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proton density MRI

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https://www.readbyqxmd.com/read/29331301/marrow-adipose-tissue-imaging-in-humans
#1
Vibha Singhal, Miriam A Bredella
Bone strength is affected not only by bone mineral density (BMD) and bone microarchitecture but also its microenvironment. Recent studies have focused on the role of marrow adipose tissue (MAT) in the pathogenesis of bone loss. Osteoblasts and adipocytes arise from a common mesenchymal stem cell within bone marrow and many osteoporotic states, including aging, medication use, immobility, over - and undernutrition are associated with increased marrow adiposity. Advancements in imaging technology allow the non-invasive quantification of MAT...
January 10, 2018: Bone
https://www.readbyqxmd.com/read/29322549/noise-properties-of-proton-density-fat-fraction-estimated-using-chemical-shift-encoded-mri
#2
Nathan T Roberts, Diego Hernando, James H Holmes, Curtis N Wiens, Scott B Reeder
PURPOSE: The purpose of this work is to characterize the noise distribution of proton density fat fraction (PDFF) measured using chemical shift-encoded MRI, and to provide alternative strategies to reduce bias in PDFF estimation. THEORY: We derived the probability density function for PDFF estimated using chemical shift-encoded MRI, and found it to exhibit an asymmetric noise distribution that contributes to signal-to-noise-ratio dependent bias. METHODS: To study PDFF noise bias, we performed (at 1...
January 10, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29315714/brain-abnormalities-in-cognition-anxiety-and-depression-regulatory-regions-in-adolescents-with-single-ventricle-heart-disease
#3
Nancy A Pike, Bhaswati Roy, Ritika Gupta, Sadhana Singh, Mary A Woo, Nancy J Halnon, Alan B Lewis, Rajesh Kumar
BACKGROUND: Single ventricle heart disease (SVHD) adolescents show cognitive impairments and anxiety and depressive symptoms, indicating the possibility of brain injury in regions that control these functions. However, brain tissue integrity in cognition, anxiety, and depression regulatory sites in SVHD remains unclear. We examined brain tissue changes in SVHD compared to controls using T2-relaxometry procedures, which measure free water content and show tissue injury. METHODS: Proton-density and T2-weighted images, using a 3...
January 6, 2018: Journal of Neuroscience Research
https://www.readbyqxmd.com/read/29313118/proton-density-fat-fraction-pdff-mri-for-differentiation-of-benign-and-malignant-vertebral-lesions
#4
Frederic Carsten Schmeel, Julian Alexander Luetkens, Peter Johannes Wagenhäuser, Michael Meier-Schroers, Daniel Lloyd Kuetting, Andreas Feißt, Jürgen Gieseke, Leonard Christopher Schmeel, Frank Träber, Hans Heinz Schild, Guido Matthias Kukuk
OBJECTIVES: To investigate whether proton density fat fraction (PDFF) measurements using a six-echo modified Dixon sequence can help to differentiate between benign and malignant vertebral bone marrow lesions. METHODS: Sixty-six patients were prospectively enrolled in our study. In addition to conventional MRI at 3.0-Tesla including at least sagittal T2-weighted/spectral attenuated inversion recovery and T1-weighted sequences, all patients underwent a sagittal six-echo modified Dixon sequence of the spine...
January 8, 2018: European Radiology
https://www.readbyqxmd.com/read/29298256/planning-for-bone-excision-in-ewing-sarcoma-post-chemotherapy-mri-more-accurate-than-pre-chemotherapy-mri-assessment
#5
Camille Thévenin-Lemoine, Louise Destombes, Julie Vial, Matthieu Wargny, Paul Bonnevialle, Yan Lefevre, Anne Gomez Brouchet, Jérome Sales de Gauzy
BACKGROUND: In determining the level of bone resection in Ewing sarcoma, the most suitable time at which to perform magnetic resonance imaging (MRI) remains controversial. Current guidelines recommend that surgical planning be based on MRI performed prior to neoadjuvant chemotherapy. The goal of this study was to determine whether pre-chemotherapy or post-chemotherapy MRI provides greater accuracy of tumor limits for planning bone excision in the management of Ewing sarcoma. METHODS: This was a single-center, retrospective study...
