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https://www.readbyqxmd.com/read/29137497/optimization-of-t2-weighted-imaging-for-shoulder-magnetic-resonance-arthrography-by-synthetic-magnetic-resonance-imaging
#1
Seung Hyun Lee, Young Han Lee, Seok Hahn, Jaemoon Yang, Ho-Taek Song, Jin-Suck Suh
Background Synthetic magnetic resonance imaging (MRI) allows reformatting of various synthetic images by adjustment of scanning parameters such as repetition time (TR) and echo time (TE). Optimized MR images can be reformatted from T1, T2, and proton density (PD) values to achieve maximum tissue contrast between joint fluid and adjacent soft tissue. Purpose To demonstrate the method for optimization of TR and TE by synthetic MRI and to validate the optimized images by comparison with conventional shoulder MR arthrography (MRA) images...
January 1, 2017: Acta Radiologica
https://www.readbyqxmd.com/read/29136287/quantification-of-mri-visibility-and-artefacts-at-3t-of-liquid-fiducial-marker-in-a-pancreas-tissue-mimicking-phantom
#2
Sergej Schneider, Rasmus Irming Jølck, Esther Gera Cornelia Troost, Aswin Louis Hoffmann
PURPOSE: X-ray based position verification of the target volume in image-guided radiation therapy (IGRT) of patients with pancreatic ductal adenocarcinoma (PDAC) is currently performed on solid fiducial markers that are implanted under endoscopic ultrasonography. A new biodegradable liquid fiducial marker has recently been introduced. To assess its potential use for magnetic resonance imaging (MRI) guided photon or proton radiotherapy of PDAC, the MRI visibility and artefacts of this marker were quantified and compared against solid gold markers...
November 14, 2017: Medical Physics
https://www.readbyqxmd.com/read/29134354/conventional-and-synthetic-mri-in-multiple-sclerosis-a-comparative-study
#3
Wolfgang Krauss, Martin Gunnarsson, Margareta Nilsson, Per Thunberg
OBJECTIVES: To compare the assessment of patients with multiple sclerosis (MS) using synthetic and conventional MRI. MATERIALS AND METHODS: Synthetic and conventional axial images were prospectively acquired for 52 patients with diagnosed MS. Quantitative MRI (qMRI) was used for measuring proton density and relaxation times (T1, T2) and then, based on these parameters, synthetic T1W, T2W and FLAIR images were calculated. Image stacks were reviewed blindly, independently and in random order by two radiologists...
November 13, 2017: European Radiology
https://www.readbyqxmd.com/read/29130539/sources-of-systematic-error-in-proton-density-fat-fraction-pdff-quantification-in-the-liver-evaluated-from-magnitude-images-with-different-numbers-of-echoes
#4
Mark Bydder, Gavin Hamilton, Ludovic de Rochefort, Ajinkya Desai, Elhamy R Heba, Rohit Loomba, Jeffrey B Schwimmer, Nikolaus M Szeverenyi, Claude B Sirlin
The purpose of this work was to investigate sources of bias in magnetic resonance imaging (MRI) liver fat quantification that lead to a dependence of the proton density fat fraction (PDFF) on the number of echoes. This was a retrospective analysis of liver MRI data from 463 subjects. The magnitude signal variation with TE from spoiled gradient echo images was curve fitted to estimate the PDFF using a model that included monoexponential R2 * decay and a multi-peak fat spectrum. Additional corrections for non-exponential decay (Gaussian), bi-exponential decay, degree of fat saturation, water frequency shift and noise bias were introduced...
November 12, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/29114904/proton-density-weighted-laryngeal-magnetic-resonance-imaging-in-systemically-dehydrated-rats
#5
Steven Oleson, Kun-Han Lu, Zhongming Liu, Abigail C Durkes, M Preeti Sivasankar
OBJECTIVES/HYPOTHESIS: Dehydrated vocal folds are inefficient sound generators. Although systemic dehydration of the body is believed to induce vocal fold dehydration, this causative relationship has not been demonstrated in vivo. Here we investigate the feasibility of using in vivo proton density (PD)-weighted magnetic resonance imaging (MRI) to demonstrate hydration changes in vocal fold tissue following systemic dehydration in rats. STUDY DESIGN: Animal study...
