Scanners.

Science.gov (United States)

Neumann, Jan-Oliver; Giese, Henrik; Biller, Armin; Nagel, Armin M; Kiening, Karl

2015-01-01

Magnetic resonance imaging (MRI) is replacing computed tomography (CT) as the main imaging modality for stereotactic transformations. MRI is prone to spatial distortion artifacts, which can lead to inaccuracy in stereotactic procedures. Modern MRI systems provide distortion correction algorithms that may ameliorate this problem. This study investigates the different options of distortion correction using standard 1.5-, 3- and 7-tesla MRI scanners. A phantom was mounted on a stereotactic frame. One CT scan and three MRI scans were performed. At all three field strengths, two 3-dimensional sequences, volumetric interpolated breath-hold examination (VIBE) and magnetization-prepared rapid acquisition with gradient echo, were acquired, and automatic distortion correction was performed. Global stereotactic transformation of all 13 datasets was performed and two stereotactic planning workflows (MRI only vs. CT/MR image fusion) were subsequently analysed. Distortion correction on the 1.5- and 3-tesla scanners caused a considerable reduction in positional error. The effect was more pronounced when using the VIBE sequences. By using co-registration (CT/MR image fusion), even a lower positional error could be obtained. In ultra-high-field (7 T) MR imaging, distortion correction introduced even higher errors. However, the accuracy of non-corrected 7-tesla sequences was comparable to CT/MR image fusion 3-tesla imaging. MRI distortion correction algorithms can reduce positional errors by up to 60%. For stereotactic applications of utmost precision, we recommend a co-registration to an additional CT dataset. © 2015 S. Karger AG, Basel.

Three-dimensional MRI-linac intra-fraction guidance using multiple orthogonal cine-MRI planes

DEFF Research Database (Denmark)

Bjerre, Troels; Crijns, Sjoerd; Rosenschöld, Per Munck af

2013-01-01

The introduction of integrated MRI-radiation therapy systems will offer live intra-fraction imaging. We propose a feasible low-latency multi-plane MRI-linac guidance strategy. In this work we demonstrate how interleaved acquired, orthogonal cine-MRI planes can be used for low-latency tracking...... of the 3D trajectory of a soft-tissue target structure. The proposed strategy relies on acquiring a pre-treatment 3D breath-hold scan, extracting a 3D target template and performing template matching between this 3D template and pairs of orthogonal 2D cine-MRI planes intersecting the target motion path....... For a 60 s free-breathing series of orthogonal cine-MRI planes, we demonstrate that the method was capable of accurately tracking the respiration related 3D motion of the left kidney. Quantitative evaluation of the method using a dataset designed for this purpose revealed a translational error of 1.15 mm...

Age determination of subdural hematomas with CT and MRI: a systematic review

NARCIS (Netherlands)

Sieswerda-Hoogendoorn, Tessa; Postema, Floor A. M.; Verbaan, Dagmar; Majoie, Charles B.; van Rijn, Rick R.

2014-01-01

To systematically review the literature on dating subdural hematomas (SDHs) on CT and MRI scans. We performed a systematic review in MEDLINE, EMBASE and Cochrane to search for articles that described the appearance of SDHs on CT or MRI in relation to time between trauma and scanning. Two researchers

Development of a new apparatus for MRI guided stereotactic surgery

International Nuclear Information System (INIS)

Iwata, Yukiya; Amano, Keiichi; Kawamura, Hirotsune; Tanikawa, Tatsuya; Kawabatake, Hiroko; Iseki, Hiroshi; Kobayashi, Naotoshi; Ono, Yuko

1990-01-01

Since Leksell et al. reported the application of NMR imaging to stereotactic surgery, MRI has been used for determination of the coordinates of target in the brain. The image of the MRI, however, is significantly distorted due to non-uniformity of the magnetic field. The authors have devised a new marker system (the imaginary inner marker system) and have also modified the Iseki CT guided stereotactic frame for utilizing MRI. In this system, the imaginary markers were set up inside the brain. The image of the grid phantom, obtained immediately before the operation, is superimposed on the image of a patient's brain. The nearest image of grid phantom is used for MRI localization as an imaginary inner marker. To prevent distortion and resolution degradation on MRI, the localizing system is composed of acrylic resin and titanium. The head ring can be fixed on both the MRI localizing system and the Iseki CT guided stereotactic frame which allows the transformation of target coordinates from the MRI localizing system to the CT guided frame. MRI guided stereotactic surgery, therefore, can be performed while monitoring with the CT scan. The system was tested using a phantom and taking T 1 -weighted images before clinical application. Coordinates of target points were determined accurately to a 2 mm cube. A 47-year-old, right-handed woman underwent a MRI guided biopsy of the right thalamic mass lesion that was more accurately detected by MRI than CT scan. The histological diagnosis was a malignant lymphoma. No complications have occurred. MRI stereotaxy, at the present time, is expected to be most useful in the biopsy of deep-seated brain lesions which are not easily detected by CT scan. In the near future, It will take the place of other imaging techniques during functional neurosurgery, with sufficient accuracy. (author)

The effect of fMRI task combinations on determining the hemispheric dominance of language functions

International Nuclear Information System (INIS)

Niskanen, Eini; Koenoenen, Mervi; Villberg, Ville; Aeikiae, Marja; Nissi, Mikko; Ranta-aho, Perttu; Karjalainen, Pasi; Saeisaenen, Laura; Mervaala, Esa; Kaelviaeinen, Reetta; Vanninen, Ritva

2012-01-01

The purpose of this study is to establish the most suitable combination of functional magnetic resonance imaging (fMRI) language tasks for clinical use in determining language dominance and to define the variability in laterality index (LI) and activation power between different combinations of language tasks. Activation patterns of different fMRI analyses of five language tasks (word generation, responsive naming, letter task, sentence comprehension, and word pair) were defined for 20 healthy volunteers (16 right-handed). LIs and sums of T values were calculated for each task separately and for four combinations of tasks in predefined regions of interest. Variability in terms of activation power and lateralization was defined in each analysis. In addition, the visual assessment of lateralization of language functions based on the individual fMRI activation maps was conducted by an experienced neuroradiologist. A combination analysis of word generation, responsive naming, and sentence comprehension was the most suitable in terms of activation power, robustness to detect essential language areas, and scanning time. In general, combination analyses of the tasks provided higher overall activation levels than single tasks and reduced the number of outlier voxels disturbing the calculation of LI. A combination of auditory and visually presented tasks that activate different aspects of language functions with sufficient activation power may be a useful task battery for determining language dominance in patients. (orig.)

The effect of fMRI task combinations on determining the hemispheric dominance of language functions

Energy Technology Data Exchange (ETDEWEB)

Niskanen, Eini [University of Eastern Finland, Department of Applied Physics, Kuopio (Finland); Kuopio University Hospital, Department of Clinical Radiology, Kuopio (Finland); Koenoenen, Mervi [Kuopio University Hospital, Department of Clinical Radiology, Kuopio (Finland); Kuopio University Hospital, Department of Clinical Neurophysiology, Kuopio (Finland); Villberg, Ville; Aeikiae, Marja [Kuopio University Hospital, Department of Neurology, Kuopio (Finland); Nissi, Mikko; Ranta-aho, Perttu; Karjalainen, Pasi [University of Eastern Finland, Department of Applied Physics, Kuopio (Finland); Saeisaenen, Laura; Mervaala, Esa [Kuopio University Hospital, Department of Clinical Neurophysiology, Kuopio (Finland); University of Eastern Finland, Institute of Clinical Medicine, Clinical Neurophysiology, Kuopio (Finland); Kaelviaeinen, Reetta [Kuopio University Hospital, Department of Neurology, Kuopio (Finland); University of Eastern Finland, Institute of Clinical Medicine, Neurology, Kuopio (Finland); Vanninen, Ritva [Kuopio University Hospital, Department of Clinical Radiology, Kuopio (Finland); University of Eastern Finland, Institute of Clinical Medicine, Clinical Radiology, Kuopio (Finland)

2012-04-15

The purpose of this study is to establish the most suitable combination of functional magnetic resonance imaging (fMRI) language tasks for clinical use in determining language dominance and to define the variability in laterality index (LI) and activation power between different combinations of language tasks. Activation patterns of different fMRI analyses of five language tasks (word generation, responsive naming, letter task, sentence comprehension, and word pair) were defined for 20 healthy volunteers (16 right-handed). LIs and sums of T values were calculated for each task separately and for four combinations of tasks in predefined regions of interest. Variability in terms of activation power and lateralization was defined in each analysis. In addition, the visual assessment of lateralization of language functions based on the individual fMRI activation maps was conducted by an experienced neuroradiologist. A combination analysis of word generation, responsive naming, and sentence comprehension was the most suitable in terms of activation power, robustness to detect essential language areas, and scanning time. In general, combination analyses of the tasks provided higher overall activation levels than single tasks and reduced the number of outlier voxels disturbing the calculation of LI. A combination of auditory and visually presented tasks that activate different aspects of language functions with sufficient activation power may be a useful task battery for determining language dominance in patients. (orig.)

The effect of fMRI task combinations on determining the hemispheric dominance of language functions.

Science.gov (United States)

Niskanen, Eini; Könönen, Mervi; Villberg, Ville; Nissi, Mikko; Ranta-Aho, Perttu; Säisänen, Laura; Karjalainen, Pasi; Aikiä, Marja; Kälviäinen, Reetta; Mervaala, Esa; Vanninen, Ritva

2012-04-01

The purpose of this study is to establish the most suitable combination of functional magnetic resonance imaging (fMRI) language tasks for clinical use in determining language dominance and to define the variability in laterality index (LI) and activation power between different combinations of language tasks. Activation patterns of different fMRI analyses of five language tasks (word generation, responsive naming, letter task, sentence comprehension, and word pair) were defined for 20 healthy volunteers (16 right-handed). LIs and sums of T values were calculated for each task separately and for four combinations of tasks in predefined regions of interest. Variability in terms of activation power and lateralization was defined in each analysis. In addition, the visual assessment of lateralization of language functions based on the individual fMRI activation maps was conducted by an experienced neuroradiologist. A combination analysis of word generation, responsive naming, and sentence comprehension was the most suitable in terms of activation power, robustness to detect essential language areas, and scanning time. In general, combination analyses of the tasks provided higher overall activation levels than single tasks and reduced the number of outlier voxels disturbing the calculation of LI. A combination of auditory and visually presented tasks that activate different aspects of language functions with sufficient activation power may be a useful task battery for determining language dominance in patients.

Fetal brain volumetry through MRI volumetric reconstruction and segmentation

Science.gov (United States)

Estroff, Judy A.; Barnewolt, Carol E.; Connolly, Susan A.; Warfield, Simon K.

2013-01-01

Purpose Fetal MRI volumetry is a useful technique but it is limited by a dependency upon motion-free scans, tedious manual segmentation, and spatial inaccuracy due to thick-slice scans. An image processing pipeline that addresses these limitations was developed and tested. Materials and methods The principal sequences acquired in fetal MRI clinical practice are multiple orthogonal single-shot fast spin echo scans. State-of-the-art image processing techniques were used for inter-slice motion correction and super-resolution reconstruction of high-resolution volumetric images from these scans. The reconstructed volume images were processed with intensity non-uniformity correction and the fetal brain extracted by using supervised automated segmentation. Results Reconstruction, segmentation and volumetry of the fetal brains for a cohort of twenty-five clinically acquired fetal MRI scans was done. Performance metrics for volume reconstruction, segmentation and volumetry were determined by comparing to manual tracings in five randomly chosen cases. Finally, analysis of the fetal brain and parenchymal volumes was performed based on the gestational age of the fetuses. Conclusion The image processing pipeline developed in this study enables volume rendering and accurate fetal brain volumetry by addressing the limitations of current volumetry techniques, which include dependency on motion-free scans, manual segmentation, and inaccurate thick-slice interpolation. PMID:20625848

Simultaneous fMRI-PET of the opioidergic pain system in human brain

DEFF Research Database (Denmark)

Wey, Hsiao-Ying; Catana, Ciprian; Hooker, Jacob M

2014-01-01

distinct components of the blood oxygenation level dependent (BOLD) fMRI signal has not yet been shown. We obtained sixteen fMRI-PET data sets from eight healthy volunteers. Each subject participated in randomized order in a pain scan and a control (nonpainful pressure) scan on the same day. Dynamic PET......MRI and PET provide complementary information for studying brain function. While the potential use of simultaneous MRI/PET for clinical diagnostic and disease staging has been demonstrated recently; the biological relevance of concurrent functional MRI-PET brain imaging to dissect neurochemically...... data were acquired with an opioid radioligand, [(11)C]diprenorphine, to detect endogenous opioid releases in response to pain. BOLD fMRI data were collected at the same time to capture hemodynamic responses. In this simultaneous human fMRI-PET imaging study, we show co-localized responses in thalamus...

Design and rationale for examining neuroimaging genetics in ischemic stroke: The MRI-GENIE study.

Science.gov (United States)

Giese, Anne-Katrin; Schirmer, Markus D; Donahue, Kathleen L; Cloonan, Lisa; Irie, Robert; Winzeck, Stefan; Bouts, Mark J R J; McIntosh, Elissa C; Mocking, Steven J; Dalca, Adrian V; Sridharan, Ramesh; Xu, Huichun; Frid, Petrea; Giralt-Steinhauer, Eva; Holmegaard, Lukas; Roquer, Jaume; Wasselius, Johan; Cole, John W; McArdle, Patrick F; Broderick, Joseph P; Jimenez-Conde, Jordi; Jern, Christina; Kissela, Brett M; Kleindorfer, Dawn O; Lemmens, Robin; Lindgren, Arne; Meschia, James F; Rundek, Tatjana; Sacco, Ralph L; Schmidt, Reinhold; Sharma, Pankaj; Slowik, Agnieszka; Thijs, Vincent; Woo, Daniel; Worrall, Bradford B; Kittner, Steven J; Mitchell, Braxton D; Rosand, Jonathan; Golland, Polina; Wu, Ona; Rost, Natalia S

2017-10-01

To describe the design and rationale for the genetic analysis of acute and chronic cerebrovascular neuroimaging phenotypes detected on clinical MRI in patients with acute ischemic stroke (AIS) within the scope of the MRI-GENetics Interface Exploration (MRI-GENIE) study. MRI-GENIE capitalizes on the existing infrastructure of the Stroke Genetics Network (SiGN). In total, 12 international SiGN sites contributed MRIs of 3,301 patients with AIS. Detailed clinical phenotyping with the web-based Causative Classification of Stroke (CCS) system and genome-wide genotyping data were available for all participants. Neuroimaging analyses include the manual and automated assessments of established MRI markers. A high-throughput MRI analysis pipeline for the automated assessment of cerebrovascular lesions on clinical scans will be developed in a subset of scans for both acute and chronic lesions, validated against gold standard, and applied to all available scans. The extracted neuroimaging phenotypes will improve characterization of acute and chronic cerebrovascular lesions in ischemic stroke, including CCS subtypes, and their effect on functional outcomes after stroke. Moreover, genetic testing will uncover variants associated with acute and chronic MRI manifestations of cerebrovascular disease. The MRI-GENIE study aims to develop, validate, and distribute the MRI analysis platform for scans acquired as part of clinical care for patients with AIS, which will lead to (1) novel genetic discoveries in ischemic stroke, (2) strategies for personalized stroke risk assessment, and (3) personalized stroke outcome assessment.

MRI of the Chest

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Full Text Available ... conditions. MRI uses a powerful magnetic field, radio frequency pulses and a computer to produce detailed pictures ... may follow your regular daily routine and take food and medications as usual. Some MRI examinations may ...

MRI of the Chest

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Full Text Available ... scans, MRI does not utilize ionizing radiation. Instead, radiofrequency pulses re-align hydrogen atoms that naturally exist ... thumping sounds when the coils that generate the radiofrequency pulses are activated. Some centers provide earplugs, while ...

MRI of the Chest

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Full Text Available ... used in tattoos may contain iron and could heat up during an MRI scan, but this is ... injection. If you do not require sedation, no recovery period is necessary. You may resume your usual ...

MRI of the Chest

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Full Text Available ... used in tattoos may contain iron and could heat up during an MRI scan, but this is ... a preferred imaging test. MR imaging can assess blood flow without risking the side effects of conventional ( ...

MRI of the Chest

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Full Text Available ... vessels, from almost any angle. MRI also provides movie-like sequential imaging of the cardiovascular system that ... headsets so that the child can watch a movie while the scan is being performed. Thus, the ...

MRI of the Chest

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Full Text Available ... used in tattoos may contain iron and could heat up during an MRI scan, but this is ... preferred imaging test. MR imaging can assess blood flow without risking the side effects of conventional (catheter) ...

MRI of the Chest

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Full Text Available ... used in tattoos may contain iron and could heat up during an MRI scan, but this is ... from the contrast material, including nausea, headache and pain at the site of injection. Similarly, patients are ...

MRI of the Chest

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Full Text Available ... as severe kidney disease, may prevent you from being given gadolinium contrast for an MRI. If you ... can watch a movie while the scan is being performed. Thus, the child remains motionless allowing for ...

POBE: A Computer Program for Optimal Design of Multi-Subject Blocked fMRI Experiments

Directory of Open Access Journals (Sweden)

Bärbel Maus

2014-01-01

Full Text Available For functional magnetic resonance imaging (fMRI studies, researchers can use multi-subject blocked designs to identify active brain regions for a certain stimulus type of interest. Before performing such an experiment, careful planning is necessary to obtain efficient stimulus effect estimators within the available financial resources. The optimal number of subjects and the optimal scanning time for a multi-subject blocked design with fixed experimental costs can be determined using optimal design methods. In this paper, the user-friendly computer program POBE 1.2 (program for optimal design of blocked experiments, version 1.2 is presented. POBE provides a graphical user interface for fMRI researchers to easily and efficiently design their experiments. The computer program POBE calculates the optimal number of subjects and the optimal scanning time for user specified experimental factors and model parameters so that the statistical efficiency is maximised for a given study budget. POBE can also be used to determine the minimum budget for a given power. Furthermore, a maximin design can be determined as efficient design for a possible range of values for the unknown model parameters. In this paper, the computer program is described and illustrated with typical experimental factors for a blocked fMRI experiment.

MRI to determine the chronological age of Ghanaian footballers

African Journals Online (AJOL)

of fusion of the distal radius on magentic resonance imaging (MRI) and comparing it with the Fédération Internationale de Football. Association (FIFA) MRI grading. Methods. MRI scans of the left wrists of 86 players aspiring to play for the national U17 football team were recruited for the study during a. 'justify your inclusion ...

Three-dimensional MRI-linac intra-fraction guidance using multiple orthogonal cine-MRI planes.

Science.gov (United States)

Bjerre, Troels; Crijns, Sjoerd; af Rosenschöld, Per Munck; Aznar, Marianne; Specht, Lena; Larsen, Rasmus; Keall, Paul

2013-07-21

The introduction of integrated MRI-radiation therapy systems will offer live intra-fraction imaging. We propose a feasible low-latency multi-plane MRI-linac guidance strategy. In this work we demonstrate how interleaved acquired, orthogonal cine-MRI planes can be used for low-latency tracking of the 3D trajectory of a soft-tissue target structure. The proposed strategy relies on acquiring a pre-treatment 3D breath-hold scan, extracting a 3D target template and performing template matching between this 3D template and pairs of orthogonal 2D cine-MRI planes intersecting the target motion path. For a 60 s free-breathing series of orthogonal cine-MRI planes, we demonstrate that the method was capable of accurately tracking the respiration related 3D motion of the left kidney. Quantitative evaluation of the method using a dataset designed for this purpose revealed a translational error of 1.15 mm for a translation of 39.9 mm. We have demonstrated how interleaved acquired, orthogonal cine-MRI planes can be used for online tracking of soft-tissue target volumes.

Placenta accreta: MRI antenatal diagnosis and surgical correlation.

Science.gov (United States)

Ha, T P; Li, K C

1998-01-01

We describe a case of a placenta previa accreta that was diagnosed antenatally by MRI with subsequent surgical confirmation. We show the advantages of ultrafast MRI single shot (SS) fast spin echo (FSE) techniques for accurate diagnosis with minimal scan time and fetal motion artifacts.

MRI of the Chest

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Full Text Available ... an MRI scan, but this is rare. Tooth fillings and braces usually are not affected by the magnetic field, but they may distort images of the facial area or brain, so you should let the ...

MRI of the Chest

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Full Text Available ... allergies and whether there’s a possibility you are pregnant. The magnetic field is not harmful, but it ... if there is any possibility that they are pregnant. MRI has been used for scanning patients since ...

Real-time motion analytics during brain MRI improve data quality and reduce costs.

Science.gov (United States)

Dosenbach, Nico U F; Koller, Jonathan M; Earl, Eric A; Miranda-Dominguez, Oscar; Klein, Rachel L; Van, Andrew N; Snyder, Abraham Z; Nagel, Bonnie J; Nigg, Joel T; Nguyen, Annie L; Wesevich, Victoria; Greene, Deanna J; Fair, Damien A

2017-11-01

Head motion systematically distorts clinical and research MRI data. Motion artifacts have biased findings from many structural and functional brain MRI studies. An effective way to remove motion artifacts is to exclude MRI data frames affected by head motion. However, such post-hoc frame censoring can lead to data loss rates of 50% or more in our pediatric patient cohorts. Hence, many scanner operators collect additional 'buffer data', an expensive practice that, by itself, does not guarantee sufficient high-quality MRI data for a given participant. Therefore, we developed an easy-to-setup, easy-to-use Framewise Integrated Real-time MRI Monitoring (FIRMM) software suite that provides scanner operators with head motion analytics in real-time, allowing them to scan each subject until the desired amount of low-movement data has been collected. Our analyses show that using FIRMM to identify the ideal scan time for each person can reduce total brain MRI scan times and associated costs by 50% or more. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Novel methods and applications of NMR and MRI. Low-power RF excitation and hyperpolarized Xenon-129

International Nuclear Information System (INIS)

Amor, Nadia

2012-01-01

Since their discovery in the middle of the last century, Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI) have become an important and very versatile tool in industry, medicine, and basic research. The aim of this work is to explore possible improvements and new applications of NMR methods. First, a recently introduced excitation NMR pulse sequence, termed Frank sequence excitation, which allows for significant reduction of rf-excitation power, is systematically analyzed and compared to conventional NMR in detail. Furthermore, its feasibility for MRI is investigated and advantages as well as drawbacks in comparison to standard MRI are discussed. The second part focuses on new biomedical applications of hyperpolarized (HP) 129 Xe which not only offers a signal enhancement of several orders of magnitude but also provides new contrast mechanisms. A setup for continuous dissolution of HP 129 Xe gas into blood and other fluids is optimized and analyzed quantitatively by NMR and MRI. On the basis of these results, blood-dissolved HP 129 Xe is used to investigate blood-gas dynamics, as well as the rheological behavior of blood.

A validated clinical MRI injury scoring system in neonatal hypoxic-ischemic encephalopathy

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Trivedi, Shamik B.; Vesoulis, Zachary A.; Rao, Rakesh; Liao, Steve M.; Mathur, Amit M. [Washington University School of Medicine, Division of Newborn Medicine, Edward Mallinckrodt Department of Pediatrics, St. Louis, MO (United States); Shimony, Joshua S.; McKinstry, Robert C. [Washington University School of Medicine, Mallinckrodt Institute of Radiology, St. Louis, MO (United States)

2017-10-15

Deep nuclear gray matter injury in neonatal hypoxic-ischemic encephalopathy (HIE) is associated with worse neurodevelopmental outcomes. We previously published a qualitative MRI injury scoring system utilizing serial T1-weighted, T2-weighted and diffusion-weighted imaging (DWI), weighted for deep nuclear gray matter injury. To establish the validity of the MRI scoring system with neurodevelopmental outcome at 18-24 months. MRI scans from neonates with moderate to severe HIE treated with therapeutic hypothermia were evaluated. Signal abnormality was scored on T1-weighted, T2-weighted and DWI sequences and assessed using an established system in five regions: (a) subcortical: caudate nucleus, globus pallidus and putamen, thalamus and the posterior limb of the internal capsule; (b) white matter; (c) cortex, (d) cerebellum and (e) brainstem. MRI injury was graded as none, mild, moderate or severe. Inter-rater reliability was tested on a subset of scans by two independent and blinded neuroradiologists. Surviving infants underwent the Bayley Scales of Infant and Toddler Development-III (Bayley-III) at 18-24 months. Data were analyzed using univariate and multivariate linear and logistic regression. Fifty-seven eligible neonates underwent at least one MRI scan in the first 2 weeks of life. Mean postnatal age at scan 1 was 4±2 days in 50/57 (88%) neonates and 48/54 (89%) surviving infants underwent scan 2 at 10±2 days. In 54/57 (95%) survivors, higher MRI injury grades were significantly associated with worse outcomes in the cognitive, motor and language domains of the Bayley-III. A qualitative MRI injury scoring system weighted for deep nuclear gray matter injury is a significant predictor of neurodevelopmental outcome at 18-24 months in neonates with HIE. (orig.)

A validated clinical MRI injury scoring system in neonatal hypoxic-ischemic encephalopathy

International Nuclear Information System (INIS)

Trivedi, Shamik B.; Vesoulis, Zachary A.; Rao, Rakesh; Liao, Steve M.; Mathur, Amit M.; Shimony, Joshua S.; McKinstry, Robert C.

2017-01-01

Deep nuclear gray matter injury in neonatal hypoxic-ischemic encephalopathy (HIE) is associated with worse neurodevelopmental outcomes. We previously published a qualitative MRI injury scoring system utilizing serial T1-weighted, T2-weighted and diffusion-weighted imaging (DWI), weighted for deep nuclear gray matter injury. To establish the validity of the MRI scoring system with neurodevelopmental outcome at 18-24 months. MRI scans from neonates with moderate to severe HIE treated with therapeutic hypothermia were evaluated. Signal abnormality was scored on T1-weighted, T2-weighted and DWI sequences and assessed using an established system in five regions: (a) subcortical: caudate nucleus, globus pallidus and putamen, thalamus and the posterior limb of the internal capsule; (b) white matter; (c) cortex, (d) cerebellum and (e) brainstem. MRI injury was graded as none, mild, moderate or severe. Inter-rater reliability was tested on a subset of scans by two independent and blinded neuroradiologists. Surviving infants underwent the Bayley Scales of Infant and Toddler Development-III (Bayley-III) at 18-24 months. Data were analyzed using univariate and multivariate linear and logistic regression. Fifty-seven eligible neonates underwent at least one MRI scan in the first 2 weeks of life. Mean postnatal age at scan 1 was 4±2 days in 50/57 (88%) neonates and 48/54 (89%) surviving infants underwent scan 2 at 10±2 days. In 54/57 (95%) survivors, higher MRI injury grades were significantly associated with worse outcomes in the cognitive, motor and language domains of the Bayley-III. A qualitative MRI injury scoring system weighted for deep nuclear gray matter injury is a significant predictor of neurodevelopmental outcome at 18-24 months in neonates with HIE. (orig.)

Neuro-pharmacological functional MRI of epilepsy

Energy Technology Data Exchange (ETDEWEB)

Kiriyama, Hideki; Makabe, Tetsuo; Tomita, Susumu; Omoto, Takashi; Asari, Shoji [Okayama Univ. (Japan). School of Medicine; Aihara, Hiroshi; Kinugasa, Kazushi; Nishimoto, Akira; Ito, Takahiko

2000-03-01

We studied patients with epilepsy by neuro-pharmacological functional MRI technique using diazepam. Five normal volunteers and 7 patients with epilepsy were investigated. MRI was performed by a 1.5 T unit (SIGNA Horizon, GE) using the following parameters: TR/TE 5000 msec/80 msec, FA 90 deg, FOV 200 mm, matrix 128 x 128, slice thickness 7 mm. We performed MRI scanning over 5 minutes (2 minutes before and 3 minutes after injection of diazepam) for each 1 session; we scanned 3 sessions for each patient at intervals of 5 minutes. The diazepam was injected rapidly from the antecubital vein. The dose of diazepam was 0.05 mg/kg/injection (total dose was 0.15 mg/kg). The data were analyzed statistically using t-test. Signal change after administration of diazepam was less than 1 to 2% in healthy volunteers. By contrast, in patient with epilepsy, the signal change was almost 3%, which was significantly greater than that of the normal area (p=0.01). The neuro-pharmacological functional MRI technique using diazepam might be a useful method to identify epileptic foci. (author)

Neuro-pharmacological functional MRI of epilepsy

International Nuclear Information System (INIS)

Kiriyama, Hideki; Makabe, Tetsuo; Tomita, Susumu; Omoto, Takashi; Asari, Shoji; Aihara, Hiroshi; Kinugasa, Kazushi; Nishimoto, Akira; Ito, Takahiko

2000-01-01

We studied patients with epilepsy by neuro-pharmacological functional MRI technique using diazepam. Five normal volunteers and 7 patients with epilepsy were investigated. MRI was performed by a 1.5 T unit (SIGNA Horizon, GE) using the following parameters: TR/TE 5000 msec/80 msec, FA 90 deg, FOV 200 mm, matrix 128 x 128, slice thickness 7 mm. We performed MRI scanning over 5 minutes (2 minutes before and 3 minutes after injection of diazepam) for each 1 session; we scanned 3 sessions for each patient at intervals of 5 minutes. The diazepam was injected rapidly from the antecubital vein. The dose of diazepam was 0.05 mg/kg/injection (total dose was 0.15 mg/kg). The data were analyzed statistically using t-test. Signal change after administration of diazepam was less than 1 to 2% in healthy volunteers. By contrast, in patient with epilepsy, the signal change was almost 3%, which was significantly greater than that of the normal area (p=0.01). The neuro-pharmacological functional MRI technique using diazepam might be a useful method to identify epileptic foci. (author)

Assessment of muscle function using hybrid PET/MRI

DEFF Research Database (Denmark)

Haddock, Bryan; Holm, Søren; Poulsen, Jákup M.

2017-01-01

-FDG while activating the quadriceps of one leg with repeated knee extension exercises followed by hand-grip exercises for one arm. Immediately following the exercises, the subjects were scanned simultaneously with 18F-FDG PET/MRI and muscle groups were evaluated for increases in 18F-FDG uptake and MRI T2......Purpose: The aim of this study was to determine the relationship between relative glucose uptake and MRI T2 changes in skeletal muscles following resistance exercise using simultaneous PET/MRI scans. Methods: Ten young healthy recreationally active men (age 21 – 28 years) were injected with 18F...... values. Results: A significant linear correlation between 18F-FDG uptake and changes in muscle T2 (R2 = 0.71) was found. for both small and large muscles and in voxel to voxel comparisons. Despite large intersubject differences in muscle recruitment, the linear correlation between 18F-FDG uptake...

CT and MRI analysis of central nervous system Rosai-Dorfman disease

International Nuclear Information System (INIS)

Zhang Jiatang; Lang Senyang; Pu Chuanqiang; Zhu Ruyuan; Wang Dianjun

2008-01-01

Objective: To study the CT and MRI imaging features of central nervous system Rosai-Dorfman disease and to enhance knowledge and differential diagnostic ability for central nervous system Rosai-Doffman disease. Methods: The CT and MRI imaging appearances in 4 cases of pathologically proven Rosai-Dorfman disease were retrospectively evaluated and the literature of central nervous system Rosai- Dorfman disease were reviewed. Results: Two cases had cranial CT scans, 4 cases had cranial MRI scans. On CT scans, cerebral edema was demonstrated in one case and the other case was normal. MRI scans showed the lesions were solitary in saddle area in 3 cases, and multiple in anterior cranial fossa in 1 case. The lesions exhibited iso- to hypointensity on both T 1 WI and T 2 WI images. Following intravenous injection of contrast medium, ring-like enhancement was seen in 2 cases and homogeneous enhancement in 1 case. Nodular enhancement was seen in the case of multiple lesions in the anterior cranial fossa. All lesions were dural-based. Conclusions: In patients with fever, headache, elevation of the erythrocyte sedimentation rate (ESR) and a polyclonal increase in γ-globulins, the possibility of central nervous system Rosai-Dorfman disease should be considered when single or multiple dural-based mass lesions, especially in sellar region, were identified by CT and MRI. (authors)

Wilson's disease: two treatment modalities. Correlations to pretreatment and posttreatment brain MRI

International Nuclear Information System (INIS)

Leiros da Costa, Maria do Desterro; Spitz, Mariana; Bacheschi, Luiz Alberto; Barbosa, Egberto Reis; Leite, Claudia Costa; Lucato, Leandro Tavares

2009-01-01

Brain magnetic resonance imaging (MRI) studies on Wilson's disease (WD) show lack of correlations between neurological and neuroimaging features. Long-term follow-up reports with sequential brain MRI in patients with neurological WD comparing different modalities of treatment are scarce. Eighteen patients with neurological WD underwent pretreatment and posttreatment brain MRI scans to evaluate the range of abnormalities and the evolution along these different periods. All patients underwent at least two MRI scans at different intervals, up to 11 years after the beginning of treatment. MRI findings were correlated with clinical picture, clinical severity, duration of neurological symptoms, and treatment with two different drugs. Patients were divided into two groups according to treatment: d-penicillamine (D-P), zinc (Zn), and Zn after the onset of severe intolerance to D-P. MRI scans before treatment showed, in all patients, hypersignal intensity lesions on T2- and proton-density-weighted images bilaterally and symmetrically at basal nuclei, thalamus, brain stem, cerebellum, brain cortex, and brain white matter. The most common neurological symptoms were: dysarthria, parkinsonism, dystonia, tremor, psychiatric disturbances, dysphagia, risus sardonicus, ataxia, chorea, and athetosis. From the neurological point of view, there was no difference on the evolution between the group treated exclusively with D-P and the one treated with Zn. Analysis of MRI scans with longer intervals after the beginning of treatment depicted a trend for neuroimaging worsening, without neurological correspondence, among patients treated with Zn. Neuroimaging pattern of evolution was more favorable for the group that received exclusively D-P. (orig.)

Bilateral symmetry analysis of breast MRI

International Nuclear Information System (INIS)

Alterson, Robert; Plewes, Donald B

2003-01-01

Mammographic interpretation often uses symmetry between left and right breasts to indicate the site of potential tumour masses. This approach has not been applied to breast images obtained from MRI. We present an automatic technique for breast symmetry detection based on feature extraction techniques which does not require any efforts to co-register breast MRI data. The approach applies computer-vision techniques to detect natural biological symmetries in breast MR scans based on three objective measures of similarity: multiresolution non-orthogonal wavelet representation, three-dimensional intensity distributions and co-occurrence matrices. Statistical distributions that are invariant to feature localization are computed for each of the extracted image features. These distributions are later compared against each other to account for perceptual similarity. Studies based on 51 normal MRI scans of randomly selected patients showed that the sensitivity of symmetry detection rate approached 94%. The symmetry analysis procedure presented in this paper can be applied as an aid in detecting breast tissue changes arising from disease

MRI of the Chest

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Full Text Available ... which they come. The MR scanner captures this energy and creates a picture of the tissues scanned based on this information. The magnetic field is produced by passing an electric current through wire coils in most MRI units. ...

A protocol for patients with cardiovascular implantable devices undergoing magnetic resonance imaging (MRI): should defibrillation threshold testing be performed post-(MRI).

Science.gov (United States)

Burke, Peter Thomas; Ghanbari, Hamid; Alexander, Patrick B; Shaw, Michael K; Daccarett, Marcos; Machado, Christian

2010-06-01

Magnetic resonance imaging (MRI) in patients with Cardiovascular Implantable Electronic Devices (CIED) has not been approved by the Food and Drug Administration. Recent data suggests MRI as a relative rather than absolute contraindication in CIED patients. Recently, the American Heart Association has recommended defibrillation threshold testing (DFTT) in implantable cardioverter defibrillator (ICD) patients undergoing MRI. We evaluated the feasibility and safety of a protocol for MRI in CIED patients, incorporating the new recommendations on DFTT. Consecutive patients with CIED undergoing MRI were included. The protocol consisted of continuous monitoring during imaging, device interrogation pre- and post-MRI, reprogramming of the pacemaker to an asynchronous mode in pacemaker-dependent (PMD) patients and a non-tracking/sensing mode for non-PMD patients. All tachyarrhythmia therapies were disabled. Devices were interrogated for lead impedance, battery life, pacing, and sensing thresholds. All patients with ICD underwent DFTT/defibrillator safety margin testing (DSMT) post-MRI. A total of 92 MRI's at 1.5 Tesla were performed in 38 patients. A total of 13 PMD patients, ten ICD patients, four cardiac resynchronization therapy with defibrillator (CRT-D) patients, and 11 non-PMD patients were scanned from four major manufacturers. No device circuitry damage, programming alterations, inappropriate shocks, failure to pace, or changes in sensing, pacing, or defibrillator thresholds were found on single or multiple MRI sessions. Our protocol for MRI in CIED patients appears safe, feasible, and reproducible. This is irrespective of the type of CIED, pacemaker dependancy or multiple 24-h scanning sessions. Our protocol addresses early detection of potential complications and establishes a response system for potential device-related complications. Our observation suggests that routine DFTT/DSMT post-MRI may not be necessary.

Getting an MRI (For Kids)

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Full Text Available ... resonancia magnética, RM (video) An MRI (magnetic resonance imaging) scan creates detailed pictures ... educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995- ...

Advanced approach for intraoperative MRI guidance and potential benefit for neurosurgical applications.

Science.gov (United States)

Busse, Harald; Schmitgen, Arno; Trantakis, Christos; Schober, Ralf; Kahn, Thomas; Moche, Michael

2006-07-01

To present an advanced approach for intraoperative image guidance in an open 0.5 T MRI and to evaluate its effectiveness for neurosurgical interventions by comparison with a dynamic scan-guided localization technique. The built-in scan guidance mode relied on successive interactive MRI scans. The additional advanced mode provided real-time navigation based on reformatted high-quality, intraoperatively acquired MR reference data, allowed multimodal image fusion, and used the successive scans of the built-in mode for quick verification of the position only. Analysis involved tumor resections and biopsies in either scan guidance (N = 36) or advanced mode (N = 59) by the same three neurosurgeons. Technical, surgical, and workflow aspects were compared. The image quality and hand-eye coordination of the advanced approach were improved. While the average extent of resection, neurologic outcome after functional MRI (fMRI) integration, and diagnostic yield appeared to be slightly better under advanced guidance, particularly for the main surgeon, statistical analysis revealed no significant differences. Resection times were comparable, while biopsies took around 30 minutes longer. The presented approach is safe and provides more detailed images and higher navigation speed at the expense of actuality. The surgical outcome achieved with advanced guidance is (at least) as good as that obtained with dynamic scan guidance. (c) 2006 Wiley-Liss, Inc.

Compact Intraoperative MRI: Stereotactic Accuracy and Future Directions.

Science.gov (United States)

Markowitz, Daniel; Lin, Dishen; Salas, Sussan; Kohn, Nina; Schulder, Michael

2017-01-01

Intraoperative imaging must supply data that can be used for accurate stereotactic navigation. This information should be at least as accurate as that acquired from diagnostic imagers. The aim of this study was to compare the stereotactic accuracy of an updated compact intraoperative MRI (iMRI) device based on a 0.15-T magnet to standard surgical navigation on a 1.5-T diagnostic scan MRI and to navigation with an earlier model of the same system. The accuracy of each system was assessed using a water-filled phantom model of the brain. Data collected with the new system were compared to those obtained in a previous study assessing the older system. The accuracy of the new iMRI was measured against standard surgical navigation on a 1.5-T MRI using T1-weighted (W) images. The mean error with the iMRI using T1W images was lower than that based on images from the 1.5-T scan (1.24 vs. 2.43 mm). T2W images from the newer iMRI yielded a lower navigation error than those acquired with the prior model (1.28 vs. 3.15 mm). Improvements in magnet design can yield progressive increases in accuracy, validating the concept of compact, low-field iMRI. Avoiding the need for registration between image and surgical space increases navigation accuracy. © 2017 S. Karger AG, Basel.

CT, MRI and MRA of cerebrovascular malformations (report of 16 cases)

International Nuclear Information System (INIS)

Ding Qingguo; Hu Chunhong; Guo Liang; Ding Yi

2000-01-01

Objective: To evaluate the value of CT, MRI and MRA in cerebrovascular malformations. Methods: 16 cases of cerebrovascular malformations were confirmed by angiography and pathology, including 12 cases of arteriovenous malformations, 4 cases of cavernous angiomas. All of these cases were performed with CT, MRI non-contrast scan and 3D-TOF MRA. Results: CT appearances of AVM were mixed density with hypo-density, iso-density or hyper-density. Some had calcification or acute hemorrhage. MRI scan showed the dilated and tortuous nidus of AVMs on T 1 WI and T 2 WI. The appearances of hemorrhage were variable. Feeding arteries and draining veins were showed clearly on MRA. The typical sign of cavernous angiomas was mixed signals with hypointensity ring on MRI, while MRA could not provide much information. Conclusions: CT, MRI and MRA had different value in diagnosis of cerebrovascular malformations. CT combined with MRI and MRA could sharply improve the accuracy of diagnosis, and aid in the comprehensive evaluation of cerebrovascular malformations

Estimating local noise power spectrum from a few FBP-reconstructed CT scans

Energy Technology Data Exchange (ETDEWEB)

Zeng, Rongping, E-mail: rongping.zeng@fda.hhs.gov; Gavrielides, Marios A.; Petrick, Nicholas; Sahiner, Berkman; Li, Qin; Myers, Kyle J. [Division of Imaging, Diagnostics, and Software Reliability, Office of Science and Engineering Laboratories, CDRH, FDA, Silver Spring, Maryland 20993 (United States)

2016-01-15

Purpose: Traditional ways to estimate 2D CT noise power spectrum (NPS) involve an ensemble average of the power spectrums of many noisy scans. When only a few scans are available, regions of interest are often extracted from different locations to obtain sufficient samples to estimate the NPS. Using image samples from different locations ignores the nonstationarity of CT noise and thus cannot accurately characterize its local properties. The purpose of this work is to develop a method to estimate local NPS using only a few fan-beam CT scans. Methods: As a result of FBP reconstruction, the CT NPS has the same radial profile shape for all projection angles, with the magnitude varying with the noise level in the raw data measurement. This allows a 2D CT NPS to be factored into products of a 1D angular and a 1D radial function in polar coordinates. The polar separability of CT NPS greatly reduces the data requirement for estimating the NPS. The authors use this property and derive a radial NPS estimation method: in brief, the radial profile shape is estimated from a traditional NPS based on image samples extracted at multiple locations. The amplitudes are estimated by fitting the traditional local NPS to the estimated radial profile shape. The estimated radial profile shape and amplitudes are then combined to form a final estimate of the local NPS. We evaluate the accuracy of the radial NPS method and compared it to traditional NPS methods in terms of normalized mean squared error (NMSE) and signal detectability index. Results: For both simulated and real CT data sets, the local NPS estimated with no more than six scans using the radial NPS method was very close to the reference NPS, according to the metrics of NMSE and detectability index. Even with only two scans, the radial NPS method was able to achieve a fairly good accuracy. Compared to those estimated using traditional NPS methods, the accuracy improvement was substantial when a few scans were available

Reducing acquisition time in clinical MRI by data undersampling and compressed sensing reconstruction

Science.gov (United States)

Hollingsworth, Kieren Grant

2015-11-01

MRI is often the most sensitive or appropriate technique for important measurements in clinical diagnosis and research, but lengthy acquisition times limit its use due to cost and considerations of patient comfort and compliance. Once an image field of view and resolution is chosen, the minimum scan acquisition time is normally fixed by the amount of raw data that must be acquired to meet the Nyquist criteria. Recently, there has been research interest in using the theory of compressed sensing (CS) in MR imaging to reduce scan acquisition times. The theory argues that if our target MR image is sparse, having signal information in only a small proportion of pixels (like an angiogram), or if the image can be mathematically transformed to be sparse then it is possible to use that sparsity to recover a high definition image from substantially less acquired data. This review starts by considering methods of k-space undersampling which have already been incorporated into routine clinical imaging (partial Fourier imaging and parallel imaging), and then explains the basis of using compressed sensing in MRI. The practical considerations of applying CS to MRI acquisitions are discussed, such as designing k-space undersampling schemes, optimizing adjustable parameters in reconstructions and exploiting the power of combined compressed sensing and parallel imaging (CS-PI). A selection of clinical applications that have used CS and CS-PI prospectively are considered. The review concludes by signposting other imaging acceleration techniques under present development before concluding with a consideration of the potential impact and obstacles to bringing compressed sensing into routine use in clinical MRI.