January 3, 2018: Journal of Bone and Joint Surgery. American Volume
https://www.readbyqxmd.com/read/29261786/resume-turning-an-swi-acquisition-into-a-fast-qmri-protocol
#6
Serena Monti, Pasquale Borrelli, Enrico Tedeschi, Sirio Cocozza, Giuseppe Palma
Susceptibility Weighted Imaging (SWI) is a common MRI technique that exploits the magnetic susceptibility differences between the tissues to provide valuable image contrasts, both in research and clinical contexts. However, despite its increased clinical use, SWI is not intrinsically suitable for quantitation purposes. Conversely, quantitative Magnetic Resonance Imaging (qMRI) provides a way to disentangle the sources of common MR image contrasts (e.g. proton density, T1, etc.) and to measure physical parameters intrinsically related to tissue microstructure...
2017: PloS One
https://www.readbyqxmd.com/read/29249127/liver-transplantation-for-non-alcoholic-fatty-liver-disease
#7
Giacomo Germani, Chiara Becchetti
Non-alcoholic fatty liver disease (NAFLD) is considered the hepatic manifestation of metabolic syndrome (MS) [1], and it is defined by the presence of steatosis in >5% of hepatocytes, according to histological analysis or detected by specific proton density fat fraction obtained MRI. The term NAFLD covers two pathologically distinct conditions: non-alcoholic fatty liver (NAFL) and non-alcoholic steatohepatitis (NASH), which can have similar clinical presentation, but with different prognosis. Both conditions can lastly lead to the development of cirrhosis...
December 15, 2017: Minerva Gastroenterologica e Dietologica
https://www.readbyqxmd.com/read/29238866/validation-of-goose-liver-fat-measurement-by-qct-and-cse-mri-with-biochemical-extraction-and-pathology-as-reference
#8
Li Xu, Yangyang Duanmu, Glen M Blake, Chenxin Zhang, Yong Zhang, Keenan Brown, Xiaoqi Wang, Peng Wang, Xingang Zhou, Manling Zhang, Chao Wang, Zhe Guo, Giuseppe Guglielmi, Xiaoguang Cheng
OBJECTIVES: This study aimed to validate the accuracy and reliability of quantitative computed tomography (QCT) and chemical shift encoded magnetic resonance imaging (CSE-MRI) to assess hepatic steatosis. METHODS: Twenty-two geese with a wide range of hepatic steatosis were collected. After QCT and CSE-MRI examinations, the liver of each goose was removed and samples were taken from the left lobe, upper and lower half of the right lobe for biochemical measurement and histology...
December 13, 2017: European Radiology
https://www.readbyqxmd.com/read/29218660/how-bariatric-surgery-affects-liver-volume-and-fat-density-in-nafld-patients
#9
Ran B Luo, Toshiaki Suzuki, Jonathan C Hooker, Yesenia Covarrubias, Alexandra Schlein, Shanglei Liu, Jeffrey B Schwimmer, Scott B Reeder, Luke M Funk, Jacob A Greenberg, Guilherme M Campos, Bryan J Sandler, Santiago Horgan, Claude B Sirlin, Garth R Jacobsen
INTRODUCTION: Nonalcoholic fatty liver disease (NAFLD) is an epidemic in the obese population. Bariatric surgery is known to reverse multiple metabolic complications of obesity such as diabetes, dyslipidemia, and NAFLD, but the timing of liver changes has not been well described. MATERIALS AND METHODS: This was an IRB-approved, two-institutional prospective study. Bariatric patients received MRIs at baseline and after a pre-operative liquid diet. Liver biopsies were performed during surgery and if NAFLD positive, the patients received MRIs at 1, 3, and 6 months...
December 7, 2017: Surgical Endoscopy
https://www.readbyqxmd.com/read/29204454/magnetic-resonance-imaging-for-patellofemoral-chondromalacia-is-there-a-role-for-t2-mapping
#10
Carola F van Eck, R Scott Kingston, John V Crues, F Daniel Kharrazi
Background: Patellofemoral pain is common, and treatment is guided by the presence and grade of chondromalacia. Purpose: To evaluate and compare the sensitivity and specificity in detecting and grading chondral abnormalities of the patella between proton density fat suppression (PDFS) and T2 mapping magnetic resonance imaging (MRI). Study Design: Cohort study; Level of evidence, 2. Methods: A total of 25 patients who underwent MRI of the knee with both a PDFS sequence and T2 mapping and subsequently underwent arthroscopic knee surgery were included...