November 8, 2017: Laryngoscope
https://www.readbyqxmd.com/read/29108123/optimal-threshold-of-controlled-attenuation-parameter-with-mri-pdff-as-the-gold-standard-for-the-detection-of-hepatic-steatosis
#6
Cyrielle Caussy, Mosab H Alquiraish, Phirum Nguyen, Carolyn Hernandez, Sandra Cepin, Lynda E Fortney, Veeral Ajmera, Ricki Bettencourt, Summer Collier, Jonathan Hooker, Ethan Sy, Emily Rizo, Lisa Richards, Claude B Sirlin, Rohit Loomba
The optimal threshold of controlled attenuation parameter (CAP) for the detection of hepatic steatosis using both M and XL probe is unknown in nonalcoholic fatty liver disease (NAFLD). Magnetic resonance imaging proton-density-fat-fraction (MRI-PDFF) is an accurate and precise method to detect presence of hepatic steatosis and is better than CAP. Thus, the aim of this study was to evaluate the diagnostic accuracy and the optimal threshold of CAP for the detection of hepatic steatosis as defined by MRI-PDFF ≥ 5%...
November 6, 2017: Hepatology: Official Journal of the American Association for the Study of Liver Diseases
https://www.readbyqxmd.com/read/29095484/quantitative-evaluation-of-contrast-agent-uptake-in-standard-fat-suppressed-dynamic-contrast-enhanced-mri-examinations-of-the-breast
#7
Evanthia Kousi, Joely Smith, Araminta E Ledger, Erica Scurr, Steven Allen, Robin M Wilson, Elizabeth O'Flynn, Romney J E Pope, Martin O Leach, Maria A Schmidt
PURPOSE: To propose a method to quantify T1 and contrast agent uptake in breast dynamic contrast enhanced (DCE) examinations undertaken with standard clinical fat-suppressed MRI sequences and to demonstrate the proposed approach by comparing the enhancement characteristics of lobular and ductal carcinomas. METHODS: A standard fat-suppressed DCE of the breast was performed at 1.5T (Siemens Aera), followed by the acquisition of a proton density (PD) weighted sequence, also fat suppressed...
November 2, 2017: Medical Physics
https://www.readbyqxmd.com/read/29094513/accuracy-of-3-tesla-magnetic-resonance-imaging-using-detection-of-fiber-loss-and-a-visual-analog-scale-for-diagnosing-partial-and-complete-cranial-cruciate-ligament-ruptures-in-dogs
#8
Constance G Fazio, Peter Muir, Susan L Schaefer, Kenneth R Waller
Canine cranial cruciate ligament rupture is often bilateral and asymmetrical, ranging from partial to complete rupture. The purpose of our diagnostic accuracy study was to assess the accuracy of 3 Tesla magnetic resonance imaging (MRI) detection of fiber loss and use of a visual analog scale in the diagnosis of complete versus partial cranial cruciate ligament rupture in 28 clinical dogs with unilateral complete rupture and contralateral partial rupture. Three Tesla MRI was performed on 56 stifles using sagittal sequences (T2-weighted fast spin echo with fat saturation, proton density fast spin echo, and T2-weighted 3D fast spin echo CUBE)...
November 1, 2017: Veterinary Radiology & Ultrasound
https://www.readbyqxmd.com/read/29091341/four-in-vivo-g-ratio-weighted-imaging-methods-comparability-and-repeatability-at-the-group-level
#9
Isabel Ellerbrock, Siawoosh Mohammadi
A recent method, denoted in vivo g-ratio-weighted imaging, has related the microscopic g-ratio, only accessible by ex vivo histology, to noninvasive MRI markers for the fiber volume fraction (FVF) and myelin volume fraction (MVF). Different MRI markers have been proposed for g-ratio weighted imaging, leaving open the question which combination of imaging markers is optimal. To address this question, the repeatability and comparability of four g-ratio methods based on different combinations of, respectively, two imaging markers for FVF (tract-fiber density, TFD, and neurite orientation dispersion and density imaging, NODDI) and two imaging markers for MVF (magnetization transfer saturation rate, MT, and, from proton density maps, macromolecular tissue volume, MTV) were tested in a scan-rescan experiment in two groups...
November 1, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/29089822/impact-of-liver-fibrosis-and-fatty-liver-on-t1rho-measurements-a-prospective-study
#10
Shuangshuang Xie, Qing Li, Yue Cheng, Yu Zhang, Zhizheng Zhuo, Guiming Zhao, Wen Shen
OBJECTIVE: To investigate the liver T1rho values for detecting fibrosis, and the potential impact of fatty liver on T1rho measurements. MATERIALS AND METHODS: This study included 18 healthy subjects, 18 patients with fatty liver, and 18 patients with liver fibrosis, who underwent T1rho MRI and mDIXON collections. Liver T1rho, proton density fat fraction (PDFF) and T2* values were measured and compared among the three groups. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the T1rho values for detecting liver fibrosis...