MRI assessment of cervical cancer for adaptive radiotherapy

International Nuclear Information System (INIS)

Dimopoulos, Johannes C.A.; Schirl, Gertrude; Baldinger, Anja; Poetter, Richard; Helbich, Thomas H.

2009-01-01

Purpose: To assess the importance of the information obtained from MRI for adaptive cervix cancer radiotherapy. Patients and methods: 49 patients with cervix cancer, treated by external-beam radiotherapy (EBRT) and MRI-assisted high-dose-rate brachytherapy ± concomitant cisplatin, underwent MRI at diagnosis and at the time of brachytherapy fractions. 190 MRI examinations were performed. Pretreatment scans were correlated with clinical examination (CE) findings. Measurements in 3-D of the tumor extension and also of the distance from the tumor to the pelvic side wall were performed using both MRI and CE. The tumor volume regression induced initially by EBRT and the subsequent regression after each brachytherapy fraction were assessed. Results: MRI and CE showed 92% agreement in overall parametrial staging and 73% agreement in terms of vaginal involvement. There was, however, disagreement in parametrial side (right/left) classification in 25% of the parametria examined. These were patients with unilateral displacement of the cervix and contralateral invasion of the parametrium. The mean tumor volume on the pretreatment MRI scan (GTVD) was 61 cm 3 . At the time of the four brachytherapy fractions the mean was 16 cm 3 , 10 cm 3 , 9 cm 3 , and 8 cm 3 , defined as the GTVBT plus the gray zones in the parametria. Conclusion: CE and MRI findings agree well in terms of overall staging. The clinical assessment of side-specific parametrial invasion improved when having access to the additional knowledge obtained from MRI. The greatest decrease in tumor volume occurs during EBRT, whereas tumor regression between the first and subsequent brachytherapy fractions is minor. (orig.)

MRI of the wrist and hand

International Nuclear Information System (INIS)

Reicher, M.A.; Kellerhouse, L.E.

1990-01-01

Magnetic resonance imaging (MRI) is becoming the preferred technique for evaluating a wide range of wrist and hand disorders and has a crucial role in planning arthroscopic and nonarthroscopic wrist surgery. This book details the capabilities of MRI for detecting wrist, hand, and finger pathology; provides a complete understanding of examination techniques, imaging protocols, and anatomy; and contains nearly 400 clear, sharp scans and numerous line drawings showing examination techniques, anatomic structures, and pathologic findings. After an introductory review of MR physics, the book describes state- of-the-art MRI techniques and explains the rationale for selecting imaging protocols. A complete MRI examination of a normal wrist is presented, along with a multiplanar atlas of cross-sectional wrist anatomy

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.

Regression and statistical shape model based substitute CT generation for MRI alone external beam radiation therapy from standard clinical MRI sequences

Science.gov (United States)

Ghose, Soumya; Greer, Peter B.; Sun, Jidi; Pichler, Peter; Rivest-Henault, David; Mitra, Jhimli; Richardson, Haylea; Wratten, Chris; Martin, Jarad; Arm, Jameen; Best, Leah; Dowling, Jason A.

2017-11-01

In MR only radiation therapy planning, generation of the tissue specific HU map directly from the MRI would eliminate the need of CT image acquisition and may improve radiation therapy planning. The aim of this work is to generate and validate substitute CT (sCT) scans generated from standard T2 weighted MR pelvic scans in prostate radiation therapy dose planning. A Siemens Skyra 3T MRI scanner with laser bridge, flat couch and pelvic coil mounts was used to scan 39 patients scheduled for external beam radiation therapy for localized prostate cancer. For sCT generation a whole pelvis MRI (1.6 mm 3D isotropic T2w SPACE sequence) was acquired. Patients received a routine planning CT scan. Co-registered whole pelvis CT and T2w MRI pairs were used as training images. Advanced tissue specific non-linear regression models to predict HU for the fat, muscle, bladder and air were created from co-registered CT-MRI image pairs. On a test case T2w MRI, the bones and bladder were automatically segmented using a novel statistical shape and appearance model, while other soft tissues were separated using an Expectation-Maximization based clustering model. The CT bone in the training database that was most ‘similar’ to the segmented bone was then transformed with deformable registration to create the sCT component of the test case T2w MRI bone tissue. Predictions for the bone, air and soft tissue from the separate regression models were successively combined to generate a whole pelvis sCT. The change in monitor units between the sCT-based plans relative to the gold standard CT plan for the same IMRT dose plan was found to be 0.3%+/-0.9% (mean  ±  standard deviation) for 39 patients. The 3D Gamma pass rate was 99.8+/-0.00 (2 mm/2%). The novel hybrid model is computationally efficient, generating an sCT in 20 min from standard T2w images for prostate cancer radiation therapy dose planning and DRR generation.

CT and MRI diagnosis of intracranial chondroma

International Nuclear Information System (INIS)

Liu Xuejun; Sui Qinglan

2006-01-01

Objective: To summarize and study the features of intracranial chondroma on CT and MRI imaging. Methods: CT and MRI findings of ten cases of intracranial chondroma proved by surgery and pathology from 1994. 1 to 2004.9 were retrospectively analyzed. Results: Among 10 cases, 4 cases were located at the skull base, 4 cases at convexity, 1 case at the region of falx cerebri, and 1 case within the brain parenchyma. CT scans showed obvious calcification and clear border of the tumors in 10 cases, mixed attenuation in 9 eases, and adjacent bone invasion in 5 cases. 4 cases of MRI scans showed hypointense signal on T 1 and T 2 -weighted images in calcified element of the tumor, intermediate to hypointense signal intensity on T 1 -weighted image, and hyperintense signal intensity on T 2 -weighted image in parenchyma of the tumor. 4 cases of CT scans showed slightly enhancement. Conclusion: Intracranial chondroma are often originated from synchondrosis of the skull base, convexity of brain and region of falx cerebri. Obvious calcification may be seen in most cases. Slightly enhancement and marked delayed contrast enhancement were characteristic. The accurate diagnosis still depends on pathology. (authors)

Hearing loss associated with repeated MRI acquisition procedure-related acoustic noise exposure: an occupational cohort study.

Science.gov (United States)

Bongers, Suzan; Slottje, Pauline; Kromhout, Hans

2017-11-01

To study the effects of repeated exposure to MRI-related acoustic noise during image acquisition procedures (scans) on hearing. A retrospective occupational cohort study was performed among workers of an MRI manufacturing facility (n=474). Longitudinal audiometry data from the facility's medical surveillance scheme collected from 1973 to 2010 were analysed by studying the association of cumulative exposure to MRI-related acoustic noise from voluntary (multiple) MRI scans and the hearing threshold of the volunteer. Repeated acoustic noise exposure during volunteer MRI scans was found to be associated with a small exposure-dependent increased rate change of hearing threshold level (dB/year), but the association was only found related to the number of voluntary MRI scans and not to modelled cumulative noise exposure (dB*hour) based on MRI-system type. The increased rate change of hearing threshold level was found to be statistically significant for the frequencies 500, 1000, 2000, 3000 and 4000 Hz in the right ear. From our longitudinal cohort study, it appeared that exposure to noise from voluntarily MRI scans may have resulted in a slight amount of hearing loss. Mandatory use of hearing protection might have prevented more severe hearing loss. Lack of consistency in findings between the left and right ears and between the two exposure measures prohibits definitive conclusions. Further research that addresses the study's methodological limitations is warranted to corroborate our findings. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Assessment of language lateralization with functional magnetic resonance imaging (fMRI)

International Nuclear Information System (INIS)

Salagierska-Barwinska, A.; Goraj, B.

2004-01-01

fMRI offers powerful methods to delineate which brain regions are engaged in language processing in the intact brain. Until now hemisphere dominance for language has been usually assessed by means of the intraoperative methods: the Wada test or electrocortical stimulation mapping. Recently functional MRI becomes the valuable method in determining hemisphere dominance for language. fMRI study was proved to be concordant with invasive measures. fMRI was carried out in 30 healthy selected participants (15 females: 10 strongly right-handed and 5 strongly left-handed; 15 males: 10 strongly right-handed and 5 strongly left-handed). The subject's handedness was assessed by standardized psychological tests inter alia the 'lateralization inventory'. Two different language tasks were used: a verb generation task and a phonological task. Subjects were scanned,while performing experimental block. The block contained alternately 8 active (language task) and 8 control conditions. Statistical analysis of evoked blood oxygenation level-dependent BOLD) responses, measured with echo planar imagining (1.5 T) were used. During a verb generation task in strongly right or left handed subjects the inferior frontal region was activated on the side opposite to the subject's handedness determined by the psychological test. Our fMRI studies demonstrated no gender effects on brain during these language tasks. Our study suggests that fMRI is a good device for the study of the language organization. The advantage of fMRI is its capacity for exact localization of activated areas. fMRI together with adequate neurolinguistic test could be promising routine preoperative tool in identification hemisphere dominance for language. These results encourage to further investigation for evaluating correlation in patients with brain injuries. (author)

The functional magnetic resonance imaging (fMRI) procedure as experienced by healthy participants and stroke patients – A pilot study

International Nuclear Information System (INIS)

Szameitat, André J; Shen, Shan; Sterr, Annette

2009-01-01

An important aspect in functional imaging research employing magnetic resonance imaging (MRI) is how participants perceive the MRI scanning itself. For instance, the knowledge of how (un)comfortable MRI scanning is perceived may help institutional review boards (IRBs) or ethics committees to decide on the approval of a study, or researchers to design their experiments. We provide empirical data from our lab gained from 70 neurologically healthy mainly student subjects and from 22 mainly elderly patients suffering from motor deficits after brain damage. All participants took part in various basic research fMRI studies using a 3T MRI scanner. Directly after the scanning, all participants completed a questionnaire assessing their experience with the fMRI procedure. 87.2% of the healthy subjects and 77.3% of the patients rated the MRI procedure as acceptable to comfortable. In healthy subjects, males found the procedure more comfortable, while the opposite was true for patients. 12.1% of healthy subjects considered scanning durations between 30 and 60 min as too long, while no patient considered their 30 min scanning interval as too long. 93.4% of the healthy subjects would like to participate in an fMRI study again, with a significantly lower rate for the subjects who considered the scanning as too long. Further factors, such as inclusion of a diffusion tensor imaging (DTI) scan, age, and study duration had no effect on the questionnaire responses. Of the few negative comments, the main issues were noise, the restriction to keep still for the whole time, and occasional feelings of dizziness. MRI scanning in the basic research setting is an acceptable procedure for elderly and patient participants as well as young healthy subjects

Bayesian segmentation of brainstem structures in MRI

DEFF Research Database (Denmark)

Iglesias, Juan Eugenio; Van Leemput, Koen; Bhatt, Priyanka

2015-01-01

the brainstem structures in novel scans. Thanks to the generative nature of the scheme, the segmentation method is robust to changes in MRI contrast or acquisition hardware. Using cross validation, we show that the algorithm can segment the structures in previously unseen T1 and FLAIR scans with great accuracy...

MRI and associated clinical characteristics of EV71-induced brainstem encephalitis in children with hand-foot-mouth disease

International Nuclear Information System (INIS)

Zeng, Hongwu; Gan, Yungen; Wen, Feiqiu; Huang, Wenxian

2012-01-01

This study was conducted to investigate MRI and associated clinical characteristics of brainstem encephalitis induced by enterovirus 71 (EV71) in children with hand-foot-mouth disease (HFMD). We analyzed clinical and imaging data from 42 HFMD cases with EV71-induced brainstem encephalitis. All patients underwent plain and enhanced MRI cranial scans and were placed into one of two groups according to MRI enhancement results, an enhanced group or a nonenhanced group. Thirty-two cases were positive on MRI exam. The primary location of the lesion for brainstem encephalitis was the dorsal pons and medulla oblongata (32 cases), followed by the cerebellar dentate nucleus (8 cases), midbrain (5 cases), and thalamus (2 cases). Plain T1-weighted images showed isointense or hypointense signals, and T2-weighted images showed isointense and hyperintense signals. Enhanced MRI scans showed that 12 cases had slight to moderate enhancement; 4 of these were normal on plain scan. The time from MRI examination to disease onset was statistically different between the enhanced (n = 12) and nonenhanced (n = 21) groups with a mean of 7.67 days (SD = 1.07) vs 11.95 days (SD = 5.33), respectively. The most common neurological symptoms for brainstem encephalitis were myoclonus and tremor. The greater the area of affected brain, the more severe the clinical symptoms were. The locations of EV71-induced HFMD-associated brainstem encephalitis lesions are relatively specific. Enhanced MRI scans could also identify the lesions missed by early plain scans. MRI scans can provide important information for clinical evaluation and treatment. (orig.)

MRI and associated clinical characteristics of EV71-induced brainstem encephalitis in children with hand-foot-mouth disease

Energy Technology Data Exchange (ETDEWEB)

Zeng, Hongwu; Gan, Yungen [Shenzhen Children' s Hospital, Department of Radiology, Shenzhen (China); Wen, Feiqiu [Shenzhen Children' s Hospital, Department of Neurology, Shenzhen (China); Huang, Wenxian [Shenzhen Children' s Hospital, Department of Respiratory, Shenzhen (China)

2012-06-15

This study was conducted to investigate MRI and associated clinical characteristics of brainstem encephalitis induced by enterovirus 71 (EV71) in children with hand-foot-mouth disease (HFMD). We analyzed clinical and imaging data from 42 HFMD cases with EV71-induced brainstem encephalitis. All patients underwent plain and enhanced MRI cranial scans and were placed into one of two groups according to MRI enhancement results, an enhanced group or a nonenhanced group. Thirty-two cases were positive on MRI exam. The primary location of the lesion for brainstem encephalitis was the dorsal pons and medulla oblongata (32 cases), followed by the cerebellar dentate nucleus (8 cases), midbrain (5 cases), and thalamus (2 cases). Plain T1-weighted images showed isointense or hypointense signals, and T2-weighted images showed isointense and hyperintense signals. Enhanced MRI scans showed that 12 cases had slight to moderate enhancement; 4 of these were normal on plain scan. The time from MRI examination to disease onset was statistically different between the enhanced (n = 12) and nonenhanced (n = 21) groups with a mean of 7.67 days (SD = 1.07) vs 11.95 days (SD = 5.33), respectively. The most common neurological symptoms for brainstem encephalitis were myoclonus and tremor. The greater the area of affected brain, the more severe the clinical symptoms were. The locations of EV71-induced HFMD-associated brainstem encephalitis lesions are relatively specific. Enhanced MRI scans could also identify the lesions missed by early plain scans. MRI scans can provide important information for clinical evaluation and treatment. (orig.)

Usefulness of MRI and SPECT studies in evaluating the lesion of aphasia

Energy Technology Data Exchange (ETDEWEB)

Hanyu, Haruo; Kobayashi, Yasutaka; Arai, Hisayuki; Hatano, Nobuyoshi; Yamaguchi, Katsuhiko; Katsunuma, Hideyo (Tokyo Medical Coll. (Japan))

1990-06-01

Since the introduction of CT scanning, correlations between neuropsychological findings and anatomical lesions have been studied. Anatomical studies by CT scans may, however, be misleading in delineating the extent of lesions in aphasia. We have carried out MRI (magnetic resonance imaging) and SPECT (single photon emission CT) examinations in 15 aphasic patients with cerebrovascular disease and discussed the usefulness of these studies. Compared to CT scan, MRI or SPECT studies were considered to be very useful in 8 of 15 patients. The useful points of these studies were: (1) easy detection of lesions with undetectable damages on CT, (2) demonstration of functional abnormalities in areas adjacent or distant from cerebrovascular lesions, and (3) precise definition of topographical abnormalities because of the three-dimensional imaging capability of MRI. As MRI or SPECT may define the actual extent of lesions and show areas of functional abnormality, these studies are useful and necessary in the assessment of lesions causing aphasia. (author).

Usefulness of MRI and SPECT studies in evaluating the lesion of aphasia

International Nuclear Information System (INIS)

Hanyu, Haruo; Kobayashi, Yasutaka; Arai, Hisayuki; Hatano, Nobuyoshi; Yamaguchi, Katsuhiko; Katsunuma, Hideyo

1990-01-01

Since the introduction of CT scanning, correlations between neuropsychological findings and anatomical lesions have been studied. Anatomical studies by CT scans may, however, be misleading in delineating the extent of lesions in aphasia. We have carried out MRI (magnetic resonance imaging) and SPECT (single photon emission CT) examinations in 15 aphasic patients with cerebrovascular disease and discussed the usefulness of these studies. Compared to CT scan, MRI or SPECT studies were considered to be very useful in 8 of 15 patients. The useful points of these studies were: 1) easy detection of lesions with undetectable damages on CT, 2) demonstration of functional abnormalities in areas adjacent or distant from cerebrovascular lesions, and 3) precise definition of topographical abnormalities because of the three-dimensional imaging capability of MRI. As MRI or SPECT may define the actual extent of lesions and show areas of functional abnormality, these studies are useful and necessary in the assessment of lesions causing aphasia. (author)

Atlas-guided generation of pseudo-CT images for MRI-only and hybrid PET-MRI-guided radiotherapy treatment planning

DEFF Research Database (Denmark)

Arabi, H.; Koutsouvelis, N.; Rouzaud, M.

2016-01-01

Magnetic resonance imaging (MRI)-guided attenuation correction (AC) of positron emission tomography (PET) data and/or radiation therapy (RT) treatment planning is challenged by the lack of a direct link between MRI voxel intensities and electron density. Therefore, even if this is not a trivial t......-CT images from conventional Dixon MRI sequences with improved bone extraction accuracy. The approach is promising for potential use in PET AC and MRI-only or hybrid PET/MRI-guided RT treatment planning. © 2016 Institute of Physics and Engineering in Medicine.......Magnetic resonance imaging (MRI)-guided attenuation correction (AC) of positron emission tomography (PET) data and/or radiation therapy (RT) treatment planning is challenged by the lack of a direct link between MRI voxel intensities and electron density. Therefore, even if this is not a trivial...... the conventional MRI segmentation technique and a recently proposed multi-atlas approach. The clinical studies consisted of pelvic CT, PET and MRI scans of 12 patients with loco-regionally advanced rectal disease. In the first step, bone segmentation of the target image is optimized through local weighted atlas...

CT and MRI matching for radiotherapy planning in head and neck cancer

Energy Technology Data Exchange (ETDEWEB)

Rasch, C; Keus, R; Touw, A; Lebesque, J; Van Herk, M [Nederlands Kanker Inst. ` Antoni van Leeuwenhoekhuis` , Amsterdam (Netherlands)

1995-12-01

The objective of this study was to evaluate the impact of matched CT and MRI information on target delineation in radiotherapy planning for head and neck tumors. MRI images of eight patients with head and neck cancer in supine position, not necessarily obtained in radiotherapy treatment position were matched to the CT scans made in radiotherapy position using automatic three-dimensional chamfer-matching of bony structures. Four independent observers delineated the Gross Tumor Volume (GTV) in CT scans and axial and sagittal MR scans. The GTV`s were compared, overlapping volumes and non-overlapping volumes between the different datasets and observers were determined. In all patients a good match of CT and MRI information was accomplished in the head region. The combined information provided a better visualisation of the GTV, oedema and normal tissues compared with CT or MRI alone. Determination of overlapping and non-overlapping volumes proved to be a valuable tool to measure uncertainties in the determination of the GTV. CT-MRI matching in patients with head and neck tumors is feasible and makes a more accurate irradiation with higher tumor doses and less normal tissue complications possible. Remaining uncertainties in the determination of the GTV can be quantified using the combined information of MRI and CT.

Novel methods and applications of NMR and MRI. Low-power RF excitation and hyperpolarized Xenon-129

Energy Technology Data Exchange (ETDEWEB)

Amor, Nadia

2012-07-01

Since their discovery in the middle of the last century, Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI) have become an important and very versatile tool in industry, medicine, and basic research. The aim of this work is to explore possible improvements and new applications of NMR methods. First, a recently introduced excitation NMR pulse sequence, termed Frank sequence excitation, which allows for significant reduction of rf-excitation power, is systematically analyzed and compared to conventional NMR in detail. Furthermore, its feasibility for MRI is investigated and advantages as well as drawbacks in comparison to standard MRI are discussed. The second part focuses on new biomedical applications of hyperpolarized (HP) {sup 129}Xe which not only offers a signal enhancement of several orders of magnitude but also provides new contrast mechanisms. A setup for continuous dissolution of HP {sup 129}Xe gas into blood and other fluids is optimized and analyzed quantitatively by NMR and MRI. On the basis of these results, blood-dissolved HP {sup 129}Xe is used to investigate blood-gas dynamics, as well as the rheological behavior of blood.

MRI and the diagnosis of glioblastomas

International Nuclear Information System (INIS)

Bowe, S.

2002-01-01

This paper is based on an oral presentation given at the Sydney conference in February 2000. Two cases will be presented to demonstrate the use of this imaging modality in the diagnosis of glioblastomas, MRI has superior soft tissue imaging abilities making it ideal for imaging the brain. Conventional MRI is good for evaluating oedema and haemorrhage and offers high resolution without associated bone artefacts. However, as with all imaging modalities there are some disadvantages. Patients with pacemakers, certain types of metallic clips, or claustrophobia may not be suitable for an MRI scan. Copyright (2002) Australian Institute of Radiography

A simulation study on proton computed tomography (CT) stopping power accuracy using dual energy CT scans as benchmark.

Science.gov (United States)

Hansen, David C; Seco, Joao; Sørensen, Thomas Sangild; Petersen, Jørgen Breede Baltzer; Wildberger, Joachim E; Verhaegen, Frank; Landry, Guillaume

2015-01-01

Accurate stopping power estimation is crucial for treatment planning in proton therapy, and the uncertainties in stopping power are currently the largest contributor to the employed dose margins. Dual energy x-ray computed tomography (CT) (clinically available) and proton CT (in development) have both been proposed as methods for obtaining patient stopping power maps. The purpose of this work was to assess the accuracy of proton CT using dual energy CT scans of phantoms to establish reference accuracy levels. A CT calibration phantom and an abdomen cross section phantom containing inserts were scanned with dual energy and single energy CT with a state-of-the-art dual energy CT scanner. Proton CT scans were simulated using Monte Carlo methods. The simulations followed the setup used in current prototype proton CT scanners and included realistic modeling of detectors and the corresponding noise characteristics. Stopping power maps were calculated for all three scans, and compared with the ground truth stopping power from the phantoms. Proton CT gave slightly better stopping power estimates than the dual energy CT method, with root mean square errors of 0.2% and 0.5% (for each phantom) compared to 0.5% and 0.9%. Single energy CT root mean square errors were 2.7% and 1.6%. Maximal errors for proton, dual energy and single energy CT were 0.51%, 1.7% and 7.4%, respectively. Better stopping power estimates could significantly reduce the range errors in proton therapy, but requires a large improvement in current methods which may be achievable with proton CT.

Magnetic Resonance Imaging (MRI) -- Head

Medline Plus

Full Text Available ... conditions. MRI uses a powerful magnetic field, radio frequency pulses and a computer to produce detailed pictures ... may follow your regular daily routine and take food and medications as usual. Some MRI examinations may ...

Statistical analysis of MRI-only based dose planning

DEFF Research Database (Denmark)

Korsholm, M. E.; Waring, L. W.; Paulsen, Rasmus Reinhold

2012-01-01

. MRIonly based RT eliminates these errors and reduce the time and costs of a CT scan. The aim of this study is to investigate the dosimetric differences of a treatment plan when the dose calculation is based on MRI as compared to CT. Materials and Methods: Four diagnostic groups are investigated; 12...... as a clinically approved treatment plan. The treatment planning software is Eclipse v.10.0 (Varian Medical Systems). The dose calculation based on MRI data is evaluated in two different ways; a homogeneous density assigned MRI (MRI unit), where the entire body is assigned an HU equal to water and a heterogeneous...... density assigned MRI (MRI bulk) where in addition the CT segmented bone is transferred to the MRI and assigned an age dependent HU based on ICRU report 46. The CT based clinical treatment plan and structure set are registered to the corresponding MRI unit and MRI bulk. The body is outlined on both the MRI...

Magnetic Resonance Imaging (MRI) -- Head

Medline Plus

Full Text Available ... scans, MRI does not utilize ionizing radiation. Instead, radiofrequency pulses re-align hydrogen atoms that naturally exist ... thumping sounds when the coils that generate the radiofrequency pulses are activated. Some centers provide earplugs, while ...

Magnetic Resonance Imaging (MRI) -- Head

Medline Plus

Full Text Available ... used in tattoos may contain iron and could heat up during an MRI scan, but this is ... injection. If you do not require sedation, no recovery period is necessary. You may resume your usual ...

Magnetic Resonance Imaging (MRI) -- Head

Medline Plus

Full Text Available ... used in tattoos may contain iron and could heat up during an MRI scan, but this is ... called MR angiography (MRA) provides detailed images of blood vessels in the brain—often without the need ...

Magnetic Resonance Imaging (MRI) -- Head

Medline Plus

Full Text Available ... used in tattoos may contain iron and could heat up during an MRI scan, but this is ... from the contrast material, including nausea, headache and pain at the site of injection. Similarly, patients are ...

ICA-based artifact removal diminishes scan site differences in multi-center resting-state fMRI

NARCIS (Netherlands)

R.A. Feis (Rogier A.); S.M. Smith (Stephen); N. Filippini (Nicola); G. Douaud (Gwenaëlle); E.G.P. Dopper (Elise); V. Heise (Verena); A.J. Trachtenberg (Aaron J.); J.C. van Swieten (John); M.A. van Buchem (Mark); S.A.R.B. Rombouts (Serge); C.E. Mackay (Clare E.)

2015-01-01

textabstractResting-state fMRI (R-fMRI) has shown considerable promise in providing potential biomarkers for diagnosis, prognosis and drug response across a range of diseases. Incorporating R-fMRI into multi-center studies is becoming increasingly popular, imposing technical challenges on data

Data on the safety of repeated MRI in healthy children

Directory of Open Access Journals (Sweden)

Scott K. Holland

2014-01-01

Conclusions: Examination of neurocognitive and biometric data from a decade-long, longitudinal fMRI study of normal language development in this small, longitudinal sample of healthy children in the age range of 5 to 18 years, who received up to 10 MRI scans, provides scientific evidence to support the belief that MRI poses minimal risk for use in research with healthy children.

{sup 99m}Tc-HDP Pinhole Bone Scan Features of Undetached Osteochondritis Dissecans of the Femoral Condyle: Report of a Case with Radiography, CT, and MRI Correlation

Energy Technology Data Exchange (ETDEWEB)

Bahk, Yong Whee [Sung Ae Hospital, Seoul (Korea, Republic of); Choi, Woo Hee [Seoul St. Mary' s Hospital, Catholic University Medical School, Seoul (Korea, Republic of)

2009-02-15

OCD may be initiated by arrest of bone growth and subchondral osteosclerosis followed by either cartilage hypertrophy with calcification or enfolding with osteochondral bridging. Diagnosis can be made in most instances using magnetic resonance imaging (MRI) or computed tomography (CT) or invasive arthroscopy. As to usefulness of conventional radiography (CR) opinions diverge as some held it to be of limited value while others valuable. The controversy seems to be due to semantic confusion of OCD from osteonecrosis (ON) which are different entities. This report will describe a case of undetached OCD occurred in the medial femoral condyle in a middle-aged female. It was free of symptom and incidentally discovered on {sup 99m}Tc-HDP pinhole scan performed for patellar injury. Pinhole scan findings of OCD are correlated to those of CR, CT, and MRI. An electronic search of literature failed to reveal earlier publication of bone scan features of undetached OCD. Pathologically, OCD differs from ON in that the fragment in the former condition comes off from a normal vascular bony bed while that in the latter separates from an avascular bony bed. Indeed, bone fragment in ON is devascularized but that in OCD maintains vascularity until weighted images, respectively and the halo showed low signal intensity on both T1 and T2 images.

Magnetic Resonance Imaging (MRI) -- Head

Medline Plus

Full Text Available ... an MRI scan, but this is rare. Tooth fillings and braces usually are not affected by the magnetic field, but they may distort images of the facial area or brain, so you should let the ...

Magnetic Resonance Imaging (MRI) -- Head

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Full Text Available ... allergies and whether there’s a possibility you are pregnant. The magnetic field is not harmful, but it ... if there is any possibility that they are pregnant. MRI has been used for scanning patients since ...

CT and MRI diagnosis of traumatic basal ganglia hemorrhage

International Nuclear Information System (INIS)

Wu Shike; Zhang Yalin; Xu Derong; Zou Gaowei; Chen Dan; He Sujun; Zhou Lichao

2009-01-01

Objective: To analyze CT and MRI features of traumatic basal ganglia hemorrhage and investigate the diagnostic value. Methods: 21 cases with traumatic basal ganglia hemorrhage diagnosed by clinic, CT and MRI in our hospital were collected in this study Plain CT scan were immediately performed in 21 cases after injury, plain MR scan were performed in 1 to 3 days. 12 cases of them underwent diffusion weighted imagine (DWI). The CT and MRI findings were retrospectively summarized. Results: 8 cases were found with simple traumatic basal ganglia hemorrhage. Complexity of basal ganglia hemorrhage occurred in 13 cases, 6 cases combined with subdural hemorrhage, 3 cases with epidural hematoma, 2 cases with subarachnoid hemorrhage, 6 cases with brain contusion and laceration in other locations, 4 cases with skull fracture. 26 lesions of basal ganglia hematoma were showed in 21 cases, 14 lesions of pallidum hemorrhage in 11 cases confirmed by MR could not be distinguished from calcification at the fast CT scan. 5 more lesions of brain contusion and laceration and 4 more lesions of brain white matter laceration were found by MR. Conclusion: CT in combination with MRI can diagnose traumatic basal ganglia hemorrhage and its complications early, comprehensively and accurately, which plays an important role in the clinical therapy selection and prognosis evaluation. (authors)

Human exposure to power frequency magnetic fields up to 7.6 mT: An integrated EEG/fMRI study.

Science.gov (United States)

Modolo, Julien; Thomas, Alex W; Legros, Alexandre

2017-09-01

We assessed the effects of power-line frequency (60 Hz in North America) magnetic fields (MF) in humans using simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). Twenty-five participants were enrolled in a pseudo-double-blind experiment involving "real" or "sham" exposure to sinusoidal 60 Hz MF exposures delivered using the gradient coil of an MRI scanner following two conditions: (i) 10 s exposures at 3 mT (10 repetitions); (ii) 2 s exposures at 7.6 mT (100 repetitions). Occipital EEG spectral power was computed in the alpha range (8-12 Hz, reportedly the most sensitive to MF exposure in the literature) with/without exposure. Brain functional activation was studied using fMRI blood oxygen level-dependent (BOLD, inversely correlated with EEG alpha power) maps. No significant effects were detected on occipital EEG alpha power during or post-exposure for any exposure condition. Consistent with EEG results, no effects were observed on fMRI BOLD maps in any brain region. Our results suggest that acute exposure (2-10 s) to 60 Hz MF from 3 to 7.6 mT (30,000 to 76,000 times higher than average public exposure levels for 60 Hz MF) does not induce detectable changes in EEG or BOLD signals. Combined with previous findings in which effects were observed on the BOLD signal after 1 h exposure to 3 mT, 60 Hz MF, this suggests that MF exposure in the low mT range (<10 mT) might require prolonged durations of exposure to induce detectable effects. Bioelectromagnetics. 38:425-435, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

TH-A-BRF-04: Intra-Fraction Motion Characterization for Early Stage Rectal Cancer Using Cine-MRI

International Nuclear Information System (INIS)

Kleijnen, J; Asselen, B; Burbach, M; Intven, M; Reerink, O; Philippens, M; Lagendijk, J; Raaymakers, B

2014-01-01

Purpose: To investigate the intra-fraction motion in patients with early stage rectal cancer using cine-MRI. Methods: Sixteen patient diagnosed with early stage rectal cancer underwent 1.5 T MR imaging prior to each treatment fraction of their short course radiotherapy (n=76). During each scan session, three 2D sagittal cine-MRIs were performed: at the beginning (Start), after 9:30 minutes (Mid), and after 18 minutes (End). Each cine-MRI has a duration of one minute at 2Hz temporal resolution, resulting in a total of 3:48 hours of cine-MRI. Additionally, standard T2-weighted (T2w) imaging was performed. Clinical target volume (CTV) an tumor (GTV) were delineated on the T2w scan and transferred to the first time-point of each cine-MRI scan. Within each cine-MRI, the first frame was registered to the remaining frames of the scan, using a non-rigid B-spline registration. To investigate potential drifts, a similar registration was performed between the first frame of the Start and End scans.To evaluate the motion, the distances by which the edge pixels of the delineations move in anterior-posterior (AP) and cranial-caudal (CC) direction, were determined using the deformation field of the registrations. The distance which incorporated 95% of these edge pixels (dist95%) was determined within each cine-MRI, and between Start- End scans, respectively. Results: Within a cine-MRI, we observed an average dist95% for the CTV of 1.3mm/1.5mm (SD=0.7mm/0.6mm) and for the GTV of 1.2mm/1.5mm (SD=0.8mm/0.9mm), in respectively AP/CC. For the CTV motion between the Start and End scan, an average dist95% of 5.5mm/5.3mm (SD=3.1mm/2.5mm) was found, in respectively AP/CC. For the GTV motion, an average dist95% of 3.6mm/3.9mm (SD=2.2mm/2.5mm) was found in AP/CC, respectively. Conclusion: Although intra-fraction motion within a one minute cine-MRI is limited, substantial intra-fraction motion was observed within the 18 minute time period between the Start and End cine-MRI

Getting an MRI (For Kids)

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Full Text Available ... site Sitio para adolescentes Body Mind Sexual Health Food & ... RM (video) An MRI (magnetic resonance imaging) scan creates detailed pictures of the inside of the body. The test is painless. All you'll need to do ...

Implementing MRI-based target delineation for cervical cancer treatment within a rapid workflow environment for image-guided brachytherapy: A practical approach for centers without in-room MRI.

Science.gov (United States)

Trifiletti, Daniel M; Libby, Bruce; Feuerlein, Sebastian; Kim, Taeho; Garda, Allison; Watkins, W Tyler; Erickson, Sarah; Ornan, Afshan; Showalter, Timothy N

2015-01-01

Magnetic resonance imaging (MRI)-based intracavitary brachytherapy offers several advantages over computed tomography (CT)-based brachytherapy, but many centers are unable to offer it at the time of brachytherapy because of logistic and/or financial considerations. We have implemented a method of integrating MRI into a CT-guided, high-dose-rate intracavitary brachytherapy workflow in clinics that do not have immediately available MRI capability. At our institution, patients receiving high-dose-rate intracavitary brachytherapy as a component of the definitive treatment of cervical cancer have a Smit sleeve placed during the first brachytherapy fraction in a dedicated suite with in-room CT-on-rails. After the first fraction of brachytherapy, an MRI is obtained with the Smit sleeve, but no applicator, in place. For each subsequent fraction, CT scans are coregistered to the MRI scan by the Smit sleeve. The gross target volume is defined by MRI and overlaid on the CT images for each brachytherapy treatment for dose optimization. This MRI-integrated workflow adds workflow is a feasible compromise to preserve an efficient workflow while integrating MRI target delineation, and it provides many of the advantages of both MRI- and CT-based brachytherapy. The future collection and analysis of clinical data will serve to compare the proposed approach to non-MRI containing techniques. Copyright © 2015 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Effect of Laser Power and Scan Speed on Melt Pool Characteristics of Commercially Pure Titanium (CP-Ti)

Science.gov (United States)

Kusuma, Chandrakanth; Ahmed, Sazzad H.; Mian, Ahsan; Srinivasan, Raghavan

2017-07-01

Selective laser melting (SLM) is an additive manufacturing technique that creates complex parts by selectively melting metal powder layer-by-layer using a laser. In SLM, the process parameters decide the quality of the fabricated component. In this study, single beads of commercially pure titanium (CP-Ti) were melted on a substrate of the same material using an in-house built SLM machine. Multiple combinations of laser power and scan speed were used for single bead fabrication, while the laser beam diameter and powder layer thickness were kept constant. This experimental study investigated the influence of laser power, scan speed, and laser energy density on the melt pool formation, surface morphology, geometry (width and height), and hardness of solidified beads. In addition, the observed unfavorable effect such as inconsistency in melt pool width formation is discussed. The results show that the quality, geometry, and hardness of solidified melt pool are significantly affected by laser power, scanning speed, and laser energy density.

3 telsa MRI: successful results with higher field strengths

International Nuclear Information System (INIS)

Schmitt, F.; Grosu, D.; Purdy, D.; Salem, K.; Scott, K.T.; Stoeckel, B.; Mohr, C.

2004-01-01

The recent development of 3Telsa MRI (3T MRI) has been fueled by the promise of increased signal-to-noise ratio (SNR). Many are excited about the opportunity to no only use the increased SNR for clearer images, but also the change to exchange it for better resolution or faster scans. These possibilities have caused a rapid increase in the market for 3T MRI, where the faster scanning tips an already advantageous economic outlook in favor of the user. As a result, the global market for 3T has grown from a research only market just a few years ago to an ever-increasing clinically oriented customer base. There are, however, significant obstacles to 3T MRI presented by the physics at higher field strength. For example the T1 relaxation times are prolongued with increasing magnet field strength. Further, the increased RF-energy deposition (ASR), the larger chemical shift and the stronger susceptibility effect have to be considered as challenges. It is critical that one looks at both the advantages and disadvantages of using 3T. While there are many issues to address and a number of different methods for doing so, to properly tackle each of these concerns will take time and effort on the part of researchers and clinicians. The optimization of 3T MRI scanning will have to be combined effort, though much work has already been done. The most active area of work to date has been in neuroimaging. Multiple applications have been explored in addition to clinical anatomical imaging, where resolutions is improved showing structure in the brain never before seen in human MRI

Fetal MRI: An approach to practice: A review

OpenAIRE

Saleem, Sahar N.

2013-01-01

MRI has been increasingly used for detailed visualization of the fetus in utero as well as pregnancy structures. Yet, the familiarity of radiologists and clinicians with fetal MRI is still limited. This article provides a practical approach to fetal MR imaging. Fetal MRI is an interactive scanning of the moving fetus owed to the use of fast sequences. Single-shot fast spin-echo (SSFSE) T2-weighted imaging is a standard sequence. T1-weighted sequences are primarily used to demonstrate fat, cal...

Low back pain: an assessment using positional MRI and MDT.

Science.gov (United States)

Hedberg, Karen; Alexander, Lyndsay A; Cooper, Kay; Hancock, Elizabeth; Ross, Jenny; Smith, Francis W

2013-04-01

Current guidelines advise against the use of routine imaging for low back pain. Positional MRI can provide enhanced assessment of the lumbar spine in functionally loaded positions which are often relevant to the presenting clinical symptoms. The purpose of this case report is to highlight the use of positional MRI in the assessment and classification of a subject with low back pain. A low back pain subject underwent a Mechanical Diagnosis and Therapy (MDT) assessment and positional MRI scan of the lumbar spine. The MDT assessment classified the subject as "other" since the subjective history indicated a possible posterior derangement whilst the objective assessment indicated a possible anterior derangement. Positional MRI scanning in flexed, upright and extended sitting postures confirmed the MDT assessment findings to reveal a dynamic spinal stenosis which reduced in flexion and increased in extension. Copyright © 2012 Elsevier Ltd. All rights reserved.

Abnormal findings of magnetic resonance imaging (MRI) in patients with systemic lupus erythematosus involving the brain

Energy Technology Data Exchange (ETDEWEB)

Ishikawa, Akira; Okada, Jun; Kondo, Hirobumi (Kitasato Univ., Sagamihara, Kanagawa (Japan). School of Medicine); Kashiwazaki, Sadao

1992-06-01

To elucidate the clinical significance of MRI on central nervous system systemic lupus erythematosus (CNS-SLE), MRI and CT scans were performed in 35 patients with SLE, of 18 patients who had CNS manifestations at the time of MRI examinations. The investigations were also carried out in 17 patients without CNS-SLE. The rate of detection of abnormal findings on MRI in patients with CNS-SLE was 77.2% (14/18), which was high, as compared with the rate of those on CT scans (50%: 9/18). Especially, all of 4 patients with seizure and 3 patients with encephalopathy showed abnormal MRI findings, although respectively 50% and 33.3% of them had abnormal CT scan findings. MRI findings were classified into 4 groups below: (1) Large focal are as increased signal intensity at T2 weighted image. These were observed in 2 of 4 patients with seizure and 1 of 3 patients with encephalopathy, which were completely resolved after treatment. (2) Patchy subcortical foci of increased signal intensity at T2 weighted image. These were observed in 11 of 18 CNS-SLE and 7 of 17 without CNS-SLE, which were not detected by CT scan. (3) All of six patients with cerebral infarctions showed high signal intensity areas at T2 weighted image and low signal intensity areas at T1 weighted image. (4) Normal findings were observed in 4 of 18 CNS-SLE (22.2%). We concluded that MRI is useful for the evaluation of CNS-SLE and provides more information than CT scan. (author).

Abnormal findings of magnetic resonance imaging (MRI) in patients with systemic lupus erythematosus involving the brain

International Nuclear Information System (INIS)

Ishikawa, Akira; Okada, Jun; Kondo, Hirobumi; Kashiwazaki, Sadao.

1992-01-01

To elucidate the clinical significance of MRI on central nervous system systemic lupus erythematosus (CNS-SLE), MRI and CT scans were performed in 35 patients with SLE, of 18 patients who had CNS manifestations at the time of MRI examinations. The investigations were also carried out in 17 patients without CNS-SLE. The rate of detection of abnormal findings on MRI in patients with CNS-SLE was 77.2% (14/18), which was high, as compared with the rate of those on CT scans (50%: 9/18). Especially, all of 4 patients with seizure and 3 patients with encephalopathy showed abnormal MRI findings, although respectively 50% and 33.3% of them had abnormal CT scan findings. MRI findings were classified into 4 groups below: 1) Large focal are as increased signal intensity at T2 weighted image. These were observed in 2 of 4 patients with seizure and 1 of 3 patients with encephalopathy, which were completely resolved after treatment. 2) Patchy subcortical foci of increased signal intensity at T2 weighted image. These were observed in 11 of 18 CNS-SLE and 7 of 17 without CNS-SLE, which were not detected by CT scan. 3) All of six patients with cerebral infarctions showed high signal intensity areas at T2 weighted image and low signal intensity areas at T1 weighted image. 4) Normal findings were observed in 4 of 18 CNS-SLE (22.2%). We concluded that MRI is useful for the evaluation of CNS-SLE and provides more information than CT scan. (author)

Magnetic Resonance Imaging (MRI) -- Head

Medline Plus

Full Text Available ... which they come. The MR scanner captures this energy and creates a picture of the tissues scanned based on this information. The magnetic field is produced by passing an electric current through wire coils in most MRI units. ...

Childhood acute disseminated encephalomyelitis: the role of brain and spinal cord MRI

International Nuclear Information System (INIS)

Khong, Pek-Lan; Cheng, Pui-Wai; Chan, Fu-Luk; Ho, Hok-Kung; Wong, Virginia C.N.; Goh, Winnie

2002-01-01

Background. It is recognised that the clinical and radiological spectrum of childhood acute disseminated encephalomyelitis (ADEM) is wide. Objective. To determine whether initial MRI features are predictive of clinical outcome and to determine the role of MRI in the management of ADEM. Materials and methods. The MRI scans of ten consecutive children (eight boys, two girls), clinically and radiologically diagnosed to have ADEM, were retrospectively reviewed. Follow-up MRI was available for eight patients. Results. Lesions ranged from small and punctate (<1 cm) to moderate sized and confluent (4-5 cm) to diffuse and extensive. Spinal cord lesions, seen in five of seven children, were contiguous or segmental. Seven children (70%) made good clinical recovery while three children (30%) remained severely handicapped. There was no correlation between the site, extent and pattern of involvement and clinical outcome. However, the evolution of MRI findings on follow-up correlated well with the subsequent clinical course and outcome. Conclusions. Although the extent and site of lesions on initial MRI scans are not predictive of clinical outcome, early MRI of the brain and spine is useful in aiding clinical diagnosis, and subsequent follow-up MRI is helpful in monitoring disease progression. (orig.)

