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https://www.readbyqxmd.com/read/28237893/dynamic-nuclear-polarization-via-thermal-mixing-beyond-the-high-temperature-approximation
#1
W Th Wenckebach
Dynamic Nuclear Polarization (DNP) via the mechanism of thermal mixing has proven itself most powerful for the orientation of nuclear spins in polarized targets and hyperpolarization for magnetic resonance imaging (MRI). Unfortunately, theoretical descriptions of this mechanism have been limited to using-at least partially-the high temperature approximation, in which Boltzmann factors are expanded linearly. However, the high nuclear spin polarization required and obtained for these applications does not justify such approximations...
February 20, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28225357/robust-sound-speed-estimation-for-ultrasound-based-hepatic-steatosis-assessment
#2
Imbault Marion, Alex Faccinetto, Bruno-Felix Osmanski, Antoine Tissier, Thomas Deffieux, Jean-Luc Gennisson, Valerie Vilgrain, Mickael Tanter
Hepatic steatosis is a common condition, the prevalence of which is increasing along with non-alcoholic fatty liver disease (NAFLD). Currently, the most accurate noninvasive imaging method for diagnosing and quantifying hepatic steatosis is MRI, which estimates the Proton-Density Fat Fraction (PDFF) as a measure of fractional fat content. However, MRI suffers several limitations including cost, contra-indications and poor availability. Although conventional ultrasound is widely used by radiologists for hepatic steatosis assessment, it remains qualitative and operator dependent...
February 22, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28220268/anterolateral-ligament-expert-group-consensus-paper-on-the-management-of-internal-rotation-and-instability-of-the-anterior-cruciate-ligament-deficient-knee
#3
REVIEW
Bertrand Sonnery-Cottet, Matthew Daggett, Jean-Marie Fayard, Andrea Ferretti, Camilo Partezani Helito, Martin Lind, Edoardo Monaco, Vitor Barion Castro de Pádua, Mathieu Thaunat, Adrian Wilson, Stefano Zaffagnini, Jacco Zijl, Steven Claes
Purpose of this paper is to provide an overview of the latest research on the anterolateral ligament (ALL) and present the consensus of the ALL Expert Group on the anatomy, radiographic landmarks, biomechanics, clinical and radiographic diagnosis, lesion classification, surgical technique and clinical outcomes. A consensus on controversial subjects surrounding the ALL and anterolateral knee instability has been established based on the opinion of experts, the latest publications on the subject and an exchange of experiences during the ALL Experts Meeting (November 2015, Lyon, France)...
February 20, 2017: Journal of Orthopaedics and Traumatology: Official Journal of the Italian Society of Orthopaedics and Traumatology
https://www.readbyqxmd.com/read/28205347/robust-universal-nonrigid-motion-correction-framework-for-first-pass-cardiac-mr-perfusion-imaging
#4
Mitchel Benovoy, Matthew Jacobs, Farida Cheriet, Nagib Dahdah, Andrew E Arai, Li-Yueh Hsu
PURPOSE: To present and assess an automatic nonrigid image registration framework that compensates motion in cardiac magnetic resonance imaging (MRI) perfusion series and auxiliary images acquired under a wide range of conditions to facilitate myocardial perfusion quantification. MATERIALS AND METHODS: Our framework combines discrete feature matching for large displacement estimation with a dense variational optical flow formulation in a multithreaded architecture...
February 15, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28190853/high-snr-acquisitions-improve-the-repeatability-of-liver-fat-quantification-using-confounder-corrected-chemical-shift-encoded-mr-imaging
#5
Utaroh Motosugi, Diego Hernando, Curtis Wiens, Peter Bannas, Scott B Reeder
PURPOSE: To determine whether high signal-to-noise ratio (SNR) acquisitions improve the repeatability of liver proton density fat fraction (PDFF) measurements using confounder-corrected chemical shift-encoded magnetic resonance (MR) imaging (CSE-MRI). MATERIALS AND METHODS: Eleven fat-water phantoms were scanned with 8 different protocols with varying SNR. After repositioning the phantoms, the same scans were repeated to evaluate the test-retest repeatability. Next, an in vivo study was performed with 20 volunteers and 28 patients scheduled for liver magnetic resonance imaging (MRI)...
