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Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine

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https://www.readbyqxmd.com/read/28321915/acceleration-of-asl-based-time-resolved-mr-angiography-by-acquisition-of-control-and-labeled-images-in-the-same-shot-actress
#1
Yuriko Suzuki, Noriyuki Fujima, Tetsuo Ogino, James Alastair Meakin, Akira Suwa, Hiroyuki Sugimori, Marc Van Cauteren, Matthias J P van Osch
PURPOSE: Noncontrast 4D-MR-angiography (MRA) using arterial spin labeling (ASL) is beneficial because high spatial and temporal resolution can be achieved. However, ASL requires acquisition of labeled and control images for each phase. The purpose of this study is to present a new accelerated 4D-MRA approach that requires only a single control acquisition, achieving similar image quality in approximately half the scan time. METHODS: In a multi-phase Look-Locker sequence, the first phase was used as the control image and the labeling pulse was applied before the second phase...
March 20, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28321914/a-compact-0-5%C3%A2-t-mr-elastography-device-and-its-application-for-studying-viscoelasticity-changes-in-biological-tissues-during-progressive-formalin-fixation
#2
Jürgen Braun, Heiko Tzschätzsch, Clara Körting, Angela Ariza de Schellenberger, Marika Jenderka, Toni Drießle, Michael Ledwig, Ingolf Sack
PURPOSE: To develop a method of compact tabletop magnetic resonance elastography (MRE) for rheological tests of tissue samples and to measure changes in viscoelastic powerlaw constants of liver and brain tissue during progressive fixation. METHODS: A 10-mm bore, 0.5-T permanent-magnet-based MRI system was equipped with a gradient-amplifier-controlled piezo-actuator and motion-sensitive spin echo sequence for inducing and measuring harmonic shear vibrations in cylindrical samples...
March 20, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28321908/reduced-field-of-view-single-shot-spiral-perfusion-imaging
#3
Yang Yang, Li Zhao, Xiao Chen, Peter W Shaw, Jorge A Gonzalez, Frederick H Epstein, Craig H Meyer, Christopher M Kramer, Michael Salerno
PURPOSE: To develop a single-shot spiral perfusion pulse sequence with outer-volume suppression (OVS) to achieve whole-heart coverage with a short temporal footprint of 10 ms per slice location. METHODS: A highly accelerated single-shot variable density spiral pulse sequence with an integrated OVS module for reduced field of view (rFOV) perfusion imaging with 2 mm spatial resolution was developed and evaluated in simulations, phantom experiments and in clinical patients with (n = 8) or without (n = 8) OVS...
March 20, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28321904/rotating-single-shot-acquisition-rosa-with-composite-reconstruction-for-fast-high-resolution-diffusion-imaging
#4
Qiuting Wen, Chandana Kodiweera, Brian M Dale, Giri Shivraman, Yu-Chien Wu
PURPOSE: To accelerate high-resolution diffusion imaging, rotating single-shot acquisition (RoSA) with composite reconstruction is proposed. Acceleration was achieved by acquiring only one rotating single-shot blade per diffusion direction, and high-resolution diffusion-weighted (DW) images were reconstructed by using similarities of neighboring DW images. A parallel imaging technique was implemented in RoSA to further improve the image quality and acquisition speed. RoSA performance was evaluated by simulation and human experiments...
March 20, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28321903/spin-lock-imaging-of-exogenous-exchange-based-contrast-agents-to-assess-tissue-ph
#5
Zhongliang Zu, Hua Li, Xiaoyu Jiang, John C Gore
PURPOSE: Some X-ray contrast agents contain exchangeable protons that give rise to exchange-based effects on MRI, including chemical exchange saturation transfer (CEST). However, CEST has poor specificity to explicit exchange parameters. Spin-lock sequences at high field are also sensitive to chemical exchange. Here, we evaluate whether spin-locking techniques can detect the contrast agent iohexol in vivo after intravenous administration, and their potential for measuring changes in tissue pH...