MRI findings of achilles tendon rupture

International Nuclear Information System (INIS)

Zhang Xuezhe

2009-01-01

Objective: To evaluate the MRI findings of achilles tendon rupture. Methods: The MRI data of 7 patients with achilles tendon rupture were retrospectively analysed. All 7 patients were male with the age ranging from 34 to 71 years. Routine MR scanning was performed in axial and sagittal planes, including T 1 WI, T 2 WI and a fat suppression MRI (SPIR). Results: Among 7 patients, complete achilles tendon rupture was seen in 6 cases, partial achilles tendon rupture 1 case. The site of tendon disruption were 2.6-11.0 cm( mean 5.4 cm) proximal to the insertion in the calcaneus. The MRI findings of a partial or complete rupture of the achilles tendon included enlarged and thickened achilles tendon (7 cases), wavy lax achilles tendon (2 cases), discontinuity of some or all of its fibers and intratendinous regions of increased signal intensity (7 cases). In the cases of complete tendon rupture, the size of the tendinous gap varied from 3.0-8.0 mm, which was filled with blood and appeared as edema of increase signal intensity on T 2 WI and SPIR. In all 7 patients, MR scanning showed medium signal intensity (7 cases) on T 1 WI, or medium signal intensity (1 cases), medium-high signal intensity (3 cases ), high signal intensity (3 cases) on T 2 WI, and medium-high signal intensity (2 cases), high signal intensity (5 cases) on fat suppression MRI. The preachilles fat pad showed obscure in 6 cases of complete achilles tendon rupture. Conclusion: MRI is an excellent method for revealing achilles tendon rupture and confirming the diagnosis. (authors)

Anatomo-clinical overlapping maps (AnaCOM): a new method to create anatomo-functional maps from neuropsychological tests and structural MRI scan of subjects with brain lesions

Science.gov (United States)

Kinkingnehun, Serge R. J.; du Boisgueheneuc, Foucaud; Golmard, Jean-Louis; Zhang, Sandy X.; Levy, Richard; Dubois, Bruno

2004-04-01

We have developed a new technique to analyze correlations between brain anatomy and its neurological functions. The technique is based on the anatomic MRI of patients with brain lesions who are administered neuropsychological tests. Brain lesions of the MRI scans are first manually segmented. The MRI volumes are then normalized to a reference map, using the segmented area as a mask. After normalization, the brain lesions of the MRI are segmented again in order to redefine the border of the lesions in the context of the normalized brain. Once the MRI is segmented, the patient's score on the neuropsychological test is assigned to each voxel in the lesioned area, while the rest of the voxels of the image are set to 0. Subsequently, the individual patient's MRI images are superimposed, and each voxel is reassigned the average score of the patients who have a lesion at that voxel. A threshold is applied to remove regions having less than three overlaps. This process leads to an anatomo-functional map that links brain areas to functional loss. Other maps can be created to aid in analyzing the functional maps, such as one that indicates the 95% confidence interval of the averaged scores for each area. This anatomo-clinical overlapping map (AnaCOM) method was used to obtain functional maps from patients with lesions in the superior frontal gyrus. By finding particular subregions more responsible for a particular deficit, this method can generate new hypotheses to be tested by conventional group methods.

A simulation study on proton computed tomography (CT) stopping power accuracy using dual energy CT scans as benchmark

DEFF Research Database (Denmark)

Hansen, David Christoffer; Seco, Joao; Sørensen, Thomas Sangild

2015-01-01

Background. Accurate stopping power estimation is crucial for treatment planning in proton therapy, and the uncertainties in stopping power are currently the largest contributor to the employed dose margins. Dual energy x-ray computed tomography (CT) (clinically available) and proton CT (in...... development) have both been proposed as methods for obtaining patient stopping power maps. The purpose of this work was to assess the accuracy of proton CT using dual energy CT scans of phantoms to establish reference accuracy levels. Material and methods. A CT calibration phantom and an abdomen cross section...... phantom containing inserts were scanned with dual energy and single energy CT with a state-of-the-art dual energy CT scanner. Proton CT scans were simulated using Monte Carlo methods. The simulations followed the setup used in current prototype proton CT scanners and included realistic modeling...

Wilson's disease: two treatment modalities. Correlations to pretreatment and posttreatment brain MRI

Energy Technology Data Exchange (ETDEWEB)

Leiros da Costa, Maria do Desterro [Federal University of Paraiba, Movement Disorders Unit, Paraiba (Brazil); Spitz, Mariana; Bacheschi, Luiz Alberto; Barbosa, Egberto Reis [University of Sao Paulo, Movement Disorders Unit, Sao Paulo (Brazil); Leite, Claudia Costa; Lucato, Leandro Tavares [University of Sao Paulo, Department of Radiology, Sao Paulo (Brazil)

2009-10-15

Brain magnetic resonance imaging (MRI) studies on Wilson's disease (WD) show lack of correlations between neurological and neuroimaging features. Long-term follow-up reports with sequential brain MRI in patients with neurological WD comparing different modalities of treatment are scarce. Eighteen patients with neurological WD underwent pretreatment and posttreatment brain MRI scans to evaluate the range of abnormalities and the evolution along these different periods. All patients underwent at least two MRI scans at different intervals, up to 11 years after the beginning of treatment. MRI findings were correlated with clinical picture, clinical severity, duration of neurological symptoms, and treatment with two different drugs. Patients were divided into two groups according to treatment: d-penicillamine (D-P), zinc (Zn), and Zn after the onset of severe intolerance to D-P. MRI scans before treatment showed, in all patients, hypersignal intensity lesions on T2- and proton-density-weighted images bilaterally and symmetrically at basal nuclei, thalamus, brain stem, cerebellum, brain cortex, and brain white matter. The most common neurological symptoms were: dysarthria, parkinsonism, dystonia, tremor, psychiatric disturbances, dysphagia, risus sardonicus, ataxia, chorea, and athetosis. From the neurological point of view, there was no difference on the evolution between the group treated exclusively with D-P and the one treated with Zn. Analysis of MRI scans with longer intervals after the beginning of treatment depicted a trend for neuroimaging worsening, without neurological correspondence, among patients treated with Zn. Neuroimaging pattern of evolution was more favorable for the group that received exclusively D-P. (orig.)

[MRI semiotics features of experimental acute intracerebral hematomas].

Science.gov (United States)

Burenchev, D V; Skvortsova, V I; Tvorogova, T V; Guseva, O I; Gubskiĭ, L V; Kupriianov, D A; Pirogov, Iu A

2009-01-01

The aim of this study was to assess the possibility of revealing intracerebral hematomas (ICH), using MRI, within the first hours after onset and to determine their MRI semiotics features. Thirty animals with experimental ICH were studied. A method of two-stage introduction of autologous blood was used to develop ICH as human spontaneous intracranial hematomas. Within 3-5h after blood introduction to the rat brain. The control MRI was performed in the 3rd and 7th days after blood injections. ICH were definitely identified in the first MRI scans. The MRI semiotics features of acute ICH and their transformations were assessed. The high sensitivity of MRI to ICH as well as the uniform manifestations in all animals were shown. In conclusion, the method has high specificity for acute ICH detection.

High prevalence of brain pathology in violent prisoners: a qualitative CT and MRI scan study.

Science.gov (United States)

Schiltz, Kolja; Witzel, Joachim G; Bausch-Hölterhoff, Josef; Bogerts, Bernhard

2013-10-01

The aim of this study was to determine the frequency and extent of brain anomalies in a large sample of incarcerated violent offenders not previously considered neuropsychiatrically ill, in comparison with non-violent offenders and non-offending controls. MRI and CT brain scans from 287 male prison inmates (162 violent and 125 non-violent) not diagnosed as mentally ill before that were obtained due to headache, vertigo or psychological complaints during imprisonment were assessed and compared to 52 non-criminal controls. Brain scans were rated qualitatively with respect to evidence of structural brain damage. Each case received a semiquantitative rating of "normal" (=0), "questionably abnormal" (=1) or "definitely abnormal" (=2) for the lateral ventricles, frontal/parietal cortex and medial temporal structures bilaterally as well as third ventricle. Overall, offenders displayed a significantly higher rate of morphological abnormality, with the violent offenders scoring significantly higher than non-violent offenders and controls. This difference was statistically detectable for frontal/parietal cortex, medial temporal structures, third ventricle and the left but not the right lateral ventricle. The remarkable prevalence of brain pathology in convicted violent prisoners detectable by neuroradiological routine assessment not only highlights the importance of frontal and temporal structures in the control of social, and specifically of violent behaviour, but also raises questions on the legal culpability of violent offenders with brain abnormalities. The high proportion of undetected presence of structural brain damage emphasizes the need that in violent criminals, the comprehensive routine neuropsychiatric assessment usually performed in routine forensic psychiatric expertises should be complemented with brain imaging.

Increased Sensitivity to Pathological Brain Changes Using Co-registration of Magnetic Resonance Imaging Scans

Energy Technology Data Exchange (ETDEWEB)

Burdett, J.; Stevens, J.; Flugel, D.; Williams, E.; Duncan, J.S.; Lemieux, L. [National Society for Epilepsy, Chalfont St Peter (United Kingdom). The MRI Unit

2006-12-15

Purpose: To compare automatic software-based co-registration of serial magnetic resonance imaging (MRI) scans with conventional visual comparison, by expert neuroradiologists.Material and Methods: Sixty-four patients who were referred to our epilepsy MRI unit for cerebral imaging were identified as having potentially, non- or slow-growing lesions or cerebral atrophy and followed with sequential scans over a period of up to 8 years, resulting in a total of 92 pairs of scans. Scans were categorized as showing either lesions or atrophy. Each pair of scans was reviewed twice for the presence of change, with and without co-registration, performed using automated software. Results: Co-registration and visual reporting without co-registration were discordant in the lesions group in nine out of 69 datasets (13%), and in 16 out of 23 pairs of scans in the atrophy group (69%). The most common cause of discordance was visual reporting not detecting changes apparent by co-registration. In three cases, changes detected visually were not detected following co-registration. Conclusion: In the group of patients studied, co-registration was more sensitive for detecting changes than visual comparison, particularly with respect to atrophic changes of the brain. With the increasing availability of sophisticated independent consoles attached to MRI scanners that may be used for image co-registration, we propose that serial T1-weighted volumetric MRI brain co-registration should be considered for integration into routine clinical practice to assess patients with suspected progressive disease.

Increased Sensitivity to Pathological Brain Changes Using Co-registration of Magnetic Resonance Imaging Scans

International Nuclear Information System (INIS)

Burdett, J.; Stevens, J.; Flugel, D.; Williams, E.; Duncan, J.S.; Lemieux, L.

2006-01-01

Purpose: To compare automatic software-based co-registration of serial magnetic resonance imaging (MRI) scans with conventional visual comparison, by expert neuroradiologists.Material and Methods: Sixty-four patients who were referred to our epilepsy MRI unit for cerebral imaging were identified as having potentially, non- or slow-growing lesions or cerebral atrophy and followed with sequential scans over a period of up to 8 years, resulting in a total of 92 pairs of scans. Scans were categorized as showing either lesions or atrophy. Each pair of scans was reviewed twice for the presence of change, with and without co-registration, performed using automated software. Results: Co-registration and visual reporting without co-registration were discordant in the lesions group in nine out of 69 datasets (13%), and in 16 out of 23 pairs of scans in the atrophy group (69%). The most common cause of discordance was visual reporting not detecting changes apparent by co-registration. In three cases, changes detected visually were not detected following co-registration. Conclusion: In the group of patients studied, co-registration was more sensitive for detecting changes than visual comparison, particularly with respect to atrophic changes of the brain. With the increasing availability of sophisticated independent consoles attached to MRI scanners that may be used for image co-registration, we propose that serial T1-weighted volumetric MRI brain co-registration should be considered for integration into routine clinical practice to assess patients with suspected progressive disease

MRI enhancing patterns of non-meningioma meningeal lesions

International Nuclear Information System (INIS)

Tao Xiaofeng; Ding Juan; Xiao Xiangsheng; Shi Zengru; Yu Hong; Gu Qian

2004-01-01

Objective: To analyze the MRI appearances of meningeal diseases and to study MRI diagnostic value of enhancing patterns in different meningeal processes. Methods: Sixty-one patients with integrated clinical data, including 27 infectious meningitis, 4 inflammatory meningitis (2 eosinophilic granuloma, 1 Wegener granuloma, and 1 unknown etiological factor), 12 meningeal metastasis, 2 meningeal lymphoma, 8 cerebrovascular disease, and 8 postoperative changes, were reviewed retrospectively. All patients were examined on MRI before and after contrast administration. Results: (1) MR plain scan: positive findings of plain scan were revealed in only 3 cases, including 1 linear meningeal thickening pattern and 2 nodular pattern. (2) MR enhancement: All cases showed 3 kinds of enhancing patterns: 19 dural-arachnoid pattern, 32 pia-arachnoid pattern, and 10 total meninges pattern, respectively. Conclusion: Different meningeal diseases have different MR imaging manifestations. Creating the enhancement patterns of various diseases can have great clinical significance. (authors)

Early studies of instant-fMRI for routine examination

International Nuclear Information System (INIS)

Sakurai, Yuuki; Harada, Kuniaki; Nagahama, Hiroshi; Akatsuka, Yoshihiro; Shinozaki, Jun

2010-01-01

Authors are developing a low-burden, short-time acquisition method of functional magnetic resonance imaging (fMRI) with 3T machine, named ''Instant-fMRI'', aiming for its application to routine examinations, of which results of early studies on identification of the language hemisphere are reported. Subjects were 10 healthy volunteers (8 males, 2 females, mean age 34.2 y, 8 right-handers) and 5 right-hander patients with brain tumor (4 males, 1 female, mean age 50 y). The machine was GE Signa HDx 3.0T ver. 14, using 8 channel head coil. For Instant-fMRI, T1-weighted imaging sequence for mapping was in fast spoiled gradient recalled acquisition in the steady state (fSPGR) mode (scan time: 1 min 44 sec) and fMRI sequence, in GRE-EPI (scan time: 1 min), which thus required only about 3 min in total. Reference was defined to be the anterior-posterior commissure line, to which parallel sections involving centriciput and cerebellum were acquired. Rest (30 sec)-task (shiritori language game, 30 sec) cycle was to be one in instant-fMRI in contrast to three in the conventional fMRI. Volunteers received both instant-fMRI and conventional fMRI and patients, the former alone. Data were analyzed by GE Brain Wave PA. Right and left hemisphere of the left and right hander, respectively, was identified to be activated by instant-fMRI in 9 of 10 volunteers and in all patients, and by the conventional fMRI, in all volunteers. The instant-fMRI can be a useful examination of other brain functions as well as identifying the language field when acquisition parameters for desired diagnostic purpose are optimized. (T.T.)

Ovarian cysts on prenatal MRI

International Nuclear Information System (INIS)

Nemec, Ursula; Nemec, Stefan F.; Bettelheim, Dieter; Brugger, Peter C.; Horcher, Ernst; Schöpf, Veronika; Graham, John M.; Rimoin, David L.; Weber, Michael; Prayer, Daniela

2012-01-01

Objective: Ovarian cysts are the most frequently encountered intra-abdominal masses in females in utero. They may, at times, require perinatal intervention. Using magnetic resonance imaging (MRI) as an adjunct to ultrasonography (US) in prenatal diagnosis, we sought to demonstrate the ability to visualize ovarian cysts on prenatal MRI. Materials and methods: This retrospective study included 17 fetal MRI scans from 16 female fetuses (23–37 gestational weeks) with an MRI diagnosis of ovarian cysts after suspicious US findings. A multiplanar MRI protocol was applied to image and to characterize the cysts. The US and MRI findings were compared, and the prenatal findings were compared with postnatal imaging findings or histopathology. Results: Simple ovarian cysts were found in 10/16 cases and complex cysts in 7/16 cases, including one case with both. In 11/16 (69%) cases, US and MRI diagnoses were in agreement, and, in 5/16 (31%) cases, MRI specified or expanded the US diagnosis. In 6/16 cases, postnatal US showed that the cysts spontaneously resolved or decreased in size, and in 1/16 cases, postnatal imaging confirmed a hemorrhagic cyst. In 4/16 cases, the prenatal diagnoses were confirmed by surgery/histopathology, and for the rest, postnatal correlation was not available. Conclusion: Our results illustrate the MRI visualization of ovarian cysts in utero. In most cases, MRI will confirm the US diagnosis. In certain cases, MRI may provide further diagnostic information, additional to US, which is the standard technique for diagnosis, monitoring, and treatment planning.

Ovarian cysts on prenatal MRI

Energy Technology Data Exchange (ETDEWEB)

Nemec, Ursula [Department of Radiology, Division of Neuroradiology and Musculoskeletal Radiology, Medical University Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Nemec, Stefan F., E-mail: stefan.nemec@meduniwien.ac.at [Department of Radiology, Division of Neuroradiology and Musculoskeletal Radiology, Medical University Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Medical Genetics Institute, Cedars Sinai Medical Center, 8700 Beverly Boulevard, PACT Suite 400, Los Angeles, CA 90048 (United States); Bettelheim, Dieter [Department of Obstetrics and Gynaecology, Division of Prenatal Diagnosis and Therapy, Medical University Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Brugger, Peter C. [Center of Anatomy and Cell Biology, Integrative Morphology Group, Medical University Vienna, Waehringerstrasse 13, A-1090 Vienna (Austria); Horcher, Ernst [Department of Pediatric Surgery, Medical University Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Schoepf, Veronika [Department of Radiology, Division of Neuroradiology and Musculoskeletal Radiology, Medical University Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Graham, John M.; Rimoin, David L. [Medical Genetics Institute, Cedars Sinai Medical Center, 8700 Beverly Boulevard, PACT Suite 400, Los Angeles, CA 90048 (United States); Weber, Michael; Prayer, Daniela [Department of Radiology, Division of Neuroradiology and Musculoskeletal Radiology, Medical University Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria)

2012-08-15

Objective: Ovarian cysts are the most frequently encountered intra-abdominal masses in females in utero. They may, at times, require perinatal intervention. Using magnetic resonance imaging (MRI) as an adjunct to ultrasonography (US) in prenatal diagnosis, we sought to demonstrate the ability to visualize ovarian cysts on prenatal MRI. Materials and methods: This retrospective study included 17 fetal MRI scans from 16 female fetuses (23-37 gestational weeks) with an MRI diagnosis of ovarian cysts after suspicious US findings. A multiplanar MRI protocol was applied to image and to characterize the cysts. The US and MRI findings were compared, and the prenatal findings were compared with postnatal imaging findings or histopathology. Results: Simple ovarian cysts were found in 10/16 cases and complex cysts in 7/16 cases, including one case with both. In 11/16 (69%) cases, US and MRI diagnoses were in agreement, and, in 5/16 (31%) cases, MRI specified or expanded the US diagnosis. In 6/16 cases, postnatal US showed that the cysts spontaneously resolved or decreased in size, and in 1/16 cases, postnatal imaging confirmed a hemorrhagic cyst. In 4/16 cases, the prenatal diagnoses were confirmed by surgery/histopathology, and for the rest, postnatal correlation was not available. Conclusion: Our results illustrate the MRI visualization of ovarian cysts in utero. In most cases, MRI will confirm the US diagnosis. In certain cases, MRI may provide further diagnostic information, additional to US, which is the standard technique for diagnosis, monitoring, and treatment planning.

Automated lesion detection on MRI scans using combined unsupervised and supervised methods

International Nuclear Information System (INIS)

Guo, Dazhou; Fridriksson, Julius; Fillmore, Paul; Rorden, Christopher; Yu, Hongkai; Zheng, Kang; Wang, Song

2015-01-01

Accurate and precise detection of brain lesions on MR images (MRI) is paramount for accurately relating lesion location to impaired behavior. In this paper, we present a novel method to automatically detect brain lesions from a T1-weighted 3D MRI. The proposed method combines the advantages of both unsupervised and supervised methods. First, unsupervised methods perform a unified segmentation normalization to warp images from the native space into a standard space and to generate probability maps for different tissue types, e.g., gray matter, white matter and fluid. This allows us to construct an initial lesion probability map by comparing the normalized MRI to healthy control subjects. Then, we perform non-rigid and reversible atlas-based registration to refine the probability maps of gray matter, white matter, external CSF, ventricle, and lesions. These probability maps are combined with the normalized MRI to construct three types of features, with which we use supervised methods to train three support vector machine (SVM) classifiers for a combined classifier. Finally, the combined classifier is used to accomplish lesion detection. We tested this method using T1-weighted MRIs from 60 in-house stroke patients. Using leave-one-out cross validation, the proposed method can achieve an average Dice coefficient of 73.1 % when compared to lesion maps hand-delineated by trained neurologists. Furthermore, we tested the proposed method on the T1-weighted MRIs in the MICCAI BRATS 2012 dataset. The proposed method can achieve an average Dice coefficient of 66.5 % in comparison to the expert annotated tumor maps provided in MICCAI BRATS 2012 dataset. In addition, on these two test datasets, the proposed method shows competitive performance to three state-of-the-art methods, including Stamatakis et al., Seghier et al., and Sanjuan et al. In this paper, we introduced a novel automated procedure for lesion detection from T1-weighted MRIs by combining both an unsupervised and a

The time window of MRI of murine atherosclerotic plaques after administration of CB2 receptor targeted micelles: inter-scan variability and relation between plaque signal intensity increase and gadolinium content of inversion recovery prepared versus non-prepared fast spin echo

NARCIS (Netherlands)

te Boekhorst, B. C. M.; Bovens, S. M.; van de Kolk, C. W. A.; Cramer, M. J. M.; Doevendans, P. A. F. M.; ten Hove, M.; van der Weerd, L.; Poelmann, R.; Strijkers, G. J.; Pasterkamp, G.; van Echteld, C. J. A.

2010-01-01

Single fast spin echo scans covering limited time frames are mostly used for contrast-enhanced MRI of atherosclerotic plaque biomarkers. Knowledge on inter-scan variability of the normalized enhancement ratio of plaque (NER(plaque)) and relation between NER(plaque) and gadolinium content for

Open access to MRI for general practitioners: 12 years' experience at one institution -- a retrospective analysis.

Science.gov (United States)

Gough-Palmer, A L; Burnett, C; Gedroyc, W M

2009-08-01

The aim of this study was to evaluate 12 years of general practitioner (GP) use of open access MRI services at a single London teaching hospital. A retrospective analysis of reports from all GP requests for MRI scans between 1994 and 2005 was performed. The date, scanned body part, and requester details from 1798 scans requested by 209 individual GPs over a continuous 12-year period were recorded. All scans were then graded into four categories based on the severity of reported findings from normal to gross abnormality. Over the study period, GP requests as a percentage of the total (MRI) department workload remained low at approximately 2.6%. Spine, knee and brain requests constituted 86% (n = 1546) of requested scans. 48% (n = 868) of scans were reported as normal or minor degenerative changes only. 26% (n = 466) of scans demonstrated serious pathology that was likely to warrant hospital consultant referral. There was a wide range of scans requested per requester, from 1 to 240 over the period, with an average of 8.5 scans per GP. In conclusion, any department wishing to set up open access to MRI services for GPs could cover the majority of requests by offering spine, knee and brain imaging. The percentage of normal report rates for GP requests is comparable with previous studies of outpatient referrals. A large variation in requesting patterns between GPs suggests the need for increased communication between GPs and imaging departments to optimise use of the service.

Focal liver lesions segmentation and classification in nonenhanced T2-weighted MRI.

Science.gov (United States)

Gatos, Ilias; Tsantis, Stavros; Karamesini, Maria; Spiliopoulos, Stavros; Karnabatidis, Dimitris; Hazle, John D; Kagadis, George C

2017-07-01

To automatically segment and classify focal liver lesions (FLLs) on nonenhanced T2-weighted magnetic resonance imaging (MRI) scans using a computer-aided diagnosis (CAD) algorithm. 71 FLLs (30 benign lesions, 19 hepatocellular carcinomas, and 22 metastases) on T2-weighted MRI scans were delineated by the proposed CAD scheme. The FLL segmentation procedure involved wavelet multiscale analysis to extract accurate edge information and mean intensity values for consecutive edges computed using horizontal and vertical analysis that were fed into the subsequent fuzzy C-means algorithm for final FLL border extraction. Texture information for each extracted lesion was derived using 42 first- and second-order textural features from grayscale value histogram, co-occurrence, and run-length matrices. Twelve morphological features were also extracted to capture any shape differentiation between classes. Feature selection was performed with stepwise multilinear regression analysis that led to a reduced feature subset. A multiclass Probabilistic Neural Network (PNN) classifier was then designed and used for lesion classification. PNN model evaluation was performed using the leave-one-out (LOO) method and receiver operating characteristic (ROC) curve analysis. The mean overlap between the automatically segmented FLLs and the manual segmentations performed by radiologists was 0.91 ± 0.12. The highest classification accuracies in the PNN model for the benign, hepatocellular carcinoma, and metastatic FLLs were 94.1%, 91.4%, and 94.1%, respectively, with sensitivity/specificity values of 90%/97.3%, 89.5%/92.2%, and 90.9%/95.6% respectively. The overall classification accuracy for the proposed system was 90.1%. Our diagnostic system using sophisticated FLL segmentation and classification algorithms is a powerful tool for routine clinical MRI-based liver evaluation and can be a supplement to contrast-enhanced MRI to prevent unnecessary invasive procedures. © 2017 American

Dislocation of cochlear implant magnet as a complication following MRI.

Science.gov (United States)

Murtojärvi, Sarita; Salonen, Jaakko

According to current best knowledge, an MRI scan can be performed for patients with cochlear implants. The warnings and recommendations of the implant manufacturers must be followed strictly to prevent complications, such as overheating, migration or demagnetization of the magnet in the implant. We report on a case of cochlear implant magnet dislocation as a complication for an MRI scan. The patient had a tight bandage around the head to hold the magnet in place as recommended by the manufacturer, but apparently the bandage was not in the correct place.

I-123 Iofetamine SPECT scan in children with neurological disorders

International Nuclear Information System (INIS)

Flamini, J.R.; Konkol, R.J.; Wells, R.G.; Sty, J.R.

1990-01-01

I-123 Iofetamine (IMP) single photon emission computed tomography (SPECT) imaging of the brain in 42 patients (ages 14 days to 23 years) was compared with other localizing studies in children with neurological diseases. All had an EEG and at least one imaging study of the brain (computed tomography (CT) or magnetic resonance imaging (MRI), or both). Seventy-eight percent of the patients had an EEG within 24-72 hours of the IMP-SPECT scan. Thirty-five (83%) had a history of seizures, and the remainder had other neurological conditions without a history of seizures. In most cases, a normal EEG reading with normal CT or MRI result predicted a normal SPECT study. When the EEG was abnormal the majority of the IMP-SPECT scans were abnormal and localized the abnormality to the same region. A comparison with CT and MRI showed that structural abnormalities involving the cortex were usually well demonstrated with IMP-SPECT imaging. Structural lesions confined to the white matter were generally not detectable with IMP-SPECT. In a few cases, SPECT scans revealed abnormalities in deep brain areas not identified by EEG. IMP-SPECT imaging is a valuable technique for the detection and localization of abnormal cerebral metabolic activity in children with seizure disorders. A correlation with CT or MRI is essential for proper interpretation of abnormalities detected with IMP SPECT imaging

Comparative study on developmental stages of the clavicle by postmortem MRI and CT imaging

DEFF Research Database (Denmark)

Larsen, Sara Tangmose; Lynnerup, Niels; Jensen, K.E.

2013-01-01

Objectives: The developmental stages of the clavicles are important for forensic age estimation purposes in adolescents. This study compares the 4-stage system to evaluate the ossification of the medial end of the clavicle as visualized by magnetic resonance imaging (MRI) and computed tomography...... (CT). As several forensic institutes routinely perform CT scans, the large amount of available data may serve as reference sample for MRI in specific cases. Material and methods: This prospective study included an MRI and CT scan of 47 autopsy cases performed prior to medico-legal autopsy (age range...

Assessing the Risks Associated with MRI in Patients with a Pacemaker or Defibrillator.

Science.gov (United States)

Russo, Robert J; Costa, Heather S; Silva, Patricia D; Anderson, Jeffrey L; Arshad, Aysha; Biederman, Robert W W; Boyle, Noel G; Frabizzio, Jennifer V; Birgersdotter-Green, Ulrika; Higgins, Steven L; Lampert, Rachel; Machado, Christian E; Martin, Edward T; Rivard, Andrew L; Rubenstein, Jason C; Schaerf, Raymond H M; Schwartz, Jennifer D; Shah, Dipan J; Tomassoni, Gery F; Tominaga, Gail T; Tonkin, Allison E; Uretsky, Seth; Wolff, Steven D

2017-02-23

The presence of a cardiovascular implantable electronic device has long been a contraindication for the performance of magnetic resonance imaging (MRI). We established a prospective registry to determine the risks associated with MRI at a magnetic field strength of 1.5 tesla for patients who had a pacemaker or implantable cardioverter-defibrillator (ICD) that was "non-MRI-conditional" (i.e., not approved by the Food and Drug Administration for MRI scanning). Patients in the registry were referred for clinically indicated nonthoracic MRI at a field strength of 1.5 tesla. Devices were interrogated before and after MRI with the use of a standardized protocol and were appropriately reprogrammed before the scanning. The primary end points were death, generator or lead failure, induced arrhythmia, loss of capture, or electrical reset during the scanning. The secondary end points were changes in device settings. MRI was performed in 1000 cases in which patients had a pacemaker and in 500 cases in which patients had an ICD. No deaths, lead failures, losses of capture, or ventricular arrhythmias occurred during MRI. One ICD generator could not be interrogated after MRI and required immediate replacement; the device had not been appropriately programmed per protocol before the MRI. We observed six cases of self-terminating atrial fibrillation or flutter and six cases of partial electrical reset. Changes in lead impedance, pacing threshold, battery voltage, and P-wave and R-wave amplitude exceeded prespecified thresholds in a small number of cases. Repeat MRI was not associated with an increase in adverse events. In this study, device or lead failure did not occur in any patient with a non-MRI-conditional pacemaker or ICD who underwent clinically indicated nonthoracic MRI at 1.5 tesla, was appropriately screened, and had the device reprogrammed in accordance with the prespecified protocol. (Funded by St. Jude Medical and others; MagnaSafe ClinicalTrials.gov number, NCT

Reviewing the process of preparing children for MRI

International Nuclear Information System (INIS)

Hallowell, Leanne M.; Stewart, Shari E.; Amorim e Silva, Cicero T. de; Ditchfield, Michael R.

2008-01-01

MRI is a common medical imaging investigation. Patients, including young children, can be required to keep still for up to 60 min for the study to be completed successfully. Children often find the confined space, noise, need to lie still and possibility of intravenous administration of contrast agent anxiety-provoking and sometimes so distressing that they are unable to cope and require general anaesthesia. A practice MRI intervention was introduced at the Royal Children's Hospital in Melbourne, Australia. The program is conducted by educational play therapists in conjunction with the Department of Medical Imaging. This study explored the effectiveness of this intervention. The intervention was conducted in a practice MRI unit devoid of magnets. Data were collected as a clinical audit with respect to age, gender, times of scans, position in bore, diagnostic scans and movement artefact. Epidata and Stata were used to analyze the data. A total of 291 children were included; their ages ranged from 3 years 7 months to 17 years (mean 7.9 years), and 48.8% were male. Of the 291 children, 218 (74.9%) were considered a pass at practice, 35 (12 %) were considered borderline pass, and diagnostic images were obtained from 218 (96%) of those children who went onto a clinical MRI. We conclude that practice MRI intervention facilitated by educational play therapists is a useful intervention in supporting children to cope with MRI without general anaesthesia. (orig.)

Reviewing the process of preparing children for MRI

Energy Technology Data Exchange (ETDEWEB)

Hallowell, Leanne M.; Stewart, Shari E. [Royal Children' s Hospital, Department of Educational Play Therapy, Melbourne, Victoria (Australia); Amorim e.Silva, Cicero T. de [Royal Children' s Hospital, Department of Medical Imaging, Melbourne (Australia); King Faisal Specialist Hospital and Research Centre, Pediatric Radiology Section, Radiology Department, Riyadh (Saudi Arabia); Ditchfield, Michael R. [Royal Children' s Hospital, Department of Medical Imaging, Melbourne (Australia)

2008-03-15

MRI is a common medical imaging investigation. Patients, including young children, can be required to keep still for up to 60 min for the study to be completed successfully. Children often find the confined space, noise, need to lie still and possibility of intravenous administration of contrast agent anxiety-provoking and sometimes so distressing that they are unable to cope and require general anaesthesia. A practice MRI intervention was introduced at the Royal Children's Hospital in Melbourne, Australia. The program is conducted by educational play therapists in conjunction with the Department of Medical Imaging. This study explored the effectiveness of this intervention. The intervention was conducted in a practice MRI unit devoid of magnets. Data were collected as a clinical audit with respect to age, gender, times of scans, position in bore, diagnostic scans and movement artefact. Epidata and Stata were used to analyze the data. A total of 291 children were included; their ages ranged from 3 years 7 months to 17 years (mean 7.9 years), and 48.8% were male. Of the 291 children, 218 (74.9%) were considered a pass at practice, 35 (12 %) were considered borderline pass, and diagnostic images were obtained from 218 (96%) of those children who went onto a clinical MRI. We conclude that practice MRI intervention facilitated by educational play therapists is a useful intervention in supporting children to cope with MRI without general anaesthesia. (orig.)

A patch-based pseudo-CT approach for MRI-only radiotherapy in the pelvis

Energy Technology Data Exchange (ETDEWEB)

Andreasen, Daniel, E-mail: dana@dtu.dk [Department of Applied Mathematics and Computer Science, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark and Radiotherapy Research Unit, Department of Oncology, Gentofte and Herlev Hospital, University of Copenhagen, 2730 Herlev (Denmark); Van Leemput, Koen [Department of Applied Mathematics and Computer Science, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark and A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129 (United States); Edmund, Jens M. [Radiotherapy Research Unit, Department of Oncology, Gentofte and Herlev Hospital, University of Copenhagen, 2730 Herlev (Denmark)

2016-08-15

Purpose: In radiotherapy based only on magnetic resonance imaging (MRI), knowledge about tissue electron densities must be derived from the MRI. This can be achieved by converting the MRI scan to the so-called pseudo-computed tomography (pCT). An obstacle is that the voxel intensities in conventional MRI scans are not uniquely related to electron density. The authors previously demonstrated that a patch-based method could produce accurate pCTs of the brain using conventional T{sub 1}-weighted MRI scans. The method was driven mainly by local patch similarities and relied on simple affine registrations between an atlas database of the co-registered MRI/CT scan pairs and the MRI scan to be converted. In this study, the authors investigate the applicability of the patch-based approach in the pelvis. This region is challenging for a method based on local similarities due to the greater inter-patient variation. The authors benchmark the method against a baseline pCT strategy where all voxels inside the body contour are assigned a water-equivalent bulk density. Furthermore, the authors implement a parallelized approximate patch search strategy to speed up the pCT generation time to a more clinically relevant level. Methods: The data consisted of CT and T{sub 1}-weighted MRI scans of 10 prostate patients. pCTs were generated using an approximate patch search algorithm in a leave-one-out fashion and compared with the CT using frequently described metrics such as the voxel-wise mean absolute error (MAE{sub vox}) and the deviation in water-equivalent path lengths. Furthermore, the dosimetric accuracy was tested for a volumetric modulated arc therapy plan using dose–volume histogram (DVH) point deviations and γ-index analysis. Results: The patch-based approach had an average MAE{sub vox} of 54 HU; median deviations of less than 0.4% in relevant DVH points and a γ-index pass rate of 0.97 using a 1%/1 mm criterion. The patch-based approach showed a significantly better

PET/MRI in head and neck cancer: initial experience

Energy Technology Data Exchange (ETDEWEB)

Platzek, Ivan; Laniado, Michael [Dresden University Hospital, Department of Radiology, Dresden (Germany); Beuthien-Baumann, Bettina [Dresden University Hospital, Department of Nuclear Medicine, Dresden (Germany); Schneider, Matthias [Dresden University Hospital, Oral and Maxillofacial Surgery, Dresden (Germany); Gudziol, Volker [Dresden University Hospital, Department of Otolaryngology, Dresden (Germany); Langner, Jens; Schramm, Georg; Hoff, Joerg van den [Institute of Bioinorganic and Radiopharmaceutical Chemistry, Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Kotzerke, Joerg [Dresden University Hospital, Nuclear Medicine, Dresden (Germany)

2013-01-15

To evaluate the feasibility of PET/MRI (positron emission tomography/magnetic resonance imaging) with FDG ({sup 18}F-fluorodeoxyglucose) for initial staging of head and neck cancer. The study group comprised 20 patients (16 men, 4 women) aged between 52 and 81 years (median 64 years) with histologically proven squamous cell carcinoma of the head and neck region. The patients underwent a PET scan on a conventional scanner and a subsequent PET/MRI examination on a whole-body hybrid system. FDG was administered intravenously prior to the conventional PET scan (267-395 MBq FDG, 348 MBq on average). The maximum standardized uptake values (SUV{sub max}) of the tumour and of both cerebellar hemispheres were determined for both PET datasets. The numbers of lymph nodes with increased FDG uptake were compared between the two PET datasets. No MRI-induced artefacts where observed in the PET images. The tumour was detected by PET/MRI in 17 of the 20 patients, by PET in 16 and by MRI in 14. The PET/MRI examination yielded significantly higher SUV{sub max} than the conventional PET scanner for both the tumour (p < 0.0001) and the cerebellum (p = 0.0009). The number of lymph nodes with increased FDG uptake detected using the PET dataset from the PET/MRI system was significantly higher the number detected by the stand-alone PET system (64 vs. 39, p = 0.001). The current study demonstrated that PET/MRI of the whole head and neck region is feasible with a whole-body PET/MRI system without impairment of PET or MR image quality. (orig.)

Incidental findings in healthy control research subjects using whole-body MRI

International Nuclear Information System (INIS)

Morin, S.H.X.; Cobbold, J.F.L.; Lim, A.K.P.; Eliahoo, J.; Thomas, E.L.; Mehta, S.R.; Durighel, G.; Fitzpatrick, J.; Bell, J.D.

2009-01-01

Aim: Magnetic resonance imaging (MRI) is a powerful clinical tool used increasingly in the research setting. We aimed to assess the prevalence of incidental findings in a sequential cohort of healthy volunteers undergoing whole-body MRI as part of a normal control database for imaging research studies. Materials and methods: 148 healthy volunteers (median age 36 years, range 21-69 years; 63.5% males, 36.5% females) were enrolled into a prospective observational study at a single hospital-based MRI research unit in London, UK. Individuals with a clinical illness, treated or under investigation were excluded from the study. Results: 43 (29.1%) scans were abnormal with a total of 49 abnormalities detected. Of these, 20 abnormalities in 19 patients (12.8%) were of clinical significance. The prevalence of incidental findings increased significantly with both increasing age and body mass index (BMI). Obese subjects had a fivefold greater risk of having an incidental abnormality on MRI (OR 5.4, CI 2.1-14.0). Conclusions: This study showed that more than one quarter of healthy volunteers have MR-demonstrable abnormalities. There was an increased risk of such findings in obese patients. This has ethical and financial implications for future imaging research, particularly with respect to informed consent and follow-up of those with abnormalities detected during the course of imaging studies.

TH-A-BRF-11: Image Intensity Non-Uniformities Between MRI Simulation and Diagnostic MRI

International Nuclear Information System (INIS)

Paulson, E

2014-01-01

Purpose: MRI simulation for MRI-based radiotherapy demands that patients be setup in treatment position, which frequently involves use of alternative radiofrequency (RF) coil configurations to accommodate immobilized patients. However, alternative RF coil geometries may exacerbate image intensity non-uniformities (IINU) beyond those observed in diagnostic MRI, which may challenge image segmentation and registration accuracy as well as confound studies assessing radiotherapy response when MR simulation images are used as baselines for evaluation. The goal of this work was to determine whether differences in IINU exist between MR simulation and diagnostic MR images. Methods: ACR-MRI phantom images were acquired at 3T using a spin-echo sequence (TE/TR:20/500ms, rBW:62.5kHz, TH/skip:5/5mm). MR simulation images were obtained by wrapping two flexible phased-array RF coils around the phantom. Diagnostic MR images were obtained by placing the phantom into a commercial phased-array head coil. Pre-scan normalization was enabled in both cases. Images were transferred offline and corrected for IINU using the MNI N3 algorithm. Coefficients of variation (CV=σ/μ) were calculated for each slice. Wilcoxon matched-pairs and Mann-Whitney tests compared CV values between original and N3 images and between MR simulation and diagnostic MR images. Results: Significant differences in CV were detected between original and N3 images in both MRI simulation and diagnostic MRI groups (p=0.010, p=0.010). In addition, significant differences in CV were detected between original MR simulation and original and N3 diagnostic MR images (p=0.0256, p=0.0016). However, no significant differences in CV were detected between N3 MR simulation images and original or N3 diagnostic MR images, demonstrating the importance of correcting MR simulation images beyond pre-scan normalization prior to use in radiotherapy. Conclusions: Alternative RF coil configurations used in MRI simulation can Result in

Optimized workflow and imaging protocols for whole-body oncologic PET/MRI.

Science.gov (United States)

Ishii, Shirou; Hara, Takamitsu; Nanbu, Takeyuki; Suenaga, Hiroki; Sugawara, Shigeyasu; Kuroiwa, Daichi; Sekino, Hirofumi; Miyajima, Masayuki; Kubo, Hitoshi; Oriuchi, Noboru; Ito, Hiroshi

2016-11-01

Although PET/MRI has the advantages of a simultaneous acquisition of PET and MRI, high soft-tissue contrast of the MRI images, and reduction of radiation exposure, its low profitability and long acquisition time are significant problems in clinical settings. Thus, MRI protocols that meet oncological purposes need to be used in order to reduce examination time while securing detectability. Currently, half-Fourier acquisition single-shot turbo spin echo and 3D-T1 volumetric interpolated breath-hold examination may be the most commonly used sequences for whole-body imaging due to their shorter acquisition time and higher diagnostic accuracy. Although there have been several reports that adding diffusion weighted image (DWI) to PET/MRI protocol has had no effect on tumor detection to date, in cases of liver, kidney, bladder, and prostate cancer, the use of DWI may be beneficial in detecting lesions. Another possible option is to scan each region with different MRI sequences instead of scanning the whole body using one sequence continuously. We herein report a workflow and imaging protocols for whole-body oncologic PET/MRI using an integrated system in the clinical routine, designed for the detection, for example by cancer screening, of metastatic lesions, in order to help future users optimize their workflow and imaging protocols.

Correction of MRI-induced geometric distortions in whole-body small animal PET-MRI

International Nuclear Information System (INIS)

Frohwein, Lynn J.; Schäfers, Klaus P.; Hoerr, Verena; Faber, Cornelius

2015-01-01

Purpose: The fusion of positron emission tomography (PET) and magnetic resonance imaging (MRI) data can be a challenging task in whole-body PET-MRI. The quality of the registration between these two modalities in large field-of-views (FOV) is often degraded by geometric distortions of the MRI data. The distortions at the edges of large FOVs mainly originate from MRI gradient nonlinearities. This work describes a method to measure and correct for these kind of geometric distortions in small animal MRI scanners to improve the registration accuracy of PET and MRI data. Methods: The authors have developed a geometric phantom which allows the measurement of geometric distortions in all spatial axes via control points. These control points are detected semiautomatically in both PET and MRI data with a subpixel accuracy. The spatial transformation between PET and MRI data is determined with these control points via 3D thin-plate splines (3D TPS). The transformation derived from the 3D TPS is finally applied to real MRI mouse data, which were acquired with the same scan parameters used in the phantom data acquisitions. Additionally, the influence of the phantom material on the homogeneity of the magnetic field is determined via field mapping. Results: The spatial shift according to the magnetic field homogeneity caused by the phantom material was determined to a mean of 0.1 mm. The results of the correction show that distortion with a maximum error of 4 mm could be reduced to less than 1 mm with the proposed correction method. Furthermore, the control point-based registration of PET and MRI data showed improved congruence after correction. Conclusions: The developed phantom has been shown to have no considerable negative effect on the homogeneity of the magnetic field. The proposed method yields an appropriate correction of the measured MRI distortion and is able to improve the PET and MRI registration. Furthermore, the method is applicable to whole-body small animal

Correction of MRI-induced geometric distortions in whole-body small animal PET-MRI

Energy Technology Data Exchange (ETDEWEB)

Frohwein, Lynn J., E-mail: frohwein@uni-muenster.de; Schäfers, Klaus P. [European Institute for Molecular Imaging, University of Münster, Münster 48149 (Germany); Hoerr, Verena; Faber, Cornelius [Department of Clinical Radiology, University Hospital of Münster, Münster 48149 (Germany)

2015-07-15

Purpose: The fusion of positron emission tomography (PET) and magnetic resonance imaging (MRI) data can be a challenging task in whole-body PET-MRI. The quality of the registration between these two modalities in large field-of-views (FOV) is often degraded by geometric distortions of the MRI data. The distortions at the edges of large FOVs mainly originate from MRI gradient nonlinearities. This work describes a method to measure and correct for these kind of geometric distortions in small animal MRI scanners to improve the registration accuracy of PET and MRI data. Methods: The authors have developed a geometric phantom which allows the measurement of geometric distortions in all spatial axes via control points. These control points are detected semiautomatically in both PET and MRI data with a subpixel accuracy. The spatial transformation between PET and MRI data is determined with these control points via 3D thin-plate splines (3D TPS). The transformation derived from the 3D TPS is finally applied to real MRI mouse data, which were acquired with the same scan parameters used in the phantom data acquisitions. Additionally, the influence of the phantom material on the homogeneity of the magnetic field is determined via field mapping. Results: The spatial shift according to the magnetic field homogeneity caused by the phantom material was determined to a mean of 0.1 mm. The results of the correction show that distortion with a maximum error of 4 mm could be reduced to less than 1 mm with the proposed correction method. Furthermore, the control point-based registration of PET and MRI data showed improved congruence after correction. Conclusions: The developed phantom has been shown to have no considerable negative effect on the homogeneity of the magnetic field. The proposed method yields an appropriate correction of the measured MRI distortion and is able to improve the PET and MRI registration. Furthermore, the method is applicable to whole-body small animal

The value of MRI, CAT-SCAN in evaluation of knee disorders

International Nuclear Information System (INIS)

Jerosch, J.; Castro, W.H.M.; Assheuer, J.