November 2017: Korean Journal of Radiology: Official Journal of the Korean Radiological Society
https://www.readbyqxmd.com/read/29080242/can-negligible-hepatic-steatosis-determined-by-mri-proton-density-fat-fraction-obviate-the-need-for-liver-biopsy-in-potential-liver-donors
#11
Janakan Satkunasingham, Hooman Hosseini Nik, Sandra Fischer, Ravi Menezes, Nazia Selzner, Mark Cattral, David Grant, Kartik Jhaveri
PURPOSE: To determine whether magnetic resonance proton density fat fraction (MR-PDFF) estimate of negligible hepatic fat percentage (<5%) can exclude significant hepatic steatosis (≥ 10%) in living liver donor candidates obviating the need for liver biopsy. To perform intra-individual comparisons between MR-PDFF techniques for hepatic steatosis quantification. MATERIALS AND METHODS: In an ethics approved retrospective study, 144 liver donor candidates with MR spectroscopy (MRS) and six-echo Dixon MRI between 2013 and 2015 were included...
October 28, 2017: Liver Transplantation
https://www.readbyqxmd.com/read/29077570/determination-of-mean-ionization-potential-using-magnetic-resonance-imaging-for-the-reduction-of-proton-beam-range-uncertainties-theory-and-application
#12
Atchar Sudhyadhom
The accurate determination of mean ionization potential (I m) has the potential to reduce range uncertainty based margins and therefore allow for more focal treatments in proton radiotherapy. Many methods have been proposed to reduce uncertainty in I m and stopping power ratios (SPR), each with varying degrees of accuracy and issues. In this work, we present a simple parameterized model to determine I m in human biological tissue, allowing for the computation of patient-specific I m at the voxel level using magnetic resonance imaging (MRI)...
October 27, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29063256/sciatic-neurosteatosis-relationship-with-age-gender-obesity-and-height
#13
Shayna Ratner, Raamis Khwaja, Lihua Zhang, Yin Xi, Riham Dessouky, Craig Rubin, Avneesh Chhabra
AIM: To evaluate inter-reader performance for cross-sectional area and fat quantification of bilateral sciatic nerves on MRI and assess correlations with anthropometrics. METHODS: In this IRB-approved, HIPPA-compliant study, three readers performed a cross-sectional analysis of 3T lumbosacral plexus MRIs over an 18-month period. Image slices were evaluated at two levels (A and B). The sciatic nerve was outlined using a free hand region of interest tool on PACS. Proton-density fat fraction (FF) and cross-sectional areas were recorded...
October 23, 2017: European Radiology
https://www.readbyqxmd.com/read/29028128/diagnostic-accuracy-of-magnetic-resonance-imaging-hepatic-proton-density-fat-fraction-in-pediatric-nonalcoholic-fatty-liver-disease
#14
Michael S Middleton, Mark L Van Natta, Elhamy R Heba, Adina Alazraki, Andrew T Trout, Prakash Masand, Elizabeth M Brunt, David E Kleiner, Edward Doo, James Tonascia, Joel E Lavine, Wei Shen, Gavin Hamilton, Jeffrey B Schwimmer, Claude B Sirlin
We assessed the performance of magnetic resonance imaging (MRI) proton density fat fraction (PDFF) in children to stratify hepatic steatosis grade before and after treatment in the Cysteamine Bitartrate Delayed-Release for the Treatment of Nonalcoholic Fatty Liver Disease in Children (CyNCh) trial, using centrally-scored histology as reference. Participants had multi-echo 1.5T or 3T MRI on scanners from three manufacturers. Of 169 enrolled children, 110 (65%) and 83 (49%) had MRI and liver biopsy at baseline and at end-of-treatment (EOT; 52-weeks), respectively...
October 13, 2017: Hepatology: Official Journal of the American Association for the Study of Liver Diseases
https://www.readbyqxmd.com/read/29022777/feasibility-of-modified-dixon-mri-techniques-for-hepatic-fat-quantification-in-hepatic-disorders-validation-with-mrs-and-histology
#15
Bo-Kyeong Kang, Mimi Kim, Soon-Young Song, Dae Won Jun, Kiseok Jang
OBJECTIVE: To assess the feasibility of proton density fat fraction (PDFF) MRI for estimating hepatic fat fraction with magnetic resonance spectroscopy (MRS) and histology as references and to investigate intrahepatic fat distribution and variability. METHODS: Between November 2014 and September 2015, 85 adults (48 males, 47 females) who underwent MRI-PDFF (n = 139), MRS-PDFF (n = 49) and liver biopsy (n = 29) were enrolled in this study. Data were compared using linear regression...