February 13, 2017: Magnetic Resonance in Medical Sciences: MRMS
https://www.readbyqxmd.com/read/28179167/mri-and-mrs-of-the-human-brain-at-magnetic-fields-of-14t-to-20t-technical-feasibility-safety-and-neuroscience-horizons
#6
Thomas F Budinger, Mark D Bird
The three goals of this paper are: 1) to evaluate the improvements in technology for increasing magnetic flux density (magnetic field) to 14T in the next few years and eventually to 20T; 2) to highlight neuroscience opportunities enabled by these advances; and, 3) to evaluate the physiological and biophysical effects associated with MRI at very high performance levels. Substantial recent advances in magnet technology including superconductor developments enable neuroscience goals that are not obtainable at contemporary magnetic fields...
February 4, 2017: NeuroImage
https://www.readbyqxmd.com/read/28177647/comprehensive-assessment-of-ankle-syndesmosis-injury-using-3d-isotropic-turbo-spin-echo-sequences-diagnostic-performance-compared-with-that-of-conventional-and-oblique-3-t-mri
#7
Minchul Kim, Yun Sun Choi, Min Sun Jeong, Mira Park, Tong Jin Chun, Jin Su Kim, Ki Won Young
OBJECTIVE: The objective of this study is to evaluate the diagnostic performance of 3D sampling perfection with application-optimized contrasts using different flip angle evolution (SPACE) sequences in the evaluation of ankle syndesmosis injuries, compared with that of conventional orthogonal MRI and oblique proton density-weighted turbo spin-echo (TSE) sequences performed with 3-T MRI. MATERIALS AND METHODS: This retrospective study included 98 patients with suspected ankle syndesmosis injuries who underwent both MRI and surgery...
February 8, 2017: AJR. American Journal of Roentgenology
https://www.readbyqxmd.com/read/28154532/whole-brain-magnetic-resonance-image-atlases-a-systematic-review-of-existing-atlases-and-caveats-for-use-in-population-imaging
#8
REVIEW
David Alexander Dickie, Susan D Shenkin, Devasuda Anblagan, Juyoung Lee, Manuel Blesa Cabez, David Rodriguez, James P Boardman, Adam Waldman, Dominic E Job, Joanna M Wardlaw
Brain MRI atlases may be used to characterize brain structural changes across the life course. Atlases have important applications in research, e.g., as registration and segmentation targets to underpin image analysis in population imaging studies, and potentially in future in clinical practice, e.g., as templates for identifying brain structural changes out with normal limits, and increasingly for use in surgical planning. However, there are several caveats and limitations which must be considered before successfully applying brain MRI atlases to research and clinical problems...
2017: Frontiers in Neuroinformatics
https://www.readbyqxmd.com/read/28141514/terahertz-imaging-of-cutaneous-edema-correlation-with-magnetic-resonance-imaging-in-burn-wounds
#9
Neha Bajwa, Shijun Sung, Daniel B Ennis, Michael C Fishbein, Bryan Nowroozi, Dan Ruan, Ashkan Maccabi, Jeffrey Alger, Maie A St John, Warren S Grundfest, Zachary D Taylor
OBJECTIVE: In vivo visualization and quantification of edema, or 'tissue swelling' following injury, remains a clinical challenge. Herein, we investigate the ability of reflective terahertz (THz) imaging to track changes in tissue water content (TWC) - the direct indicator of edema- by comparison to depth-resolved magnetic resonance imaging (MRI) in a burn-induced model of edema. METHODS: A partial thickness and full thickness burn were induced in an in vivo rat model to elicit unique TWC perturbations corresponding to burn severity...
January 26, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28121631/prediction-and-compensation-of-magnetic-beam-deflection-in-mr-integrated-proton-therapy-a-method-optimized-regarding-accuracy-versatility-and-speed
#10
Sonja M Schellhammer, Aswin L Hoffmann
The integration of magnetic resonance imaging (MRI) and proton therapy for on-line image-guidance is expected to reduce dose delivery uncertainties during treatment. Yet, the proton beam experiences a Lorentz force induced deflection inside the magnetic field of the MRI scanner, and several methods have been proposed to quantify this effect. We analyze their structural differences and compare results of both analytical and Monte Carlo models. We find that existing analytical models are limited in accuracy and applicability due to critical approximations, especially including the assumption of a uniform magnetic field...