1990-01-01

A prospective study is presented containing 107 examined knees. All patients subsequently underwent arthroscopy. The findings of arthroscopy were compared with those of CT and MRI. (author). 13 refs.; 4 figs.; 1 tab

Numbering of vertebrae on MRI using a PACS cross-referencing tool

International Nuclear Information System (INIS)

Paik, Nam Chull; Lim, Chun Soo; Jang, Ho Suk

2012-01-01

Background: For the detection and documentation of numeric variations on spine magnetic resonance imaging (MRI), different techniques have previously been introduced. However, these methods require additional special imaging algorithms, software, or devices. We intend to introduce a vertebral numbering method using the existing picture archiving and communication system (PACS) and MRI system. Purpose: To assess the accuracy of a method for numbering presacral vertebrae based on the cross-referencing of two sagittal MRI series. Material and Methods: This study was a retrospective review of 224 consecutive patients who underwent both lumbar MRI with cervicothoracic scan and whole spine radiographic examinations. A radiologist and a neurosurgeon independently counted the number of presacral vertebrae in a cranial-to-caudal approach with cross-referencing of cervicothoracic and lumbar MRI sagittal series on the PACS workstation. Radiographic numbering from the cervical through the thoracic to the lumbar vertebrae, as a reference standard, was completed independently by the two reviewers. An analysis of the inter-observer and intermodality agreements of radiography and MRI was done. Results: In all cases except one, concordant numbering existed between the two modalities of MRI cross-referencing and radiographs combination. Both observers agreed completely, with no inter-observer discordance. Conclusion: The number of vertebrae could be identified consistently by counting caudally from C2 with cross-referencing cervicothoracic and lumbosacral sagittal MRI scans on the PACS workstation

Numbering of vertebrae on MRI using a PACS cross-referencing tool

Energy Technology Data Exchange (ETDEWEB)

Paik, Nam Chull [Dept. of Radiology, Arumdaun Wooldul Spine Hospital, Ulsan (Korea, Republic of)], e-mail: srsna@freechal.com; Lim, Chun Soo; Jang, Ho Suk [Dept. of Neurosurgery, Arumdaun Wooldul Spine Hospital, Ulsan (Korea, Republic of)

2012-09-15

Background: For the detection and documentation of numeric variations on spine magnetic resonance imaging (MRI), different techniques have previously been introduced. However, these methods require additional special imaging algorithms, software, or devices. We intend to introduce a vertebral numbering method using the existing picture archiving and communication system (PACS) and MRI system. Purpose: To assess the accuracy of a method for numbering presacral vertebrae based on the cross-referencing of two sagittal MRI series. Material and Methods: This study was a retrospective review of 224 consecutive patients who underwent both lumbar MRI with cervicothoracic scan and whole spine radiographic examinations. A radiologist and a neurosurgeon independently counted the number of presacral vertebrae in a cranial-to-caudal approach with cross-referencing of cervicothoracic and lumbar MRI sagittal series on the PACS workstation. Radiographic numbering from the cervical through the thoracic to the lumbar vertebrae, as a reference standard, was completed independently by the two reviewers. An analysis of the inter-observer and intermodality agreements of radiography and MRI was done. Results: In all cases except one, concordant numbering existed between the two modalities of MRI cross-referencing and radiographs combination. Both observers agreed completely, with no inter-observer discordance. Conclusion: The number of vertebrae could be identified consistently by counting caudally from C2 with cross-referencing cervicothoracic and lumbosacral sagittal MRI scans on the PACS workstation.

Application of the McDonald MRI criteria in multiple sclerosis.

Science.gov (United States)

Chan, Ling Ling; Sitoh, Yih Yian; Chong, June; See, Siew Ju; Umapathi, Thirugnanam N; Lim, Shih Hui; Ong, Benjamin

2007-08-01

The aim of this study was to assess the sensitivity of McDonald's magnetic resonance imaging (MRI) criteria for the diagnosis of multiple sclerosis (MS) in a group of Asian patients diagnosed with clinically definite MS, based on lesion characterisation on MRI scans. Forty-nine patients from 3 major neurological institutions were classified as having Asian- or Western-type MS based on clinical assessment. Each MRI scan was reviewed by 2 neuroradiologists for the presence and characteristics of brain and spinal lesions. The McDonald's MRI criteria were then applied and its sensitivity evaluated. Nine patients were excluded, leaving 34 females and 6 males who were dominantly Chinese (90%), with a mean age of 36.2 years. The MRI brain and spinal findings were detailed and tabulated. Statistically significant differences (P McDonald's MRI criteria were found between our Asian- and Western-type MS patients. The diagnostic yield of McDonald's MRI criteria increased by 20% when we substituted a cord for a brain lesion, and applied the substitution for enhancing cord lesions as well. The diagnosis is more likely to be made when using McDonald MRI criteria based on brain findings, in a patient who presents clinically with Western-type MS. The provision for substitution of "one brain for a spinal lesion" is helpful in Asian-type MS, where there is preponderance of spinal lesion load. Our findings suggest that minor modifications in the interpretation of McDonald's MRI criteria have significant impact on the diagnosis in patients clinically presenting as Asian-type MS, with potential bearing on their subsequent management.

Application of functional MRI in breast diseases

International Nuclear Information System (INIS)

Feng Yun; Liu Shiyuan; Wang Chenguang; Tao Xiaofeng; Wang Jinlin; Wang Jian

2007-01-01

Objective: To investigate the value of functional MRI in the diagnosis and differential diagnosis of breast diseases. Methods: Sixty-five patients with 68 lesions were enrolled in this study. Conventional T 1 WI and T 2 WI scan, dynamic contrast enhanced MRI, diffusion weighted imaging and 1 H single voxel MR spectroscopy were performed consequently. All lesions were verified by pathology, including 4 cases of breast adenosis, 22 fibroadenomas, 2 chronic inflammations, 3 cysts, 33 infitrating ductal carcinomas, 1 intraductal carcinoma and 3 cystosarcoma phyllodes tumors. Morphological features, maximum enhancement ratio, time-intensity curve, apparent diffusion coefficient and Choline peak were analyzed. Results: The detection rates of T 1 WI and T 2 WI were 14.7% (n=10) and 51.5% (n=35). The sensitivity, specificity, accuracy of dynamic contrast enhanced MRI for the malignant tumor were 94. 6%, 71.4% and 76.5% respectively. Retrospective study showed that diffusion weighted imaging, with the b value from 800 s/mm 2 to 1000 s/mm 2 , could be used to differentiate various types of breast lesions. 1 H signal voxel spectroscopy had a sensitivity of 51.4%, specificity of 82.6%, and accuracy of 67.6% for the malignent. The sensitivity, specificity and accuracy could reach 97.3%, 90.0% and 92.6% respectively by combining conventional scan, dynamic contrast enhanced MRI and MR spectroscopy. Conclusion: Functional MRI, with high sensitivity, specificity and accuracy, can be used widely in the diagnosis of malignant breast lesions. (authors)

SU-E-J-240: Development of a Novel 4D MRI Sequence for Real-Time Liver Tumor Tracking During Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Zhuang, L; Burmeister, J [Department of Oncology, Wayne State Univ School of Medicine, Detroit, MI (United States); Ye, Y [Department of Radiology, Wayne State Univ School of Medicine, Detroit, MI (United States)

2015-06-15

Purpose: To develop a Novel 4D MRI Technique that is feasible for realtime liver tumor tracking during radiotherapy. Methods: A volunteer underwent an abdominal 2D fast EPI coronal scan on a 3.0T MRI scanner (Siemens Inc., Germany). An optimal set of parameters was determined based on image quality and scan time. A total of 23 slices were scanned to cover the whole liver in the test scan. For each scan position, the 2D images were retrospectively sorted into multiple phases based on breathing signal extracted from the images. Consequently the 2D slices with same phase numbers were stacked to form one 3D image. Multiple phases of 3D images formed the 4D MRI sequence representing one breathing cycle. Results: The optimal set of scan parameters were: TR= 57ms, TE= 19ms, FOV read= 320mm and flip angle= 30°, which resulted in a total scan time of 14s for 200 frames (FMs) per slice and image resolution of (2.5mm,2.5mm,5.0mm) in three directions. Ten phases of 3D images were generated, each of which had 23 slices. Based on our test scan, only 100FMs were necessary for the phase sorting process which may lower the scan time to 7s/100FMs/slice. For example, only 5 slices/35s are necessary for a 4D MRI scan to cover liver tumor size ≤ 2cm leading to the possibility of tumor trajectory tracking every 35s during treatment. Conclusion: The novel 4D MRI technique we developed can reconstruct a 4D liver MRI sequence representing one breathing cycle (7s/ slice) without an external monitor. This technique can potentially be used for real-time liver tumor tracking during radiotherapy.

Modelling large motion events in fMRI studies of patients with epilepsy

DEFF Research Database (Denmark)

Lemieux, Louis; Salek-Haddadi, Afraim; Lund, Torben E

2007-01-01

-positive activation. Head motion can lead to severe image degradation and result in false-positive activation and is usually worse in patients than in healthy subjects. We performed general linear model fMRI data analysis on simultaneous EEG-fMRI data acquired in 34 cases with focal epilepsy. Signal changes...... associated with large inter-scan motion events (head jerks) were modelled using modified design matrices that include 'scan nulling' regressors. We evaluated the efficacy of this approach by mapping the proportion of the brain for which F-tests across the additional regressors were significant. In 95......% of cases, there was a significant effect of motion in 50% of the brain or greater; for the scan nulling effect, the proportion was 36%; this effect was predominantly in the neocortex. We conclude that careful consideration of the motion-related effects in fMRI studies of patients with epilepsy is essential...

Comparison of CT and MRI artefacts from coils and vascular plugs used for portal vein embolization

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Geisel, Dominik, E-mail: dominik.geisel@charite.de [Department of Diagnostic and Interventional Radiology, Charité, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin (Germany); Gebauer, Bernhard [Department of Diagnostic and Interventional Radiology, Charité, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin (Germany); Malinowski, Maciej; Stockmann, Martin [Department of General, Visceral and Transplantation Surgery, Charité, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin (Germany); Denecke, Timm [Department of Diagnostic and Interventional Radiology, Charité, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin (Germany)

2014-04-15

Purpose: To retrospectively analyze the degree of artefacts in CT and MRI scans caused by coils and vascular plugs used for portal vein embolization (PVE). Materials and methods: All patients who underwent PVE between July 2011 and December 2012 and received either plug or coil embolization additional to particle embolization were retrospectively analyzed. Artefacts causes by embolization materials were measured in CT and MRI scans following PVE. Results: The sum of the artefact diameters caused from coils was significantly higher in CT (188.3 ± 26.1 mm) than in MRI T1 (50.5 ± 6.5 mm) or T2 imaging (39.5 ± 9.7 mm) (P < 0.05). In MRI, the diameter in T1 and T2 sequences did not differ significantly (P = 0.977). The sum of the artefact diameters from vascular plugs in MRI T1 sequences (62.5 ± 8.7 mm) was significantly higher than in CT (46.6 ± 4.8 mm; P < 0.05) and MRI T2 sequences (52.8 ± 3.8 mm; P < 0.05). Conclusion: PVE with particles and vascular plug causes significantly fewer artefacts than PVE with particles and coils on CT scans following embolization, which can be important in the event of vascular complications or in follow-up scans, should the patient become unresectable.

Target Volume Delineation in Oropharyngeal Cancer: Impact of PET, MRI, and Physical Examination

International Nuclear Information System (INIS)

Thiagarajan, Anuradha; Caria, Nicola; Schöder, Heiko; Iyer, N. Gopalakrishna; Wolden, Suzanne; Wong, Richard J.; Sherman, Eric; Fury, Matthew G.; Lee, Nancy

2012-01-01

Introduction: Sole utilization of computed tomography (CT) scans in gross tumor volume (GTV) delineation for head-and-neck cancers is subject to inaccuracies. This study aims to evaluate contributions of magnetic resonance imaging (MRI), positron emission tomography (PET), and physical examination (PE) to GTV delineation in oropharyngeal cancer (OPC). Methods: Forty-one patients with OPC were studied. All underwent contrast-enhanced CT simulation scans (CECTs) that were registered with pretreatment PETs and MRIs. For each patient, three sets of primary and nodal GTV were contoured. First, reference GTVs (GTVref) were contoured by the treating radiation oncologist (RO) using CT, MRI, PET, and PE findings. Additional GTVs were created using fused CT/PET scans (GTVctpet) and CT/MRI scans (GTVctmr) by two other ROs blinded to GTVref. To compare GTVs, concordance indices (CI) were calculated by dividing the respective overlap volumes by overall volumes. To evaluate the contribution of PE, composite GTVs derived from CT, MRI, and PET (GTVctpetmr) were compared with GTVref. Results: For primary tumors, GTVref was significantly larger than GTVctpet and GTVctmr (p 0.75), indicating that although the modalities were complementary, the added benefit was small in the context of CECTs. In addition, PE did not aid greatly in nodal GTV delineation. Conclusion: PET and MRI are complementary and combined use is ideal. However, the low CI (ctpetmr vs. ref) particularly for primary tumors underscores the limitations of defining GTVs using imaging alone. PE is invaluable and must be incorporated.

MRI evidence of structural changes in the sacroiliac joints of patients with non-radiographic axial spondyloarthritis even in the absence of MRI inflammation.

Science.gov (United States)

Maksymowych, Walter P; Wichuk, Stephanie; Dougados, Maxime; Jones, Heather; Szumski, Annette; Bukowski, Jack F; Marshall, Lisa; Lambert, Robert G

2017-06-06

Studies have shown that structural lesions may be present in patients with non-radiographic axial spondyloarthritis (nr-axSpA). However, the relevance of structural lesions in these patients is unclear, particularly without signs of inflammation on magnetic resonance imaging (MRI). We assessed the presence of structural lesions at baseline on MRI in the sacroiliac joints (SIJ) of patients with nr-axSpA with and without SIJ inflammation on MRI. Bone marrow edema (BME) was assessed on short tau inversion recovery (STIR) scans from 185 patients with nr-axSpA, by two independent readers at baseline using the Spondyloarthritis Research Consortium of Canada (SPARCC) score. Structural lesions were evaluated on T1 weighted spin echo scans, with readers blinded to STIR scans, using the SPARCC MRI SIJ structural score. Disease characteristics and structural lesions were compared in patients with SIJ BME (score ≥2) and without SIJ BME (score <2). Both SIJ BME and structural lesions scores were available for 183 patients; 128/183 (69.9%) patients had SIJ BME scores ≥2 and 55/183 (30.1%) had scores <2. Frequencies of MRI structural lesions in patients with vs without SIJ BME were: erosions (45.3% vs 10.9%, P < 0.001), backfill (20.3% vs 0%, P < 0.001), fat metaplasia (10.9% vs 1.8%, P = 0.04), and ankylosis (2.3% vs 1.8%, P = ns). Significantly more patients with both SIJ BME and structural lesions were male and/or HLA-B27 positive than patients with only SIJ BME. Mean (SD) spinal scores (23 discovertebral units) were significantly higher in patients with SIJ structural lesions than without: 6.5 (11.5) vs 3.3 (5.1), respectively, P = 0.01. In patients with nr-axSpA, SIJ structural lesions, particularly erosions, may be present on MRI when radiographs are normal or inconclusive, even in patients negative for MRI SIJ inflammation. They may reflect more severe disease with greater spinal inflammation. ClinicalTrials.gov, NCT01258738 . Registered on 9

Multiple imaging procedures including MRI for the bladder cancer

International Nuclear Information System (INIS)

Mikata, Noriharu; Suzuki, Makoto; Takeuchi, Takumi; Kunisawa, Yositaka; Fukutani, Keiko; Kawabe, Kazuki

1986-01-01

Endoscopic photography, double contrast cystography, transurethral echography, X-ray CT scan, and MRI (magnetic resonance imaging) were utilized for the staging diagnosis of the four patients with carcinoma of the bladder. In the first case, a 70-year-old man, since all of the five imaging procedures suggested a superficial and pedunculated tumor, his bladder cancer was considered T1. The classification of stage T3 carcinoma was made for the second 86-year-old male. Because all of his imaging examinations showed a tumor infiltrating deep muscle and penetrating the bladder wall. The third case was a 36-year-old male. His clinical stage was diagnosed as T2 or T3a by cystophotography, double contrast cystogram, ultrasonography, and X-ray CT scan. However, MRI showed only thickened bladder wall and the infiltrating tumor could not be distinguished from the hypertrophic wall. The last patient, a 85-year-old female, had a smaller Ta cancer. Her double contrast cystography revealed the small tumor at the lateral bladder wall. But, the tumor could not be detected by transaxial, sagittal and coronal scans. Multiple imaging procedures combining MRI and staging diagnosis of the bladder carcinoma were discussed. (author)

Patellofemoral instability: Quantitative evaluation of predisposing factors by MRI

Directory of Open Access Journals (Sweden)

Noha Mohamed Osman, M.D.

2016-12-01

Full Text Available Objective: To determine the contribution of MRI in evaluating patellofemoral instability (PFI and to compare the underlying predisposing factors between the study and control groups. Materials and methods: We enrolled knee MRI scans of 38 patients with lateral patellar dislocation (LPD and 38 control subjects. All MRI scans were examined for LPD and patellofemoral joint (PFJ morphological abnormalities. The lateral trochlear inclination angle, sulcus angle and trochlear depth were the MR measures for trochlear dysplasia (TD, patellar height ratio was used for evaluation of patella alta, the patellar tilt angle, and the tibial tuberosity-trochlear groove (TT-TG distance were also measured. Results: MRI confirmed PFI in 84.2% of study group and detected abnormal PFJ morphological factors in all cases. The prevalences and mean values of all MR parameters showed significant differences (p < 0.001 between the study and control groups. MR parameters for TD had the highest sensitivity of 57.9%, while the TT-TG distance was the most specific 97.4% for PFI. The prevalence of combined PFJ abnormal morphological factors was 36.8% in the study group. Conclusion: MRI was useful in quantitative measuring of the predisposing factors contributing to PFI resulting in significant difference in all MR parameters between the study and control groups.

A raster scanning power supply system for controlling relativistic heavy ion beams at the Bevalac Biomedical Facility

International Nuclear Information System (INIS)

Stover, G.; Nyman, M.; Halliwell, J.; Lutz, I.; Dwinell, R.

1987-03-01

A power supply system is currently being designed and constructed to sweep an 8.0 Tesla-meter relativistic heavy ion beam in a raster scanning mode for radiotherapy use. Two colinear dipole magnets with orthogonally oriented magnetic fields are driven by the system to produce a rectangular field (40 x 40 cm max.) with a uniform dose (+-2.5%) to a target volume 6 meters away. The ''fast'' horizontal scanning magnet is driven by a single power supply which in conjunction with a triac bridge network and a current regulated linear actuator will produce a 1200 cm/sec max. sweep rate. The ''slow'' (40 cm/sec) vertical scanning magnet will be controlled by dual current regulated linear actuators in a push-pull configuration. The scanner system can provide off-axis treatment profiles with large aspect ratios and unusual dimensions

A graphics processing unit accelerated motion correction algorithm and modular system for real-time fMRI.

Science.gov (United States)

Scheinost, Dustin; Hampson, Michelle; Qiu, Maolin; Bhawnani, Jitendra; Constable, R Todd; Papademetris, Xenophon

2013-07-01

Real-time functional magnetic resonance imaging (rt-fMRI) has recently gained interest as a possible means to facilitate the learning of certain behaviors. However, rt-fMRI is limited by processing speed and available software, and continued development is needed for rt-fMRI to progress further and become feasible for clinical use. In this work, we present an open-source rt-fMRI system for biofeedback powered by a novel Graphics Processing Unit (GPU) accelerated motion correction strategy as part of the BioImage Suite project ( www.bioimagesuite.org ). Our system contributes to the development of rt-fMRI by presenting a motion correction algorithm that provides an estimate of motion with essentially no processing delay as well as a modular rt-fMRI system design. Using empirical data from rt-fMRI scans, we assessed the quality of motion correction in this new system. The present algorithm performed comparably to standard (non real-time) offline methods and outperformed other real-time methods based on zero order interpolation of motion parameters. The modular approach to the rt-fMRI system allows the system to be flexible to the experiment and feedback design, a valuable feature for many applications. We illustrate the flexibility of the system by describing several of our ongoing studies. Our hope is that continuing development of open-source rt-fMRI algorithms and software will make this new technology more accessible and adaptable, and will thereby accelerate its application in the clinical and cognitive neurosciences.

Use of 3.0-T MRI for Stereotactic Radiosurgery Planning for Treatment of Brain Metastases: A Single-Institution Retrospective Review

International Nuclear Information System (INIS)

Saconn, Paul A.; Shaw, Edward G.; Chan, Michael D.; Squire, Sarah E.; Johnson, Annette J.; McMullen, Kevin P.; Tatter, Stephen B.; Ellis, Thomas L.; Lovato, James; Bourland, J. Daniel; Ekstrand, Kenneth E.; DeGuzman, Allan F.; Munley, Michael T.

2010-01-01

Purpose: To investigate the efficacy of 3.0-T magnetic resonance imaging (MRI) for detecting brain metastases for stereotactic radiosurgery (SRS) planning. Methods and Materials: All adult patients scheduled for SRS treatment for brain metastases at our institution between October 2005 and January 2008 were eligible for analysis. All patients underwent radiosurgery treatment planning 3.0-T MRI on the day of scheduled radiosurgery and a diagnostic 1.5-T MRI in the days or weeks prior to radiosurgery for comparison. Both scans were interpreted by neuroradiologists who reported their findings in the radiology reports. We performed a retrospective review of the radiology reports to determine the number of brain metastases identified using each MRI system. Results: Of 254 patients scheduled for treatment from October 2005 to January 2008, 138 patients had radiology reports that explicitly described the number of metastases identified on both scans. With a median interval of 17 days (range, 1-82) between scans, the number of metastases detected using 1.5-T MRI system ranged from 1 to 5 and from 1 to 8 using the 3.0 T-MRI system. Twenty-two percent of patients were found to have a greater number of metastases with the 3.0 T-MRI system. The difference in number of metastases detected between the two scans for the entire cohort ranged from 0 to 6. Neither histology (p = 0.52 by chi-sq test) nor time between scans (p = 0.62 by linear regression) were significantly associated with the difference in number of metastases between scans. Conclusions: The 3.0-T MRI system appears to be superior to a 1.5-T MRI system for detecting brain metastases, which may have significant implications in determining the appropriate treatment modality. Our findings suggest the need for a prospectively designed study to further evaluate the use of a 3.0 T-MRI system for stereotactic radiosurgery planning in the treatment of brain metastases.

Cat-Scan and nuclear magnetic resonance imaging in abnormalities of neuronal migration

International Nuclear Information System (INIS)

Wilms, G.; Marchal, G.; Decrop, E.; Van Hecke, P.; Baert, A.L.; Casaer, P.

1989-01-01

This is a report of the CAT-scan and MRI characteristics in 14 patients with anomalies of neuronal migration. There were 3 cases of heterotopia of the gray matter, 2 cases of agyria, 3 cases of pachygyria, 2 cases of schizencephaly and 4 cases of hemimegalencephaly. The primary advantages of MRI in comparison with CAT-scanning, are better contrast between the white and gray matter; better delineation of the cerebral cortex and the possibility of direct mutiplanar imaging. NMRI will become the investigation of choice in children with epilepsy or psychomotor retardation [fr

Multiparametric prostate MRI: technical conduct, standardized report and clinical use.

Science.gov (United States)

Manfredi, Matteo; Mele, Fabrizio; Garrou, Diletta; Walz, Jochen; Fütterer, Jurgen J; Russo, Filippo; Vassallo, Lorenzo; Villers, Arnauld; Emberton, Mark; Valerio, Massimo

2018-02-01

Multiparametric prostate MRI (mp-MRI) is an emerging imaging modality for diagnosis, characterization, staging, and treatment planning of prostate cancer (PCa). The technique, results reporting, and its role in clinical practice have been the subject of significant development over the last decade. Although mp-MRI is not yet routinely used in the diagnostic pathway, almost all urological guidelines have emphasized the potential role of mp-MRI in several aspects of PCa management. Moreover, new MRI sequences and scanning techniques are currently under evaluation to improve the diagnostic accuracy of mp-MRI. This review presents an overview of mp-MRI, summarizing the technical applications, the standardized reporting systems used, and their current roles in various stages of PCa management. Finally, this critical review also reports the main limitations and future perspectives of the technique.

EEG, CT scan and MRI as diagnostic tools for ADHD in population between 6 and 19 years: a systematic review

Directory of Open Access Journals (Sweden)

José Calleja

2012-09-01

Full Text Available Introduction: Attention deficit and hyperactivity disorder (ADHD is generally diagnosed based on the criteria of DSM-IV. Because several diagnostic tests have appeared such as electroencephalography (EEG, CT scan and magnetic resonance imaging (MRI, there is a particular interest in determining the usefulness and diagnostic accuracy of these tests for the diagnosis of ADHD. Purpose: To identify, synthesize and evaluate the best available evidence on the usefulness of EEG, CT and MRI as a diagnostic tool in ADHD in the 6-19 year-old population. Methods: A systematic review of studies on diagnostic tests that assessed the validity, reliability and effectiveness of the implementation of EEG, CT and MRI in the diagnosis of ADHD in the 6-19 year-old population was conducted. Searches were done in PubMed/MEDLINE, LILACS, Cochrane, DARE and National Guideline Clearinghouse databases, until February 2012, in English and Spanish. The articles that met the inclusion criteria were independently assessed by two investigators for methodological quality using standard checklists for review articles and diagnostic test articles. Results: Of the 115 studies found, eight studies were included, among which two medium-quality systematic reviews and a good-quality primary article on diagnostic tests. Additionally, five evidence-based clinical guidelines that address this issue were also included. Conclusions: The available evidence on the validity, reliability and effectiveness of the electroencephalogram, computed tomography and magnetic resonance imaging, does not recommend their use as diagnostic tools for ADHD. Clinical practice guidelines do not recommend their use either. These tests are recommended for the assessment of the individual patient with the disorder.

An MRI Scan of the nucleus

Science.gov (United States)

Hoffman, Calem

2017-09-01

In the pursuit of a global description of nuclei, extensive experimental studies on short-lived isotopes have provided a wealth of new empirical information. Such data has been used to test theoretical concepts and in the development of innovative ideas. More directly, a novel device at Argonne National Laboratory, the HELIcal Orbit Spectrometer (HELIOS), was focused on providing detailed single-particle information on the malleability of the nuclear magic numbers. Once thought as immovable pillars in nuclear structure, the shell-gaps in nuclei defining magic numbers of nucleons are now well-known to evolve as proton-to-neutron ratios change. And, determination of the underlying components of the nuclear force driving the evolution is at the forefront of nuclear structure research. Additionally, the HELIOS device mentioned above also carries its own aura being that it is formed by a decommissioned MRI solenoid magnet. In this talk recent highlights and advancements in our description of nuclear shell evolution will be the focus along with a few sidestepping comments on the life-cycle and interplay between basic research and the applications of nuclear physics. This material is based upon work supported by the U.S. Department of Energy, Office of Science, under Contract Number DE-AC02-06CH11357.

Positron emission tomography/magnetic resonance imaging (PET/MRI: An update and initial experience at HC-FMUSP

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Marcelo A. Queiroz

Full Text Available Summary The new technology of PET/MRI is a prototype of hybrid imaging, allowing for the combination of molecular data from PET scanning and morphofunctional information derived from MRI scanning. Recent advances regarding the technical aspects of this device, especially after the development of MRI-compatible silicon photomultipliers of PET, permitted an increase in the diagnostic performance of PET/MRI translated into dose reduction and higher imaging quality. Among several clinical applications, PET/MRI gains ground initially in oncology, where MRI per se plays an essential role in the assessment of primary tumors (which is limited in the case of PET/CT, including prostate, rectal and gynecological tumors. On the other hand, the evaluation of the lungs remains an enigma although new MRI sequences are being designed to overcome this. More clinical indications of PET/MRI are seen in the fields of neurology, cardiology and inflammatory processes, and the use of PET/MRI also opens perspectives for pediatric populations as it involves very low radiation exposure. Our review aimed to highlight the current indications of PET/MRI and discuss the challenges and perspectives of PET/MRI at HC-FMUSP.

Imaging features of colovesical fistulae on MRI.

Science.gov (United States)

Tang, Y Z; Booth, T C; Swallow, D; Shahabuddin, K; Thomas, M; Hanbury, D; Chang, S; King, C

2012-10-01

MRI is routinely used in the investigation of colovesical fistulae at our institute. Several papers have alluded to its usefulness in achieving the diagnosis; however, there is a paucity of literature on its imaging findings. Our objective was to quantify the MRI characteristics of these fistulae. We selected all cases over a 4-year period with a final clinical diagnosis of colovesical fistula which had been investigated with MRI. The MRI scans were reviewed in a consensus fashion by two consultant uroradiologists. Their MRI features were quantified. There were 40 cases of colovesical fistulae. On MRI, the fistula morphology consistently fell into three patterns. The most common pattern (71%) demonstrated an intervening abscess between the bowel wall and bladder wall. The second pattern (15%) had a visible track between the affected bowel and bladder. The third pattern (13%) was a complete loss of fat plane between the affected bladder and bowel wall. MRI correctly determined the underlying aetiology in 63% of cases. MRI is a useful imaging modality in the diagnosis of colovesical fistulae. The fistulae appear to have three characteristic morphological patterns that may aid future diagnoses of colovesical fistulae. To the authors' knowledge, this is the first publication of the MRI findings in colovesical fistulae.

Primary ureteral carcinoma: MRI diagnosis and comparison with other diagnostic imaging facilities

International Nuclear Information System (INIS)

An Ningyu; Jiang Bo; Cai Youquan; Liang Yan

2004-01-01

Objective: To investigate MRI examination methods and imaging manifestations of primary ureteral carcinoma, and to evaluate its clinical values when comparing with other diagnostic imaging facilities. Methods: Eighty-seven cases of primary ureteral carcinoma who were operated within recent 8 years came into the study, among which, 35 cases had MRI examinations. For MRI examination, coronal heavy T 2 WI (water imaging) was performed to show the dilated ureter, then axial T 2 WI and T 1 WI were scanned at the obstruction level. 11 cases underwent additional Gd-DTPA dynamic contrast enhanced scans. The original pre-operative diagnostic reports of various imaging facilities were analyzed comparing with the results of operation and pathology. Results: MRI showed ureteral dilatation in 33 of 35 cases, no abnormal appearance in 1 case, and only primary kidney atrophy post renal transplantation in 1 case. Among the 33 cases with ureteral obstruction, soft mass at the obstruction level was detected on axial scans in 32 cases. The lesions showed gradual and homogeneous mild to moderate enhancement on contrast MRI. The overall employment rate of imaging facilities was as follows: ultrasound (94.3%), IVU (59.8%), CT (52.9%), MRI (40.2%), and RUP (35.6%). The accurate diagnostic rate was as follows :MRI (91.4%), RUP (80.6%), CT (63.0%), ultrasound (47.6%), and IVU (11.5%). Conclusion: Combination of MR water imaging and conventional sequences can demonstrate most primary ureteral carcinoma lesions and has a highest diagnostic accuracy among the current diagnostic imaging facilities. It should be taken as the first diagnostic imaging method of choice when primary ureteral carcinoma is suspected after ultrasound screening

Correlativity study on MRI morphologic features, pathology, and molecular biology of breast cancer

International Nuclear Information System (INIS)

Chen Rong; Gong Shuigen; Zhang Weiguo; Chen Jinhua; He Shuangwu; Liu Baohua; Li Zengpeng

2004-01-01

Objective: To investigate the correlation among MRI morphologic features, pathology, and molecular biology of breast cancer. Methods: MR scanning was performed in 78 patients with breast cancer before operation and MRI morphologic features of breast cancer were analyzed. The mastectomy specimens of the breast neoplasm were stained with immunohistochemistry, and the expression of estrogen receptor (ER), progesterone receptor (PR), C-erbB-2, p53, and the distribution of microvessel density (MVD) was measured. The pathologic results were compared with MRI features. Results: Among the 80 breast cancers, ER positive expression was positively correlated with the spiculate margin of breast cancer (P 0.05). Among the 41 breast cancers with dynamic MR scans, there was positive correlation between the spatial distribution of contrast agent and MVD (P<0.01). Conclusion: There exists some correlation among MRI morphologic features, pathology, and molecular biology factors in breast cancer to certain extent. The biologic behavior and prognosis of the breast cancer can be assessed according to MRI features

Determination of position and shape of flexible mri surface coils using the Microsoft Kinect for attenuation correction in PET/MRI

Energy Technology Data Exchange (ETDEWEB)

Frohwein, Lynn; He, Mirco; Buther, Florian; Safers, Klaus [European Institute for Molecular Imaging, University of Muenster (Germany)

2015-05-18

Due to the varying position and shape of flexible MRI RF surface coils, the creation of attenuation maps for these coils is a challenging task. Nevertheless, coil material (metal, plastic, rubber) attenuates the PET signal to a considerable amount. Thus, including a coil μ-map into the human μ-map is essential. In this work, we present a method to determine the position and shape of flexible coils with the help of the Microsoft Kinect depth camera. Phantom PET/MRI (Siemens Biograph mMR) and CT scans (Siemens Biograph mCT) were performed with and without the flexible 32-channel coil equipped with 15 markers visible in CT and Kinect. Prior to the PET/MRI acquisition, Kinect data is acquired of the phantom with the coil on top. The manually extracted marker positions from CT and Kinect are used to non-rigidly transform the template CT according to the Kinect marker positions describing the shape of the coil during PET/MRI acquisition. An appropriate μ-map can then be calculated from the transformed CT dataset. Subsequently, the μ-map is placed in relation to the patient table according to the Kinect-derived marker positions. First results show that the coil shape can be determined with the help of the Kinect camera. The transformation of the template CT dataset according to Kinect marker positions during PET/MRI leads to appropriate results. Furthermore, the position of the coil can also be determined for an accurate placement of the μ-map in relation to the patient table. The determination of position and shape of flexible surface coils using the Kinect camera can be a way to include the CT-based coil μ-map in PET/MRI acquisitions without the need for additional MRI scans. Accuracy and practicability of the method have to be tested in further experiments.

Determination of position and shape of flexible mri surface coils using the Microsoft Kinect for attenuation correction in PET/MRI

International Nuclear Information System (INIS)

Frohwein, Lynn; He, Mirco; Buther, Florian; Safers, Klaus

2015-01-01

Due to the varying position and shape of flexible MRI RF surface coils, the creation of attenuation maps for these coils is a challenging task. Nevertheless, coil material (metal, plastic, rubber) attenuates the PET signal to a considerable amount. Thus, including a coil μ-map into the human μ-map is essential. In this work, we present a method to determine the position and shape of flexible coils with the help of the Microsoft Kinect depth camera. Phantom PET/MRI (Siemens Biograph mMR) and CT scans (Siemens Biograph mCT) were performed with and without the flexible 32-channel coil equipped with 15 markers visible in CT and Kinect. Prior to the PET/MRI acquisition, Kinect data is acquired of the phantom with the coil on top. The manually extracted marker positions from CT and Kinect are used to non-rigidly transform the template CT according to the Kinect marker positions describing the shape of the coil during PET/MRI acquisition. An appropriate μ-map can then be calculated from the transformed CT dataset. Subsequently, the μ-map is placed in relation to the patient table according to the Kinect-derived marker positions. First results show that the coil shape can be determined with the help of the Kinect camera. The transformation of the template CT dataset according to Kinect marker positions during PET/MRI leads to appropriate results. Furthermore, the position of the coil can also be determined for an accurate placement of the μ-map in relation to the patient table. The determination of position and shape of flexible surface coils using the Kinect camera can be a way to include the CT-based coil μ-map in PET/MRI acquisitions without the need for additional MRI scans. Accuracy and practicability of the method have to be tested in further experiments.

Assessment and Monitoring of RF Safety for Ultra-High Field MRI

NARCIS (Netherlands)

Restivo, MC

2017-01-01

The radio frequency (RF) energy deposited in a human subject undergoing a 7T MRI scan has the potential to cause localized tissue heating. The use of parallel transmit MRI at 7T increases the risk of localized heating due interference effects among the simultaneously transmitting channels. The

A computational atlas of the hippocampal formation using ex vivo, ultra-high resolution MRI: Application to adaptive segmentation of in vivo MRI.

Science.gov (United States)

Iglesias, Juan Eugenio; Augustinack, Jean C; Nguyen, Khoa; Player, Christopher M; Player, Allison; Wright, Michelle; Roy, Nicole; Frosch, Matthew P; McKee, Ann C; Wald, Lawrence L; Fischl, Bruce; Van Leemput, Koen

2015-07-15

Automated analysis of MRI data of the subregions of the hippocampus requires computational atlases built at a higher resolution than those that are typically used in current neuroimaging studies. Here we describe the construction of a statistical atlas of the hippocampal formation at the subregion level using ultra-high resolution, ex vivo MRI. Fifteen autopsy samples were scanned at 0.13 mm isotropic resolution (on average) using customized hardware. The images were manually segmented into 13 different hippocampal substructures using a protocol specifically designed for this study; precise delineations were made possible by the extraordinary resolution of the scans. In addition to the subregions, manual annotations for neighboring structures (e.g., amygdala, cortex) were obtained from a separate dataset of in vivo, T1-weighted MRI scans of the whole brain (1mm resolution). The manual labels from the in vivo and ex vivo data were combined into a single computational atlas of the hippocampal formation with a novel atlas building algorithm based on Bayesian inference. The resulting atlas can be used to automatically segment the hippocampal subregions in structural MRI images, using an algorithm that can analyze multimodal data and adapt to variations in MRI contrast due to differences in acquisition hardware or pulse sequences. The applicability of the atlas, which we are releasing as part of FreeSurfer (version 6.0), is demonstrated with experiments on three different publicly available datasets with different types of MRI contrast. The results show that the atlas and companion segmentation method: 1) can segment T1 and T2 images, as well as their combination, 2) replicate findings on mild cognitive impairment based on high-resolution T2 data, and 3) can discriminate between Alzheimer's disease subjects and elderly controls with 88% accuracy in standard resolution (1mm) T1 data, significantly outperforming the atlas in FreeSurfer version 5.3 (86% accuracy) and

Unexplained mental retardation: is brain MRI useful?

Energy Technology Data Exchange (ETDEWEB)

Decobert, Fabrice; Merzoug, Valerie; Kalifa, Gabriel; Adamsbaum, Catherine [Saint Vincent de Paul Hospital, Department of Radiology, 75674 Paris Cedex 14 (France); Grabar, Sophie [Cochin Hospital, Department of Biostatistics and Medical Information, Paris (France); Ponsot, Gerard [Saint Vincent de Paul Hospital, Department of Neuropaediatrics, Paris (France); Des Portes, Vincent [Saint Vincent de Paul Hospital, Department of Neuropaediatrics, Paris (France); Debrousse Hospital, Department of Neuropaediatrics, Lyon (France)

2005-06-01

Mental retardation (MR), defined as an IQ below 70, is a frequent cause of consultation in paediatrics. To evaluate the yield of brain MRI in the diagnostic work-up of unexplained MR in children. Patients and methods: The MRI features and clinical data of 100 patients (age 1-18 years) affected with non-progressive MR of unknown origin were compared to an age-matched control group (n=100). Two radiologists conducted an independent review of the MRI scans. Univariate and multivariate analyses showed a higher incidence of brain anomalies in the MR group than in the control group (53 vs 17, OR=5.7 [2.9-11.1]), for signal abnormalities within the periventricular white matter (OR=20.3 [2.6-155.3]), lateral ventricular dilatation (OR=15.6 [2.0-124]), mild corpus callosum abnormalities (shortness, atrophy) (OR=6.8 [1.8-25.6]) and subtle cerebellar abnormalities, including fissure enlargement (OR=5.2 [1.1-26.2]). The diagnostic value of MRI abnormalities was considered good in 5% of patients (Alexander disease n=1, diffuse cortical malformation n=1, leukomalacia n=1, vermian agenesis n=1, commissural agenesis n=1), and weak in 48% of patients, in whom non-specific abnormalities did not lead to a diagnosis. Some clinical features resulted in a significantly higher percentage of abnormal MRI scans: abnormal neurological examination (82% vs 47%, P=0.008), abnormal skull circumference (66% vs 49%, P=0.04). Motor delay was associated with cerebellar abnormalities (P=0.01). (orig.)

Unexplained mental retardation: is brain MRI useful?

International Nuclear Information System (INIS)

Decobert, Fabrice; Merzoug, Valerie; Kalifa, Gabriel; Adamsbaum, Catherine; Grabar, Sophie; Ponsot, Gerard; Des Portes, Vincent

2005-01-01

Mental retardation (MR), defined as an IQ below 70, is a frequent cause of consultation in paediatrics. To evaluate the yield of brain MRI in the diagnostic work-up of unexplained MR in children. Patients and methods: The MRI features and clinical data of 100 patients (age 1-18 years) affected with non-progressive MR of unknown origin were compared to an age-matched control group (n=100). Two radiologists conducted an independent review of the MRI scans. Univariate and multivariate analyses showed a higher incidence of brain anomalies in the MR group than in the control group (53 vs 17, OR=5.7 [2.9-11.1]), for signal abnormalities within the periventricular white matter (OR=20.3 [2.6-155.3]), lateral ventricular dilatation (OR=15.6 [2.0-124]), mild corpus callosum abnormalities (shortness, atrophy) (OR=6.8 [1.8-25.6]) and subtle cerebellar abnormalities, including fissure enlargement (OR=5.2 [1.1-26.2]). The diagnostic value of MRI abnormalities was considered good in 5% of patients (Alexander disease n=1, diffuse cortical malformation n=1, leukomalacia n=1, vermian agenesis n=1, commissural agenesis n=1), and weak in 48% of patients, in whom non-specific abnormalities did not lead to a diagnosis. Some clinical features resulted in a significantly higher percentage of abnormal MRI scans: abnormal neurological examination (82% vs 47%, P=0.008), abnormal skull circumference (66% vs 49%, P=0.04). Motor delay was associated with cerebellar abnormalities (P=0.01). (orig.)

The use of parallel imaging for MRI assessment of knees in children and adolescents.

Science.gov (United States)

Doria, Andrea S; Chaudry, Gulraiz A; Nasui, Cristina; Rayner, Tammy; Wang, Chenghua; Moineddin, Rahim; Babyn, Paul S; White, Larry M; Sussman, Marshall S

2010-03-01

Parallel imaging provides faster scanning at the cost of reduced signal-to-noise ratio (SNR) and increased artifacts. To compare the diagnostic performance of two parallel MRI protocols (PPs) for assessment of pathologic knees using an 8-channel knee coil (reference standard, conventional protocol [CP]) and to characterize the SNR losses associated with parallel imaging. Two radiologists blindly interpreted 1.5 Tesla knee MRI images in 21 children (mean 13 years, range 9-18 years) with clinical indications for an MRI scan. Sagittal proton density, T2-W fat-saturated FSE, axial T2-W fat-saturated FSE, and coronal T1-W (NEX of 1,1,1) images were obtained with both CP and PP. Images were read for soft tissue and osteochondral findings. There was a 75% decrease in acquisition time using PP in comparison to CP. The CP and PP protocols fell within excellent or upper limits of substantial agreement: CP, kappa coefficient, 0.81 (95% CIs, 0.73-0.89); PP, 0.80-0.81 (0.73-0.89). The sensitivity of the two PPs was similar for assessment of soft (0.98-1.00) and osteochondral (0.89-0.94) tissues. Phantom data indicated an SNR of 1.67, 1.6, and 1.51 (axial, sagittal and coronal planes) between CP and PP scans. Parallel MRI provides a reliable assessment for pediatric knees in a significantly reduced scan time without affecting the diagnostic performance of MRI.