November 2017: Orthopaedic Journal of Sports Medicine
https://www.readbyqxmd.com/read/29199057/epidemiology-of-hepatic-steatosis-at-a-tertiary-care-center-an-mri-based-analysis
#11
Tyler J Fraum, Daniel R Ludwig, Scott Kilian, William A Curtis, Thomas K Pilgram, Claude B Sirlin, Kathryn J Fowler
RATIONALE AND OBJECTIVES: Little is known about the frequency and risk factors of hepatic steatosis in the tertiary care setting. Such knowledge is essential to clinicians making decisions about testing for this condition. Thus, our aim was to describe the epidemiology of hepatic steatosis, as captured by magnetic resonance imaging (MRI), at a tertiary care center. MATERIALS AND METHODS: A near-consecutive cohort of 1006 adult patients underwent standard-of-care liver MRIs...
December 1, 2017: Academic Radiology
https://www.readbyqxmd.com/read/29181872/validation-of-t1w-based-segmentations-of-white-matter-hyperintensity-volumes-in-large-scale-datasets-of-aging
#12
Mahsa Dadar, Josefina Maranzano, Simon Ducharme, Owen T Carmichael, Charles Decarli, D Louis Collins
INTRODUCTION: Fluid-attenuated Inversion Recovery (FLAIR) and dual T2w and proton density (PD) magnetic resonance images (MRIs) are considered to be the optimum sequences for detecting white matter hyperintensities (WMHs) in aging and Alzheimer's disease populations. However, many existing large multisite studies forgo their acquisition in favor of other MRI sequences due to economic and time constraints. METHODS: In this article, we have investigated whether FLAIR and T2w/PD sequences are necessary to detect WMHs in Alzheimer's and aging studies, compared to using only T1w images...
November 27, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/29170813/mri-in-chronic-groin-pain-sequence-diagnostic-reliability-compared-to-systematic-surgical-assessment
#13
Emmanuel Ducouret, Gilles Reboul, François Dalmay, Christina Iosif, Charbel Mounayer, Lionel Pesquer, Benjamin Dallaudiere
OBJECTIVE: To determine the diagnostic reliability of magnetic resonance imaging (MRI) sequences in chronic groin pain (CGP) compared to surgery and try to propose a suitable MRI protocol. MATERIALS AND METHODS: Forty-three consecutive patients with resistant clinical CGP underwent a pre-surgical pelvis MRI. Eight MRI sequences were acquired: axial fast spin-echo T1-weighted (FSE T1), coronal FSE T1, axial-oblique (in symphysis plane) proton density weighted with fat saturation (PDFS), coronal PDFS, sagittal PDFS, axial FSE T1 with fat saturation and gadolinium enhancement (FSGE), coronal FSE T1 FSGE and axial FSE T1 with Valsalva maneuver (VM)...
November 23, 2017: Skeletal Radiology
https://www.readbyqxmd.com/read/29157260/high-resolution-and-accelerated-multi-parametric-mapping-with-automated-characterization-of-vessel-disease-using-intravascular-mri
#14
Guan Wang, Yi Zhang, Shashank Sathyanarayana Hegde, Paul A Bottomley
BACKGROUND: Atherosclerosis is prevalent in cardiovascular disease, but present imaging modalities have limited capabilities for characterizing lesion stage, progression and response to intervention. This study tests whether intravascular magnetic resonance imaging (IVMRI) measures of relaxation times (T1, T2) and proton density (PD) in a clinical 3 Tesla scanner could characterize vessel disease, and evaluates a practical strategy for accelerated quantification. METHODS: IVMRI was performed in fresh human artery segments and swine vessels in vivo, using fast multi-parametric sequences, 1-2 mm diameter loopless antennae and 200-300 μm resolution...
November 20, 2017: Journal of Cardiovascular Magnetic Resonance
https://www.readbyqxmd.com/read/29151468/-numerical-and-visual-evaluation-of-compressed-sensing-mri-using-3d-cartesian-sampling
#15
Hiroyuki Shinohara, Takeyuki Hashimoto, Nobuyuki Takeyama, Eriko Tanaka, Takaki Hayashi, Touji Hashimoto
We performed numerical and visual evaluation of compressed sensing MRI (CS-MRI) using 3D Cartesian sampling by numerical simulation. Three brain anatomical ROIs (white matter, gray matter, cerebrospinal fluid) of a T1-weighted image (T1WI), a T2-weighted image (T2WI) and a proton density-weighted image (PDWI) were used for numerical evaluation. Sampling ratio of the Cartesian grid was 30%. Reconstruction was performed by the projection onto convex sets (POCS) method with soft thresholding, subject to data fidelity constraints...
2017: Japanese Journal of Medical Physics
https://www.readbyqxmd.com/read/29137497/optimization-of-t2-weighted-imaging-for-shoulder-magnetic-resonance-arthrography-by-synthetic-magnetic-resonance-imaging
#16
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
#17
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
#18
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
#19
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
#20
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
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