November 8, 2017: British Journal of Radiology
https://www.readbyqxmd.com/read/28986678/fluid-distribution-in-ankle-and-midfoot-joints-mr-findings-in-asymptomatic-volunteers
#16
Veerle De Grove, Inneke Willekens, Leon Lenchik, Maryam Shahabpour, Johan de Mey, Michel De Maeseneer
PURPOSE: The purpose of this study is to assess the amount of fluid in the joints of the ankle and midfoot on MR imaging in asymptomatic volunteers. MATERIALS AND METHODS: Twenty-one healthy asymptomatic volunteers (42 ankles) were evaluated with MRI imaging. There were 13 men and 8 women. The mean age was 24.7 years (19-42 years). MR imaging was performed on a 3T MR system using proton density weighted images with fat saturation (TR 2969, TE 30 ms, NA 2, slice thickness 2...
October 6, 2017: Surgical and Radiologic Anatomy: SRA
https://www.readbyqxmd.com/read/28982788/quantitative-synthetic-mri-in-children-normative-intracranial-tissue-segmentation-values-during-development
#17
A McAllister, J Leach, H West, B Jones, B Zhang, S Serai
BACKGROUND AND PURPOSE: Synthetic MR imaging is a new technique to create absolute R1 relaxivity (1/T1), R2 relaxivity (1/T2), and proton-density maps using a single multiple-spin-echo saturation recovery sequence. These relaxivity maps allow rapid automated intracranial segmentation of tissue types. To assess its utility in children, we created a normative data base of intracranial volume and brain parenchymal, GM, WM, CSF, and myelin volumes in a pediatric population with normal brain MRI findings using synthetic MR imaging...
October 5, 2017: AJNR. American Journal of Neuroradiology
https://www.readbyqxmd.com/read/28964929/towards-quantification-of-myelin-by-solid-state-mri-of-the-lipid-matrix-protons
#18
Alan C Seifert, Cheng Li, Michael J Wilhelm, Suzanne L Wehrli, Felix W Wehrli
PURPOSE: Direct assessment of myelin has the potential to reveal central nervous system abnormalities and serve as a means to follow patients with demyelinating disorders during treatment. Here, we investigated the feasibility of direct imaging and quantification of the myelin proton pool, without the many possible confounds inherent to indirect methods, via long-T2 suppressed 3D ultra-short echo-time (UTE) and zero echo-time (ZTE) MRI in ovine spinal cord. METHODS: ZTE and UTE experiments, with and without inversion-recovery (IR) preparation, were conducted in ovine spinal cords before and after D2O exchange of tissue water, on a 9...
September 28, 2017: NeuroImage
https://www.readbyqxmd.com/read/28951942/proton-density-fat-suppressed-mri-in-3t-increases-the-sensitivity-of-multiple-sclerosis-lesion-detection-in-the-cervical-spinal-cord
#19
Efstratios Karavasilis, George Velonakis, George Argiropoulos, Athanasios Athanasakos, Loukia S Poulou, Panagiotis Toulas, Nikolaos L Kelekis, Efstathios P Efstathopoulos
PURPOSE: Considering the number of multiple sclerosis (MS) patients referred for clinical spinal cord imaging, the optimization of imaging protocols plays a crucial role. We aimed to evaluate the use of proton density (PD) turbo spin-echo (TSE) with spectral attenuated inversion recovery (SPAIR) fat suppression and compare it with the currently recommended T2-TSE-SPAIR in sagittal plane in cervical spinal cord imaging. METHODS: In this study 35 MS patients with clinically suspected or known spinal cord lesions were scanned on a 3...
September 26, 2017: Clinical Neuroradiology
https://www.readbyqxmd.com/read/28913930/accuracy-repeatability-and-interplatform-reproducibility-of-t1-quantification-methods-used-for-dce-mri-results-from-a-multicenter-phantom-study
#20
Octavia Bane, Stefanie J Hectors, Mathilde Wagner, Lori L Arlinghaus, Madhava P Aryal, Yue Cao, Thomas L Chenevert, Fiona Fennessy, Wei Huang, Nola M Hylton, Jayashree Kalpathy-Cramer, Kathryn E Keenan, Dariya I Malyarenko, Robert V Mulkern, David C Newitt, Stephen E Russek, Karl F Stupic, Alina Tudorica, Lisa J Wilmes, Thomas E Yankeelov, Yi-Fei Yen, Michael A Boss, Bachir Taouli
PURPOSE: To determine the in vitro accuracy, test-retest repeatability, and interplatform reproducibility of T1 quantification protocols used for dynamic contrast-enhanced MRI at 1.5 and 3 T. METHODS: A T1 phantom with 14 samples was imaged at eight centers with a common inversion-recovery spin-echo (IR-SE) protocol and a variable flip angle (VFA) protocol using seven flip angles, as well as site-specific protocols (VFA with different flip angles, variable repetition time, proton density, and Look-Locker inversion recovery)...
September 14, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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