Brain tissue- and region-specific abnormalities on volumetric MRI scans in 21 patients with Bardet-Biedl syndrome (BBS

Directory of Open Access Journals (Sweden)

Johnston Jennifer

2011-07-01

Full Text Available Abstract Background Bardet-Biedl syndrome (BBS is a heterogeneous human disorder inherited in an autosomal recessive pattern, and characterized by the primary findings of obesity, polydactyly, hypogonadism, and learning and behavioural problems. BBS mouse models have a neuroanatomical phenotype consisting of third and lateral ventriculomegaly, thinning of the cerebral cortex, and reduction in the size of the corpus striatum and hippocampus. These abnormalities raise the question of whether humans with BBS have a characteristic morphologic brain phenotype. Further, although behavioral, developmental, neurological and motor defects have been noted in patients with BBS, to date, there are limited reports of brain findings in BBS. The present study represents the largest systematic evaluation for the presence of structural brain malformations and/or progressive changes, which may contribute to these functional problems. Methods A case-control study of 21 patients, most aged 13-35 years, except for 2 patients aged 4 and 8 years, who were diagnosed with BBS by clinical criteria and genetic analysis of known BBS genes, and were evaluated by qualitative and volumetric brain MRI scans. Healthy controls were matched 3:1 by age, sex and race. Statistical analysis was performed using SAS language with SAS STAT procedures. Results All 21 patients with BBS were found to have statistically significant region- and tissue-specific patterns of brain abnormalities. There was 1 normal intracranial volume; 2 reduced white matter in all regions of the brain, but most in the occipital region; 3 preserved gray matter volume, with increased cerebral cortex volume in only the occipital lobe; 4 reduced gray matter in the subcortical regions of the brain, including the caudate, putamen and thalamus, but not in the cerebellum; and 5 increased cerebrospinal fluid volume. Conclusions There are distinct and characteristic abnormalities in tissue- and region- specific volumes

High-resolution whole-brain DCE-MRI using constrained reconstruction: Prospective clinical evaluation in brain tumor patients

International Nuclear Information System (INIS)

Guo, Yi; Zhu, Yinghua; Lingala, Sajan Goud; Nayak, Krishna; Lebel, R. Marc; Shiroishi, Mark S.; Law, Meng

2016-01-01

Purpose: To clinically evaluate a highly accelerated T1-weighted dynamic contrast-enhanced (DCE) MRI technique that provides high spatial resolution and whole-brain coverage via undersampling and constrained reconstruction with multiple sparsity constraints. Methods: Conventional (rate-2 SENSE) and experimental DCE-MRI (rate-30) scans were performed 20 minutes apart in 15 brain tumor patients. The conventional clinical DCE-MRI had voxel dimensions 0.9 × 1.3 × 7.0 mm 3 , FOV 22 × 22 × 4.2 cm 3 , and the experimental DCE-MRI had voxel dimensions 0.9 × 0.9 × 1.9 mm 3 , and broader coverage 22 × 22 × 19 cm 3 . Temporal resolution was 5 s for both protocols. Time-resolved images and blood–brain barrier permeability maps were qualitatively evaluated by two radiologists. Results: The experimental DCE-MRI scans showed no loss of qualitative information in any of the cases, while achieving substantially higher spatial resolution and whole-brain spatial coverage. Average qualitative scores (from 0 to 3) were 2.1 for the experimental scans and 1.1 for the conventional clinical scans. Conclusions: The proposed DCE-MRI approach provides clinically superior image quality with higher spatial resolution and coverage than currently available approaches. These advantages may allow comprehensive permeability mapping in the brain, which is especially valuable in the setting of large lesions or multiple lesions spread throughout the brain.

Knowledge processes, distribution and alignment: Spatio-materialities and transformations in MRI praxis

DEFF Research Database (Denmark)

Yoshinaka, Yutaka

2002-01-01

This paper explores the mediation of sociomaterial practices and the spaces of their unfolding in diagnostic imaging as relates to Magnetic Resonance Imaging (MRI). In the course of an MRI exam, from the screening of the patient to the scanning itself, and onto the subsequent processing and analy......This paper explores the mediation of sociomaterial practices and the spaces of their unfolding in diagnostic imaging as relates to Magnetic Resonance Imaging (MRI). In the course of an MRI exam, from the screening of the patient to the scanning itself, and onto the subsequent processing....... The individual elements are, in and of themselves, conditioned, in part, by the ontological basis of their production, and inclusion within the new collective. The study takes its outset in this inherent tension, problematizing the knowledge processes that enter into the construction and mediation of the images...... (PACS). Paradoxically, in spite of MRI being a digital modality, the very sociomaterial contingencies of IT and electronic media come to have significant bearing on the spaces in which MRI’s can be articulated in practice through ‘filmless’ radiology....

MRI Evaluation and Safety in the Developing Brain

Science.gov (United States)

Tocchio, Shannon; Kline-Fath, Beth; Kanal, Emanuel; Schmithorst, Vincent J.; Panigrahy, Ashok

2015-01-01

Magnetic resonance imaging (MRI) evaluation of the developing brain has dramatically increased over the last decade. Faster acquisitions and the development of advanced MRI sequences such as magnetic resonance spectroscopy (MRS), diffusion tensor imaging (DTI), perfusion imaging, functional MR imaging (fMRI), and susceptibility weighted imaging (SWI), as well as the use of higher magnetic field strengths has made MRI an invaluable tool for detailed evaluation of the developing brain. This article will provide an overview of the use and challenges associated with 1.5T and 3T static magnetic fields for evaluation of the developing brain. This review will also summarize the advantages, clinical challenges and safety concerns specifically related to MRI in the fetus and newborn, including the implications of increased magnetic field strength, logistics related to transporting and monitoring of neonates during scanning, sedation considerations and a discussion of current technologies such as MRI-conditional neonatal incubators and dedicated small-foot print neonatal intensive care unit (NICU) scanners. PMID:25743582

[Dobutamine stress magnetic resonance imaging (DS-MRI), a valuable tool for the diagnosis of ischemic heart disease].

Science.gov (United States)

van Dijkman, P R M; Kuijpers, Th J A; Blom, B M; van Herpen, G

2002-07-13

Assessment of the clinical applicability of DS-MRI for the detection of myocardial ischemia and myocardial viability. Prospective. In the period from 1 November 1999 to 31 October 2000, patients with suspected coronary artery disease who could not be studied by means of conventional bicycle ergometry underwent breath-hold DS-MRI (1 Tesla) 4 days after cessation of anti-ischemic medication. Three left ventricular short-axis planes were examined for the occurrence of disorders in wall movement during infusion of increasing doses of dobutamine (10, 20, 30 and 40 micrograms/kg/min). Temporary recovery of wall thickening in a previously diminished or non-contracting segment under 5 micrograms/kg/min of dobutamine was considered proof of viability. Development of hypo-, a- or dyskinesia at higher doses of dobutamine was taken to indicate ischemia. If the DS-MRI test was positive for ischemia, coronary angiography was performed. If indicated, this was followed by revascularisation. If DS-MRI did not reveal ischemia, the patient was seen at the outpatient department. Of the 100 patients (62 men and 38 women with an average age of 62 years, SD = 12) subjected to DS-MRI, 95 yielded results that were suitable for diagnosis. Of the 42 patients with DS-MRI scans that were considered positive for ischemia and in whom coronary angiography was subsequently performed, 41 had such coronary abnormalities that revascularisation was indicated. One patient was false-positive. All 53 patients with non-ischemic DS-MRI scans were followed-up for 11-23 months (mean 17 months). One patient died suddenly 2 weeks after the MRI-test. The other 52 patients did not experience any coronary events nor sudden cardiac death. The predictive value of a positive DS-MRI scan for ischemia was 98% and the predictive value of a negative DS-MRI scan was also 98%. DS-MRI is a safe diagnostic method for the detection or exclusion of myocardial ischemia and viability in patients with suspected coronary artery

Positive findings on bone scan in multiple myeloma

International Nuclear Information System (INIS)

Lin Lin

2004-01-01

We report a case of multiple myeloma in which the CT only shows osteolytic lesions and MRI only shows compressive fractrue, but the scan shows some interesting imaging that make us to think of multiple myeloma. (authors)

Prenatal MRI evaluation of limb-body wall complex

Energy Technology Data Exchange (ETDEWEB)

Aguirre-Pascual, Elisa [Perelman School of Medicine at the University of Pennsylvania, Department of Radiology, The Children' s Hospital of Philadelphia, Philadelphia, PA (United States); Hospital Universitario Doce de Octubre, Department of Radiology, Madrid (Spain); Epelman, Monica [Perelman School of Medicine at the University of Pennsylvania, Department of Radiology, The Children' s Hospital of Philadelphia, Philadelphia, PA (United States); Nemours Children' s Hospital, Department of Medical Imaging, Orlando, FL (United States); Johnson, Ann M.; Chauvin, Nancy A.; Coleman, Beverly G.; Victoria, Teresa [Perelman School of Medicine at the University of Pennsylvania, Department of Radiology, The Children' s Hospital of Philadelphia, Philadelphia, PA (United States)

2014-11-15

The sonographic (US) features of limb-body wall complex have been well documented; however the literature regarding the findings on MRI in limb-body wall complex is scant. To characterize the prenatal MRI features of limb-body wall complex. We performed a retrospective review of all MRI scans of fetuses diagnosed with limb-body wall complex at our institution from 2001 to 2011. Fetuses without correlating US scans or follow-up information were excluded. Three pediatric radiologists blinded to the specific US findings reviewed the prenatal MRIs. Images were evaluated for the organ location and attachment, the body part affected, characterization of the body wall defect, and spinal, limb and umbilical cord abnormalities. Ten subjects met inclusion criteria. MRI was able to detect and characterize the body part affected and associated abnormalities. All fetuses had ventral wall defects, a small thorax and herniated liver and bowel. The kidneys were extracorporeal in three cases. The extruded organs were attached to the placenta or the uterine wall in all cases. Abnormal spinal curvatures of various degrees of severity were present in all cases. Eight cases had a short, uncoiled cord. Limb anomalies were present in 6 of the 10 cases. We illustrate the common fetal MRI findings of limb-body wall complex. The prenatal diagnosis of limb-body wall complex and the differentiation of this defect from treatable abdominal wall defects are crucial to providing appropriate guidance for patient counseling and management. (orig.)

MRI-only treatment planning: benefits and challenges

Science.gov (United States)

Owrangi, Amir M.; Greer, Peter B.; Glide-Hurst, Carri K.

2018-03-01

Over the past decade, the application of magnetic resonance imaging (MRI) has increased, and there is growing evidence to suggest that improvements in the accuracy of target delineation in MRI-guided radiation therapy may improve clinical outcomes in a variety of cancer types. However, some considerations should be recognized including patient motion during image acquisition and geometric accuracy of images. Moreover, MR-compatible immobilization devices need to be used when acquiring images in the treatment position while minimizing patient motion during the scan time. Finally, synthetic CT images (i.e. electron density maps) and digitally reconstructed radiograph images should be generated from MRI images for dose calculation and image guidance prior to treatment. A short review of the concepts and techniques that have been developed for implementation of MRI-only workflows in radiation therapy is provided in this document.

Three dimensional and high resolution magnetic resonance imaging of the inner ear. Normal ears and anomaly scanned with 3D-CISS sequence

International Nuclear Information System (INIS)

Edamatsu, Hideo; Uechi, Yoko; Honjyo, Shiro; Yamashita, Koichi; Tonami, Hisao.

1997-01-01

The MRI system used in this study was a new scanning sequence, 3D-CISS (Three dimensional-constructive interference in steady state) with 1.5 Tesla. Ten normal ears and one ear with Mondini type anomaly were scanned and reconstructed. In imagings of normal inner ears, the cochlea has three spiral layers; basal, middle and apical turns. Each turn was separated into three parts; the scala vestibuli, osseous spiral lamina and scala tympani. Three semicircular ducts, utricle and saccule were also reconstructed in one frame. In the inner ear of Mondini anomaly, 3D MRI showed cochlear aplasia, hypoplasia of semicircular ducts and widely dilated vestibule. The imaging was identical with findings of ''common cavity''. The anomaly was easily recognized in 3D MRI more than in 2D imagings. The detailed and cubic imagings of the Mondini anomaly in 3D MRI could not be observed with conventional 2D MRI. 3D MRI is not invasive method and can scan a target very quickly. (author)

Comparison of MRI and DXA to measure muscle size and age-related atrophy in thigh muscles.

Science.gov (United States)

Maden-Wilkinson, T M; Degens, H; Jones, D A; McPhee, J S

2013-09-01

Magnetic resonance imaging (MRI) and dual-energy x-ray absorptiometry (DXA) were used to examine the thigh lean mass in young and old men and women. A whole-body DXA scan was used to estimate thigh lean mass in young (20 men; 22.4±3.1y; 18 women; 22.1±2.0y) and older adults (25 men; 72.3±4.9y; 28 women; 72.0±4.5y). Thigh lean mass determined with a thigh scan on the DXA or full thigh MRI scans were compared. Although the thigh lean mass quantified by DXA and MRI in young and older participants were correlated (R(2)=0.88; polder than young individuals, while the other thigh muscles were only 18% smaller. DXA underestimates the age-related loss of thigh muscle mass in comparison to MRI. The quadriceps muscles were more susceptible to age-related atrophy compared with other thigh muscles.

'Peripheric' pancreatic cysts: performance of CT scan, MRI and endoscopy according to final pathological examination.

Science.gov (United States)

Duconseil, P; Turrini, O; Ewald, J; Soussan, J; Sarran, A; Gasmi, M; Moutardier, V; Delpero, J R

2015-06-01

To assess the accuracy of pre-operative staging in patients with peripheral pancreatic cystic neoplasms (pPCNs). From 2005 to 2011, 148 patients underwent a pancreatectomy for pPCNs. The pre-operative examination methods of computed tomography (CT), magnetic resonance imaging (MRI), endoscopic ultrasonography (EUS) were compared for their ability to predict the suggested diagnosis accurately, and the definitive diagnosis was affirmed by pathological examination. A mural nodule was detected in 34 patients (23%): only 1 patient (3%) had an invasive pPCN at the final histological examination. A biopsy was performed in 79 patients (53%) during EUS: in 55 patients (70%), the biopsy could not conclude a diagnosis; the biopsy provided the correct and wrong diagnosis in 19 patients (24%) and 5 patients (6%), respectively. A correct diagnosis was affirmed by CT, EUS and pancreatic MRI in 60 (41%), 103 (74%) and 80 (86%) patients (when comparing EUS and MRI; P = 0.03), respectively. The positive predictive values (PPVs) of CT, EUS and MRI were 70%, 75% and 87%, respectively. Pancreatic MRI appears to be the most appropriate examination to diagnose pPCNs accurately. EUS alone had a poor PPV. Mural nodules in a PCN should not be considered an indisputable sign of pPCN invasiveness. © 2015 International Hepato-Pancreato-Biliary Association.

MRI findings of Guillain-Barre syndrome

Energy Technology Data Exchange (ETDEWEB)

Park, Won Kyu; Lee, Hwa Jin; Byun, Woo Mok [Yeungnam Univ. College of Medicine, Taegu (Korea, Republic of)

1997-04-01

To evaluate MRI findings of Guillain-Barre syndrome. In six patients with Guillain-Barre syndrome diagnosed by clinical, cerebrospinal fluid and electrophysiologic findings, a retrospective review of MR findings was conducted. Follow-up MRI scans were carried out in two patients showing minimal clinical improvement. Marked or moderate enhancement of thickened nerve roots was seen in all cases on gadopentetate dimeglumine enhanced axial T1-weighted images. Two patterns were seen; one was even enhancement of both anterior and posterior nerve roots (n=1) and the other was enhancement of anterior nerve roots only (n=5). Enhancement and thickness of nerve roots was seen to have slightly decreased on MRI follow-up at 32 and 50 days; clinical and electrophysiologic examination showed minimal improvement. Although MRI findings of nerve root enhancement are nonspecific and can be seen in neoplastic and other inflammatory diseases, the enhancement of thickened anterior nerve roots within the cal sac suggests Guillain-Barre syndrome.

MRI findings of Guillain-Barre syndrome

International Nuclear Information System (INIS)

Park, Won Kyu; Lee, Hwa Jin; Byun, Woo Mok

1997-01-01

To evaluate MRI findings of Guillain-Barre syndrome. In six patients with Guillain-Barre syndrome diagnosed by clinical, cerebrospinal fluid and electrophysiologic findings, a retrospective review of MR findings was conducted. Follow-up MRI scans were carried out in two patients showing minimal clinical improvement. Marked or moderate enhancement of thickened nerve roots was seen in all cases on gadopentetate dimeglumine enhanced axial T1-weighted images. Two patterns were seen; one was even enhancement of both anterior and posterior nerve roots (n=1) and the other was enhancement of anterior nerve roots only (n=5). Enhancement and thickness of nerve roots was seen to have slightly decreased on MRI follow-up at 32 and 50 days; clinical and electrophysiologic examination showed minimal improvement. Although MRI findings of nerve root enhancement are nonspecific and can be seen in neoplastic and other inflammatory diseases, the enhancement of thickened anterior nerve roots within the cal sac suggests Guillain-Barre syndrome

Position-history and spin-history artifacts in fMRI time-series

NARCIS (Netherlands)

Muresan, L; Renken, R; Roerdink, JBTM; Duifhuis, H; Clough, AN; Chen, CT

2002-01-01

What is the impact of the spin history and position history on signal intensity after the alignment of acquired volumes? This question arises in many fMRI studies. We will focus on spin-history artefacts generated by the position-history of the scanned object. In fMRI an object is driven to steady

Automatic delineation of brain regions on MRI and PET images from the pig.

Science.gov (United States)

Villadsen, Jonas; Hansen, Hanne D; Jørgensen, Louise M; Keller, Sune H; Andersen, Flemming L; Petersen, Ida N; Knudsen, Gitte M; Svarer, Claus

2018-01-15

The increasing use of the pig as a research model in neuroimaging requires standardized processing tools. For example, extraction of regional dynamic time series from brain PET images requires parcellation procedures that benefit from being automated. Manual inter-modality spatial normalization to a MRI atlas is operator-dependent, time-consuming, and can be inaccurate with lack of cortical radiotracer binding or skull uptake. A parcellated PET template that allows for automatic spatial normalization to PET images of any radiotracer. MRI and [ 11 C]Cimbi-36 PET scans obtained in sixteen pigs made the basis for the atlas. The high resolution MRI scans allowed for creation of an accurately averaged MRI template. By aligning the within-subject PET scans to their MRI counterparts, an averaged PET template was created in the same space. We developed an automatic procedure for spatial normalization of the averaged PET template to new PET images and hereby facilitated transfer of the atlas regional parcellation. Evaluation of the automatic spatial normalization procedure found the median voxel displacement to be 0.22±0.08mm using the MRI template with individual MRI images and 0.92±0.26mm using the PET template with individual [ 11 C]Cimbi-36 PET images. We tested the automatic procedure by assessing eleven PET radiotracers with different kinetics and spatial distributions by using perfusion-weighted images of early PET time frames. We here present an automatic procedure for accurate and reproducible spatial normalization and parcellation of pig PET images of any radiotracer with reasonable blood-brain barrier penetration. Copyright © 2017 Elsevier B.V. All rights reserved.

The evaluation of CT and MRI in the diagnosis of pancreatic tuberculosis and peripancreatic tuberculous lymphadenopathy

International Nuclear Information System (INIS)

Yang Zenian; Wang Xiaoyan; Peng Zhenpeng; Lin Jianqin; Zhang Ting

2008-01-01

Objective: To study the manifestations and its pathologic basis of pancreatic tubeiculosis and peripancreatic tuberculous lymphadenopathy. And evaluate the diagnostic values of CT and MRI. Methods: Two cases of pancreatic tuberculosis and eleven cases of peripancreatic tuberculous lymphadenopathy were collected. All cases were conformed by pathology or clinic. Plain scan and enhanced scan with spiral CT were performed in all cases. Plain scan and enhanced scan with MRI were performed in two cases. The CT and MRI features of 13 cases were analyzed retrospectively. Results: Pancreatic tuberculosis showed that the lesion was located mainly at the head of the pancreas and displayed on CT as a low-density mass with marginal or honeycomb enhancement. Peripancreatic tuberculous lymphadenopathy was seen in 11 cases, of which ring-like enhancement was seen in seven cases, calcifications in two cases and mixed in two cases. Splenic involvement was found in five cases. Conclusion: Pancreatic tuberculosis and peripancreatic tuberculous lymphadenopathy have the main features of low-density mass With marginal or honeycomb enhancement and ting-like enhancement in petipancreatic lymphadenopathy. CT and MRI are feasible methods in diagnosis of pancreatic tuberculosis and peripancreatic tuberculous lymphadenopathy. (authors)

Animated educational video to prepare children for MRI without sedation: evaluation of the appeal and value

International Nuclear Information System (INIS)

Szeszak, Szofia; Man, Rachel; Love, Andrew; Langmack, Gill; Wharrad, Heather; Dineen, Robert A.

2016-01-01

MRI scans can be distressing for children and often require sedation. Educating children about what to expect reduces anxiety and increases likelihood of successful non-sedated MRI scans. Multimedia tools are a popular means of education. Animated video could provide a free, accessible method of preparing children for MRI scans. To evaluate a new animation video for preparing children for MRI, specifically for decreasing in-scanner motion and examination failure. We recruited 24 healthy children ages 5-11 years. Participants underwent pre- and post-viewing questionnaires and structured interviews. We then compared median Likert scale score changes between pre- and post-animation questions and analyzed the interview framework. Participants were filmed viewing the animation to calculate time spent looking at the screen to assess how well the video retained children's attention. There were significant improvements in median scores regarding what to expect, checking for metal and keeping still. There were no significant changes in other knowledge-based topics. There were significant improvements in median scores for anxiety-based topics. On average, children watched the screen for 98.9% of the 174-s animation. The animation improved knowledge, reduced anxiety, retained attention and was enjoyed by participants. It can be accessed freely via the Internet to help prepare children ages 5-11 for having an MRI scan. (orig.)

Animated educational video to prepare children for MRI without sedation: evaluation of the appeal and value

Energy Technology Data Exchange (ETDEWEB)

Szeszak, Szofia [University of Nottingham, Radiological Sciences, Division of Clinical Neuroscience, Queen' s Medical Centre, Nottingham (United Kingdom); Man, Rachel; Love, Andrew [Nottingham Trent University, School of Art and Design, Nottingham (United Kingdom); Langmack, Gill; Wharrad, Heather [University of Nottingham, Health E-learning and Media group, School of Health Sciences, Queen' s Medical Centre, Nottingham (United Kingdom); Dineen, Robert A. [University of Nottingham, Radiological Sciences, Division of Clinical Neuroscience, Queen' s Medical Centre, Nottingham (United Kingdom); University of Nottingham, Sir Peter Mansfield Imaging Centre, Queen' s Medical Centre, Nottingham (United Kingdom)

2016-11-15

MRI scans can be distressing for children and often require sedation. Educating children about what to expect reduces anxiety and increases likelihood of successful non-sedated MRI scans. Multimedia tools are a popular means of education. Animated video could provide a free, accessible method of preparing children for MRI scans. To evaluate a new animation video for preparing children for MRI, specifically for decreasing in-scanner motion and examination failure. We recruited 24 healthy children ages 5-11 years. Participants underwent pre- and post-viewing questionnaires and structured interviews. We then compared median Likert scale score changes between pre- and post-animation questions and analyzed the interview framework. Participants were filmed viewing the animation to calculate time spent looking at the screen to assess how well the video retained children's attention. There were significant improvements in median scores regarding what to expect, checking for metal and keeping still. There were no significant changes in other knowledge-based topics. There were significant improvements in median scores for anxiety-based topics. On average, children watched the screen for 98.9% of the 174-s animation. The animation improved knowledge, reduced anxiety, retained attention and was enjoyed by participants. It can be accessed freely via the Internet to help prepare children ages 5-11 for having an MRI scan. (orig.)

Pathological findings correlated with MRI in HIV infection

International Nuclear Information System (INIS)

Hawkins, C.P.; McLaughlin, J.E.; Kendall, B.E.; McDonald W.I.

1993-01-01

MRI forms an important part of the assessment of patients with HIV-related disease presenting with cerebral symptoms. Eleven formalin-fixed brains were studied at 0.5 T using T2- and T1-weighted sequences. In two cases of progressive multifocal leucoencephalopathy and one case each of toxoplasmosis and lymphoma, the extent of white matter abnormality seen on MRI corresponded broadly with that on pathological examination. In general, however, histological changes were more frequent than lesions on MRI. Cases in wich abnormalities were not seen with standard MRI included those with multiple tuberculous granulomata, multinucleate giant cells, microglial nodules, perivascular cuffing and cytomegalovirus inclusions. A common finding on MRI was punctate or patchy high signal in the basal ganglia on T2-weighted scans, seen in six cases. Corresponding histological changes included calcification of vessels with widened perivascular spaces, and mineralised neurones. (orig.)

Clinical efficacy of FDG-PET scan in the patients with primary or recurrent gynecologic malignancies: clinical experiences with FDG-PET scan in cervical carcinoma of uterus

Energy Technology Data Exchange (ETDEWEB)

Kim, Jong Hoon

1998-12-01

This study was done to evaluate the clinical feasibility of FDG-PET scan in patients with cervical carcinoma. PET-scans were performed in 74 patients with cervical carcinoma from March, 1998 to September, 1998. Fourteen cases were done at pretreatment period and sixty cases were done at post-treatment follow up period. In this study, the scans were obtained after bladder emptying by foley catheter insertion and diuretics to reduce the tracer activity in the bladder and improve the images of central lesions. We could find some incidental recurrent or metastatic lesions by FDG-PET scan (at pretreatment; 5 cases, at post-treatment; clinically no evidence of disease; 8 cases). FDG-PET scan had high sensitivity (100%) for central lesions and metastatic lymph nodes of cervical cancer but could not precisely define the anatomic location of the cancer and the sensitivity was not superior than MRI. Earlier detection of metastatic lymph nodes was superior than CT/MRI (sensitivity; 100 %) for metastatic lymph nodes. Also we found 3 double primary cancers incidentally (2 lung cancers and 1 thyroid cancer). In conclusion, FDG-FET scan might be useful for the earlier of hidden lesions that cannot be detected by routine conventional methods and differential diagnosis with radiation fibrosis and benign lymph adenophy.

Musculoskeletal MRI: dedicated systems

International Nuclear Information System (INIS)

Masciocchi, C.; Barile, A.; Satragno, L.

2000-01-01

The ''dedicated'' MRI units have characteristics of high diagnostic accuracy and lower installation and management costs as compared with whole-body systems. The dedicated MRI units are easy to install. The low weight allows their installation also under unfavorable circumstances. In a dedicated system cost-effectiveness and ease of installation must be accompanied by the capability of providing high-quality images. In our experience, the high number of examinations performed, the most part of which provided with the surgical controls, allowed an accurate evaluation of the diagnostic potentialities of the dedicated magnet. We were not able to perform the examinations in only 3 % of cases due to the physical shape of the patient and the clinical condition of the patient which may hinder the correct positioning of the limb. The overlapping of the diagnostic accuracy of the E-scan and Artoscan units in the study of the lower limbs, compared with whole-body units and surgery, prompted us to exploit the potentialities of the E-Scan in the study of the shoulder. We had a good correlation between E-Scan, whole-body units, and surgical findings, which confirmed the high diagnostic accuracy of the dedicated system. In conclusion, in our experience carried out in the musculoskeletal system, the dedicated magnets showed promising results. Their diagnostic reliability and utility was comparable to that obtained from conventional units operating at higher magnetic fields. (orig.)

Mechanisms of cognitive impairment in cerebral small vessel disease: multimodal MRI results from the St George's cognition and neuroimaging in stroke (SCANS study.

Directory of Open Access Journals (Sweden)

Andrew J Lawrence

Full Text Available Cerebral small vessel disease (SVD is a common cause of vascular cognitive impairment. A number of disease features can be assessed on MRI including lacunar infarcts, T2 lesion volume, brain atrophy, and cerebral microbleeds. In addition, diffusion tensor imaging (DTI is sensitive to disruption of white matter ultrastructure, and recently it has been suggested that additional information on the pattern of damage may be obtained from axial diffusivity, a proposed marker of axonal damage, and radial diffusivity, an indicator of demyelination. We determined the contribution of these whole brain MRI markers to cognitive impairment in SVD. Consecutive patients with lacunar stroke and confluent leukoaraiosis were recruited into the ongoing SCANS study of cognitive impairment in SVD (n = 115, and underwent neuropsychological assessment and multimodal MRI. SVD subjects displayed poor performance on tests of executive function and processing speed. In the SVD group brain volume was lower, white matter hyperintensity volume higher and all diffusion characteristics differed significantly from control subjects (n = 50. On multi-predictor analysis independent predictors of executive function in SVD were lacunar infarct count and diffusivity of normal appearing white matter on DTI. Independent predictors of processing speed were lacunar infarct count and brain atrophy. Radial diffusivity was a stronger DTI predictor than axial diffusivity, suggesting ischaemic demyelination, seen neuropathologically in SVD, may be an important predictor of cognitive impairment in SVD. Our study provides information on the mechanism of cognitive impairment in SVD.

Clinical evaluation of 3D/3D MRI-CBCT automatching on brain tumors for online patient setup verification - A step towards MRI-based treatment planning

DEFF Research Database (Denmark)

Buhl, S.K.; Duun-Christensen, Anne Katrine; Kristensen, B.H.

2010-01-01

undergoing postoperative radiotherapy for malignant brain tumors received a weekly CBCT. In total 18 scans was matched with both CT and MRI as reference. The CBCT scans were acquired using a Clinac iX 2300 linear accelerator (Varian Medical Systems) with an On-Board Imager (OBI). Results. For the phantom...

Time-delayed contrast-enhanced MRI improves detection of brain metastases and apparent treatment volumes.

Science.gov (United States)

Kushnirsky, Marina; Nguyen, Vinh; Katz, Joel S; Steinklein, Jared; Rosen, Lisa; Warshall, Craig; Schulder, Michael; Knisely, Jonathan P S

2016-02-01

Contrast-enhanced MRI is the preeminent diagnostic test for brain metastasis (BM). Detection of BMs for stereotactic radiosurgery (SRS) planning may improve with a time delay following administration of a high-relaxivity agent for 1.5-T and 3-T imaging systems. Metastasis detection with time-delayed MRI was evaluated in this study. Fifty-three volumetric MRI studies from 38 patients undergoing SRS for BMs were evaluated. All studies used 0.1-mmol/kg gadobenate dimeglumine (MultiHance; Bracco Diagnostics) immediately after injection, followed by 2 more axial T1-weighted sequences after 5-minute intervals (final image acquisition commenced 15 minutes after contrast injection). Two studies were motion limited and excluded. Two hundred eighty-seven BMs were identified. The studies were randomized and examined separately by 3 radiologists, who were blinded to the temporal sequence. Each radiologist recorded the number of BMs detected per scan. A Wilcoxon signed-rank test compared BM numbers between scans. One radiologist determined the scan on which BMs were best defined. All confirmed, visible tumors were contoured using iPlan RT treatment planning software on each of the 3 MRI data sets. A linear mixed model was used to analyze volume changes. The interclass correlations for Scans 1, 2, and 3 were 0.7392, 0.7951, and 0.7290, respectively, demonstrating excellent interrater reliability. At least 1 new lesion was detected in the second scan as compared with the first in 35.3% of subjects (95% CI 22.4%-49.9%). The increase in BM numbers between Scans 1 and 2 ranged from 1 to 10. At least 1 new lesion was detected in the third scan as compared with the second in 21.6% of subjects (95% CI 11.3%-35.3%). The increase in BM numbers between Scans 2 and 3 ranged from 1 to 9. Between Scans 1 and 3, additional tumors were seen on 43.1% of scans (increase ranged from 1 to 14). The median increase in tumor number for all comparisons was 1. There was a significant increase in number

Estimating achievable signal-to-noise ratios of MRI transmit-receive coils from radiofrequency power measurements: applications in quality control

International Nuclear Information System (INIS)

Redpath, T.W.

2000-01-01

The inverse relationship between the radiofrequency (RF) power needed to transmit a 90 deg. RF pulse, and the signal-to-noise ratio (SNR) available from a transmit-receive RF coil is well known. The theory is restated and a formula given for the signal-to-noise ratio from water, achievable from a single-shot MRI experiment, in terms of the net forward RF power needed for a rectangular 90 deg. RF pulse of known shape and duration. The result is normalized to a signal bandwidth of 1 Hz and a sample mass of 1 g. The RF power information needed is available on most commercial scanners, as it is used to calculate specific absorption rates for RF tissue heating. The achievable SNR figure will normally be larger that that actually observed, mainly because of receiver noise, but also because of inaccuracies in setting RF pulse angles, and relaxation effects. Phantom experiments were performed on the transmit-receive RF head coil of a commercial MRI system at 0.95 T using a projection method. The measured SNR agreed with that expected from the formula for achievable SNR once a correction was made for the noise figure of the receiving chain. Comparisons of measured SNR figures with those calculated from RF power measurements are expected to be of value in acceptance testing and quality control. (author)

Automatic, accurate, and reproducible segmentation of the brain and cerebro-spinal fluid in T1-weighted volume MRI scans and its application to serial cerebral and intracranial volumetry

Science.gov (United States)

Lemieux, Louis

2001-07-01

A new fully automatic algorithm for the segmentation of the brain and cerebro-spinal fluid (CSF) from T1-weighted volume MRI scans of the head was specifically developed in the context of serial intra-cranial volumetry. The method is an extension of a previously published brain extraction algorithm. The brain mask is used as a basis for CSF segmentation based on morphological operations, automatic histogram analysis and thresholding. Brain segmentation is then obtained by iterative tracking of the brain-CSF interface. Grey matter (GM), white matter (WM) and CSF volumes are calculated based on a model of intensity probability distribution that includes partial volume effects. Accuracy was assessed using a digital phantom scan. Reproducibility was assessed by segmenting pairs of scans from 20 normal subjects scanned 8 months apart and 11 patients with epilepsy scanned 3.5 years apart. Segmentation accuracy as measured by overlap was 98% for the brain and 96% for the intra-cranial tissues. The volume errors were: total brain (TBV): -1.0%, intra-cranial (ICV):0.1%, CSF: +4.8%. For repeated scans, matching resulted in improved reproducibility. In the controls, the coefficient of reliability (CR) was 1.5% for the TVB and 1.0% for the ICV. In the patients, the Cr for the ICV was 1.2%.

A rare combination of cardiopulmonary anomalies demonstrated on ventilation-perfusion scan

International Nuclear Information System (INIS)

Khan, S.; Dunn, J.; Al-Nahhas, A.; Ariff, B.; Juli, C.; Karunanithy, N.; Strickland, N.

2008-01-01

In this case report we describe an unusual appearance seen on a ventilation-perfusion (V/Q) scan in a woman with pulmonary hypertension. Although the pulmonary hypertension was not caused by pulmonary emboli, the V/Q scan suggested several cardiac anomalies which may lead to pulmonary hypertension. Most of the cardiac anomalies, including right-sided aortic arch and right-to-left shunt, can be deduced from careful examination of the V/Q scan. A subsequent cardiac MRI scan confirmed the anomalies. (authors)

The hemodynamic response of the alpha rhythm: an EEG/fMRI study.

NARCIS (Netherlands)

de Munck, J.C.; Goncalves, S.I.; Huijboom, L.; Kuijer, J.P.; Pouwels, P.J.; Heethaar, R.M.; Lopes da Silva, F.H.

2007-01-01

EEG was recorded during fMRI scanning of 16 normal controls in resting condition with eyes closed. Time variations of the occipital alpha band amplitudes were correlated to the fMRI signal variations to obtain insight into the hemodynamic correlates of the EEG alpha activity. Contrary to earlier

Age determination of subdural hematomas with CT and MRI: A systematic review

Energy Technology Data Exchange (ETDEWEB)

Sieswerda-Hoogendoorn, Tessa, E-mail: t.sieswerda@amc.nl [Section of Forensic Pediatrics, Department of Forensic Medicine, Netherlands Forensic Institute, PO Box 24044, 2490 AA The Hague (Netherlands); Department of Radiology, Academic Medical Center/Emma Children' s Hospital, Meibergdreef 9, 1105 AZ Amsterdam (Netherlands); Postema, Floor A.M., E-mail: f.a.postema@amc.nl [Faculty of Medicine, University of Amsterdam, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam (Netherlands); Verbaan, Dagmar, E-mail: d.verbaan@amc.nl [Department of Neurosurgery, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam (Netherlands); Majoie, Charles B., E-mail: c.b.majoie@amc.nl [Department of Radiology, Academic Medical Center/Emma Children' s Hospital, Meibergdreef 9, 1105 AZ Amsterdam (Netherlands); Rijn, Rick R. van, E-mail: r.r.vanrijn@amc.nl [Section of Forensic Pediatrics, Department of Forensic Medicine, Netherlands Forensic Institute, PO Box 24044, 2490 AA The Hague (Netherlands); Department of Radiology, Academic Medical Center/Emma Children' s Hospital, Meibergdreef 9, 1105 AZ Amsterdam (Netherlands)

2014-07-15

Objectives: To systematically review the literature on dating subdural hematomas (SDHs) on CT and MRI scans. Methods: We performed a systematic review in MEDLINE, EMBASE and Cochrane to search for articles that described the appearance of SDHs on CT or MRI in relation to time between trauma and scanning. Two researchers independently screened the articles, assessed methodological quality and performed data extraction. Medians with interquartile ranges were calculated. Differences were tested with a Mann–Whitney U or Kruskal–Wallis H test. Results: We included 22 studies describing 973 SDHs on CT and 4 studies describing 83 SDHs on MRI. Data from 17 studies (413 SDHs) could be pooled. There were significant differences between time intervals for the different densities on CT (p < 0.001). Time interval differed significantly between children and adults for iso- and hypodensity (p = 0.000) and hyperdensity (p = 0.046). Time interval did not differ significantly between abused and non-abused children. On MRI, time intervals for different signal intensities on T1 and T2 did not differ significantly (p = 0.108 and p = 0.194, respectively). Conclusions: Most time intervals of the different appearances of SDHs on CT and MRI are broad and overlapping. Therefore CT or MRI findings cannot be used to accurately date SDHs.

Age determination of subdural hematomas with CT and MRI: A systematic review

International Nuclear Information System (INIS)

Sieswerda-Hoogendoorn, Tessa; Postema, Floor A.M.; Verbaan, Dagmar; Majoie, Charles B.; Rijn, Rick R. van

2014-01-01

Objectives: To systematically review the literature on dating subdural hematomas (SDHs) on CT and MRI scans. Methods: We performed a systematic review in MEDLINE, EMBASE and Cochrane to search for articles that described the appearance of SDHs on CT or MRI in relation to time between trauma and scanning. Two researchers independently screened the articles, assessed methodological quality and performed data extraction. Medians with interquartile ranges were calculated. Differences were tested with a Mann–Whitney U or Kruskal–Wallis H test. Results: We included 22 studies describing 973 SDHs on CT and 4 studies describing 83 SDHs on MRI. Data from 17 studies (413 SDHs) could be pooled. There were significant differences between time intervals for the different densities on CT (p < 0.001). Time interval differed significantly between children and adults for iso- and hypodensity (p = 0.000) and hyperdensity (p = 0.046). Time interval did not differ significantly between abused and non-abused children. On MRI, time intervals for different signal intensities on T1 and T2 did not differ significantly (p = 0.108 and p = 0.194, respectively). Conclusions: Most time intervals of the different appearances of SDHs on CT and MRI are broad and overlapping. Therefore CT or MRI findings cannot be used to accurately date SDHs

Comparative study between MRI and echocardiography in noncompaction of ventricular myocardium

International Nuclear Information System (INIS)

Sun Ziyan; Xia Liming; Wang Chengyuan; Rao Jingjing; Shenyu Weihui

2007-01-01

Objective: To investigate the MRI and echocardiography manifestations of noncompaction of ventricular myocardium(NVM) and assess the role of MR1 in the diagnosis of NVM by comparing it with echocardiography. Methods: Fourteen cases of NVM diagnosed by echocardiography were examined with MRI, including scanning of black-blood sequences, double inversion recovery fast spin echo (DIBFSE) and triple inversion recovery fast spin echo (TIRFSE), and white blood sequence: fast imaging employ steady state acquisition (FIESTA). Scanning plane includes short axis view, four-chamber view and long axis view. Results: Both MRI and echocardiography displayed involvement of left ventricles in thirteen cases and involvement of double ventricles in one case. Apexes of heart and the intermedius are commonly affected. MRI showed 54 segments and echocardiography showed 53 segments affected, and there is no significant difference between the capability of MRI and echocardiography (P=1,000). The affected myocardium consisted of two layers: subendocardial noncompacted myocardium and epicardial compacted myocardium, and the ratio measurement of N/C by MRI was 3.37±0.89 and it was 3.19±0.82 by echocardiography. Noncompacted myocardium was characterized by prominent and excessive myocardial trabeculations and deep intratrabecular recesses, in which the blood flow was communicated with the ventricle. One case was complicated with ventricular aneurysm, and coronary arteriography was performed with unremarkable findings. One case underwent heart transplantation because of progressive heart failure, Gross findings demonstrated prominent muscular' trabeculations with deep intratrabecular recesses, which coincided well with MRI findings. Conclusion: The MRI manifestation of NVM is characteristic, and MRI with multiple series and planes is helpful in the diagnose of NVM. Compared with echocardiography, MRI could display the pathological cardiac muscle more clearly, because of its high soft

Lead arthropathy: radiographic, CT and MRI findings

International Nuclear Information System (INIS)

Fernandes, Joao Luiz; Lopes Rocha, Arthemizio Antonio; Veloso Ayrimoraes Soares, Mayra; Lopes Viana, Sergio

2007-01-01

Lead arthropathy is a well-known complication of gunshot injuries with retained intra-articular bullets. Although several previous reports have discussed the radiological findings of this entity, computed tomography (CT) and magnetic resonance imaging (MRI) findings have never been described before in this setting. In this paper the authors review the imaging findings of 11 patients with lead arthropathy (1 of whom had clinical signs of lead poisoning as well), all of them studied by means of radiographs. In addition, non-enhanced CT scans were obtained in 3 patients and gadolinium-enhanced MRI in 1. Classic findings of intra-articular speckled lead deposits (occasionally with a ''lead arthrogram'' appearance), joint space narrowing and preserved bone density were found at radiographs in the great majority of cases. Furthermore, extension of intra-articular lead to adjacent tendon sheaths was observed in almost half of the patients, an observation rarely reported in the literature. CT scans and MRI, in their turn, were superior with regard to soft tissue abnormalities, accurately depicting joint effusion and the thickened synovium with lead particles embedded in it. Post-gadolinium MRI had the advantage of showing the enhancement pattern of the inflamed synovium and associated bone marrow edema pattern. Although it is not possible to establish the role of axial imaging in lead arthropathy from the small number of cases studied, this initial experience shows that both methods hold promise in this setting and may be useful, at least in selected cases. (orig.)

