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https://www.readbyqxmd.com/read/28643447/simultaneous-mapping-of-metabolites-and-individual-macromolecular-components-via-ultra-short-acquisition-delay-1-h-mrsi-in-the-brain-at-7t
#1
Michal Považan, Bernhard Strasser, Gilbert Hangel, Eva Heckova, Stephan Gruber, Siegfried Trattnig, Wolfgang Bogner
PURPOSE: Short-echo-time proton MR spectra at 7T feature nine to 10 distinct macromolecule (MM) resonances that overlap with the signals of metabolites. Typically, a metabolite-nulled in vivo MM spectrum is included in the quantification`s prior knowledge to provide unbiased metabolite quantification. However, this MM model may fail if MMs are pathologically altered. In addition, information about the individual MM peaks is lost. In this study, we aimed to create an improved MM model by parameterization of the in vivo MM spectrum into individual components, and to use this new model to quantify free induction decay MR spectroscopic imaging (FID-MRSI) data...
June 22, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28643408/the-effect-of-concomitant-fields-in-fast-spin-echo-acquisition-on-asymmetric-mri-gradient-systems
#2
Shengzhen Tao, Paul T Weavers, Joshua D Trzasko, John Huston, Yunhong Shu, Erin M Gray, Thomas K F Foo, Matt A Bernstein
PURPOSE: To investigate the effect of the asymmetric gradient concomitant fields (CF) with zeroth and first-order spatial dependence on fast/turbo spin-echo acquisitions, and to demonstrate the effectiveness of their real-time compensation. METHODS: After briefly reviewing the CF produced by asymmetric gradients, the effects of the additional zeroth and first-order CFs on these systems are investigated using extended-phase graph simulations. Phantom and in vivo experiments are performed to corroborate the simulation...
June 22, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28643387/non-gaussian-diffusion-imaging-with-a-fractional-order-calculus-model-to-predict-response-of-gastrointestinal-stromal-tumor-to-second-line-sunitinib-therapy
#3
Lei Tang, Yi Sui, Zheng Zhong, Frederick C Damen, Jian Li, Lin Shen, Yingshi Sun, Xiaohong Joe Zhou
PURPOSE: To demonstrate the clinical value of a non-Gaussian diffusion model using fractional order calculus (FROC) for early prediction of the response of gastrointestinal stromal tumor to second-line sunitinib targeted therapy. METHODS: Fifteen patients underwent sunitinib treatment after imatinib resistance. Diffusion-weighted imaging with multiple b-values was performed before treatment (baseline) and 2 weeks (for early prediction of response) after initiating sunitinib treatment...
June 22, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28643383/multiecho-pseudo-golden-angle-stack-of-stars-thermometry-with-high-spatial-and-temporal-resolution-using-k-space-weighted-image-contrast
#4
Bryant T Svedin, Allison Payne, Bradley D Bolster, Dennis L Parker
PURPOSE: Implement and evaluate a 3D MRI method to measure temperature changes with high spatial and temporal resolution and large field of view. METHODS: A multiecho pseudo-golden angle stack-of-stars (SOS) sequence with k-space weighted image contrast (KWIC) reconstruction was implemented to simultaneously measure multiple quantities, including temperature, initial signal magnitude M(0), transverse relaxation time ( T2*), and water/fat images. Respiration artifacts were corrected using self-navigation...
June 22, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28643359/an-open-8-channel-parallel-transmission-coil-for-static-and-dynamic-7t-mri-of-the-knee-and-ankle-joints-at-multiple-postures
#5
Jin Jin, Ewald Weber, Aurelien Destruel, Kieran O'Brien, Bassem Henin, Craig Engstrom, Stuart Crozier
PURPOSE: We present the initial in vivo imaging results of an open architecture eight-channel parallel transmission (pTx) transceive radiofrequency (RF) coil array that was designed and constructed for static and dynamic 7T MRI of the knee and ankle joints. METHODS: The pTx coil has a U-shaped dual-row configuration (200 mm overall length longitudinally) that allows static and dynamic imaging of the knee and ankle joints at various postures and during active movements...