March 20, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28321902/modeling-real-shim-fields-for-very-high-degree-and-order-b0-shimming-of-the-human-brain-at-9-4%C3%A2-t
#6
Paul Chang, Sahar Nassirpour, Anke Henning
PURPOSE: To describe the process of calibrating a B0 shim system using high-degree (or high order) spherical harmonic models of the measured shim fields, to provide a method that considers amplitude dependency of these models, and to show the advantage of very high-degree B0 shimming for whole-brain and single-slice applications at 9.4 Tesla (T). METHODS: An insert shim with up to fourth and partial fifth/sixth degree (order) spherical harmonics was used with a Siemens 9...
March 20, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28321901/a-pneumatic-phantom-for-mimicking-respiration-induced-artifacts-in-spinal-mri
#7
Philippe De Tillieux, Ryan Topfer, Alexandru Foias, Iris Leroux, Imanne El Maâchi, Hugues Leblond, Nikola Stikov, Julien Cohen-Adad
PURPOSE: To design a phantom capable of mimicking human respiration to serve as a testing platform for correction of the static and time-evolving magnetic field distortions typically encountered in MRI of the spinal cord. METHODS: An inflation system to mimic the air variation of the human lungs was constructed. The inflation system was linked to a phantom containing synthetic lungs and an ex vivo human spine. The relationship between air pressure and phantom lung volume was evaluated via imaging experiment...
March 20, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28321900/coronary-mr-angiography-using-image-based-respiratory-motion-compensation-with-inline-correction-and-fixed-gating-efficiency
#8
Markus Henningsson, Jouke Smink, Gerald van Ensbergen, Rene Botnar
PURPOSE: The purpose of this study was to evaluate a new inline motion compensation approach called image-based navigation with Constant Respiratory efficiency UsIng Single End-expiratory threshold (iNAV-CRUISE) for coronary MR angiography (CMRA). METHODS: The CRUISE gating technique was combined with iNAV motion correction and implemented inline for motion-compensated CMRA on a 1.5 Tesla scanner. The approach was compared to conventional diaphragmatic navigator gating (dNAVG) in 10 healthy subjects...
March 20, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28317261/diffusion-relaxation-correlation-spectroscopic-imaging-a-multidimensional-approach-for-probing-microstructure
#9
Daeun Kim, Eamon K Doyle, Jessica L Wisnowski, Joong Hee Kim, Justin P Haldar
PURPOSE: To propose and evaluate a novel multidimensional approach for imaging subvoxel tissue compartments called Diffusion-Relaxation Correlation Spectroscopic Imaging. THEORY AND METHODS: Multiexponential modeling of MR diffusion or relaxation data is commonly used to infer the many different microscopic tissue compartments that contribute signal to macroscopic MR imaging voxels. However, multiexponential estimation is known to be difficult and ill-posed. Observing that this ill-posedness is theoretically reduced in higher dimensions, diffusion-relaxation correlation spectroscopic imaging uses a novel multidimensional imaging experiment that jointly encodes diffusion and relaxation information, and then uses a novel constrained reconstruction technique to generate a multidimensional diffusion-relaxation correlation spectrum for every voxel...
March 19, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28303617/joint-system-relaxometry-jsr-and-cr%C3%A3-mer-rao-lower-bound-optimization-of-sequence-parameters-a-framework-for-enhanced-precision-of-despot-t1-and-t2-estimation
#10
Rui Pedro A G Teixeira, Shaihan J Malik, Joseph V Hajnal
PURPOSE: This study aims to increase the precision of single-compartment DESPOT relaxometry by two means: (i) a joint system relaxometry (JSR) approach that estimates parameters in a single step using all available data; and (ii) optimizing acquisition parameters by deploying a robust design tool based on the Crámer-Rao lower bound (CRLB). METHODS: Following the development of the analysis and design capabilities, phantom and four in vivo subject experiments were performed to compare directly the precision achieved with DESPOT and JSR estimation using published protocols and protocols designed using a proposed CRLB framework...
March 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28303611/improving-left-ventricular-segmentation-in-four-dimensional-flow-mri-using-intramodality-image-registration-for-cardiac-blood-flow-analysis
#11
Vikas Gupta, Mariana Bustamante, Alexandru Fredriksson, Carl-Johan Carlhäll, Tino Ebbers
PURPOSE: Assessment of blood flow in the left ventricle using four-dimensional flow MRI requires accurate left ventricle segmentation that is often hampered by the low contrast between blood and the myocardium. The purpose of this work is to improve left-ventricular segmentation in four-dimensional flow MRI for reliable blood flow analysis. METHOD: The left ventricle segmentations are first obtained using morphological cine-MRI with better in-plane resolution and contrast, and then aligned to four-dimensional flow MRI data...