Improved detection of localized prostate cancer using co-registered MRI and {sup 11}C-acetate PET/CT

Energy Technology Data Exchange (ETDEWEB)

Jambor, Ivan, E-mail: ivjamb@utu.fi [Department of Diagnostic Radiology, University of Turku, Turku (Finland); 2nd Department of Radiology, Comenius University and St. Elisabeth Oncology Institute, Bratislava (Slovakia); Turku PET Centre, University of Turku, Turku (Finland); Borra, Ronald, E-mail: ronald.borra@tyks.fi [Department of Diagnostic Radiology, University of Turku, Turku (Finland); Turku PET Centre, University of Turku, Turku (Finland); Medical Imaging Centre of Southwest Finland, Turku University Hospital, Turku (Finland); Kemppainen, Jukka, E-mail: Jukka.Kemppainen@tyks.fi [Turku PET Centre, University of Turku, Turku (Finland); Department of Clinical Physiology and Nuclear Medicine, Turku University Hospital, Turku (Finland); Lepomaeki, Virva, E-mail: Virva.Lepomaki@tyks.fi [Turku PET Centre, University of Turku, Turku (Finland); Parkkola, Riitta, E-mail: Riitta.Parkkola@tyks.fi [Department of Diagnostic Radiology, University of Turku, Turku (Finland); Turku PET Centre, University of Turku, Turku (Finland); Medical Imaging Centre of Southwest Finland, Turku University Hospital, Turku (Finland); Dean, Kirsti, E-mail: Kirsti.Dean@tyks.fi [Department of Diagnostic Radiology, University of Turku, Turku (Finland); Medical Imaging Centre of Southwest Finland, Turku University Hospital, Turku (Finland); Alanen, Kalle, E-mail: Kalle.Alanen@tyks.fi [Department of Pathology, Turku University Hospital, Turku (Finland); Arponen, Eveliina, E-mail: Eveliina.Arponen@utu.fi [Turku PET Centre, University of Turku, Turku (Finland); Nurmi, Martti, E-mail: Martti.Nurmi@tyks.fi [Department of Surgery, Division of Urology, Turku University Hospital, Turku (Finland); Aronen, Hannu J., E-mail: Hannu.Aronen@tyks.fi [Department of Diagnostic Radiology, University of Turku, Turku (Finland); Medical Imaging Centre of Southwest Finland, Turku University Hospital, Turku (Finland); and others

2012-11-15

Objectives: We aimed to study the ability of contrast enhanced MRI at 1.5 T and {sup 11}C-acetate PET/CT, both individually and using fused data, to detect localized prostate cancer. Methods: Thirty-six men with untreated prostate cancer and negative for metastatic disease on pelvic CT and bone scan were prospectively enrolled. A pelvic {sup 11}C-acetate PET/CT scan was performed in all patients, and a contrast enhanced MRI scan in 33 patients (6 examinations using both endorectal coil and surface coils, and 27 examinations using surface coils only). After the imaging studies 10 patients underwent prostatectomy and 26 were treated by image guided external beam radiation treatment. Image fusion of co-registered PET and MRI data was performed based on anatomical landmarks visible on CT and MRI using an advanced in-house developed software package. PET/CT, MRI and fused PET/MRI data were evaluated visually and compared with biopsy findings on a lobar level, while a sextant approach was used for patients undergoing prostatectomy. Results: When using biopsy samples as method of reference, the sensitivity, specificity and accuracy for visual detection of prostate cancer on a lobar level by contrast enhanced MRI was 85%, 37%, 73% and that of {sup 11}C-acetate PET/CT 88%, 41%, 74%, respectively. Fusion of PET with MRI data increased sensitivity, specificity and accuracy to 90%, 72% and 85%, respectively. Conclusions: Fusion of sequentially obtained PET/CT and MRI data for the localization of prostate cancer is feasible and superior to the performance of each individual modality alone.

ELABORATION OF THE 3D MODEL AND SURVEY OF THE POWER LINES USING DATA FROM AIRBORNE LASER SCANNING

Directory of Open Access Journals (Sweden)

Bogusława Kwoczyńska

2016-09-01

Full Text Available One of the methods of obtaining highly accurate and current spatial data about the terrain, as well as objects situated on it, is laser scanning. LIDAR (Light Detection and Ranging is among the most modern, dynamically developing technologies and reveals in surveying new capabilities that have been unachievable in a traditional way so far. The aim of the publication is to show the possibilities of using data from airborne laser scanning to perform the survey and visualization of the energy network, and also identification of hazards which the present network constitutes for the immediate environment using the TerraSolid software package. The survey was conducted for two independent sections of the power line, on the basis of two different clouds of points obtained from the airborne laser scanning. The first one had a density of 16 points/m2, while the other 22 pts/m2. The project was created in an environment of MicroStation V8i software using special overlays – TerraScan and TerraModeler of Finnish TerraSolid Company. The use of the test clouds of different densities was intended to indicate an optimal density of the cloud of points, which allows carrying out a survey and visualization of the energy network based on data derived from airborne laser scanning. The publication presents on particular examples the procedure of vectorization and visualization of the power line and detection of objects within a dangerous distance from it. The possibility of using applied LIDAR data, meeting the industry requirements, to the survey of power lines has been also confirmed.

The non-typical MRI findings of the branchial cleft cysts

International Nuclear Information System (INIS)

Hu Chunhong; Wu Qingde; Yao Xuanjun; Chen Jie; Zhu Wei; Chen Jianhua; Xing Jianming; Ding Yi; Ge Zili

2006-01-01

Objective: To investigate the non-typical MRI findings of the branchial cleft cysts in order to improve their diagnoses. Methods: 10 cases with branchial cleft cysts proven by surgery and pathology were collected and their MRI features were analyzed. There were 6 male and 4 female, aged 15 to 70, with an averaged age of 37. All patients underwent plain MR scan, 6 patients underwent enhanced scan, and 4 patients underwent magnetic resonance angiography. Results: All 10 cases were second branchial cleft cysts, including 4 of Bailey type I and 6 of type II. The non-typical MRI findings were composed of haematocele (2 cases), extraordinarily thick cyst wall (4 cases), solidified cystic fluid (2 cases), and concomitant canceration (2 cases), which made the diagnoses more difficult. Conclusion: The diagnoses of the branchial cleft cysts with non-typical MRI features should combined with its characteristic of position that located at the lateral portion of the neck adjacent to the anterior border of the sternocleidomastoid muscle at the mandibular angle. The findings, such as thickened wall, ill-defined margin, and vascular involvement or jugular lymphadenectasis, strongly suggest cancerous tendency. (authors)

MRI isotropic resolution reconstruction from two orthogonal scans

Science.gov (United States)

Tamez-Pena, Jose G.; Totterman, Saara; Parker, Kevin J.

2001-07-01

An algorithm for the reconstructions of ISO-resolution volumetric MR data sets from two standard orthogonal MR scans having anisotropic resolution has been developed. The reconstruction algorithm starts by registering a pair of orthogonal volumetric MR data sets. The registration is done by maximizing the correlation between the gradient magnitude using a simple translation-rotation model in a multi-resolution approach. Then algorithm assumes that the individual voxels on the MR data are an average of the magnetic resonance properties of an elongated imaging volume. Then, the process is modeled as the projection of MR properties into a single sensor. This model allows the derivation of a set of linear equations that can be used to recover the MR properties of every single voxel in the SO-resolution volume given only two orthogonal MR scans. Projections on convex sets (POCS) was used to solve the set of linear equations. Experimental results show the advantage of having a ISO-resolution reconstructions for the visualization and analysis of small and thin muscular structures.

Prenatal brain MRI of fetuses with Zika virus infection

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Guillemette-Artur, Prisca [Centre Hospitalier de Polynesie Francaise, Service de Radiologie, Pirae, Tahiti (Country Unknown); Besnard, Marianne [Centre Hospitalier de Polynesie Francaise, Service de Reanimation Neo-natale, Pirae, Tahiti (Country Unknown); Eyrolle-Guignot, Dominique [Centre Hospitalier de Polynesie Francaise, Service d' Obstetrique, Pirae, Tahiti (Country Unknown); Jouannic, Jean-Marie [Universite Pierre et Marie Curie, Service de Medecine Foetale, Hopital d' Enfants Armand-Trousseau, Paris (France); Garel, Catherine [Hopital d' Enfants Armand-Trousseau, Department of Radiology, Paris (France)

2016-06-15

An outbreak of Zika virus was observed in French Polynesia in 2013-2014. Maternal Zika virus infection has been associated with fetal microcephaly and severe cerebral damage. To analyze the MRI cerebral findings in fetuses with intrauterine Zika virus infection. We retrospectively analyzed prospectively collected data. Inclusion criteria comprised cases with (1) estimated conception date between June 2013 and May 2014, (2) available US and MRI scans revealing severe fetal brain lesions and (3) positive polymerase chain reaction for Zika virus in the amniotic fluid. We recorded pregnancy history of Zika virus infection and analyzed US and MRI scans. Three out of 12 cases of severe cerebral lesions fulfilled all inclusion criteria. History of maternal Zika virus infection had been documented in two cases. Calcifications and ventriculomegaly were present at US in all cases. MRI showed micrencephaly (n = 3), low cerebellar biometry (n = 2), occipital subependymal pseudocysts (n = 2), polymicrogyria with laminar necrosis and opercular dysplasia (n = 3), absent (n = 1) or hypoplastic (n = 1) corpus callosum and hypoplastic brainstem (n = 1). Severe cerebral damage was observed in our series, with indirect findings suggesting that the germinal matrix is the principal target for Zika virus. The lesions are very similar to severe forms of congenital cytomegalovirus and lymphocytic choriomeningitis virus infections. (orig.)

CT and MRI diagnosis of posterior fossa atypical ependymoma

International Nuclear Information System (INIS)

Yu Bolang; Zhang Ming; Luo Lin; Wang Shijie; Zhu Liping

2000-01-01

Objective: To analyse the CT and MRI features of posterior fossa atypical ependymoma. Methods: Sixteen cases of posterior fossa atypical ependymoma proved by surgery and pathology had CT and (or) MRI scanning. There were 11 males and 5 females. The age ranged from 17 to 46 (mean, 31.2). Twelve cases ranged from 20 to 40 years old. the main symptoms of all cases were dizziness, unsteady walking and vomiting. Results: The locations of all cases were cerebellum (12 cases), vermis (3 cases) and cerebellopontile angle (1 cases). Fifteen cases were solid with multiple cystic changes and 1 case in the cerebellopontile angle was cystic. The tumor was usually close to the surface of cerebellum with rather extensive connection with dura mater or tentorium. Calcifications were shown in 3 cases. The tumors revealed inhomogeneous density on CT scan and inhomogeneous intensity on MRI. Mild inhomogeneous enhancement was shown in most cases, while intense irregular enhancement in the others. Conclusions: The characteristic findings of the posterior fossa atypical ependymoma ependymoma were cerebellar intraparenchymatous multiple small cystic changes within solid tumor in most cases and inhomogeneous density and intensity on CT and MRI. The differential diagnosis is meningioma, metastasis and acoustic schwannoma

Prenatal brain MRI of fetuses with Zika virus infection

International Nuclear Information System (INIS)

Guillemette-Artur, Prisca; Besnard, Marianne; Eyrolle-Guignot, Dominique; Jouannic, Jean-Marie; Garel, Catherine

2016-01-01

An outbreak of Zika virus was observed in French Polynesia in 2013-2014. Maternal Zika virus infection has been associated with fetal microcephaly and severe cerebral damage. To analyze the MRI cerebral findings in fetuses with intrauterine Zika virus infection. We retrospectively analyzed prospectively collected data. Inclusion criteria comprised cases with (1) estimated conception date between June 2013 and May 2014, (2) available US and MRI scans revealing severe fetal brain lesions and (3) positive polymerase chain reaction for Zika virus in the amniotic fluid. We recorded pregnancy history of Zika virus infection and analyzed US and MRI scans. Three out of 12 cases of severe cerebral lesions fulfilled all inclusion criteria. History of maternal Zika virus infection had been documented in two cases. Calcifications and ventriculomegaly were present at US in all cases. MRI showed micrencephaly (n = 3), low cerebellar biometry (n = 2), occipital subependymal pseudocysts (n = 2), polymicrogyria with laminar necrosis and opercular dysplasia (n = 3), absent (n = 1) or hypoplastic (n = 1) corpus callosum and hypoplastic brainstem (n = 1). Severe cerebral damage was observed in our series, with indirect findings suggesting that the germinal matrix is the principal target for Zika virus. The lesions are very similar to severe forms of congenital cytomegalovirus and lymphocytic choriomeningitis virus infections. (orig.)

PET/MRI: Technical challenges and recent advances

International Nuclear Information System (INIS)

Jung, Jin Ho; Choi, Yong; Im, Ki Chun

2016-01-01

Integrated positron emission tomography (PET)/magnetic resonance imaging (MRI), which can provide complementary functional and anatomical information about a specific organ or body system at the molecular level, has become a powerful imaging modality to understand the molecular biology details, disease mechanisms, and pharmacokinetics in animals and humans. Although the first experiment on the PET/MRI was performed in the early 1990s, its clinical application was accomplished in recent years because there were various technical challenges in integrating PET and MRI in a single system with minimum mutual interference between PET and MRI. This paper presents the technical challenges and recent advances in combining PET and MRI along with several approaches for improving PET image quality of the PET/MRI hybrid imaging system

Improving fMRI reliability in presurgical mapping for brain tumours.

Science.gov (United States)

Stevens, M Tynan R; Clarke, David B; Stroink, Gerhard; Beyea, Steven D; D'Arcy, Ryan Cn

2016-03-01

Functional MRI (fMRI) is becoming increasingly integrated into clinical practice for presurgical mapping. Current efforts are focused on validating data quality, with reliability being a major factor. In this paper, we demonstrate the utility of a recently developed approach that uses receiver operating characteristic-reliability (ROC-r) to: (1) identify reliable versus unreliable data sets; (2) automatically select processing options to enhance data quality; and (3) automatically select individualised thresholds for activation maps. Presurgical fMRI was conducted in 16 patients undergoing surgical treatment for brain tumours. Within-session test-retest fMRI was conducted, and ROC-reliability of the patient group was compared to a previous healthy control cohort. Individually optimised preprocessing pipelines were determined to improve reliability. Spatial correspondence was assessed by comparing the fMRI results to intraoperative cortical stimulation mapping, in terms of the distance to the nearest active fMRI voxel. The average ROC-r reliability for the patients was 0.58±0.03, as compared to 0.72±0.02 in healthy controls. For the patient group, this increased significantly to 0.65±0.02 by adopting optimised preprocessing pipelines. Co-localisation of the fMRI maps with cortical stimulation was significantly better for more reliable versus less reliable data sets (8.3±0.9 vs 29±3 mm, respectively). We demonstrated ROC-r analysis for identifying reliable fMRI data sets, choosing optimal postprocessing pipelines, and selecting patient-specific thresholds. Data sets with higher reliability also showed closer spatial correspondence to cortical stimulation. ROC-r can thus identify poor fMRI data at time of scanning, allowing for repeat scans when necessary. ROC-r analysis provides optimised and automated fMRI processing for improved presurgical mapping. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence

SU-E-J-192: Verification of 4D-MRI Internal Target Volume Using Cine MRI

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Lafata, K; Czito, B; Palta, M; Bashir, M; Yin, F; Cai, J [Duke University Medical Center, Durham, NC (United States)

2014-06-01

Purpose: To investigate the accuracy of 4D-MRI in determining the Internal Target Volume (ITV) used in radiation oncology treatment planning of liver cancers. Cine MRI is used as the standard baseline in establishing the feasibility and accuracy of 4D-MRI tumor motion within the liver. Methods: IRB approval was obtained for this retrospective study. Analysis was performed on MR images from four patients receiving external beam radiation therapy for liver cancer at our institution. Eligible patients received both Cine and 4D-MRI scans before treatment. Cine images were acquired sagittally in real time at a slice bisecting the tumor, while 4D images were acquired volumetrically. Cine MR DICOM headers were manipulated such that each respiratory frame was assigned a unique slice location. This approach permitted the treatment planning system (Eclipse, Varian Medical Systems) to recognize a complete respiratory cycle as a “volume”, where the gross tumor was contoured temporally. Software was developed to calculate the union of all frame contours in the structure set, resulting in the corresponding plane of the ITV projecting through the middle of the tumor, defined as the Internal Target Area (ITA). This was repeated for 4D-MRI, at the corresponding slice location, allowing a direct comparison of ITAs obtained from each modality. Results: Four patients have been analyzed. ITAs contoured from 4D-MRI correlate with contours from Cine MRI. The mean error of 4D values relative to Cine values is 7.67 +/− 2.55 %. No single ITA contoured from 4D-MRI demonstrated more than 10.5 % error compared to its Cine MRI counterpart. Conclusion: Motion management is a significant aspect of treatment planning within dynamic environments such as the liver, where diaphragmatic and cardiac activity influence plan accuracy. This small pilot study suggests that 4D-MRI based ITA measurements agree with Cine MRI based measurements, an important step towards clinical implementation. NIH 1R21

SU-E-J-192: Verification of 4D-MRI Internal Target Volume Using Cine MRI

International Nuclear Information System (INIS)

Lafata, K; Czito, B; Palta, M; Bashir, M; Yin, F; Cai, J

2014-01-01

Purpose: To investigate the accuracy of 4D-MRI in determining the Internal Target Volume (ITV) used in radiation oncology treatment planning of liver cancers. Cine MRI is used as the standard baseline in establishing the feasibility and accuracy of 4D-MRI tumor motion within the liver. Methods: IRB approval was obtained for this retrospective study. Analysis was performed on MR images from four patients receiving external beam radiation therapy for liver cancer at our institution. Eligible patients received both Cine and 4D-MRI scans before treatment. Cine images were acquired sagittally in real time at a slice bisecting the tumor, while 4D images were acquired volumetrically. Cine MR DICOM headers were manipulated such that each respiratory frame was assigned a unique slice location. This approach permitted the treatment planning system (Eclipse, Varian Medical Systems) to recognize a complete respiratory cycle as a “volume”, where the gross tumor was contoured temporally. Software was developed to calculate the union of all frame contours in the structure set, resulting in the corresponding plane of the ITV projecting through the middle of the tumor, defined as the Internal Target Area (ITA). This was repeated for 4D-MRI, at the corresponding slice location, allowing a direct comparison of ITAs obtained from each modality. Results: Four patients have been analyzed. ITAs contoured from 4D-MRI correlate with contours from Cine MRI. The mean error of 4D values relative to Cine values is 7.67 +/− 2.55 %. No single ITA contoured from 4D-MRI demonstrated more than 10.5 % error compared to its Cine MRI counterpart. Conclusion: Motion management is a significant aspect of treatment planning within dynamic environments such as the liver, where diaphragmatic and cardiac activity influence plan accuracy. This small pilot study suggests that 4D-MRI based ITA measurements agree with Cine MRI based measurements, an important step towards clinical implementation. NIH 1R21

Inventory of MRI applications and workers exposed to MRI-related electromagnetic fields in the Netherlands.

Science.gov (United States)

Schaap, Kristel; Christopher-De Vries, Yvette; Slottje, Pauline; Kromhout, Hans

2013-12-01

This study aims to characterise and quantify the population that is occupationally exposed to electromagnetic fields (EMF) from magnetic resonance imaging (MRI) devices and to identify factors that determine the probability and type of exposure. A questionnaire survey was used to collect information about scanners, procedures, historical developments and employees working with or near MRI scanners in clinical and research MRI departments in the Netherlands. Data were obtained from 145 MRI departments. A rapid increase in the use of MRI and field strength of the scanners was observed and quantified. The strongest magnets were employed by academic hospitals and research departments. Approximately 7000 individuals were reported to be working inside an MRI scanner room and were thus considered to have high probability of occupational exposure to static magnetic fields (SMF). Fifty-four per cent was exposed to SMF at least one day per month. The largest occupationally exposed group were radiographers (n ~ 1700). Nine per cent of the 7000 involved workers were regularly present inside a scanner room during image acquisition, when exposure to additional types of EMF is considered a possibility. This practice was most prevalent among workers involved in scanning animals. The data illustrate recent trends and historical developments in magnetic resonance imaging and provide an extensive characterisation of the occupationally exposed population. A considerable number of workers are potentially exposed to MRI-related EMF. Type and frequency of potential exposure depend on the job performed, as well as the type of workplace. Copyright © 2013 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Inventory of MRI applications and workers exposed to MRI-related electromagnetic fields in the Netherlands

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Schaap, Kristel; Christopher-De Vries, Yvette; Slottje, Pauline; Kromhout, Hans, E-mail: h.kromhout@uu.nl

2013-12-01

Objective: This study aims to characterise and quantify the population that is occupationally exposed to electromagnetic fields (EMF) from magnetic resonance imaging (MRI) devices and to identify factors that determine the probability and type of exposure. Materials and methods: A questionnaire survey was used to collect information about scanners, procedures, historical developments and employees working with or near MRI scanners in clinical and research MRI departments in the Netherlands. Results: Data were obtained from 145 MRI departments. A rapid increase in the use of MRI and field strength of the scanners was observed and quantified. The strongest magnets were employed by academic hospitals and research departments. Approximately 7000 individuals were reported to be working inside an MRI scanner room and were thus considered to have high probability of occupational exposure to static magnetic fields (SMF). Fifty-four per cent was exposed to SMF at least one day per month. The largest occupationally exposed group were radiographers (n ∼ 1700). Nine per cent of the 7000 involved workers were regularly present inside a scanner room during image acquisition, when exposure to additional types of EMF is considered a possibility. This practice was most prevalent among workers involved in scanning animals. Conclusion: The data illustrate recent trends and historical developments in magnetic resonance imaging and provide an extensive characterisation of the occupationally exposed population. A considerable number of workers are potentially exposed to MRI-related EMF. Type and frequency of potential exposure depend on the job performed, as well as the type of workplace.

Patients with liver FNH and HCC patients with negative AFP: plain and dynamic enhanced MRI and CT findings

Directory of Open Access Journals (Sweden)

LI Mingtong

2015-05-01

Full Text Available ObjectiveTo investigate plain and dynamic enhanced magnetic resonance imaging (MRI and computed tomography (CT findings in patients with focal nodular hyperplasia (FNH of the liver and hepatocellular carcinoma (HCC patients with negative alpha-fetoprotein (AFP. MethodsA statistical analysis was performed on the clinical data of 124 cases of liver tumor admitted to Beijing Miyun County Hospital from April 2012 to April 2014. ResultsFifty-five of the 74 patients with FNH underwent CT examination, among whom 38 patients received three-phase dynamic enhanced scan and 16 received only plain scan; 62 cases had plain and enhanced MRI with the application of contrast agent Gd-BOPTA in 42 patients. Among the 50 HCC patients with negative AFP, CT examination was performed in 40 and 10 only had plain scan; 46 patients received plain and enhanced MRI with the use of contrast agent Gd-BOPTA in 30. Delayed scan after 1-2 h demonstrated low signal in 30 lesions of the 30 cases. ConclusionFor patients with liver FNH and AFP-negative HCC patients, their plain and dynamic enhanced MRI and CT scan have respective characteristics. A combination of multiple examination methods can significantly improve diagnostic yield of the two diseases.

Diagnosis of vertebral artery dissection with basiparallel anatomical scanning magnetic resonance imaging

International Nuclear Information System (INIS)

Katsuno, Makoto; Kobayashi, Shiro

2011-01-01

There is no consensus regarding the optimal method for diagnosing the dissection of intracranial arteries. We have developed a rapid and accurate examination method to diagnose vertebral artery dissection in the acute stage of cerebral infarction. Twenty-two patients with severe headache and neck pain and/or symptoms of brain stem or cerebellar ischemia underwent magnetic resonance imaging (MRI) with a 1.5-T scanner. Our protocol generated 3 contrast-weighted scans (T2-weighted, diffusion-weighted, and basi-parallel anatomical scanning [BPAS]-MRI) and conventional angiographs within 3 hours of the onset of symptoms. Then, we retrospectively analyzed the findings to identify the most reliable imaging method for diagnosing vertebral artery dissection in the acute stage of cerebral infarction. Based on the symptoms and the findings of T2-weighted imaging and conventional angiography, the initial diagnosis was dissection in 17 patients, lacunar infarction in 3 patients, and atherothrombosis in 2 patients. After follow-up studies the diagnosis was changed in 7 patients. The diagnosis based on symptoms and the findings of T2-weighted MRI and BPAS-MRI was dissection in 13 patients, atherothrombosis in 6 patients, and lacunar infarction in 3 patients. In 3 patients the diagnosis was changed during the follow-up phase. The diagnostic accuracy rate was higher with T2-weighted MRI and BPAS-MRI than with T2-weighted MRI and conventional angiography. We suggest that when intracranial vascular dissection is suspected, both the inner and outer contours of vessels must be inspected and that BPAS-MRI should be performed instead of conventional angiography to establish the definite diagnosis. (author)

An implemented MRI program to eliminate radiation from the evaluation of pediatric appendicitis.

Science.gov (United States)

Kulaylat, Afif N; Moore, Michael M; Engbrecht, Brett W; Brian, James M; Khaku, Aliasgher; Hollenbeak, Christopher S; Rocourt, Dorothy V; Hulse, Michael A; Olympia, Robert P; Santos, Mary C; Methratta, Sosamma T; Dillon, Peter W; Cilley, Robert E

2015-08-01

Recent efforts have been directed at reducing ionizing radiation delivered by CT scans to children in the evaluation of appendicitis. MRI has emerged as an alternative diagnostic modality. The clinical outcomes associated with MRI in this setting are not well-described. Review of a 30-month institutional experience with MRI as the primary diagnostic evaluation for suspected appendicitis (n=510). No intravenous contrast, oral contrast, or sedation was administered. Radiologic and clinical outcomes were abstracted. MRI diagnostic characteristics were: sensitivity 96.8% (95% CI: 92.1%-99.1%), specificity 97.4% (95% CI: 95.3-98.7), positive predictive value 92.4% (95% CI: 86.5-96.3), and negative predictive value 98.9% (95% CI: 97.3%-99.7%). Radiologic time parameters included: median time from request to scan, 71 minutes (IQR: 51-102), imaging duration, 11 minutes (IQR: 8-17), and request to interpretation, 2.0 hours (IQR: 1.6-2.6). Clinical time parameters included: median time from initial assessment to admit order, 4.1 hours (IQR: 3.1-5.1), assessment to antibiotic administration 4.7 hours (IQR: 3.9-6.7), and assessment to operating room 9.1 hours (IQR: 5.8-12.7). Median length of stay was 1.2 days (range: 0.2-19.5). Given the diagnostic accuracy and favorable clinical outcomes, without the potential risks of ionizing radiation, MRI may supplant the role of CT scans in pediatric appendicitis imaging. Copyright © 2015 Elsevier Inc. All rights reserved.

Postoperative enhancement on breast MRI: Time course and pattern of changes.

Science.gov (United States)

Mahoney, Mary C; Sharda, Radhika G

2018-04-23

Expected postoperative enhancement on breast MRI can appear similar to enhancement seen in recurrent or residual malignancy. Our aim was to assess the time course and patterns of enhancement at the surgical site, thereby helping to distinguish between benign and malignant postoperative enhancement. In 200 MRI scans performed in 153 patients after breast conservation treatment, 43 after surgical excision of atypia, and 4 patients after benign excisional biopsy were categorized by postoperative time interval. We defined 4 patterns of morphologic enhancement on MRI: cavity wall/seroma (Pattern I); thin linear (Pattern II); mass (Pattern III); and fat necrosis (Pattern IV). Of 200 MRI scans, 66 (33%) demonstrated enhancement at the surgical site. Enhancement typically decreased through the postoperative follow-up period. Enhancement was observed in 41% (28/68) of cases beyond the 18-month interval but was uncommon after 5 years. Pattern III enhancement was the morphologic pattern seen most commonly with malignancy (5/19 cases, 26%). When associated with delayed washout kinetics, it was even more strongly predictive of malignancy (4/5 cases, 80%). In patients with a history of excisional biopsy and no prior radiation treatment, the percentage of MRI scans showing enhancement was significantly lower than (21% vs 49% with P-value .0027) in patients who had undergone radiation. Enhancement at the surgical site occurred in one-third of cases up to 5 years after surgery, particularly in patients who underwent both radiation and surgery. Mass enhancement, particularly in conjunction with delayed washout kinetics, is most predictive of malignancy and should prompt biopsy or re-excision. © 2018 Wiley Periodicals, Inc.

Guidelines for scanning twins and triplets with US and MRI

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Calvo-Garcia, Maria A. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, Cincinnati, OH (United States)

2016-02-15

Multiple-fetus gestations have an increased risk of discordant anomalies, aneuploidy and growth restriction compared to singleton pregnancies. In addition, twins sharing the same placenta are at risk for developing specific conditions that are potentially amenable to surgical management. In those scenarios, patients might need to be evaluated not only with US but with fetal MRI as well. This paper outlines basic guidelines to consider when imaging complicated multiple-fetus gestations during the 2nd and 3rd trimesters. (orig.)

MRI of neuronal migration disorders

International Nuclear Information System (INIS)

Engelbrecht, V.

1996-01-01

Twenty-one MRI examinations of the brain were performed in 19 children with neuronal migration disorders. Multiplanar oriented spin-echo sequences were on a scanner with 1.5 T. In 8 children we performed an additional turbo-inversion recovery (TIR) sequence. Results of sonography or CT from five children were compared with MRI scans. Using the actual nomenclature, we found the following migration disorders: Lissencephaly (n=6), cobblestone lissencephaly with Walker-Warbung syndrome (WWS) (n=2), polymicrogyria and schizencephaly (n=2), focal heterotopia (n=5), diffuse heterotopie (n=2) and hemimegalencephaly (n=2). MRI was superior to CT and sonography in all children. Except for the two boys with WWS, the TIR sequence was the best to demonstrate the changes in migration disorder because of the high contrast between gray and white matter. We demonstrate the characteristic features of the different migration disorders and compare them with the existing literature. (orig.) [de

What expects orthopedic surgeon from bone scan?

International Nuclear Information System (INIS)

Sutter, B.; Cazenave, A.

2003-01-01

The isotope bone scan continues to be one of the 'lost widely performed nuclear medicine investigations. Beyond the common clinical indication like detection of skeletal metastases, bone scan use is increasing in benign orthopedic conditions, and after orthopedic surgery, despite development of new investigations modalities (US, MRI). Three (or two) phase bone scintigraphy, Single Photon Emission Computer Tomography have increased its value and provided new clinical roles. This review emphasizes through some practical clinical examples how to increase diagnostic value of the method and to offer an adapted response to the orthopedic surgeon's attempts. (author)

Case of herpes simplex encephalitis without neurologic symptoms. A comparison between CT scan and MRI

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Kawabata, N.; Tanaka, T.; Hiramoto, N.; Takazuka, K.; Komatsu, T.

1987-03-01

The lack of neurologic symptoms is rare in herpes simplex encephalitis (HSE). A 42-year-old woman presented with psychiatric features alone, such as Korsakoff syndrome and abortive type Kluver-Bucy syndrome. The diagnosis of HSE was confirmed by serologically elevated antibody titer. The patient underwent both X-ray computed tomography and magnetic resonance imaging (MRI). X-ray computed tomography showed transient contrast enhancement and low density area confined to the lateral lobe. Magnetic resonance imaging revealed diffuse areas with a high MRI signal intensity. Considering that the lack of neurologic features, as seen in the present HSE patient, may sometimes rule out the possibility of parenchymal disease, imaging modalities, especially MRI, may be of value in the detection of lesions for HSE.

A power comparison of generalized additive models and the spatial scan statistic in a case-control setting

Directory of Open Access Journals (Sweden)

Ozonoff Al

2010-07-01

Full Text Available Abstract Background A common, important problem in spatial epidemiology is measuring and identifying variation in disease risk across a study region. In application of statistical methods, the problem has two parts. First, spatial variation in risk must be detected across the study region and, second, areas of increased or decreased risk must be correctly identified. The location of such areas may give clues to environmental sources of exposure and disease etiology. One statistical method applicable in spatial epidemiologic settings is a generalized additive model (GAM which can be applied with a bivariate LOESS smoother to account for geographic location as a possible predictor of disease status. A natural hypothesis when applying this method is whether residential location of subjects is associated with the outcome, i.e. is the smoothing term necessary? Permutation tests are a reasonable hypothesis testing method and provide adequate power under a simple alternative hypothesis. These tests have yet to be compared to other spatial statistics. Results This research uses simulated point data generated under three alternative hypotheses to evaluate the properties of the permutation methods and compare them to the popular spatial scan statistic in a case-control setting. Case 1 was a single circular cluster centered in a circular study region. The spatial scan statistic had the highest power though the GAM method estimates did not fall far behind. Case 2 was a single point source located at the center of a circular cluster and Case 3 was a line source at the center of the horizontal axis of a square study region. Each had linearly decreasing logodds with distance from the point. The GAM methods outperformed the scan statistic in Cases 2 and 3. Comparing sensitivity, measured as the proportion of the exposure source correctly identified as high or low risk, the GAM methods outperformed the scan statistic in all three Cases. Conclusions The GAM

A power comparison of generalized additive models and the spatial scan statistic in a case-control setting.

Science.gov (United States)

Young, Robin L; Weinberg, Janice; Vieira, Verónica; Ozonoff, Al; Webster, Thomas F

2010-07-19

A common, important problem in spatial epidemiology is measuring and identifying variation in disease risk across a study region. In application of statistical methods, the problem has two parts. First, spatial variation in risk must be detected across the study region and, second, areas of increased or decreased risk must be correctly identified. The location of such areas may give clues to environmental sources of exposure and disease etiology. One statistical method applicable in spatial epidemiologic settings is a generalized additive model (GAM) which can be applied with a bivariate LOESS smoother to account for geographic location as a possible predictor of disease status. A natural hypothesis when applying this method is whether residential location of subjects is associated with the outcome, i.e. is the smoothing term necessary? Permutation tests are a reasonable hypothesis testing method and provide adequate power under a simple alternative hypothesis. These tests have yet to be compared to other spatial statistics. This research uses simulated point data generated under three alternative hypotheses to evaluate the properties of the permutation methods and compare them to the popular spatial scan statistic in a case-control setting. Case 1 was a single circular cluster centered in a circular study region. The spatial scan statistic had the highest power though the GAM method estimates did not fall far behind. Case 2 was a single point source located at the center of a circular cluster and Case 3 was a line source at the center of the horizontal axis of a square study region. Each had linearly decreasing logodds with distance from the point. The GAM methods outperformed the scan statistic in Cases 2 and 3. Comparing sensitivity, measured as the proportion of the exposure source correctly identified as high or low risk, the GAM methods outperformed the scan statistic in all three Cases. The GAM permutation testing methods provide a regression

Value of MRI in the staging of laryngeal neoplasms. Comparison with CT based on a series of twenty-one cases

International Nuclear Information System (INIS)

Boisserie-Lacroix, M.; Cassier, C.; Calas, V.; Stoll, D.; Delorme, G.; Raffin, B.

1988-01-01

21 cases of laryngeal neoplasm evaluated by CT and MRI as part of pretreatment staging are reported. The two examinations evaluated local extension of the tumour and invasion of carcinologically important zones determining the surgeon's decision for conservative or radical management. CT and MRI are unable to detect mucosal extension observed with suspension laryngoscopy. The laryngeal sinus, vestibular folds and vocal cords are identified on median sagittal scans but rarely on coronal scans. MRI provides good visualisation of the anterior commissure on sagittal scans and shows subglottal involvement at least as clearly as CT. It does not provide any arguments to differentiate a primary tumour of the pyriform fossa from a purely supra-glottal cancer. MRI is very reliable in the analysis of the connective tissue spaces, but appears to be less reliable than CT in the study of the cartilages [fr

SU-E-J-153: MRI Based, Daily Adaptive Radiotherapy for Rectal Cancer: Contour Adaptation

International Nuclear Information System (INIS)

Kleijnen, J; Burbach, M; Verbraeken, T; Weggers, R; Zoetelief, A; Reerink, O; Lagendijk, J; Raaymakers, B; Asselen, B

2014-01-01

Purpose: A major hurdle in adaptive radiotherapy is the adaptation of the planning MRI's delineations to the daily anatomy. We therefore investigate the accuracy and time needed for online clinical target volume (CTV) adaptation by radiation therapists (RTT), to be used in MRI-guided adaptive treatments on a MRI-Linac (MRL). Methods: Sixteen patients, diagnosed with early stage rectal cancer, underwent a T2-weighted MRI prior to each fraction of short-course radiotherapy, resulting in 4–5 scans per patient. On these scans, the CTV was delineated according to guidelines by an experienced radiation oncologist (RO) and considered to be the gold standard. For each patient, the first MRI was considered as the planning MRI and matched on bony anatomy to the 3–4 daily MRIs. The planning MRI's CTV delineation was rigidly propagated to the daily MRI scans as a proposal for adaptation. Three RTTs in training started the adaptation of the CTV conform guidelines, after a two hour training lecture and a two patient (n=7) training set. To assess the inter-therapist variation, all three RTTs altered delineations of 3 patients (n=12). One RTT altered the CTV delineations (n=53) of the remaining 11 patients. Time needed for adaptation of the CTV to guidelines was registered.As a measure of agreement, the conformity index (CI) was determined between the RTTs' delineations as a group. Dice similarity coefficients were determined between delineations of the RTT and the RO. Results: We found good agreement between RTTs' and RO's delineations (average Dice=0.91, SD=0.03). Furthermore, the inter-observer agreement between the RTTs was high (average CI=0.94, SD=0.02). Adaptation time reduced from 10:33 min (SD= 3:46) to 2:56 min (SD=1:06) between the first and last ten delineations, respectively. Conclusion: Daily CTV adaptation by RTTs, seems a feasible and safe way to introduce daily, online MRI-based plan adaptation for a MRL

Third degree skin burns caused by a MRI conditional electrocardiographic monitoring system

Directory of Open Access Journals (Sweden)

Brix L

2016-10-01

Full Text Available Two unusual cases of third degree skin burns are reported using MRI approved electrocardiographic leads. This is very uncommon as it is most often the electrodes which are the source of heat related issues. Both patients were sedated due to pain related issues of their lower spine. The burns were caused by a combination of using a 3 Tesla MRI scanner and the inability to cry out during scanning. We would like to bring forward a message that even when using MRI conditional equipment, clinical staff must be extremely careful in order to secure safe image acquisition using MRI.

Automatic Substitute Computed Tomography Generation and Contouring for Magnetic Resonance Imaging (MRI)-Alone External Beam Radiation Therapy From Standard MRI Sequences

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Dowling, Jason A., E-mail: jason.dowling@csiro.au [CSIRO Australian e-Health Research Centre, Herston, Queensland (Australia); University of Newcastle, Callaghan, New South Wales (Australia); Sun, Jidi [University of Newcastle, Callaghan, New South Wales (Australia); Pichler, Peter [Calvary Mater Newcastle Hospital, Waratah, New South Wales (Australia); Rivest-Hénault, David; Ghose, Soumya [CSIRO Australian e-Health Research Centre, Herston, Queensland (Australia); Richardson, Haylea [Calvary Mater Newcastle Hospital, Waratah, New South Wales (Australia); Wratten, Chris; Martin, Jarad [University of Newcastle, Callaghan, New South Wales (Australia); Calvary Mater Newcastle Hospital, Waratah, New South Wales (Australia); Arm, Jameen [Calvary Mater Newcastle Hospital, Waratah, New South Wales (Australia); Best, Leah [Department of Radiology, Hunter New England Health, New Lambton, New South Wales (Australia); Chandra, Shekhar S. [School of Information Technology and Electrical Engineering, University of Queensland, Brisbane, Queensland (Australia); Fripp, Jurgen [CSIRO Australian e-Health Research Centre, Herston, Queensland (Australia); Menk, Frederick W. [University of Newcastle, Callaghan, New South Wales (Australia); Greer, Peter B. [University of Newcastle, Callaghan, New South Wales (Australia); Calvary Mater Newcastle Hospital, Waratah, New South Wales (Australia)

2015-12-01

Purpose: To validate automatic substitute computed tomography CT (sCT) scans generated from standard T2-weighted (T2w) magnetic resonance (MR) pelvic scans for MR-Sim prostate treatment planning. Patients and Methods: A Siemens Skyra 3T MR imaging (MRI) scanner with laser bridge, flat couch, and pelvic coil mounts was used to scan 39 patients scheduled for external beam radiation therapy for localized prostate cancer. For sCT generation a whole-pelvis MRI scan (1.6 mm 3-dimensional isotropic T2w SPACE [Sampling Perfection with Application optimized Contrasts using different flip angle Evolution] sequence) was acquired. Three additional small field of view scans were acquired: T2w, T2*w, and T1w flip angle 80° for gold fiducials. Patients received a routine planning CT scan. Manual contouring of the prostate, rectum, bladder, and bones was performed independently on the CT and MR scans. Three experienced observers contoured each organ on MRI, allowing interobserver quantification. To generate a training database, each patient CT scan was coregistered to their whole-pelvis T2w using symmetric rigid registration and structure-guided deformable registration. A new multi-atlas local weighted voting method was used to generate automatic contours and sCT results. Results: The mean error in Hounsfield units between the sCT and corresponding patient CT (within the body contour) was 0.6 ± 14.7 (mean ± 1 SD), with a mean absolute error of 40.5 ± 8.2 Hounsfield units. Automatic contouring results were very close to the expert interobserver level (Dice similarity coefficient): prostate 0.80 ± 0.08, bladder 0.86 ± 0.12, rectum 0.84 ± 0.06, bones 0.91 ± 0.03, and body 1.00 ± 0.003. The change in monitor units between the sCT-based plans relative to the gold standard CT plan for the same dose prescription was found to be 0.3% ± 0.8%. The 3-dimensional γ pass rate was 1.00 ± 0.00 (2 mm/2%). Conclusions: The MR-Sim setup and automatic s

Automatic Substitute Computed Tomography Generation and Contouring for Magnetic Resonance Imaging (MRI)-Alone External Beam Radiation Therapy From Standard MRI Sequences

International Nuclear Information System (INIS)

Dowling, Jason A.; Sun, Jidi; Pichler, Peter; Rivest-Hénault, David; Ghose, Soumya; Richardson, Haylea; Wratten, Chris; Martin, Jarad; Arm, Jameen; Best, Leah; Chandra, Shekhar S.; Fripp, Jurgen; Menk, Frederick W.; Greer, Peter B.

2015-01-01

Purpose: To validate automatic substitute computed tomography CT (sCT) scans generated from standard T2-weighted (T2w) magnetic resonance (MR) pelvic scans for MR-Sim prostate treatment planning. Patients and Methods: A Siemens Skyra 3T MR imaging (MRI) scanner with laser bridge, flat couch, and pelvic coil mounts was used to scan 39 patients scheduled for external beam radiation therapy for localized prostate cancer. For sCT generation a whole-pelvis MRI scan (1.6 mm 3-dimensional isotropic T2w SPACE [Sampling Perfection with Application optimized Contrasts using different flip angle Evolution] sequence) was acquired. Three additional small field of view scans were acquired: T2w, T2*w, and T1w flip angle 80° for gold fiducials. Patients received a routine planning CT scan. Manual contouring of the prostate, rectum, bladder, and bones was performed independently on the CT and MR scans. Three experienced observers contoured each organ on MRI, allowing interobserver quantification. To generate a training database, each patient CT scan was coregistered to their whole-pelvis T2w using symmetric rigid registration and structure-guided deformable registration. A new multi-atlas local weighted voting method was used to generate automatic contours and sCT results. Results: The mean error in Hounsfield units between the sCT and corresponding patient CT (within the body contour) was 0.6 ± 14.7 (mean ± 1 SD), with a mean absolute error of 40.5 ± 8.2 Hounsfield units. Automatic contouring results were very close to the expert interobserver level (Dice similarity coefficient): prostate 0.80 ± 0.08, bladder 0.86 ± 0.12, rectum 0.84 ± 0.06, bones 0.91 ± 0.03, and body 1.00 ± 0.003. The change in monitor units between the sCT-based plans relative to the gold standard CT plan for the same dose prescription was found to be 0.3% ± 0.8%. The 3-dimensional γ pass rate was 1.00 ± 0.00 (2 mm/2%). Conclusions: The MR-Sim setup and automatic s

3 Tesla MRI of patients with a vagus nerve stimulator: initial experience using a T/R head coil under controlled conditions.

Science.gov (United States)

Gorny, Krzysztof R; Bernstein, Matt A; Watson, Robert E

2010-02-01

To assess safety of clinical MRI of the head in patients with implanted model 100, 102, and 103 vagus nerve stimulation (VNS) Therapy Systems (Cyberonics, Inc., Houston, TX) in 3.0 Tesla MRI (GE Healthcare, Milwaukee, WI). The distributions of the radiofrequency B(1) (+)-field produced by the clinically used transmit/receive (T/R) head coil (Advanced Imaging Research Incorporated, Cleveland, OH) and body coil were measured in a head and shoulders phantom. These measurements were supplemented by temperature measurements on the lead tips and the implantable pulse generator (IPG) of the VNS devices in a head and torso phantom with the same two coils. Clinical 3T MRI head scans were then acquired under highly controlled conditions in a series of 17 patients implanted with VNS. Phantom studies showed only weak B(1) (+) fields at the location of the VNS IPG and leads for MRI scans using the T/R head coil. The MRI-related heating on a VNS scanned in vitro at 3T was also found to be minimal (0.4-0.8 degrees C at the leads, negligible at the IPG). The patient MRI examinations were completed successfully without any adverse incidents. No patient reported any heating, discomfort, or any other unusual sensation. Safe clinical MRI head scanning of patients with implanted VNS is shown to be feasible on a GE Signa Excite 3T MRI system using one specific T/R head coil. These results apply to this particular MRI system configuration. Extrapolation or generalization of these results to more general or less controlled imaging situations without supporting data of safety is highly discouraged.