February 21, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28117922/elevated-adiabatic-t1%C3%AF-and-t2%C3%AF-in-articular-cartilage-are-associated-with-cartilage-and-bone-lesions-in-early-osteoarthritis-a-preliminary-study
#11
Victor Casula, Mikko J Nissi, Jana Podlipská, Marianne Haapea, Juhani M Koski, Simo Saarakkala, Ali Guermazi, Eveliina Lammentausta, Miika T Nieminen
PURPOSE: To evaluate adiabatic T1ρ and T2ρ of articular cartilage in symptomatic osteoarthritis (OA) patients and asymptomatic volunteers, and to determine their association with magnetic resonance imaging (MRI)-based structural abnormalities in cartilage and bone. MATERIALS AND METHODS: A total of 24 subjects (age range: 50-68 years; 12 female) were enrolled, including 12 early OA patients and 12 volunteers with normal joint function. Patients and volunteers underwent 3T MRI...
January 24, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28116801/assessment-of-treatment-response-in-non-alcoholic-steatohepatitis-using-advanced-magnetic-resonance-imaging
#12
S C Lin, E Heba, R Bettencourt, G Y Lin, M A Valasek, O Lunde, G Hamilton, C B Sirlin, R Loomba
BACKGROUND: Magnetic resonance imaging-derived measures of liver fat and volume are emerging as accurate, non-invasive imaging biomarkers in non-alcoholic steatohepatitis (NASH). Little is known about these measures in relation to histology longitudinally. AIM: To examine any relationship between MRI-derived proton-density fat-fraction (PDFF), total liver volume (TLV), total liver fat index (TLFI), vs. histology in a NASH trial. METHODS: This is a secondary analysis of a 24-week randomised, double-blind, placebo-controlled trial of 50 patients with biopsy-proven NASH randomised to oral ezetimibe 10 mg daily (n = 25) vs...
January 24, 2017: Alimentary Pharmacology & Therapeutics
https://www.readbyqxmd.com/read/28114107/generation-of-synthetic-ct-data-using-patient-specific-daily-mr-image-data-and-image-registration
#13
Kim Melanie Kraus, Oliver Jäkel, Nina I Niebuhr, Asja Pfaffenberger
To fully exploit the advantages of magnetic resonance imaging (MRI) for radiotherapy (RT) treatment planning, a method is required to overcome the problem of lacking electron density information. We aim to establish and evaluate a new method for computed tomography (CT) data generation based on MRI and image registration. The thereby generated CT data is used for dose accumulation. We developed a process flow based on an initial pair of rigidly co-registered CT and T2-weighted MR image representing the same anatomical situation...
February 21, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28113801/simultaneous-quantitative-imaging-of-electrical-properties-and-proton-density-from-b1-maps-using-mri
#14
Jiaen Liu, Pierre-Francois Van de Moortele, Xiaotong Zhang, Yicun Wang, Bin He
Electrical conductivity and permittivity of biological tissues are important diagnostic parameters and are useful for calculating subject-specific specific absorption rate distribution. On the other hand, water proton density also has clinical relevance for diagnosis purposes. These two kinds of tissue properties are inevitably associated in the technique of electrical properties tomography (EPT), which can be used to map in vivo electrical properties based on the measured B1 field distribution at Larmor frequency using magnetic resonance imaging (MRI)...
March 29, 2016: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28110367/accurate-simultaneous-quantification-of-liver-steatosis-and-iron-overload-in-diffuse-liver-diseases-with-mri
#15
Manuela França, Ángel Alberich-Bayarri, Luis Martí-Bonmatí, Pedro Oliveira, Francisca Emanuel Costa, Graça Porto, José Ramón Vizcaíno, Javier Sanchez Gonzalez, Eduardo Ribeiro, João Oliveira, Helena Pessegueiro Miranda
PURPOSE: To evaluate the diagnostic performances of 3 Tesla multi-echo chemical shift-encoded gradient echo magnetic resonance (MECSE-MR) imaging to simultaneously quantify liver steatosis and iron overload in a wide spectrum of diffuse liver diseases having biopsy as reference standard. METHODS: MECSE-MR-acquired images were used to calculate fat fraction and iron content in a single breath-hold in 109 adult patients. Proton density fat fraction (PDFF) was prospectively estimated using complex-based data reconstruction with multipeak fat modeling...