March 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28303591/-31-p-magnetization-transfer-magnetic-resonance-spectroscopy-assessing-the-activation-induced-change-in-cerebral-atp-metabolic-rates-at-3-t
#12
Chen Chen, Mary C Stephenson, Andrew Peters, Peter G Morris, Susan T Francis, Penny A Gowland
PURPOSE: In vivo (31) P magnetic resonance spectroscopy (MRS) magnetization transfer (MT) provides a direct measure of neuronal activity at the metabolic level. This work aims to use functional (31) P MRS-MT to investigate the change in cerebral adenosine triphosphate (ATP) metabolic rates in healthy adults upon repeated visual stimuli. METHODS: A magnetization saturation transfer sequence with narrowband selective saturation of γ-ATP was developed for (31) P MT experiments at 3 T...
March 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28295552/high-resolution-dynamic-oxygen-17-mr-imaging-of-mouse-brain-with-golden-ratio-based-radial-sampling-and-k-space-weighted-image-reconstruction
#13
Yuchi Liu, Yifan Zhang, Chunying Wu, Junqing Zhu, Charlie Wang, Nicholas Tomko, Mikhail D Linetsky, Robert G Salomon, Ciro Ramos-Estebanez, Yanming Wang, Xin Yu
PURPOSE: The current study aimed to develop a three-dimensional (3D) dynamic oxygen-17 ((17) O) MR imaging method with high temporal and spatial resolution to delineate the kinetics of (17) O water uptake and washout in the brains of mice with glioblastoma (GBM). METHODS: A 3D imaging method with a stack-of-stars golden-ratio-based radial sampling scheme was employed to acquire (17) O signal in vivo. A k-space-weighted image reconstruction method was used to improve the temporal resolution while preserving spatial resolution...
March 13, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28295563/in-vivo-mri-of-the-human-finger-at-7-t
#14
Elmar Laistler, Barbara Dymerska, Jürgen Sieg, Sigrun Goluch, Roberta Frass-Kriegl, Andre Kuehne, Ewald Moser
PURPOSE: To demonstrate a dedicated setup for ultrahigh resolution MR imaging of the human finger in vivo. METHODS: A radiofrequency coil was designed for optimized signal homogeneity and sensitivity in the finger at ultrahigh magnetic field strength (7 T), providing high measurement sensitivity. Imaging sequences (2D turbo-spin echo (TSE) and 3D magnetization-prepared rapid acquisition gradient echo (MPRAGE)) were adapted for high spatial resolution and good contrast of different tissues in the finger, while keeping acquisition time below 10 minutes...
March 10, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28295523/quantitative-susceptibility-mapping-based-cerebral-metabolic-rate-of-oxygen-mapping-with-minimum-local-variance
#15
Jingwei Zhang, Junghun Cho, Dong Zhou, Thanh D Nguyen, Pascal Spincemaille, Ajay Gupta, Yi Wang
PURPOSE: The objective of this study was to demonstrate the feasibility of a cerebral metabolic rate of oxygen (CMRO2 ) mapping method based on its minimum local variance (MLV) without vascular challenge using quantitative susceptibility mapping (QSM) and cerebral blood flow (CBF). METHODS: Three-dimensional multi-echo gradient echo imaging and arterial spin labeling were performed in 11 healthy subjects to calculate QSM and CBF. Minimum local variance was used to compute whole-brain CMRO2 map from QSM and CBF...
March 10, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28266079/in-vitro-and-in-silico-assessment-of-rf-induced-heating-around-intracranial-aneurysm-clips-at-7-tesla
#16
Yacine Noureddine, Oliver Kraff, Mark E Ladd, Karsten H Wrede, Bixia Chen, Harald H Quick, Gregor Schaefers, Andreas K Bitz
PURPOSE: To examine radiofrequency-induced tissue heating around intracranial aneurysm clips during a 7 Tesla (T) head MR examination. METHODS: Radiofrequency (RF), temperature simulations, and RF measurements were employed to investigate the effects of polarization and clip length on the electric field (E-field) and temperature. Heating in body models was studied using both a conservative approach and realistic exposure scenarios. RESULTS: Worst-case orientation was found for clips aligned parallel to the E-field polarization...