June 22, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28643355/ultra-short-echo-time-images-quantify-high-liver-iron
#6
Eamon K Doyle, Kristin Toy, Bertin Valdez, Jonathan M Chia, Thomas Coates, John C Wood
PURPOSE: 1.5T gradient echo-based R2∗ estimates are standard-of-care for assessing liver iron concentration (LIC). Despite growing popularity of 3T, echo time (TE) limitations prevent 3T liver iron quantitation in the upper half of the clinical range (LIC ⪆20 mg/g). In this work, a 3D radial pulse sequence was assessed to double the dynamic range of 3T LIC estimates. THEORY AND METHODS: The minimum TE limits the dynamic range of pulse sequences to estimate R2∗...
June 22, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28643347/off-resonance-based-assessment-of-metallic-wear-debris-near-total-hip-arthroplasty
#7
Kevin M Koch, Matthew F Koff, Thomas W Bauer, Parina H Shah, Andrew S Nencka, S Sivaram Kaushik, Hollis G Potter
PURPOSE: The presence of metallic debris near total hip arthroplasty can have a significant impact on longitudinal patient management. Methods for magnetic resonance imaging-based quantification of metallic debris near painful total hip replacements are described and applied to cohorts of symptomatic and control subject cases. METHODS: A combination of metal artifact reduction, off-resonance mapping, off-resonance background removal, and spatial clustering methods are utilized to quantify off-resonance signatures in cases of suspected metallosis...
June 22, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28639370/b0-concomitant-field-compensation-for-mri-systems-employing-asymmetric-transverse-gradient-coils
#8
Paul T Weavers, Shengzhen Tao, Joshua D Trzasko, Louis M Frigo, Yunhong Shu, Matthew A Frick, Seung-Kyun Lee, Thomas K-F Foo, Matt A Bernstein
PURPOSE: Imaging gradients result in the generation of concomitant fields, or Maxwell fields, which are of increasing importance at higher gradient amplitudes. These time-varying fields cause additional phase accumulation, which must be compensated for to avoid image artifacts. In the case of gradient systems employing symmetric design, the concomitant fields are well described with second-order spatial variation. Gradient systems employing asymmetric design additionally generate concomitant fields with global (zeroth-order or B0 ) and linear (first-order) spatial dependence...
June 21, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28639338/registration-strategies-for-multi-modal-whole-body-mri-mosaicing
#9
Jakub Ceranka, Mathias Polfliet, Frédéric Lecouvet, Nicolas Michoux, Johan de Mey, Jef Vandemeulebroucke
PURPOSE: To test and compare different registration approaches for performing whole-body diffusion-weighted (wbDWI) image station mosaicing, and its alignment to corresponding anatomical T1 whole-body image. METHODS: Four different registration strategies aiming at mosaicing of diffusion-weighted image stations, and their alignment to the corresponding whole-body anatomical image, were proposed and evaluated. These included two-step approaches, where diffusion-weighted stations are first combined in a pairwise (Strategy 1) or groupwise (Strategy 2) manner and later non-rigidly aligned to the anatomical image; a direct pairwise mapping of DWI stations onto the anatomical image (Strategy 3); and simultaneous mosaicing of DWI and alignment to the anatomical image (Strategy 4)...
June 21, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28639310/high-resolution-31-p-echo-planar-spectroscopic-imaging-in-vivo-at-7t
#10
Andreas Korzowski, Peter Bachert
PURPOSE: Conventional (31) P chemical shift imaging is time-consuming and yields only limited spatial resolution. The purpose of this study was to demonstrate feasibility of (31) P echo-planar spectroscopic imaging (EPSI) in vivo at 7T. METHODS: A 3D (31) P EPSI sequence with trapezoidal-shaped gradient pulses was implemented on a 7T MR scanner. To increase spectral width with reduced demand on gradient performance, a multishot approach was chosen. Acquisition weighting and (31) P-{(1) H} double resonance for nuclear Overhauser signal enhancement were applied to increase sensitivity...