[18F]FDG PET/CT outperforms [18F]FDG PET/MRI in differentiated thyroid cancer

International Nuclear Information System (INIS)

Vrachimis, Alexis; Wenning, Christian; Weckesser, Matthias; Stegger, Lars; Burg, Matthias Christian; Allkemper, Thomas; Schaefers, Michael

2016-01-01

To evaluate the diagnostic potential of PET/MRI with [ 18 F]FDG in comparison to PET/CT in patients with differentiated thyroid cancer suspected or known to have dedifferentiated. The study included 31 thyroidectomized and remnant-ablated patients who underwent a scheduled [ 18 F]FDG PET/CT scan and were then enrolled for a PET/MRI scan of the neck and thorax. The datasets (PET/CT, PET/MRI) were rated regarding lesion count, conspicuity, diameter and characterization. Standardized uptake values were determined for all [ 18 F]FDG-positive lesions. Histology, cytology, and examinations before and after treatment served as the standards of reference. Of 26 patients with a dedifferentiated tumour burden, 25 were correctly identified by both [ 18 F]FDG PET/CT and PET/MRI. Detection rates by PET/CT and PET/MRI were 97 % (113 of 116 lesions) and 85 % (99 of 113 lesions) for malignant lesions, and 100 % (48 of 48 lesions) and 77 % (37 of 48 lesions) for benign lesions, respectively. Lesion conspicuity was higher on PET/CT for both malignant and benign pulmonary lesions and in the overall rating for malignant lesions (p < 0.001). There was a difference between PET/CT and PET/MRI in overall evaluation of malignant lesions (p < 0.01) and detection of pulmonary metastases (p < 0.001). Surgical evaluation revealed three malignant lesions missed by both modalities. PET/MRI additionally failed to detect 14 pulmonary metastases and 11 benign lesions. In patients with thyroid cancer and suspected or known dedifferentiation, [ 18 F]FDG PET/MRI was inferior to low-dose [ 18 F]FDG PET/CT for the assessment of pulmonary status. However, for the assessment of cervical status, [ 18 F]FDG PET/MRI was equal to contrast-enhanced neck [ 18 F]FDG PET/CT. Therefore, [ 18 F]FDG PET/MRI combined with a low-dose CT scan of the thorax may provide an imaging solution when high-quality imaging is needed and high-energy CT is undesirable or the use of a contrast agent is contraindicated. (orig.)

Early Changes in Alpha Band Power and DMN BOLD Activity in Alzheimer’s Disease: A Simultaneous Resting State EEG-fMRI Study

Directory of Open Access Journals (Sweden)

Katharina Brueggen

2017-10-01

Full Text Available Simultaneous resting state functional magnetic resonance imaging (rsfMRI–resting state electroencephalography (rsEEG studies in healthy adults showed robust positive associations of signal power in the alpha band with BOLD signal in the thalamus, and more heterogeneous associations in cortical default mode network (DMN regions. Negative associations were found in occipital regions. In Alzheimer’s disease (AD, rsfMRI studies revealed a disruption of the DMN, while rsEEG studies consistently reported a reduced power within the alpha band. The present study is the first to employ simultaneous rsfMRI-rsEEG in an AD sample, investigating the association of alpha band power and BOLD signal, compared to healthy controls (HC. We hypothesized to find reduced positive associations in DMN regions and reduced negative associations in occipital regions in the AD group. Simultaneous resting state fMRI–EEG was recorded in 14 patients with mild AD and 14 HC, matched for age and gender. Power within the EEG alpha band (8–12 Hz, 8–10 Hz, and 10–12 Hz was computed from occipital electrodes and served as regressor in voxel-wise linear regression analyses, to assess the association with the BOLD signal. Compared to HC, the AD group showed significantly decreased positive associations between BOLD signal and occipital alpha band power in clusters in the superior, middle and inferior frontal cortex, inferior temporal lobe and thalamus (p < 0.01, uncorr., cluster size ≥ 50 voxels. This group effect was more pronounced in the upper alpha sub-band, compared to the lower alpha sub-band. Notably, we observed a high inter-individual heterogeneity. Negative associations were only reduced in the lower alpha range in the hippocampus, putamen and cerebellum. The present study gives first insights into the relationship of resting-state EEG and fMRI characteristics in an AD sample. The results suggest that positive associations between alpha band power and BOLD

Development and Validation of MRI Sacroiliac Joint Scoring Methods for the Semiaxial Scan Plane Corresponding to the Berlin and SPARCC MRI Scoring Methods, and of a New Global MRI Sacroiliac Joint Method

DEFF Research Database (Denmark)

Hededal, Pernille; Østergaard, Mikkel; Sørensen, Inge Juul

2018-01-01

OBJECTIVE: To develop semiaxial magnetic resonance imaging (MRI) scoring methods for assessment of sacroiliac joint (SIJ) bone marrow edema (BME) in patients with axial spondyloarthritis, and to compare the reliability with equivalent semicoronal scoring methods. METHODS: Two semiaxial SIJ MRI sc...

Preliminary evaluation of a brain PET insertable to MRI

International Nuclear Information System (INIS)

Cho, Gyuseng; Choi, Yong; Lee, Jae Sung; An, Hyun Joon; Jung, Jin Ho; Park, Hyun Wook; Oh, Chang Hyun; Park, Kyeongjin; Lim, Kyung Taek; Cho, Minsik; Sul, Woo Suk; Kim, Hyoungtaek; Kim, Hyunduk

2014-01-01

There is a new trend of the medical image that diagnoses a brain disease as like Alzheimer dementia. The first qualified candidate is a PET-MRI fusion modality because MRI is a more powerful anatomic diagnosis tool than other modalities. In our study, in order to solve the high magnetic field from MRI, the development was consisted with four main items such as photo-sensor, PET scanner, MRI head-coil and attenuation correction algorithm development.

Preliminary evaluation of a brain PET insertable to MRI

Energy Technology Data Exchange (ETDEWEB)

Cho, Gyuseng [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon, 305-701 South (Korea, Republic of); Choi, Yong [Department of Electronic Engineering, Sogang University, Seoul, 121-742 South (Korea, Republic of); Lee, Jae Sung; An, Hyun Joon [Department of Nuclear Medicine, Seoul National University, Seoul, 110-744 South (Korea, Republic of); Jung, Jin Ho [Department of Electronic Engineering, Sogang University, Seoul, 121-742 South (Korea, Republic of); Park, Hyun Wook; Oh, Chang Hyun; Park, Kyeongjin; Lim, Kyung Taek; Cho, Minsik [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon, 305-701 South (Korea, Republic of); Sul, Woo Suk [National NanoFab Center, Deajeon, 305-806 South (Korea, Republic of); Kim, Hyoungtaek; Kim, Hyunduk [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon, 305-701 South (Korea, Republic of)

2014-07-29

There is a new trend of the medical image that diagnoses a brain disease as like Alzheimer dementia. The first qualified candidate is a PET-MRI fusion modality because MRI is a more powerful anatomic diagnosis tool than other modalities. In our study, in order to solve the high magnetic field from MRI, the development was consisted with four main items such as photo-sensor, PET scanner, MRI head-coil and attenuation correction algorithm development.

Adrenal cavernous hemangioma: MRI, CT, and US appearance

International Nuclear Information System (INIS)

Marotti, M.; Sucic, Z.; Krolo, I.; Dimanovski, J.; Klaric, R.; Ferencic, Z.; Karapanda, N.; Babic, N.; Pavlekovic, K.

1997-01-01

Two cases of rare adrenal cavernous hemangiomas are reported, one imaged with conventional X-ray techniques, US, CT, and MRI, and the other with US and CT. The CT technique clearly demonstrated calcifications and the internal structure of the lesions in both cases and peripheral rim enhancement on the postcontrast scan in one patient. Although MRI demonstrated accurately the complex nature of the lesion, the inability to visualize the calcified areas do not allow to make a specific histologic diagnosis. (orig.). With 8 figs

Broadband Electrophysiological Dynamics Contribute to Global Resting-State fMRI Signal.

Science.gov (United States)

Wen, Haiguang; Liu, Zhongming

2016-06-01

Spontaneous activity observed with resting-state fMRI is used widely to uncover the brain's intrinsic functional networks in health and disease. Although many networks appear modular and specific, global and nonspecific fMRI fluctuations also exist and both pose a challenge and present an opportunity for characterizing and understanding brain networks. Here, we used a multimodal approach to investigate the neural correlates to the global fMRI signal in the resting state. Like fMRI, resting-state power fluctuations of broadband and arrhythmic, or scale-free, macaque electrocorticography and human magnetoencephalography activity were correlated globally. The power fluctuations of scale-free human electroencephalography (EEG) were coupled with the global component of simultaneously acquired resting-state fMRI, with the global hemodynamic change lagging the broadband spectral change of EEG by ∼5 s. The levels of global and nonspecific fluctuation and synchronization in scale-free population activity also varied across and depended on arousal states. Together, these results suggest that the neural origin of global resting-state fMRI activity is the broadband power fluctuation in scale-free population activity observable with macroscopic electrical or magnetic recordings. Moreover, the global fluctuation in neurophysiological and hemodynamic activity is likely modulated through diffuse neuromodulation pathways that govern arousal states and vigilance levels. This study provides new insights into the neural origin of resting-state fMRI. Results demonstrate that the broadband power fluctuation of scale-free electrophysiology is globally synchronized and directly coupled with the global component of spontaneous fMRI signals, in contrast to modularly synchronized fluctuations in oscillatory neural activity. These findings lead to a new hypothesis that scale-free and oscillatory neural processes account for global and modular patterns of functional connectivity observed

Use of FET in automatic scanning of measurements using thermocouples and self-powered neutron detectors

International Nuclear Information System (INIS)

Plaige, Yves.

1977-01-01

Advantages lying in using FET switches in the relays of multiplexing systems are shown with two examples of application. Their performance as regard fast reliable operation are used in temperature measurement scanning inside nuclear reactors. As for current measurements using self-powered neutron detectors, the weak leakage currents of said switches ( [fr

An Observational Study to Assess Brain MRI Change and Disease Progression in Multiple Sclerosis Clinical Practice-The MS-MRIUS Study.

Science.gov (United States)

Zivadinov, Robert; Khan, Nasreen; Medin, Jennie; Christoffersen, Pia; Price, Jennifer; Korn, Jonathan R; Bonzani, Ian; Dwyer, Michael G; Bergsland, Niels; Carl, Ellen; Silva, Diego; Weinstock-Guttman, Bianca

2017-05-01

To describe methodology, interim baseline, and longitudinal magnetic resonance imaging (MRI) acquisition parameter characteristics of the multiple sclerosis clinical outcome and MRI in the United States (MS-MRIUS). The MS-MRIUS is an ongoing longitudinal and retrospective study of MS patients on fingolimod. Clinical and brain MRI image scan data were collected from 600 patients across 33 MS centers in the United States. MRI brain outcomes included change in whole-brain volume, lateral ventricle volume, T2- and T1-lesion volumes, and new/enlarging T2 and gadolinium-enhancing lesions. Interim baseline and longitudinal MRI acquisition parameters results are presented for 252 patients. Mean age was 44 years and 81% were female. Forty percent of scans had 3-dimensional (3D) T1 sequence in the preindex period, increasing to 50% in the postindex period. Use of 2-dimensional (2D) T1 sequence decreased over time from 85% in the preindex period to 65% in the postindex. About 95% of the scans with FLAIR and 2D T1-WI were considered acceptable or good quality compared to 99-100% with 3D T1-WI. There were notable changes in MRI hardware, software, and coil (39.5% in preindex to index and 50% in index to postindex). MRI sequence parameters (orientation, thickness, or protocol) differed for 36%, 29%, and 20% of index/postindex scans for FLAIR, 2D T1-WI, and 3D T1-WI, respectively. The MS-MRIUS study linked the clinical and brain MRI outcomes into an integrated database to create a cohort of fingolimod patients in real-world practice. Variability was observed in MRI acquisition protocols overtime. © 2016 The Authors. Journal of Neuroimaging published by Wiley Periodicals, Inc. on behalf of American Society of Neuroimaging.

MRI findings of temporal lobe epilepsy

International Nuclear Information System (INIS)

Nakahara, Ichiro; Yin, Dali; Fukami, Masahiro; Kondo, Seiji; Takeuchi, Juji; Kanemoto, Kousuke; Sengoku, Akira; Kawai, Itsuo

1992-01-01

MRI findings were analyzed retrospectively in 46 patients with temporal lobe epilepsy in which the side of epileptogenic focus had been confirmed by EEG studies. T 1 - and T 2 -weighted images were obtained by the use of a 1.0 or 1.5 T superconducting-type MRI machine with a coronal scan perpendicular to the axis of the temporal horn of the lateral ventricle. Additional axial and sagittal scans were performed in some cases. The area of the hippocampal body was measured quantitatively using a computerized image-analysis system in 26 cases in which the hippocampus had been visualized with enough contrast on T 1 -weighted coronal images. Abnormal findings were observed in 31/46 (67%) cases. Hippocampal (HC) and temporal lobe (TL) atrophy were observed in 18/46 (39%) and 23/46 (50%) cases respectively, and the side of the atrophy corresponded with the side of the epileptogenic focus, as confirmed by EEG studies, with specificities of 89% and 74% respectively. A quantitative measurement of the area of the hippocampal body showed unilateral hippocampal atrophy more than 10% in 18/25 (69%) cases (10-25%: 10 cases, 25-50%: 7 cases, 50% 2 abnormality was observed in only 4 cases. Structural lesions were observed in 4 cases including an arachnoid cyst, an astrocytoma in amygdala, the Dandy-Walker syndrome, and tuberous sclerosis, using the more efficient imaging qualities than the CT scan. From these observations, it is apparant that superconducting MRI is extremely useful in the diagnosis of the epileptogenic topography of temporal lobe epilepsy. Particularly, hippocampal atrophy was found to correspond with the side of the epileptogenic focus on EEG with a high specificity; its quantitative evaluation could be one of the most important standards in detecting the operative indications for temporal lobe epilepsy. (author)

Multi-modal MRI of mild traumatic brain injury

Directory of Open Access Journals (Sweden)

Ponnada A. Narayana

2015-01-01

Full Text Available Multi-modal magnetic resonance imaging (MRI that included high resolution structural imaging, diffusion tensor imaging (DTI, magnetization transfer ratio (MTR imaging, and magnetic resonance spectroscopic imaging (MRSI were performed in mild traumatic brain injury (mTBI patients with negative computed tomographic scans and in an orthopedic-injured (OI group without concomitant injury to the brain. The OI group served as a comparison group for mTBI. MRI scans were performed both in the acute phase of injury (~24 h and at follow-up (~90 days. DTI data was analyzed using tract based spatial statistics (TBSS. Global and regional atrophies were calculated using tensor-based morphometry (TBM. MTR values were calculated using the standard method. MRSI was analyzed using LC Model. At the initial scan, the mean diffusivity (MD was significantly higher in the mTBI cohort relative to the comparison group in several white matter (WM regions that included internal capsule, external capsule, superior corona radiata, anterior corona radiata, posterior corona radiata, inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, forceps major and forceps minor of the corpus callosum, superior longitudinal fasciculus, and corticospinal tract in the right hemisphere. TBSS analysis failed to detect significant differences in any DTI measures between the initial and follow-up scans either in the mTBI or OI group. No significant differences were found in MRSI, MTR or morphometry between the mTBI and OI cohorts either at the initial or follow-up scans with or without family wise error (FWE correction. Our study suggests that a number of WM tracts are affected in mTBI in the acute phase of injury and that these changes disappear by 90 days. This study also suggests that none of the MRI-modalities used in this study, with the exception of DTI, is sensitive in detecting changes in the acute phase of mTBI.

Magnet dislocation: an increasing and serious complication following MRI in patients with cochlear implants.

Science.gov (United States)

Hassepass, F; Stabenau, V; Arndt, S; Beck, R; Bulla, S; Grauvogel, T; Aschendorff, A

2014-07-01

Cochlear implantation (CI) represents the gold standard in the treatment of children born deaf and postlingually deafened adults. Initial magnetic resonance imaging (MRI) was contraindicated in CI users. Meanwhile, there are specific recommendations concerning MRI compatibility depending on the type of CI system and the device manufacturer. Some CI systems are even approved for MRI with the internal magnet left in place. The aim of this study was to analyze all magnet revision surgeries in CI patients at one CI center and the relationship to MRI scans over time. Between 2000 and 2013, a total of 2027 CIs were implanted. The number of magnet dislocation (MD) surgeries and their causes was assessed retrospectively. In total 12 cases of MD resulting from an MRI scan (0.59 %) were observed, accounting for 52.2 % of all magnetic revision surgeries. As per the labeling, it was considered safe to leave the internal magnet in place during MRI while following specific manufacturer recommendations: MRI intensity of 1.5 Tesla (T) and compression head bandage during examination. A compression head bandage in a 1.5 T MRI unit does not safely prevent MD and the related serious complications in CI recipients. We recommend a Stenvers view radiograph after MRI with the internal magnet in place for early identification of MD, at least in the case of pain during or after MRI examination. MRI in CI patients should be indicated with restraint and patients should be explicitly informed about the possible risks. Recommendations regarding MRI compatibility and the handling of CI patients issued with MRI for the most common CI systems are summarized. © Georg Thieme Verlag KG Stuttgart · New York.

{sup 18}F-FDG PET/MRI in patients suffering from lymphoma: how much MRI information is really needed?

Energy Technology Data Exchange (ETDEWEB)

Kirchner, Julian; Heusch, Philipp; Antoch, Gerald [University Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Dusseldorf (Germany); Deuschl, Cornelius; Grueneisen, Johannes; Forsting, Michael; Umutlu, Lale [University of Duisburg-Essen, Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen (Germany); Herrmann, Ken [University of Duisburg-Essen, Department of Nuclear Medicine, University Hospital Essen, Essen (Germany)

2017-06-15

To evaluate and compare the diagnostic potential of different reading protocols, entailing non-enhanced/contrast-enhanced and diffusion-weighted {sup 18}F-FDG PET/MR imaging for lesion detection and determination of the tumor stage in lymphoma patients. A total of 101 {sup 18}F-FDG PET/MRI datasets including a (1) transverse T2-w HASTE and {sup 18}F-FDG PET (PET/MRI{sub 1}), (2) with an additional contrast enhanced VIBE (PET/MRI{sub 2}), and (3) with additional diffusion-weighted imaging (PET/MRI{sub 3}) were evaluated. Scans were performed for initial staging, restaging during treatment, or at the end of treatment and under surveillance with suspicion for tumor relapse. In all datasets lymphoma manifestations as well as tumor stage in analogy to the revised criteria of the Ann Arbor staging system were determined. Furthermore, potential changes in therapy compared to the reference standard were evaluated. Hitherto performed PET/CT and all available follow-up and prior examinations as well as histopathology served as reference standard. PET/MRI{sub 1} correctly identified 53/55 patients with active lymphoma and 190/205 lesions. Respective values were 55/55, 202/205 for PET/MRI{sub 2} and 55/55, 205/205 for PET/MRI{sub 3}. PET/MRI{sub 1} determined correct tumor stage in 88 out of 101 examinations, and corresponding results for PET/MRI{sub 2} were 95 out of 101 and 96 out of 101 in PET/MRI{sub 3}. Relating to the reference standard changes in treatment would occur in 11% based on PET/MRI{sub 1}, in 6% based on PET/MRI{sub 2}, and in 3% based on PET/MRI{sub 3}. The additional application of contrast-enhanced and diffusion-weighted imaging to {sup 18}F-FDG PET/MRI resulted in higher diagnostic competence, particularly for initial staging and correct classification of the disease extent with potential impact on patient and therapy management. (orig.)

Comprehensive MRI simulation methodology using a dedicated MRI scanner in radiation oncology for external beam radiation treatment planning

International Nuclear Information System (INIS)

Paulson, Eric S.; Erickson, Beth; Schultz, Chris; Allen Li, X.

2015-01-01

Purpose: The use of magnetic resonance imaging (MRI) in radiation oncology is expanding rapidly, and more clinics are integrating MRI into their radiation therapy workflows. However, radiation therapy presents a new set of challenges and places additional constraints on MRI compared to diagnostic radiology that, if not properly addressed, can undermine the advantages MRI offers for radiation treatment planning (RTP). The authors introduce here strategies to manage several challenges of using MRI for virtual simulation in external beam RTP. Methods: A total of 810 clinical MRI simulation exams were performed using a dedicated MRI scanner for external beam RTP of brain, breast, cervix, head and neck, liver, pancreas, prostate, and sarcoma cancers. Patients were imaged in treatment position using MRI-optimal immobilization devices. Radiofrequency (RF) coil configurations and scan protocols were optimized based on RTP constraints. Off-resonance and gradient nonlinearity-induced geometric distortions were minimized or corrected prior to using images for RTP. A multidisciplinary MRI simulation guide, along with window width and level presets, was created to standardize use of MR images during RTP. A quality assurance program was implemented to maintain accuracy and repeatability of MRI simulation exams. Results: The combination of a large bore scanner, high field strength, and circumferentially wrapped, flexible phased array RF receive coils permitted acquisition of thin slice images with high contrast-to-noise ratio (CNR) and image intensity uniformity, while simultaneously accommodating patient setup and immobilization devices. Postprocessing corrections and alternative acquisition methods were required to reduce or correct off-resonance and gradient nonlinearity induced geometric distortions. Conclusions: The methodology described herein contains practical strategies the authors have implemented through lessons learned performing clinical MRI simulation exams. In

Comprehensive MRI simulation methodology using a dedicated MRI scanner in radiation oncology for external beam radiation treatment planning

Energy Technology Data Exchange (ETDEWEB)

Paulson, Eric S., E-mail: epaulson@mcw.edu [Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 and Department of Radiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 (United States); Erickson, Beth; Schultz, Chris; Allen Li, X. [Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 (United States)

2015-01-15

Purpose: The use of magnetic resonance imaging (MRI) in radiation oncology is expanding rapidly, and more clinics are integrating MRI into their radiation therapy workflows. However, radiation therapy presents a new set of challenges and places additional constraints on MRI compared to diagnostic radiology that, if not properly addressed, can undermine the advantages MRI offers for radiation treatment planning (RTP). The authors introduce here strategies to manage several challenges of using MRI for virtual simulation in external beam RTP. Methods: A total of 810 clinical MRI simulation exams were performed using a dedicated MRI scanner for external beam RTP of brain, breast, cervix, head and neck, liver, pancreas, prostate, and sarcoma cancers. Patients were imaged in treatment position using MRI-optimal immobilization devices. Radiofrequency (RF) coil configurations and scan protocols were optimized based on RTP constraints. Off-resonance and gradient nonlinearity-induced geometric distortions were minimized or corrected prior to using images for RTP. A multidisciplinary MRI simulation guide, along with window width and level presets, was created to standardize use of MR images during RTP. A quality assurance program was implemented to maintain accuracy and repeatability of MRI simulation exams. Results: The combination of a large bore scanner, high field strength, and circumferentially wrapped, flexible phased array RF receive coils permitted acquisition of thin slice images with high contrast-to-noise ratio (CNR) and image intensity uniformity, while simultaneously accommodating patient setup and immobilization devices. Postprocessing corrections and alternative acquisition methods were required to reduce or correct off-resonance and gradient nonlinearity induced geometric distortions. Conclusions: The methodology described herein contains practical strategies the authors have implemented through lessons learned performing clinical MRI simulation exams. In

A Fabry-Perot Interferometry Based MRI-Compatible Miniature Uniaxial Force Sensor for Percutaneous Needle Placement

OpenAIRE

Shang, Weijian; Su, Hao; Li, Gang; Furlong, Cosme; Fischer, Gregory S.

2013-01-01

Robot-assisted surgical procedures, taking advantage of the high soft tissue contrast and real-time imaging of magnetic resonance imaging (MRI), are developing rapidly. However, it is crucial to maintain tactile force feedback in MRI-guided needle-based procedures. This paper presents a Fabry-Perot interference (FPI) based system of an MRI-compatible fiber optic sensor which has been integrated into a piezoelectrically actuated robot for prostate cancer biopsy and brachytherapy in 3T MRI scan...

TU-F-CAMPUS-J-02: Evaluation of Textural Feature Extraction for Radiotherapy Response Assessment of Early Stage Breast Cancer Patients Using Diffusion Weighted MRI and Dynamic Contrast Enhanced MRI

Energy Technology Data Exchange (ETDEWEB)

Xie, Y; Wang, C; Horton, J; Chang, Z [Duke University Medical Center, Durham, NC (United States)

2015-06-15

Purpose: To investigate the feasibility of using classic textural feature extraction in radiotherapy response assessment, we studied a unique cohort of early stage breast cancer patients with paired pre - and post-radiation Diffusion Weighted MRI (DWI-MRI) and Dynamic Contrast Enhanced MRI (DCE-MRI). Methods: 15 female patients from our prospective phase I trial evaluating preoperative radiotherapy were included in this retrospective study. Each patient received a single-fraction radiation treatment, and DWI and DCE scans were conducted before and after the radiotherapy. DWI scans were acquired using a spin-echo EPI sequence with diffusion weighting factors of b = 0 and b = 500 mm{sup 2} /s, and the apparent diffusion coefficient (ADC) maps were calculated. DCE-MRI scans were acquired using a T{sub 1}-weighted 3D SPGR sequence with a temporal resolution of about 1 minute. The contrast agent (CA) was intravenously injected with a 0.1 mmol/kg bodyweight dose at 2 ml/s. Two parameters, volume transfer constant (K{sup trans} ) and k{sub ep} were analyzed using the two-compartment Tofts kinetic model. For DCE parametric maps and ADC maps, 33 textural features were generated from the clinical target volume (CTV) in a 3D fashion using the classic gray level co-occurrence matrix (GLCOM) and gray level run length matrix (GLRLM). Wilcoxon signed-rank test was used to determine the significance of each texture feature’s change after the radiotherapy. The significance was set to 0.05 with Bonferroni correction. Results: For ADC maps calculated from DWI-MRI, 24 out of 33 CTV features changed significantly after the radiotherapy. For DCE-MRI pharmacokinetic parameters, all 33 CTV features of K{sup trans} and 33 features of k{sub ep} changed significantly. Conclusion: Initial results indicate that those significantly changed classic texture features are sensitive to radiation-induced changes and can be used for assessment of radiotherapy response in breast cancer.

Data collection and analysis strategies for phMRI.

Science.gov (United States)

Mandeville, Joseph B; Liu, Christina H; Vanduffel, Wim; Marota, John J A; Jenkins, Bruce G

2014-09-01

Although functional MRI traditionally has been applied mainly to study changes in task-induced brain function, evolving acquisition methodologies and improved knowledge of signal mechanisms have increased the utility of this method for studying responses to pharmacological stimuli, a technique often dubbed "phMRI". The proliferation of higher magnetic field strengths and the use of exogenous contrast agent have boosted detection power, a critical factor for successful phMRI due to the restricted ability to average multiple stimuli within subjects. Receptor-based models of neurovascular coupling, including explicit pharmacological models incorporating receptor densities and affinities and data-driven models that incorporate weak biophysical constraints, have demonstrated compelling descriptions of phMRI signal induced by dopaminergic stimuli. This report describes phMRI acquisition and analysis methodologies, with an emphasis on data-driven analyses. As an example application, statistically efficient data-driven regressors were used to describe the biphasic response to the mu-opioid agonist remifentanil, and antagonism using dopaminergic and GABAergic ligands revealed modulation of the mesolimbic pathway. Results illustrate the power of phMRI as well as our incomplete understanding of mechanisms underlying the signal. Future directions are discussed for phMRI acquisitions in human studies, for evolving analysis methodologies, and for interpretative studies using the new generation of simultaneous PET/MRI scanners. This article is part of the Special Issue Section entitled 'Neuroimaging in Neuropharmacology'. Copyright © 2014 Elsevier Ltd. All rights reserved.

Functional MRI studies in children with attention deficit hyperactivity disorder

International Nuclear Information System (INIS)

Zhang Lei; Jin Zhen; Zeng Yawei; Wang Yan; Zang Yufeng

2004-01-01

Objective: To investigate the brain activation map during Go-NoGo tasks in children with attention deficit hyperactivity disorder (ADHD) and matched controls using functional MRI. Methods: Block designed BOLD functional MRI scan covering the whole brain was performed on 10 boys having ADHD and 11 healthy boys. The 2 groups were matched by age, sex, and handedness. Executing advanced inhibitory Go-NoGo tasks served as stimuli for all subjects. The fMRI data was analyzed by SPM99 (Statistical Parametric Mapping) software with statistic t-test to generate the activation map. Results: (1) The normal children showed significant activations in left thalamus and right cingulate gyrus and fewer activations in right middle frontal gyrus during stimulate controlled Go task, but the children with ADHD showed less activations in left thalamus. (2) In response controlled Go task, the normal children showed activations in right insula, cingulate gyrus and left frontal gyrus, while the ADHD children showed lower power of response in the right middle frontal gyrus.(3) In NoGo task, right middle frontal gyrus was the dominant activated regions, and left anterior cingulate, left middle frontal gyrus and right thalamus also had some activations in normal children, while the activations of right prefrontal decreased and the thalamus increased in ADHD boys. Conclusion: In children with ADHD, some dysfunctional brain areas, mainly the prefrontal lobe and anterior cingulate gyrus were found. Thalamus was also involved according to the brain activation map

Functional MRI studies in children with attention deficit hyperactivity disorder

Energy Technology Data Exchange (ETDEWEB)

Lei, Zhang; Zhen, Jin; Yawei, Zeng; Yan, Wang [fMRI Center, Lab of Cognition Science and Learning, National Education Ministry and Department of Radiology, 306 Hospital of PLA, Beijing (China); Yufeng, Zang

2004-06-01

Objective: To investigate the brain activation map during Go-NoGo tasks in children with attention deficit hyperactivity disorder (ADHD) and matched controls using functional MRI. Methods: Block designed BOLD functional MRI scan covering the whole brain was performed on 10 boys having ADHD and 11 healthy boys. The 2 groups were matched by age, sex, and handedness. Executing advanced inhibitory Go-NoGo tasks served as stimuli for all subjects. The fMRI data was analyzed by SPM99 (Statistical Parametric Mapping) software with statistic t-test to generate the activation map. Results: (1) The normal children showed significant activations in left thalamus and right cingulate gyrus and fewer activations in right middle frontal gyrus during stimulate controlled Go task, but the children with ADHD showed less activations in left thalamus. (2) In response controlled Go task, the normal children showed activations in right insula, cingulate gyrus and left frontal gyrus, while the ADHD children showed lower power of response in the right middle frontal gyrus.(3) In NoGo task, right middle frontal gyrus was the dominant activated regions, and left anterior cingulate, left middle frontal gyrus and right thalamus also had some activations in normal children, while the activations of right prefrontal decreased and the thalamus increased in ADHD boys. Conclusion: In children with ADHD, some dysfunctional brain areas, mainly the prefrontal lobe and anterior cingulate gyrus were found. Thalamus was also involved according to the brain activation map.

Enhancement pattern of small hepatic hemangioma: findings on multiphase spiral CT and dynamic MRI

International Nuclear Information System (INIS)

Choi, Byung In; Lee, Seung Koo; Kim, Myeong Jin; Chung, Jae Joon; Yoo, Hyung Sik; Lee, Jong Tae

1999-01-01

To compare the enhancement characteristics of small hemangiomas seen on multiphase spiral CT and dynamic MR imaging. Thirteen patients with 20 hepatic hemangiomas less than 25mm in diameter underwent both multiphase spiral CT and dynamic MR imaging. All lesions were assigned to one of three classified into 3 categories according to the enhancement pattern seen on multiphase spiral CT : typical delayed pooling, atypical early enhancement, or continuous low attenuation. The enhancement patterns seen on spiral CT and on dynamic MRI were correlated. On CT scans, ten lesions (50%) showed delayed pooling. Six (30%) showed early arterial enhancement and four (20%) showed continuous low attenuation. On delayed-phase MRI, all lesions showed delayed high signal intensity compared to adjacent liver parenchyma. Four of six lesions with early enhancement on CT showed peripheral globular enhancement on early arterial-phase MRI. On multiphase spiral CT scans, small hemangiomas can show variable atypical enhancement features. In this situation, contrast-enhanced dynamic MRI is helpful for the diagnosis of hemangiomas

Pediatric neuro MRI. Tricks to minimize sedation

Energy Technology Data Exchange (ETDEWEB)

Barkovich, Matthew J.; Desikan, Rahul S. [University of California, San Francisco, Department of Radiology and Diagnostic Imaging, San Francisco, CA (United States); Xu, Duan; Barkovich, A.J. [University of California, San Francisco, Department of Radiology and Diagnostic Imaging, San Francisco, CA (United States); UCSF-Benioff Children' s Hospital, Department of Radiology, San Francisco, CA (United States); Williams, Cassandra [UCSF-Benioff Children' s Hospital, Department of Radiology, San Francisco, CA (United States)

2018-01-15

Magnetic resonance imaging (MRI) is the workhorse modality in pediatric neuroimaging because it provides excellent soft-tissue contrast without ionizing radiation. Until recently, studies were uninterpretable without sedation; however, given development of shorter sequences, sequences that correct for motion, and studies showing the potentially deleterious effects of sedation on immature laboratory animals, it is prudent to minimize sedation when possible. This manuscript provides basic guidelines for performing pediatric neuro MRI without sedation by both modifying technical factors to reduce scan time and noise, and using a multi-disciplinary team to coordinate imaging with the patient's biorhythms. (orig.)

Comparison of early and late MRI in neonatal hypoxic-ischemic encephalopathy using three assessment methods

International Nuclear Information System (INIS)

Charon, Valerie; Proisy, Maia; Bruneau, Bertrand; Treguier, Catherine; Rozel, Celine; Ferre, Jean-Christophe; Beuchee, Alain; Chauvel, Jennifer

2015-01-01

There is no consensus on the optimum timing of MRI in neonates with hypoxic-ischemic encephalopathy treated with hypothermia. Reliable early imaging assessment might help managing treatment. To assess non-random differences between early and late MRI that might influence intensive-care decisions. This single-center retrospective study included all asphyxiated term neonates eligible for hypothermia treatment November 2009-July 2012. MRI scans were systematically performed at day 4 (early MRI) and day 11 of life as part of routine protocol. Two experienced pediatric radiologists reviewed both scans according to three assessment methods: a pattern classification, a scoring system and a simplified classification. Agreement between early and late imaging findings was assessed using Cohen's kappa coefficients. Thirty-three neonates were included. Interobserver agreement was excellent. Early MRI detected all severe injuries. Agreement between early and late MRI was excellent for the simplified classification (κ = 0.82), good for the pattern classification (κ = 0.64), and good to excellent for 3 scores out of 4 in the scoring system (κ = 0.70-0.89). Early MRI may provide valuable information about brain injury to help parents and neonatologists in intensive-care decisions at the end of hypothermia treatment. (orig.)

Comparison of early and late MRI in neonatal hypoxic-ischemic encephalopathy using three assessment methods

Energy Technology Data Exchange (ETDEWEB)

Charon, Valerie; Proisy, Maia; Bruneau, Bertrand; Treguier, Catherine; Rozel, Celine [University Hospital, Department of Imaging, Hopital Sud, Rennes, Cedex 2 (France); Ferre, Jean-Christophe [University Hospital, Department of Neuroradiology, Hopital Pontchaillou, Rennes (France); Beuchee, Alain [University Hospital, Department of Neonatology, Hopital Sud, Rennes (France); Chauvel, Jennifer [Saint Brieuc Hospital, Department of Neonatology, Saint-Brieuc (France)

2015-12-15

There is no consensus on the optimum timing of MRI in neonates with hypoxic-ischemic encephalopathy treated with hypothermia. Reliable early imaging assessment might help managing treatment. To assess non-random differences between early and late MRI that might influence intensive-care decisions. This single-center retrospective study included all asphyxiated term neonates eligible for hypothermia treatment November 2009-July 2012. MRI scans were systematically performed at day 4 (early MRI) and day 11 of life as part of routine protocol. Two experienced pediatric radiologists reviewed both scans according to three assessment methods: a pattern classification, a scoring system and a simplified classification. Agreement between early and late imaging findings was assessed using Cohen's kappa coefficients. Thirty-three neonates were included. Interobserver agreement was excellent. Early MRI detected all severe injuries. Agreement between early and late MRI was excellent for the simplified classification (κ = 0.82), good for the pattern classification (κ = 0.64), and good to excellent for 3 scores out of 4 in the scoring system (κ = 0.70-0.89). Early MRI may provide valuable information about brain injury to help parents and neonatologists in intensive-care decisions at the end of hypothermia treatment. (orig.)

Prenatal brain MRI of fetuses with Zika virus infection.

Science.gov (United States)

Guillemette-Artur, Prisca; Besnard, Marianne; Eyrolle-Guignot, Dominique; Jouannic, Jean-Marie; Garel, Catherine

2016-06-01

An outbreak of Zika virus was observed in French Polynesia in 2013-2014. Maternal Zika virus infection has been associated with fetal microcephaly and severe cerebral damage. To analyze the MRI cerebral findings in fetuses with intrauterine Zika virus infection. We retrospectively analyzed prospectively collected data. Inclusion criteria comprised cases with (1) estimated conception date between June 2013 and May 2014, (2) available US and MRI scans revealing severe fetal brain lesions and (3) positive polymerase chain reaction for Zika virus in the amniotic fluid. We recorded pregnancy history of Zika virus infection and analyzed US and MRI scans. Three out of 12 cases of severe cerebral lesions fulfilled all inclusion criteria. History of maternal Zika virus infection had been documented in two cases. Calcifications and ventriculomegaly were present at US in all cases. MRI showed micrencephaly (n = 3), low cerebellar biometry (n = 2), occipital subependymal pseudocysts (n = 2), polymicrogyria with laminar necrosis and opercular dysplasia (n = 3), absent (n = 1) or hypoplastic (n = 1) corpus callosum and hypoplastic brainstem (n = 1). Severe cerebral damage was observed in our series, with indirect findings suggesting that the germinal matrix is the principal target for Zika virus. The lesions are very similar to severe forms of congenital cytomegalovirus and lymphocytic choriomeningitis virus infections.

Automated identification of spinal cord and vertebras on sagittal MRI

Science.gov (United States)

Zhou, Chuan; Chan, Heang-Ping; Dong, Qian; He, Bo; Wei, Jun; Hadjiiski, Lubomir M.; Couriel, Daniel

2014-03-01

We are developing an automated method for the identification of the spinal cord and the vertebras on spinal MR images, which is an essential step for computerized analysis of bone marrow diseases. The spinal cord segment was first enhanced by a newly developed hierarchical multiscale tubular (HMT) filter that utilizes the complementary hyper- and hypo- intensities in the T1-weighted (T1W) and STIR MRI sequences. An Expectation-Maximization (EM) analysis method was then applied to the enhanced tubular structures to extract candidates of the spinal cord. The spinal cord was finally identified by a maximum-likelihood registration method by analysis of the features extracted from the candidate objects in the two MRI sequences. Using the identified spinal cord as a reference, the vertebras were localized based on the intervertebral disc locations extracted by another HMT filter applied to the T1W images. In this study, 5 and 30 MRI scans from 35 patients who were diagnosed with multiple myeloma disease were collected retrospectively with IRB approval as training and test set, respectively. The vertebras manually outlined by a radiologist were used as reference standard. A total of 422 vertebras were marked in the 30 test cases. For the 30 test cases, 100% (30/30) of the spinal cords were correctly segmented with 4 false positives (FPs) mistakenly identified on the back muscles in 4 scans. A sensitivity of 95.0% (401/422) was achieved for the identification of vertebras, and 5 FPs were marked in 4 scans with an average FP rate of 0.17 FPs/scan.

Diagnostic Value of MRI in Patients With Implanted Pacemakers and Implantable Cardioverter-Defibrillators Across a Cross Population: Does the Benefit Justify the Risk? A Proof of Concept Study.

Science.gov (United States)

Samar, Huma; Yamrozik, June A; Williams, Ronald B; Doyle, Mark; Shah, Moneal; Bonnet, Christopher A; Biederman, Robert W W

2017-09-01

The objective of this study was to assess the diagnostic usefulness of thoracic and nonthoracic magnetic resonance imaging (MRI) imaging in patients with implantable cardiac devices (permanent pacemaker or implantable cardioverter-defibrillators [ICDs]) to determine if there was a substantial benefit to patients with regard to diagnosis and/or management. MRI is infrequently performed on patients with conventional pacemakers or ICDs. Multiple studies have documented the safety of MRI scans in patients with implanted devices, yet the diagnostic value of this approach has not been established. Evaluation data were acquired in 136 patients with implanted cardiac devices who underwent MRIs during a 10-year period at a single institution. Specific criteria were followed for all patients to objectively define if the diagnosis by MRI enhanced patient care; 4 questions were answered after scan interpretation by both MRI technologists and MRI physicians who performed the scan. 1) Did the primary diagnosis change? 2) Did the MRI provide additional information to the existing diagnosis? 3) Was the pre-MRI (tentative) diagnosis confirmed? 4) Did patient management change? If "Yes" was answered to any of the preceding questions, the MRI scan was considered to be of value to patient diagnosis and/or therapy. In 97% (n = 132) of patients, MR added value to patient diagnosis and management. In 49% (n = 67) of patients, MRI added additional valuable information to the primary diagnosis, and in 30% (n = 41) of patients, MRI changed the principle diagnosis and subsequent management of the patient. No safety issues were encountered, and no adverse effects of undergoing the MRI scan were noted in any patient. MRI in patients with implanted pacemakers and defibrillators added value to patient diagnosis and management, which justified the risk of the procedure. Published by Elsevier Inc.

Triple dose of gadolinium-DTPA and delayed MRI in patients with benign multiple sclerosis.

Science.gov (United States)

Filippi, M; Capra, R; Campi, A; Colombo, B; Prandini, F; Marcianò, N; Gasparotti, R; Comi, G

1996-01-01

OBJECTIVES--To evaluate whether a triple dose of gadolinium-DTPA (Gd-DTPA) or delayed MRI increase the number, size, and conspicuousness of enhancing lesions in patients with benign multiple sclerosis. METHODS--T1 weighted brain MRI was carried out on 20 patients with benign multiple sclerosis (expanded disability status scale 10 years) in two sessions. In the first session, one scan was obtained before and two scans five to seven minutes and 20-30 minutes after the injection of 0.1 mmol/kg Gd-DTPA (standard dose). In the second session, six to 24 hours later, the same procedure was repeated with 0.3 mmol/kg Gd-DTPA (triple dose). RESULTS--Nine enhancing lesions were found in seven patients (35%) using the standard dose of Gd-DTPA. The numbers of enhancing lesions increased to 13 (P = 0.03) and the number of patients with such lesions to eight (40%) on the delayed standard dose scans. On the early triple dose scans, we found 19 enhancing lesions in 10 patients (50%). The number of enhancing lesions was significantly higher (P = 0.01) than that obtained with the early standard dose. The number of enhancing lesions was 18 and the number of "active" patients 11 (55%) on the delayed triple dose scans. The enhancing areas increased progressively from the early standard dose scans to the delayed triple dose scans. The contrast ratios of the lesions detected in early standard dose scans was lower than those of lesions present in the early (P = 0.01) and delayed (P = 0.04) triple dose scans. CONCLUSIONS--More enhancing lesions were detected in patients with benign multiple sclerosis with both delay of MRI and the use of triple dose of Gd-DTPA suggesting that the amount of inflammation in the lesions of such patients is mild and heterogeneous. Images PMID:8778257

Utility of MRI in the follow-up of pyogenic spinal infection in children

International Nuclear Information System (INIS)

Wang, Qiuyan; Babyn, Paul; Branson, Helen; Davila, Jorge; Mueller, Edrise L.; Tran, Dat

2010-01-01

MRI is used at an increasing rate in evaluation of pediatric spinal infections both at the time of diagnosis and in follow-up. However, the impact of MRI in follow-up has been rarely evaluated to date. To evaluate serial follow-up spinal MRI changes compared to clinical outcome and assess their impact on clinical management. All pediatric (<18 years) patients with pyogenic spinal infection over a 9-year period with at least one follow-up after treatment were included. Atypical infections were excluded. We examined 35 whole-spine and 16 localized spinal scans from 17 patients (2 months to 16 years, 9F:8 M) who had 51 follow-ups done 2 weeks to 4.75 years after baseline. Seven children (41%) younger than 3 years underwent 33 follow-ups (65%); most required GA or sedation. Short-term follow-up scans demonstrated epidural and/or paraspinal soft-tissue changes correlating with clinical status and laboratory findings in all cases. However, MRI showed that bone and/or disc abnormalities continued and progressed in some cases despite clinical improvement. Long-term follow-up scans showed bone, disc and soft-tissue changes 1-3 years after baseline, despite children being symptom free. Extension of antibiotics occurred in 47% of children partly based on follow-up MRI. Epidural and paraspinal soft-tissue changes correlated with children's clinical symptoms. Progression of bone and disc changes can manifest despite adequate clinical response. Long-term or serial routine follow-ups were not necessary. Management should be made based on clinical response. (orig.)