January 21, 2017: Abdominal Radiology
https://www.readbyqxmd.com/read/28104123/diffusion-tensor-imaging-mri-with-spin-echo-sequence-and-long-duration-measurement-for-evaluation-of-renal-fibrosis-in-a-rat-fibrosis-model
#16
J-Y Kaimori, Y Isaka, M Hatanaka, S Yamamoto, N Ichimaru, A Fujikawa, H Shibata, A Fujimori, S Miyoshi, T Yokawa, K Kuroda, T Moriyama, H Rakugi, S Takahara
BACKGROUND: Renal fibrosis (RF) is a well-known marker for chronic kidney disease (CKD) progression, including chronic renal injury after renal transplantation. However, invasive biopsy is an available examination for evaluation of RF. Diffusion MRI was once recognized as a promising option for RF. However, it is now controversial for RF evaluation in a unilateral ureteral obstruction (UUO) model. METHODS: To seek an optimal imaging method applicable for RF in UUO model kidneys, we attempted a series of MRI methods, including proton density-weighted imaging, T1-weighted imaging, T2-weighted imaging, T2*-weighted imaging, diffusion-weighted imaging, and diffusion tensor imaging (DTI)...
January 2017: Transplantation Proceedings
https://www.readbyqxmd.com/read/28076290/tailored-interactive-sequences-for-continuous-mr-image-guided-freehand-biopsies-of-different-organs-in-an-open-system-at-1-0-tesla-t-initial-experience
#17
Florian Streitparth, Christian Althoff, Martin Jonczyk, Felix Guettler, Martin Maurer, Hendrik Rathke, Keno Moritz Sponheuer, Bernd Hamm, Ulf K Teichgräber, Maximilian de Bucourt
OBJECTIVES: To assess the feasibility, image quality, and accuracy of freehand biopsies of liver, bone, muscle, vertebral disc, soft tissue, and other lesions using balanced steady-state free precession (SSFP, balanced fast field echo: bFFE), spoiled and nonspoiled gradient echo (FFE), and turbo spin echo (TSE) sequences for interactive continuous navigation in an open magnetic resonance imaging (MRI) system at 1.0 tesla (T). METHODS: Twenty-six MR-guided biopsies (five liver, five bone, four muscle, four vertebral disc, one lung, one kidney, one suprarenal gland, and five soft or other tissue) were performed in 23 patients in a 1...
January 11, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/28063601/bone-marrow-fat-content-is-correlated-with-hepatic-fat-content-in-paediatric-non-alcoholic-fatty-liver-disease
#18
N Y Yu, T Wolfson, M S Middleton, G Hamilton, A Gamst, J E Angeles, J B Schwimmer, C B Sirlin
AIM: To investigate the relationship between bone marrow fat content and hepatic fat content in children with known or suspected non-alcoholic fatty liver disease (NAFLD). MATERIALS AND METHODS: This was an institutional review board-approved, Health Insurance Portability and Accountability Act (HIPAA)-compliant, cross-sectional, prospective analysis of data collected between October 2010 to March 2013 in 125 children with known or suspected NAFLD. Written informed consent was obtained for same-day research magnetic resonance imaging (MRI) of the lumbar spine, liver, and abdominal adiposity...
January 4, 2017: Clinical Radiology
https://www.readbyqxmd.com/read/28048262/su-g-iep1-07-inaccuracy-of-lesion-blood-flow-quantification-related-to-the-proton-density-reference-image-in-arterial-spin-labeling-mri-of-brain-tumors
#19
M Jen, J Johnson, P Hou, H Liu
PURPOSE: Cerebral blood flow quantification in arterial spin labeling (ASL) MRI requires an estimate of the equilibrium magnetization of blood, which is often obtained by a set of proton density (PD) reference image. Normally, a constant blood-brain partition coefficient is assumed across the brain. However, this assumption may not be valid for brain lesions. This study aimed to evaluate the impact of lesion-related PD variations on ASL quantification in patients with brain tumors. METHODS: MR images for posttreatment evaluation of 42 patients with brain tumors were retrospectively analyzed...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28046967/su-g-iep1-09-mri-evaluation-of-a-direction-modulated-brachytherapy-dmbt-tandem-applicator-for-cervical-cancer-on-3t
#20
A Soliman, D Han, A Elzibak, H Safigholi, S Mashouf, A Owrangi, A Ravi, W Song
PURPOSE: To assess image quality and artifact extent of a novel direction modulated brachytherapy (DMBT) tandem applicator on a 3T MRI using various clinical imaging sequences. METHODS: The tandem applicator is composed of a tungsten alloy with 6 peripheral grooves covered with a PEEK tip. An MR-compatible phantom with similar dimensions to the female pelvis was manufactured. To visually assess the spatial shift of the applicator's tip, a mountable radial-fiducial with 4 plastic rods, each of 3mm diameter, was designed to tightly fit on the applicator...
June 2016: Medical Physics
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