June 21, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28639301/improving-the-detection-sensitivity-of-ph-weighted-amide-proton-transfer-mri-in-acute-stroke-patients-using-extrapolated-semisolid-magnetization-transfer-reference-signals
#11
Hye-Young Heo, Yi Zhang, Tina M Burton, Shanshan Jiang, Yansong Zhao, Peter C M van Zijl, Richard Leigh, Jinyuan Zhou
PURPOSE: To quantify amide protein transfer (APT) effects in acidic ischemic lesions and assess the spatial-temporal relationship among diffusion, perfusion, and pH deficits in acute stroke patients. METHODS: Thirty acute stroke patients were scanned at 3 T. Quantitative APT (APT(#) ) effects in acidic ischemic lesions were measured using an extrapolated semisolid magnetization transfer reference signal technique and compared with commonly used MTRasym (3.5ppm) or APT-weighted parameters...
June 21, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28632286/consort-extension-for-chinese-herbal-medicine-formulas-2017-recommendations-explanation-and-elaboration-traditional-chinese-version
#12
Chung-Wah Cheng, Tai-Xiang Wu, Hong-Cai Shang, You-Ping Li, Douglas G Altman, David Moher, Zhao-Xiang Bian
Editors' Note: This article is the traditional Chinese version of the CONSORT Extension for Chinese Herbal Medicine Formulas 2017: Recommendations, Explanation, and Elaboration. (Cheng C, Wu T, Shang H, Li, Y, Altman D, Moher D; CONSORT-CHM Formulas 2017 Group. CONSORT Extension for Chinese Herbal Medicine Formulas 2017: Recommendations, Explanation, and Elaboration. Ann Intern Med. 2017. [Epub 27 June 2017]. doi:10.7326/M16-2977).
June 27, 2017: Annals of Internal Medicine
https://www.readbyqxmd.com/read/28632281/consort-extension-for-chinese-herbal-medicine-formulas-2017-recommendations-explanation-and-elaboration-simplified-chinese-version
#13
Chung-Wah Cheng, Tai-Xiang Wu, Hong-Cai Shang, You-Ping Li, Douglas G Altman, David Moher, Zhao-Xiang Bian
Editors' Note: This article is the simplified Chinese version of the CONSORT Extension for Chinese Herbal Medicine Formulas 2017: Recommendations, Explanation, and Elaboration. (Cheng C, Wu T, Shang H, Li, Y, Altman D, Moher D; CONSORT-CHM Formulas 2017 Group. CONSORT Extension for Chinese Herbal Medicine Formulas 2017: Recommendations, Explanation, and Elaboration. Ann Intern Med. 2017. [Epub 27 June 2017]. doi:10.7326/M16-2977).
June 27, 2017: Annals of Internal Medicine
https://www.readbyqxmd.com/read/28631853/high-sensitivity-mr-acoustic-radiation-force-imaging-using-transition-band-balanced-steady-state-free-precession
#14
Yuan Zheng, Michael Marx, G Wilson Miller, Kim Butts Pauly
PURPOSE: MR acoustic radiation force imaging (MR-ARFI) provides a method to visualize the focal spot of a focused ultrasound (FUS) beam without introducing a significant temperature rise. With conventional spoiled MR-ARFI pulse sequences, the ARFI phase always equals the motion-encoded phase. In this work, MR-ARFI using transition band balanced steady-state free precession (bSSFP) is presented, which improves the sensitivity of MR-ARFI with high acquisition speed. THEORY AND METHODS: Motion-encoding gradients (MEG) are inserted into bSSFP sequences for MR-ARFI...
June 20, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28631337/a-method-to-assess-the-loss-of-a-dipole-antenna-for-ultra-high-field-mri
#15
Gang Chen, Christopher M Collins, Daniel K Sodickson, Graham C Wiggins
PURPOSE: To describe a new bench measurement based on quality (Q) factors to estimate the coil noise relative to the sample noise of dipole antennas at 7 T. METHODS: Placing a dipole antenna close to a highly conductive sample surrogate (HCSS) greatly reduces radiation loss, and using QHCSS gives a more accurate estimate of coil resistance than Qunloaded . Instead of using the ratio of unloaded and sample-loaded Q factors, the ratio of HCSS-loaded and sample-loaded Q factors should be used at ultra-high fields...