A tool for validating MRI-guided strategies: a digital breathing CT/MRI phantom of the abdominal site.

Science.gov (United States)

Paganelli, Chiara; Summers, Paul; Gianoli, Chiara; Bellomi, Massimo; Baroni, Guido; Riboldi, Marco

2017-11-01

Dynamic magnetic resonance imaging (MRI) is emerging as the elected image modality for organ motion quantification and management in image-guided radiotherapy. However, the lack of validation tools is an open issue for image guidance in the abdominal and thoracic organs affected by organ motion due to respiration. We therefore present an abdominal four-dimensional (4D) CT/MRI digital phantom, including the estimation of MR tissue parameters, simulation of dedicated abdominal MR sequences, modeling of radiofrequency coil response and noise, followed by k-space sampling and image reconstruction. The phantom allows the realistic simulation of images generated by MR pulse sequences with control of scan and tissue parameters, combined with co-registered CT images. In order to demonstrate the potential of the phantom in a clinical scenario, we describe the validation of a virtual T1-weighted 4D MRI strategy. Specifically, the motion extracted from a T2-weighted 4D MRI is used to warp a T1-weighted breath-hold acquisition, with the aim of overcoming trade-offs that limit T1-weighted acquisitions. Such an application shows the applicability of the digital CT/MRI phantom as a validation tool, which should be especially useful for cases unsuited to obtain real imaging data.

MRI of the Chest

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Full Text Available ... MRI) of the chest uses a powerful magnetic field, radio waves and a computer to produce detailed ... there’s a possibility you are pregnant. The magnetic field is not harmful, but it may cause some ...

Prospective analysis of in vivo landmark point-based MRI geometric distortion in head and neck cancer patients scanned in immobilized radiation treatment position: Results of a prospective quality assurance protocol

Directory of Open Access Journals (Sweden)

Abdallah S.R. Mohamed

2017-12-01

Full Text Available Purpose: Uncertainties related to geometric distortion are a major obstacle for effectively utilizing MRI in radiation oncology. We aim to quantify the geometric distortion in patient images by comparing their in-treatment position MRIs with the corresponding planning CTs, using CT as the non-distorted gold standard. Methods: Twenty-one head and neck cancer patients were imaged with MRI as part of a prospective Institutional Review Board approved study. MR images were acquired with a T2 SE sequence (0.5 × 0.5 × 2.5 mm voxel size in the same immobilization position as in the CTs. MRI to CT rigid registration was then done and geometric distortion comparison was assessed by measuring the corresponding anatomical landmarks on both the MRI and the CT images. Several landmark measurements were obtained including; skin to skin (STS, bone to bone, and soft tissue to soft tissue at specific levels in horizontal and vertical planes of both scans. Inter-observer variability was assessed and interclass correlation (ICC was calculated. Results: A total of 430 landmark measurements were obtained. The median distortion for all landmarks in all scans was 1.06 mm (IQR 0.6–1.98. For each patient 48% of the measurements were done in the right-left direction and 52% were done in the anteroposterior direction. The measured geometric distortion was not statistically different in the right-left direction compared to the anteroposterior direction (1.5 ± 1.6 vs. 1.6 ± 1.7 mm, respectively, p = 0.4. The magnitude of distortion was higher in the STS peripheral landmarks compared to the more central landmarks (2.0 ± 1.9 vs. 1.2 ± 1.3 mm, p < 0.0001. The mean distortion measured by observer one was not significantly different compared to observer 2, 3, and 4 (1.05, 1.23, 1.06 and 1.05 mm, respectively, p = 0.4 with ICC = 0.84. Conclusion: MRI geometric distortions were

Clinical safety of an MRI conditional implantable cardioverter defibrillator system: A prospective Monocenter ICD-Magnetic resonance Imaging feasibility study (MIMI).

Science.gov (United States)

Kypta, Alexander; Blessberger, Hermann; Hoenig, Simon; Saleh, Karim; Lambert, Thomas; Kammler, Juergen; Fellner, Franz; Lichtenauer, Michael; Steinwender, Clemens

2016-03-01

The aim of this study was to evaluate the safety and efficacy of the Lumax 740(®) Implantable Cardioverter Defibrillator (ICD) system in patients undergoing a defined 1.5 Tesla (T) MRI. Between November 2013 and April 2014, eighteen patients (age range, 41-78 years; mean age, 64 years) implanted with a Lumax 740(®) ICD system for at least 6 weeks before an MRI were enrolled into this single-center feasibility study. The local ethics committee approved the study before patients gave written informed consent. Patients underwent defined MRI 1.5T of the brain and lower lumbar spine with three safety follow-up evaluations obtained during the 3-month study period. Data were analyzed descriptively. Study endpoints were the absence of either MRI and pacing system related serious adverse device effects (SADE), or of a ventricular pacing threshold increase >0.5V, or of an R-wave amplitude attenuation battery status. Sixteen patients completed the MRI and the follow-up period. As no SADE occurred, the SADE free rate was 100%. Freedom from ventricular pacing threshold increase was 100% (16/16; 95%CI: 82.9%; 100.0%). There were no significant differences between baseline and follow-up measurements of sensing amplitudes (-0.58 ± 2.07 mV, P = 0.239, -0.41 ± 1.04 mV, P = 0.133, and -0.25 ± 1.36 mV, P = 0.724, for immediately after, 1 month and 3 months after MRI scan, respectively) and pacing thresholds (-0.047 ± 0.18 V, P = 0.317, -0.019 ± 0.11 V, P = 0.490, and 0.075 ± 0.19 V, P = 0.070, for immediately after, 1 month and 3 months after MRI scan, respectively). Lead impedances after the MRI scan were significantly lower as compared with baseline values (-22.8 ± 21.69 Ω, P = 0.001, -21.62 ± 39.71 Ω, P = 0.040, and -33.68 ± 57.73 Ω, P = 0.018, for immediately after, 1 month and 3 months after MRI scan, respectively). MRI scans in patients with MRI conditional ICD system (Lumax 740(�

SU-G-JeP2-14: MRI-Based HDR Prostate Brachytherapy: A Phantom Study for Interstitial Catheter Reconstruction with 0.35T MRI Images

International Nuclear Information System (INIS)

Park, S; Kamrava, M; Yang, Y

2016-01-01

Purpose: To evaluate the accuracy of interstitial catheter reconstruction with 0.35T MRI images for MRI-based HDR prostate brachytherapy. Methods: Recently, a real-time MRI-guided radiotherapy system combining a 0.35T MRI system and three cobalt 60 heads (MRIdian System, ViewRay, Cleveland, OH, USA) was installed in our department. A TrueFISP sequence for MRI acquisition at lower field on Viewray was chosen due to its fast speed and high signal-to-noise efficiency. Interstitial FlexiGuide needles were implanted into a tissue equivalent ultrasound prostate phantom (CIRS, Norfolk, Virginia, USA). After an initial 15s pilot MRI to confirm the location of the phantom, planning MRI was acquired with a 172s TrueFISP sequence. The pulse sequence parameters included: flip angle = 60 degree, echo time (TE) =1.45 ms, repetition time (TR) = 3.37 ms, slice thickness = 1.5 mm, field of view (FOV) =500 × 450mm. For a reference image, a CT scan was followed. The CT and MR scans were then fused with the MIM Maestro (MIM software Inc., Cleveland, OH, USA) and sent to the Oncentra Brachy planning system (Elekta, Veenendaal, Netherlands). Automatic catheter reconstruction using CT and MR image intensities followed by manual reconstruction was used to digitize catheters. The accuracy of catheter reconstruction was evaluated from the catheter tip location. Results: The average difference between the catheter tip locations reconstructed from the CT and MR in the transverse, anteroposterior, and craniocaudal directions was −0.1 ± 0.1 mm (left), 0.2 ± 0.2 mm (anterior), and −2.3 ± 0.5 mm (cranio). The average distance in 3D was 2.3 mm ± 0.5 mm. Conclusion: This feasibility study proved that interstitial catheters can be reconstructed with 0.35T MRI images. For more accurate catheter reconstruction which can affect final dose distribution, a systematic shift should be applied to the MR based catheter reconstruction in HDR prostate brachytherapy.

Acute pyelonephritis in pediatric age: comparative study between power Doppler ultrasound scan and DMSA

International Nuclear Information System (INIS)

Muro, M. D.; Sanguesa, C.; Otero, M. C.; Piqueras, A. I.; Lloret, M. T.

2002-01-01

To evaluate the usefulness of power Doppler (PD) Ultrasound Scan in the study of acute pyelonephritis (APN). To compare ultrasound scan results with those obtained with renal gammagraphy (DMSA). To relate the findings to the clinical criteria and to determine the presence of vesicoureteral reflux (VUR) in the serial micturition cystography (SMC). Prospective study of 92 patients (ages between 1 month and 10 years) with suspected clinical PNA. All children were initially subjected to PD ultrasound scan and DMSA. Those under 3 years old were also subjected to SMC for the study of VUR. PNA in the PD ultrasound scan was manifested by decrease in vascularisation and in the DMSA by decrease in caption in the affected zones. 87 renal units (RU) with PNA foci were detected. Conformity between the PD ultrasound scan and DMSA was 157 RU (92%): 52 positives, 22 negatives with PNA and 83 normal RU. The sensitivities of PD and DMSA were 65.5% and 69.0%. 51 SMC were performed, with VUR being detected in 18 (13 bilateral and 5 unilateral), in which the sensitivities of PD and DMSA were 65.5% and 69.0%. 51 SMC were performed, with VUR being detected in 18 (13 bilateral and 5 unilateral), in which the sensitivities of PD and DMSA were 80% and 85%, respectively. Mode B ultrasound scan and PD can replace DMSA in the initial study of PPNA. It is non-invasive, simple, economical and just as reliable as DMSA in expert hands. it can also postpone by up to 6 months the need to perform DMSA for detection of permanent renal damage. (Author) 22 refs

MRI of the carotid artery at 7 Tesla: Quantitative comparison with 3 Tesla

NARCIS (Netherlands)

Koning, Wouter; De Rotte, Alexandra A J; Bluemink, Johanna J.; Van Der Velden, Tijl A.; Luijten, Peter R.; Klomp, DWJ; Zwanenburg, Jaco J M

2015-01-01

Purpose: To evaluate the 7 Tesla (T) MRI of the carotid arteries, as quantitatively compared with 3T. Materials and Methods: The 7T MRI of the carotid arteries was performed in six healthy subjects and in two patients with carotid stenosis. The healthy group was scanned at 3T and at 7T, using

MRI diagnosis of intracranial tuberculosis (73 cases report)

International Nuclear Information System (INIS)

Zeng Qingyong; Li Xin; He Zhihui; Cheng Chuanhu; Deng Kaijun; Deng Ming

2008-01-01

Objective: To assess the MRI features, classification and diagnostic value for intracranial tuberculosis. Methods MRI findings of 73 patients suffering from intracranial tuberculosis proved by pathology or clinic were analyzed respectively. Among the total 73 patients, 39 cases were tuberculosis meningitis, 12 cases simple intracranial tuberculoma, while 22 cases were tuberculoma combining with meningitis. Results: The MRI features of tuberculous meningitis are cerebral infarction, hydrocephalus, abnormal meningeal and cerebral cistern enhancement. 12 cases mature tuberculoma demon- strated typical features with high or low density on T 2 WI images and ring contrast enhancement; 22 cases non-mature tuberculoma showed focal nodular contrast enhancement with evident cerebral edema. FLAIR is more sensitive to find out focus than T 2 WI. Small lesions could be showed definitively by contrast-enhanced scan. Conclusion: MRI possess typical features in the diagnosis of intracranial tuberculosis. It plays an important role in evaluating location, range, classification of intracranial tuberculosis, and is helpful to clinical treatment. (authors)

MRI diagnosis of criss-cross heart

International Nuclear Information System (INIS)

Du Jing; Jiang Tao; Lv Biao; Zhang Zhaoqi; Du Jiahui

2007-01-01

Objective: To investigate the value of MRI and MRA in the diagnosis of criss-cross heart(CCH). Methods: Four cases diagnosed as CCH received MRI examination. According to the methods and considerations of segmental analysis, the scan was performed with multiple sequences, multiple angles, and multiple positions in order to show the complicated anatomical malformations of CCH. Results: In all patients, atrioventricular connection was concordant. Both atrioventricular valves were aligned vertically from the anterior-superior to the posterior-inferior position in four patients. The blood streams in the inlet of both ventricles crossed in the midheart. The morphologic right ventricle was superiorly positioned on the morphologic left ventricle. There was horizontal ventricular septum and huge VSD in all patients. The ventriculoarterial connections were discordant, including total transposition of great arteries in 1 patient and double-outlet right ventricle in 3 patients. In addition, associated anomalies were found, including pulmonary stenosis (n=3), pulmonary hypertension (n=1), ASD (n=1), and right aortic arch and decending aorta (n=1). Conclusions: CCH can be accurately diagnosed by using MRI, and MRI has important value in clinical application. (authors)

Intraoperative MRI in pediatric brain tumors

Energy Technology Data Exchange (ETDEWEB)

Choudhri, Asim F. [Le Bonheur Children' s Hospital, Department of Radiology, Memphis, TN (United States); University of Tennessee Health Science Center, Department of Radiology, Memphis, TN (United States); University of Tennessee Health Science Center, Department of Neurosurgery, Memphis, TN (United States); University of Tennessee Health Science Center, Department of Ophthalmology, Memphis, TN (United States); Le Bonheur Children' s Hospital, Le Bonheur Neuroscience Institute, Memphis, TN (United States); Siddiqui, Adeel [University of Tennessee Health Science Center, Department of Radiology, Memphis, TN (United States); Le Bonheur Children' s Hospital, Le Bonheur Neuroscience Institute, Memphis, TN (United States); Klimo, Paul; Boop, Frederick A. [University of Tennessee Health Science Center, Department of Neurosurgery, Memphis, TN (United States); Le Bonheur Children' s Hospital, Le Bonheur Neuroscience Institute, Memphis, TN (United States); Semmes-Murphey Neurologic and Spine Institute, Memphis, TN (United States); St. Jude Children' s Hospital, Division of Neurosurgery, Department of Surgery, Memphis, TN (United States)

2015-09-15

Intraoperative magnetic resonance imaging (iMRI) has emerged as an important tool in guiding the surgical management of children with brain tumors. Recent advances have allowed utilization of high field strength systems, including 3-tesla MRI, resulting in diagnostic-quality scans that can be performed while the child is on the operating table. By providing information about the possible presence of residual tumor, it allows the neurosurgeon to both identify and resect any remaining tumor that is thought to be safely accessible. By fusing the newly obtained images with the surgical guidance software, the images have the added value of aiding in navigation to any residual tumor. This is important because parenchyma often shifts during surgery. It also gives the neurosurgeon insight into whether any immediate postoperative complications have occurred. If any complications have occurred, the child is already in the operating room and precious minutes lost in transport and communications are saved. In this article we review the three main approaches to an iMRI system design. We discuss the possible roles for iMRI during intraoperative planning and provide guidance to help radiologists and neurosurgeons alike in the collaborative management of these children. (orig.)

Intraoperative MRI in pediatric brain tumors

International Nuclear Information System (INIS)

Choudhri, Asim F.; Siddiqui, Adeel; Klimo, Paul; Boop, Frederick A.

2015-01-01

Intraoperative magnetic resonance imaging (iMRI) has emerged as an important tool in guiding the surgical management of children with brain tumors. Recent advances have allowed utilization of high field strength systems, including 3-tesla MRI, resulting in diagnostic-quality scans that can be performed while the child is on the operating table. By providing information about the possible presence of residual tumor, it allows the neurosurgeon to both identify and resect any remaining tumor that is thought to be safely accessible. By fusing the newly obtained images with the surgical guidance software, the images have the added value of aiding in navigation to any residual tumor. This is important because parenchyma often shifts during surgery. It also gives the neurosurgeon insight into whether any immediate postoperative complications have occurred. If any complications have occurred, the child is already in the operating room and precious minutes lost in transport and communications are saved. In this article we review the three main approaches to an iMRI system design. We discuss the possible roles for iMRI during intraoperative planning and provide guidance to help radiologists and neurosurgeons alike in the collaborative management of these children. (orig.)

Hearing loss associated with repeated MRI acquisition procedure-related acoustic noise exposure: an occupational cohort study

NARCIS (Netherlands)

Bongers, Suzan; Slottje, Pauline; Kromhout, Hans

2017-01-01

OBJECTIVE: To study the effects of repeated exposure to MRI-related acoustic noise during image acquisition procedures (scans) on hearing. METHODS: A retrospective occupational cohort study was performed among workers of an MRI manufacturing facility (n=474). Longitudinal audiometry data from the

Extraction of Overt Verbal Response from the Acoustic Noise in a Functional Magnetic Resonance Imaging Scan by Use of Segmented Active Noise Cancellation

Science.gov (United States)

Jung, Kwan-Jin; Prasad, Parikshit; Qin, Yulin; Anderson, John R.

2013-01-01

A method to extract the subject's overt verbal response from the obscuring acoustic noise in an fMRI scan is developed by applying active noise cancellation with a conventional MRI microphone. Since the EPI scanning and its accompanying acoustic noise in fMRI are repetitive, the acoustic noise in one time segment was used as a reference noise in suppressing the acoustic noise in subsequent segments. However, the acoustic noise from the scanner was affected by the subject's movements, so the reference noise was adaptively adjusted as the scanner's acoustic properties varied in time. This method was successfully applied to a cognitive fMRI experiment with overt verbal responses. PMID:15723385

A Tool for Interactive Data Visualization: Application to Over 10,000 Brain Imaging and Phantom MRI Data Sets

OpenAIRE

Panta, Sandeep R.; Wang, Runtang; Fries, Jill; Kalyanam, Ravi; Speer, Nicole; Banich, Marie; Kiehl, Kent; King, Margaret; Milham, Michael; Wager, Tor D.; Turner, Jessica A.; Plis, Sergey M.; Calhoun, Vince D.

2016-01-01

In this paper we propose a web-based approach for quick visualization of big data from brain magnetic resonance imaging (MRI) scans using a combination of an automated image capture and processing system, nonlinear embedding, and interactive data visualization tools. We draw upon thousands of MRI scans captured via the COllaborative Imaging and Neuroinformatics Suite (COINS). We then interface the output of several analysis pipelines based on structural and functional data to a t-distributed ...

Novel use of gamma correction for precise 99mTc-HDP pinhole bone scan diagnosis and classification of knee occult fractures

International Nuclear Information System (INIS)

Bahk, Yong-Whee; Jeon, Ho-Seung; Kim, Jang Min; Park, Jung Mee; Kim, Sung-Hoon; Chung, Soo-Kyo; Chung, Yong-An; Kim, E.E.

2010-01-01

The aim of this study was to introduce gamma correction pinhole bone scan (GCPBS) to depict specific signs of knee occult fractures (OF) on 99m Tc-hydroxydiphosphonate (HDP) scan. Thirty-six cases of six different types of knee OF in 27 consecutive patients (male = 20, female = 7, and age = 18-86 years) were enrolled. The diagnosis was made on the basis of a history of acute or subacute knee trauma, local pain, tenderness, cutaneous injury, negative conventional radiography, and positive magnetic resonance imaging (MRI). Because of the impracticability of histological verification of individual OF, MRI was utilized as a gold standard of diagnosis and classification. All patients had 99m Tc-HDP bone scanning and supplementary GCPBS. GCPBS signs were correlated and compared with those of MRI. The efficacy of gamma correction of ordinary parallel collimator and pinhole collimator scans were collated. Gamma correction pinhole bone scan depicted the signs characteristic of six different types of OF. They were well defined stuffed globular tracer uptake in geographic I fractures (n = 9), block-like uptake in geographic II fractures (n = 7), simple or branching linear uptake in linear cancellous fractures (n = 4), compression in impacted fractures (n = 2), stippled-serpentine uptake in reticular fractures (n = 11), and irregular subcortical uptake in osteochondral fractures (n = 3). All fractures were equally well or more distinctly depicted on GCPBS than on MRI except geographic II fracture, the details of which were not appreciated on GCPBS. Parallel collimator scan also yielded to gamma correction, but the results were inferior to those of the pinhole scan. Gamma correction pinhole bone scan can depict the specific diagnostic signs in six different types of knee occult fractures. The specific diagnostic capability along with the lower cost and wider global availability of bone scanning would make GCPBS an effective alternative. (orig.)

Test-retest reliability of evoked BOLD signals from a cognitive-emotive fMRI test battery.

Science.gov (United States)

Plichta, Michael M; Schwarz, Adam J; Grimm, Oliver; Morgen, Katrin; Mier, Daniela; Haddad, Leila; Gerdes, Antje B M; Sauer, Carina; Tost, Heike; Esslinger, Christine; Colman, Peter; Wilson, Frederick; Kirsch, Peter; Meyer-Lindenberg, Andreas

2012-04-15

Even more than in cognitive research applications, moving fMRI to the clinic and the drug development process requires the generation of stable and reliable signal changes. The performance characteristics of the fMRI paradigm constrain experimental power and may require different study designs (e.g., crossover vs. parallel groups), yet fMRI reliability characteristics can be strongly dependent on the nature of the fMRI task. The present study investigated both within-subject and group-level reliability of a combined three-task fMRI battery targeting three systems of wide applicability in clinical and cognitive neuroscience: an emotional (face matching), a motivational (monetary reward anticipation) and a cognitive (n-back working memory) task. A group of 25 young, healthy volunteers were scanned twice on a 3T MRI scanner with a mean test-retest interval of 14.6 days. FMRI reliability was quantified using the intraclass correlation coefficient (ICC) applied at three different levels ranging from a global to a localized and fine spatial scale: (1) reliability of group-level activation maps over the whole brain and within targeted regions of interest (ROIs); (2) within-subject reliability of ROI-mean amplitudes and (3) within-subject reliability of individual voxels in the target ROIs. Results showed robust evoked activation of all three tasks in their respective target regions (emotional task=amygdala; motivational task=ventral striatum; cognitive task=right dorsolateral prefrontal cortex and parietal cortices) with high effect sizes (ES) of ROI-mean summary values (ES=1.11-1.44 for the faces task, 0.96-1.43 for the reward task, 0.83-2.58 for the n-back task). Reliability of group level activation was excellent for all three tasks with ICCs of 0.89-0.98 at the whole brain level and 0.66-0.97 within target ROIs. Within-subject reliability of ROI-mean amplitudes across sessions was fair to good for the reward task (ICCs=0.56-0.62) and, dependent on the particular ROI

MRI features of bilateral parotid haemangiomas of infancy

International Nuclear Information System (INIS)

Andronikou, Savvas; Jadwat, Saaleeha; McHugh, Kieran; Linward, Jane

2003-01-01

The aim of this article is to report the MRI features of bilateral parotid haemangiomas of infancy and highlight the diagnostic and prognostic value of MRI especially with regard to those lesions that may cause respiratory compromise. Retrospective review of MRI scans in six infants with bilateral parotid haemangiomas. The bilateral haemangiomas were symmetrical in all but one patient. On T1-weighted images the masses were isointense to muscle and on T2 they were hyperintense with numerous small vessels giving a septated appearance. There was vivid enhancement with gadolinium in all cases. In three patients, deep bilateral extensions were demonstrated involving the parapharyngeal spaces resulting in respiratory compromise which required tracheostomy. Bilateral parotid haemangiomas are rare, but when present may have deep extensions, which can result in respiratory compromise requiring tracheostomy. (orig.)

MRI features of bilateral parotid haemangiomas of infancy

Energy Technology Data Exchange (ETDEWEB)

Andronikou, Savvas; Jadwat, Saaleeha [Institute of Child Health, University of Cape Town, Klipfontein Road, Rondebosch, 7700, Cape Town (South Africa); McHugh, Kieran; Linward, Jane [Department of Radiology, Great Ormond Street Hospital for Children, London, WC1N 3JH (United Kingdom)

2003-04-01

The aim of this article is to report the MRI features of bilateral parotid haemangiomas of infancy and highlight the diagnostic and prognostic value of MRI especially with regard to those lesions that may cause respiratory compromise. Retrospective review of MRI scans in six infants with bilateral parotid haemangiomas. The bilateral haemangiomas were symmetrical in all but one patient. On T1-weighted images the masses were isointense to muscle and on T2 they were hyperintense with numerous small vessels giving a septated appearance. There was vivid enhancement with gadolinium in all cases. In three patients, deep bilateral extensions were demonstrated involving the parapharyngeal spaces resulting in respiratory compromise which required tracheostomy. Bilateral parotid haemangiomas are rare, but when present may have deep extensions, which can result in respiratory compromise requiring tracheostomy. (orig.)

A review of MRI evaluation of demyelination in cuprizone murine model

Energy Technology Data Exchange (ETDEWEB)

Krutenkova, E., E-mail: len--k@yandex.ru; Pan, E.; Khodanovich, M., E-mail: khodanovich@mail.tsu.ru [National Research Tomsk State University, Lenina pr., 36, Tomsk (Russian Federation)

2015-11-17

The cuprizone mouse model of non-autoimmune demyelination reproduces some phenomena of multiple sclerosis and is appropriate for validation and specification of a new method of non-invasive diagnostics. In the review new data which are collected using the new MRI method are compared with one or more conventional MRI tools. Also the paper reviewed the validation of MRI approaches using histological or immunohistochemical methods. Luxol fast blue histological staining and myelin basic protein immunostaining is widespread. To improve the accuracy of non-invasive conventional MRI, multimodal scanning could be applied. The new quantitative MRI method of fast mapping of the macromolecular proton fraction is a reliable biomarker of myelin in the brain and can be used for research of demyelination in animals. To date, a validation of MPF method on the CPZ mouse model of demyelination is not performed, although this method is probably the best way to evaluate demyelination using MRI.

MRI and pathology in persistent postherniotomy pain

DEFF Research Database (Denmark)

Aasvang, Eske Kvanner; Jensen, Karl-Erik; Fiirgaard, Bente

2009-01-01

-free unoperated groins scanned. Two blinded observers separately assessed groins using a predefined list of possible MRI pathology and anatomic landmarks. Primary outcomes included interobserver agreement assessed by calculating kappa-coefficients. Secondary outcomes included frequency of MRI pathology in painful...... groins versus unoperated and pain-free groins. RESULTS: Interobserver agreement was poor, ranging from kappa = 0.24 to 0.55 ("fair" to "moderate") except for "contrast enhancement in groin" (kappa = 0.69, substantial). Pathologic changes in the form of "contrast enhancement in groin," "edema......," and "spermatic cord caliber increased" were significantly more often seen in painful versus unoperated groins (p pathologic finding was specific or seen in all painful groins. CONCLUSIONS...

Multiparametric MRI of Epiphyseal Cartilage Necrosis (Osteochondrosis with Histological Validation in a Goat Model.

Directory of Open Access Journals (Sweden)

Luning Wang

Full Text Available To evaluate multiple MRI parameters in a surgical model of osteochondrosis (OC in goats.Focal ischemic lesions of two different sizes were induced in the epiphyseal cartilage of the medial femoral condyles of goats at 4 days of age by surgical transection of cartilage canal blood vessels. Goats were euthanized and specimens harvested 3, 4, 5, 6, 9 and 10 weeks post-op. Ex vivo MRI scans were conducted at 9.4 Tesla for mapping the T1, T2, T1ρ, adiabatic T1ρ and TRAFF relaxation times of articular cartilage, unaffected epiphyseal cartilage, and epiphyseal cartilage within the area of the induced lesion. After MRI scans, safranin O staining was conducted to validate areas of ischemic necrosis induced in the medial femoral condyles of six goats, and to allow comparison of MRI findings with the semi-quantitative proteoglycan assessment in corresponding safranin O-stained histological sections.All relaxation time constants differentiated normal epiphyseal cartilage from lesions of ischemic cartilage necrosis, and the histological staining results confirmed the proteoglycan (PG loss in the areas of ischemia. In the scanned specimens, all of the measured relaxation time constants were higher in the articular than in the normal epiphyseal cartilage, consistently allowing differentiation between these two tissues.Multiparametric MRI provided a sensitive approach to discriminate between necrotic and viable epiphyseal cartilage and between articular and epiphyseal cartilage, which may be useful for diagnosing and monitoring OC lesions and, potentially, for assessing effectiveness of treatment interventions.

Image registration/fusion software for PET and CT/MRI by using simultaneous emission and transmission scans

International Nuclear Information System (INIS)

Kitamura, Keishi; Amano, Masaharu; Sato, Tomohiko; Okumura, Takeshi; Konishi, Norihiro; Komatsu, Masahiko

2003-01-01

When PET (positron emission tomography) is used for oncology studies, it is important to register and over-lay PET images with the images of other anatomical modalities, such as those obtained by CT (computed tomography) or MRI (magnetic resonance imaging), in order for the lesions to be anatomically located with high accuracy. The Shimadzu SET-2000W Series PET scanners provide simultaneous acquisition of emission and transmission data, which is capable of complete spatial alignment of both functional and attenuation images. This report describes our newly developed image registration/fusion software, which reformats PET emission images to the CT/MRI grid by using the transform matrix obtained by matching PET transmission images with CT/MRI images. Transmission images are registered and fused either automatically or manually, through 3-dimensional rotation and translation, with the transaxial, sagittal, and coronal fused images being monitored on the screen. This new method permits sufficiently accurate registration and efficient data processing with promoting effective use of CT/MRI images of the DICOM format, without using markers in data acquisition or any special equipment, such as a combined PET/CT scanner. (author)

Health complaints among nurses working near MRI scanners-A descriptive pilot study

International Nuclear Information System (INIS)

Wilen, Jonna; Vocht, Frank de

2011-01-01

A questionnaire-based descriptive pilot study was conducted among all nurses routinely working with MRI in the Northern part of Sweden to provide an indication of the self-reported prevalence of health complaints related to working with MRI systems. Fifty-nine nurses (88% response rate), with on average 8 (±6) years experience with MRI scanning procedures, returned the questionnaire. In total, 9 nurses (15%) reported regularly experiencing at least one of the health complaints (1-5% for specific health complaints) attributed to arise or be aggravated by their presence in the MRI scanning room. Stratification of the results indicated that reporting of adverse symptoms was not related to the level of occupational workload/stress. However, reporting of health complaints was related to the strength of the magnet(s) the nurses worked with, with 57% of symptoms reported by those nurses working with the strongest systems (both 1.5 and 3 T scanners in this population). Although this descriptive study did not include a control population and was based on self-reporting of health complaints, these data indicate that the prevalence of reported health complaints is not related to perceived work load or occupational stress, but does confirm data from other occupational sectors and indicates that the prevalence of adverse health complaints increases with the strength of the MRI system for nurses as well.

The usefulness of MRI for the diagnosis of abnormal pregnancies

International Nuclear Information System (INIS)

Amano, Yasuo

1994-01-01

The clinical usefulness of MRI for the diagnosis of abnormal pregnancies was evaluated. Pelvic MRI was carried out on 29 cases suspected of abnormal pregnancy by ultrasonography and clinical examinations. The abnormal pregnancies were classified into three categories: (1) maternal abnormalities, (2) fetal abnormalities and (3) placental abnormalities. MRI was of great value for the diagnosis of maternal abnormalities, particularly in cases of coexistent pelvic tumor. MRI allowed diagnosis of uterine leiomyomas and dermoid cyst through its excellent tissue characterization and broad range of vision. MRI was useful in making diagnoses of fetal central nervous anomalies and fetal death, since the lack of fetal movement and the lesions were clear enough to be detected by MRI. However, anomalies in the fetal trunk or extremities could only be demonstrated, but not diagnosed, by MRI owing to its inferior spatial and time resolution. MRI showed placenta accreta and placental hematoma. Although accurate diagnosis was difficult because of their rarity, MRI revealed the hemorrhagic component of the lesions, which was not shown by ultrasonography. The author believes MRI has potential usefulness in making diagnoses of placental abnormalities through its tissue characterization. MRI was superior to ultrasonography in the soft tissue characterization, field of view, while MRI was inferior in time and spatial resolution. In summary, MRI hould be used in case of abnormal pregnancies such as pelvic tumors, fetal nervous anomalies and placental hemorrhagic lesions. MRI will become useful for the diagnosis of other abnormalities as its spatial resolution and fast scan technology advances. (author)

The usefulness of MRI for the diagnosis of abnormal pregnancies

Energy Technology Data Exchange (ETDEWEB)

Amano, Yasuo (Nippon Medical School, Tokyo (Japan))

1994-02-01

The clinical usefulness of MRI for the diagnosis of abnormal pregnancies was evaluated. Pelvic MRI was carried out on 29 cases suspected of abnormal pregnancy by ultrasonography and clinical examinations. The abnormal pregnancies were classified into three categories: (1) maternal abnormalities, (2) fetal abnormalities and (3) placental abnormalities. MRI was of great value for the diagnosis of maternal abnormalities, particularly in cases of coexistent pelvic tumor. MRI allowed diagnosis of uterine leiomyomas and dermoid cyst through its excellent tissue characterization and broad range of vision. MRI was useful in making diagnoses of fetal central nervous anomalies and fetal death, since the lack of fetal movement and the lesions were clear enough to be detected by MRI. However, anomalies in the fetal trunk or extremities could only be demonstrated, but not diagnosed, by MRI owing to its inferior spatial and time resolution. MRI showed placenta accreta and placental hematoma. Although accurate diagnosis was difficult because of their rarity, MRI revealed the hemorrhagic component of the lesions, which was not shown by ultrasonography. The author believes MRI has potential usefulness in making diagnoses of placental abnormalities through its tissue characterization. MRI was superior to ultrasonography in the soft tissue characterization, field of view, while MRI was inferior in time and spatial resolution. In summary, MRI hould be used in case of abnormal pregnancies such as pelvic tumors, fetal nervous anomalies and placental hemorrhagic lesions. MRI will become useful for the diagnosis of other abnormalities as its spatial resolution and fast scan technology advances. (author).

Sensitivity and specificity of CT- and MRI-scanning in evaluation of occult fracture of the proximal femur

DEFF Research Database (Denmark)

Haubro, M; Stougaard, C; Torfing, T

2015-01-01

AND METHODS: 67 patients (27 males, 40 females, mean age 80.5) seen in the emergency room with hip pain after fall, inability to stand and a primary X-ray without fracture were evaluated with both CT and MRI. The images were analysed by a senior consulting musculoskeletal radiologist, a resident in radiology...... and a resident in orthopaedic surgery. Sensitivity and specificity were estimated with MRI as the golden standard. Kappa value was used to assess level of agreement in both MRI and CT finding. RESULTS: 15 fractures of the proximal femur were found (7 intertrochanteric-, 3 femoral neck and 5 fractures...

A comparison of serial MRI with X-ray CT in a patient with Reye-like syndrome

International Nuclear Information System (INIS)

Fujii, Yasushi; Kuriyama, Masanori; Yoshimoto, Masahiro; Konishi, Yukuo; Fujisawa, Shinichi; Sudo, Masakatsu; Hayakawa, Katsumi

1988-01-01

Serial MRI and X-ray CT scans were performed on a one-year 7-month old girl with Reye-like syndrome. X-ray CT scan revealed marked hemispheric brain edema in the acute stage and moderate ventricular dilatation with diffuse low density area and cortical atrophy in the chronic stage. MRI performed in the chronic stage showed marked progressive changes. Linear high intensity areas were demonstrated on T 2 weighted MRI performed 21 days after the onset. These high intensity areas increased gradually and 60 days after the onset these high intensity areas spread to the grey matter. These high intensity changes seemed to be correspond to cortical necrosis, and those in the white matter to gliosis or degeneration of myelin. (author)

Fourier transform power spectrum is a potential measure of tissue alignment in standard MRI: A multiple sclerosis study.

Science.gov (United States)

Sharma, Shrushrita; Zhang, Yunyan

2017-01-01

Loss of tissue coherency in brain white matter is found in many neurological diseases such as multiple sclerosis (MS). While several approaches have been proposed to evaluate white matter coherency including fractional anisotropy and fiber tracking in diffusion-weighted imaging, few are available for standard magnetic resonance imaging (MRI). Here we present an image post-processing method for this purpose based on Fourier transform (FT) power spectrum. T2-weighted images were collected from 19 patients (10 relapsing-remitting and 9 secondary progressive MS) and 19 age- and gender-matched controls. Image processing steps included: computation, normalization, and thresholding of FT power spectrum; determination of tissue alignment profile and dominant alignment direction; and calculation of alignment complexity using a new measure named angular entropy. To test the validity of this method, we used a highly organized brain white matter structure, corpus callosum. Six regions of interest were examined from the left, central and right aspects of both genu and splenium. We found that the dominant orientation of each ROI derived from our method was significantly correlated with the predicted directions based on anatomy. There was greater angular entropy in patients than controls, and a trend to be greater in secondary progressive MS patients. These findings suggest that it is possible to detect tissue alignment and anisotropy using traditional MRI, which are routinely acquired in clinical practice. Analysis of FT power spectrum may become a new approach for advancing the evaluation and management of patients with MS and similar disorders. Further confirmation is warranted.

Fourier transform power spectrum is a potential measure of tissue alignment in standard MRI: A multiple sclerosis study.

Directory of Open Access Journals (Sweden)

Shrushrita Sharma

Full Text Available Loss of tissue coherency in brain white matter is found in many neurological diseases such as multiple sclerosis (MS. While several approaches have been proposed to evaluate white matter coherency including fractional anisotropy and fiber tracking in diffusion-weighted imaging, few are available for standard magnetic resonance imaging (MRI. Here we present an image post-processing method for this purpose based on Fourier transform (FT power spectrum. T2-weighted images were collected from 19 patients (10 relapsing-remitting and 9 secondary progressive MS and 19 age- and gender-matched controls. Image processing steps included: computation, normalization, and thresholding of FT power spectrum; determination of tissue alignment profile and dominant alignment direction; and calculation of alignment complexity using a new measure named angular entropy. To test the validity of this method, we used a highly organized brain white matter structure, corpus callosum. Six regions of interest were examined from the left, central and right aspects of both genu and splenium. We found that the dominant orientation of each ROI derived from our method was significantly correlated with the predicted directions based on anatomy. There was greater angular entropy in patients than controls, and a trend to be greater in secondary progressive MS patients. These findings suggest that it is possible to detect tissue alignment and anisotropy using traditional MRI, which are routinely acquired in clinical practice. Analysis of FT power spectrum may become a new approach for advancing the evaluation and management of patients with MS and similar disorders. Further confirmation is warranted.

CT and MRI in progressive multifocal leukoencephalopathy

International Nuclear Information System (INIS)

Lanfermann, H.; Heindel, W.; Schroeder, R.; Lackner, K.

1994-01-01

Radiological findings and course of progressive multifocal leukoencephalopathy in 14 patients (1 woman, 13 men; 13 HIV seropositive, 1 chronic lymphatic leukaemia) were analysed retrospectively and correlated with clinical symptoms. A total of 21 CT and 16 MRI studies were evaluated. CT scans and MR images of 9 patients, which had been obtained in less than two weeks, could be compared to each other. MRI was superior to CT: 6 lesions with a diameter of 1 cm and below were not detected on CT scans, in 5 patients the extent of lesions was underestimated. Cortical involvement, mass effect or signs of atrophy were missing. Only 1 of 65 lesions showed a tiny enhancement after Gd injection. Due to the pattern and spread of lesions, which showed a close correlation to the neurologic symptoms, three different types of PML are suggested: 1. Initial precentral demyelinisation with contralateral hemiparesis (n=8); 2. lesions in temporo-occipital locations with visual disturbances (n=2); 3. predominantly bilateral lesions of cerebellar white matter with ataxia (n=4). (orig.) [de

Advanced imaging techniques in pediatric body MRI

Energy Technology Data Exchange (ETDEWEB)

Courtier, Jesse [UCSF Benioff Children' s Hospital, Department of Radiology and Biomedical Imaging, San Francisco, CA (United States); Rao, Anil G. [Medical University of South Carolina, Department of Radiology, Charleston, SC (United States); Anupindi, Sudha A. [Children' s Hospital of Philadelphia, Department of Radiology, Philadelphia, PA (United States)

2017-05-15

While there are many challenges specific to pediatric abdomino-pelvic MRI, many recent advances are addressing these challenges. It is therefore essential for radiologists to be familiar with the latest advances in MR imaging. Laudable efforts have also recently been implemented in many centers to improve the overall experience of pediatric patients, including the use of dedicated radiology child life specialists, MRI video goggles, and improved MR suite environments. These efforts have allowed a larger number of children to be scanned while awake, with fewer studies being done under sedation or anesthesia; this has resulted in additional challenges from patient motion and difficulties with breath-holding and tolerating longer scan times. In this review, we highlight common challenges faced in imaging the pediatric abdomen and pelvis and discuss the application of the newest techniques to address these challenges. Additionally, we highlight the newest advances in quantified imaging techniques, specifically in MR liver iron quantification. The techniques described in this review are all commercially available and can be readily implemented. (orig.)

MRI diagnosis of intraspinal dermoid ruptured into central spinal canal

International Nuclear Information System (INIS)

Zhang Yong; Cheng Jingliang; Wang Juan; Li Huali; Ren Cuiping; Zhang Yan; Gao Xuemei

2009-01-01

Objective: To evaluate the appearances of intraspinal dermoid ruptured into the central spinal canal, as well as the MRI diagnosis and differential diagnosis. Methods: Eleven cases of intraspinal dermoid ruptured into the central spinal canal were reviewed. Six cases underwent whole spine MRI scan, 2 cases with thoracic and lumbar spine MRI, as well as 3 cases only with lumbar spine MRI. Results: Free fat droplets within spinal cord central canal demonstrated high signal intensity on T 1 WI, slight declined signal intensity on T 2 WI, and extremely low signal on fat suppression sequence. Of the 11 cases, 2 cases broke into neighboring central spinal canal of the dermoid, 3 cases scattered within thoracic spinal cord central canal, 4 cases discontinuously distributed in the whole spinal cord central canal, 2 cases showed continuous distribution. Conclusion: Intraspinal dermoid ruptured in the central spinal canal had specific appearance on MRI, when a dermoid tumor is suspected, MRI of the entire spine were recommended to detect possible leakage of' fat within central spinal canal. (authors)

MRI findings of the brainstem of the neuro-Behcet syndrome

Energy Technology Data Exchange (ETDEWEB)

Fujiki, Naoto; Tashiro, Kunio; Yamada, Takayoshi; Ito, Kazunori; Honma, Sanae; Doi, Shizuki; Moriwaka, Fumio

1987-10-01

We reported three cases of neuro-Behcet's syndrome which showed brainstem lesions on MRI compatible with the clinical symptoms. In Case 1, MRI showed a large, abnormal signal-intensity area in the pons and small, abnormal signal-intensity areas at the right cerebral peduncle, the bilateral basal ganglia, and the left thalamus. These lesions disappeared on MRI, in accordance with the remission of clinical symptoms. On the other hand, CT showed no positive findings. In Case 2, an abnormal signal-intensity area was disclosed at the left cerebral peduncle on MRI. This lesion was also identified on the CT scan. In Case 3, an abnormal signal-intensity area was present in the pons on MRI. In this case, CT showed no positive findings. In Cases 2 and 3, these lesions seemed to represent inflammatory or necrotic areas attributable to vasculitis;however, the extensive brainstem lesion seen on the MRI of Case 1 was a quite unique finding, for which no exact pathophysiological explanation is possible at the present time.

MRI-based quantification of brain damage in cerebrovascular disorders

NARCIS (Netherlands)

de Bresser, J.H.J.M.

2011-01-01

Brain diseases can lead to diverse structural abnormalities that can be assessed on magnetic resonance imaging (MRI) scans. These abnormalities can be quantified by (semi-)automated techniques. The studies described in this thesis aimed to optimize and apply cerebral quantification techniques in