March 7, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28266062/k-t-accelerated-aortic-4d-flow-mri-in-under-two-minutes-feasibility-and-impact-of-resolution-k-space-sampling-patterns-and-respiratory-navigator-gating-on-hemodynamic-measurements
#17
Emilie Bollache, Alex J Barker, Ryan Scott Dolan, James C Carr, Pim van Ooij, Rouzbeh Ahmadian, Alex Powell, Jeremy D Collins, Julia Geiger, Michael Markl
PURPOSE: To assess the performance of highly accelerated free-breathing aortic four-dimensional (4D) flow MRI acquired in under 2 minutes compared to conventional respiratory gated 4D flow. METHODS: Eight k-t accelerated nongated 4D flow MRI (parallel MRI with extended and averaged generalized autocalibrating partially parallel acquisition kernels [PEAK GRAPPA], R = 5, TRes = 67.2 ms) using four ky -kz Cartesian sampling patterns (linear, center-out, out-center-out, random) and two spatial resolutions (SRes1 = 3...
March 7, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28266059/fractional-anisotropy-derived-from-the-diffusion-tensor-distribution-function-boosts-power-to-detect-alzheimer-s-disease-deficits
#18
Talia M Nir, Neda Jahanshad, Julio E Villalon-Reina, Dmitry Isaev, Artemis Zavaliangos-Petropulu, Liang Zhan, Alex D Leow, Clifford R Jack, Michael W Weiner, Paul M Thompson
PURPOSE: In diffusion MRI (dMRI), fractional anisotropy derived from the single-tensor model (FA(DTI) ) is the most widely used metric to characterize white matter (WM) microarchitecture, despite known limitations in regions with crossing fibers. Due to time constraints when scanning patients in clinical settings, high angular resolution diffusion imaging acquisition protocols, often used to overcome these limitations, are still rare in clinical population studies. However, the tensor distribution function (TDF) may be used to model multiple underlying fibers by representing the diffusion profile as a probabilistic mixture of tensors...
March 7, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28261904/high-resolution-in-vivo-diffusion-imaging-of-the-human-brain-with-generalized-slice-dithered-enhanced-resolution-simultaneous-multislice-gslider-sms
#19
Kawin Setsompop, Qiuyun Fan, Jason Stockmann, Berkin Bilgic, Susie Huang, Stephen F Cauley, Aapo Nummenmaa, Fuyixue Wang, Yogesh Rathi, Thomas Witzel, Lawrence L Wald
PURPOSE: To develop an efficient acquisition for high-resolution diffusion imaging and allow in vivo whole-brain acquisitions at 600- to 700-μm isotropic resolution. METHODS: We combine blipped-controlled aliasing in parallel imaging simultaneous multislice (SMS) with a novel slab radiofrequency (RF) encoding gSlider (generalized slice-dithered enhanced resolution) to form a signal-to-noise ratio-efficient volumetric simultaneous multislab acquisition. Here, multiple thin slabs are acquired simultaneously with controlled aliasing, and unaliased with parallel imaging...
March 5, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28261872/tracking-discrete-off-resonance-markers-with-three-spokes-trackdots-for-compensation-of-head-motion-and-b0-perturbations-accuracy-and-performance-in-anatomical-imaging
#20
João Jorge, Frédéric Gretsch, Daniel Gallichan, José P Marques
PURPOSE: To develop a novel approach for head motion and B0 field monitoring based on tracking discrete off-resonance markers with three spokes (trackDOTS). METHODS: Small markers filled with acetic acid were built and attached to a head cap. Marker positions and phase were tracked with fast MR navigators (DotNavs) consisting of three off-resonance, double-echo, orthogonal one-dimensional projections. Individual marker signals were extracted using optimized coil combinations, and used to estimate head motion and field perturbations...
March 5, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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