June 19, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28627037/quantitative-gd-dota-uptake-from-cerebrospinal-fluid-into-rat-brain-using-3d-vfa-spgr-at-9-4t
#16
Hedok Lee, Kristian Mortensen, Simon Sanggaard, Palle Koch, Hans Brunner, Bjørn Quistorff, Maiken Nedergaard, Helene Benveniste
PURPOSE: We propose a quantitative technique to assess solute uptake into the brain parenchyma based on dynamic contrast-enhanced MRI (DCE-MRI). With this approach, a small molecular weight paramagnetic contrast agent (Gd-DOTA) is infused in the cerebral spinal fluid (CSF) and whole brain gadolinium concentration maps are derived. METHODS: We implemented a 3D variable flip angle spoiled gradient echo (VFA-SPGR) longitudinal relaxation time (T1) technique, the accuracy of which was cross-validated by way of inversion recovery rapid acquisition with relaxation enhancement (IR-RARE) using phantoms...
June 19, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28626999/presence-of-time-dependent-diffusion-in-the-brachial-plexus
#17
Zaid B Mahbub, Andrew M Peters, Penny A Gowland
PURPOSE: This work describes the development of a method to measure the variation of apparent diffusion coefficient (ADC) with diffusion time (Δ) in the brachial plexus, as a potential method of probing microstructure. METHODS: Diffusion-weighted MRI with body signal suppression was used to highlight the nerves from surrounding tissues, and sequence parameters were optimized for sensitivity to change with diffusion time. A porous media-restricted diffusion model based on the Latour-Mitra equation was fitted to the diffusion time-dependent ADC data from the brachial plexus nerves and cord...
June 19, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28626998/large-coverage-black-bright-blood-interleaved-imaging-sequence-labbi-for-3d-dynamic-contrast-enhanced-mri-of-vessel-wall
#18
Haikun Qi, Feng Huang, Zechen Zhou, Peter Koken, Niranjan Balu, Bida Zhang, Chun Yuan, Huijun Chen
PURPOSE: To propose a large coverage black-bright blood interleaved imaging sequence (LaBBI) for 3D dynamic contrast-enhanced MRI (DCE-MRI) of the vessel wall. METHODS: LaBBI consists of a 3D black-blood stack-of-stars golden angle radial acquisition with high spatial resolution for vessel wall imaging and a 2D bright-blood Cartesian acquisition with high temporal resolution for arterial input function estimation. The two acquisitions were performed in an interleaved fashion within a single scan...
June 19, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28626964/impact-of-prior-distributions-and-central-tendency-measures-on-bayesian-intravoxel-incoherent-motion-model-fitting
#19
Oscar Gustafsson, Mikael Montelius, Göran Starck, Maria Ljungberg
PURPOSE: Bayesian model fitting has been proposed as a robust alternative for intravoxel incoherent motion (IVIM) model-fitting parameter estimation. However, consensus regarding choice of prior distribution and posterior distribution central tendency measure is needed. The aim of this study was to compare the quality of IVIM parameter estimates produced by different prior distributions and central tendency measures, and to gain knowledge about the effect of these choices. METHODS: Three prior distributions (uniform, reciprocal, and lognormal) and two measures of central tendency (mean and mode) found in the literature were studied using simulations and in vivo data from a tumor mouse model...
June 19, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28626962/three-dimensional-motion-corrected-sensitivity-encoding-reconstruction-for-multi-shot-multi-slice-mri-application-to-neonatal-brain-imaging
#20
Lucilio Cordero-Grande, Emer J Hughes, Jana Hutter, Anthony N Price, Joseph V Hajnal
PURPOSE: To introduce a methodology for the reconstruction of multi-shot, multi-slice magnetic resonance imaging able to cope with both within-plane and through-plane rigid motion and to describe its application in structural brain imaging. THEORY AND METHODS: The method alternates between motion estimation and reconstruction using a common objective function for both. Estimates of three-dimensional motion states for each shot and slice are gradually refined by improving on the fit of current reconstructions to the partial k-space information from multiple coils...
June 19, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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