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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/28812315/metabolite-cycled-steam-and-semi-laser-localization-for-mr-spectroscopy-of-the-human-brain-at-9-4t
#1
Ioannis-Angelos Giapitzakis, Tingting Shao, Nikolai Avdievich, Ralf Mekle, Roland Kreis, Anke Henning
PURPOSE: Metabolite cycling (MC) is an MRS technique for the simultaneous acquisition of water and metabolite spectra that avoids chemical exchange saturation transfer effects and for which water may serve as a reference signal or contain additional information in functional or diffusion studies. Here, MC was developed for human investigations at ultrahigh field. METHODS: MC-STEAM and MC-semi-LASER are introduced at 9.4T with an optimized inversion pulse and elaborate coil setup...
August 15, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28812309/murine-pulmonary-imaging-at-7t-t2-and-t1-with-anisotropic-ute
#2
Jinbang Guo, Xuefeng Cao, Zackary I Cleveland, Jason C Woods
PURPOSE: To measure the T2* and T1 of mouse lung at 7T via anisotropic-resolution radial ultrashort echo-time imaging with ellipsoidal k-space coverage. METHODS: Ellipsoidal field-of-view was created by expanding uniform spherical k-space coverage. The effects of T2* and ellipsoidal sampling on image resolution were investigated by using point-spread-function analysis and resolution phantoms. Finally, this ellipsoidal sampling approach was used to measure the lung T2* and T1 of healthy C57BL/6 mice at the increasingly common preclinical field strength of 7T...
August 15, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28804918/low-rank-approximation-methods-for-mr-fingerprinting-with-large-scale-dictionaries
#3
Mingrui Yang, Dan Ma, Yun Jiang, Jesse Hamilton, Nicole Seiberlich, Mark A Griswold, Debra McGivney
PURPOSE: This work proposes new low rank approximation approaches with significant memory savings for large scale MR fingerprinting (MRF) problems. THEORY AND METHODS: We introduce a compressed MRF with randomized singular value decomposition method to significantly reduce the memory requirement for calculating a low rank approximation of large sized MRF dictionaries. We further relax this requirement by exploiting the structures of MRF dictionaries in the randomized singular value decomposition space and fitting them to low-degree polynomials to generate high resolution MRF parameter maps...
August 13, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28799210/whole-brain-arteriography-and-venography-using-improved-velocity-selective-saturation-pulse-trains
#4
Wenbo Li, Feng Xu, Michael Schär, Jing Liu, Taehoon Shin, Yansong Zhao, Peter C M van Zijl, Bruce A Wasserman, Ye Qiao, Qin Qin
PURPOSE: To develop velocity-selective (VS) MR angiography (MRA) protocols for arteriography and venography with whole-brain coverage. METHODS: Tissue suppression using velocity-selective saturation (VSS) pulse trains is sensitive to radiofrequency field (B1 +) inhomogeneity. To reduce its sensitivity, we replaced the low-flip-angle hard pulses in the VSS pulse train with optimal composite (OCP) pulses. Additionally, new pulse sequences for arteriography and venography were developed by placing spatially selective inversion pulses with a delay to null signals from either venous or arterial blood...
August 10, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28796368/regularly-incremented-phase-encoding-mr-fingerprinting-ripe-mrf-for-enhanced-motion-artifact-suppression-in-preclinical-cartesian-mr-fingerprinting
#5
Christian E Anderson, Charlie Y Wang, Yuning Gu, Rebecca Darrah, Mark A Griswold, Xin Yu, Chris A Flask
PURPOSE: The regularly incremented phase encoding-magnetic resonance fingerprinting (RIPE-MRF) method is introduced to limit the sensitivity of preclinical MRF assessments to pulsatile and respiratory motion artifacts. METHODS: As compared to previously reported standard Cartesian-MRF methods (SC-MRF), the proposed RIPE-MRF method uses a modified Cartesian trajectory that varies the acquired phase-encoding line within each dynamic MRF dataset. Phantoms and mice were scanned without gating or triggering on a 7T preclinical MRI scanner using the RIPE-MRF and SC-MRF methods...
August 10, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28795419/simultaneous-mr-thermometry-and-acoustic-radiation-force-imaging-using-interleaved-acquisition
#6
Joshua T de Bever, Henrik Odéen, Lorne W Hofstetter, Dennis L Parker
PURPOSE: A novel and practical method for simultaneously performing MR acoustic radiation force imaging (ARFI) and proton resonance frequency (PRF)-shift thermometry has been developed and tested. This could be an important tool for evaluating the success of MR-guided focused ultrasound procedures for which MR-thermometry measures temperature and thermal dose and MR-ARFI detects changes in tissue mechanical properties. METHODS: MR imaging was performed using a gradient recalled echo segmented echo-planar imaging pulse sequence with bipolar motion encoding gradients (MEG)...
August 10, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28786132/application-of-pattern-recognition-techniques-for-classification-of-pediatric-brain-tumors-by-in-vivo-3t-1-h-mr-spectroscopy-a-multi-center-study
#7
Niloufar Zarinabad, Laurence J Abernethy, Shivaram Avula, Nigel P Davies, Daniel Rodriguez Gutierrez, Tim Jaspan, Lesley MacPherson, Dipayan Mitra, Heather E L Rose, Martin Wilson, Paul S Morgan, Simon Bailey, Barry Pizer, Theodoros N Arvanitis, Richard G Grundy, Dorothee P Auer, Andrew Peet
PURPOSE: 3T magnetic resonance scanners have boosted clinical application of (1) H-MR spectroscopy (MRS) by offering an improved signal-to-noise ratio and increased spectral resolution, thereby identifying more metabolites and extending the range of metabolic information. Spectroscopic data from clinical 1.5T MR scanners has been shown to discriminate between pediatric brain tumors by applying machine learning techniques to further aid diagnosis. The purpose of this multi-center study was to investigate the discriminative potential of metabolite profiles obtained from 3T scanners in classifying pediatric brain tumors...
August 8, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28782173/silent-navigator-triggered-silent-mri-of-the-abdomen
#8
Yuji Iwadate, Atsushi Nozaki, Yoshinobu Nunokawa, Shigeo Okuda, Masahiro Jinzaki, Hiroyuki Kabasawa
PURPOSE: To develop and demonstrate the feasibility of a silent respiratory navigator technique for prospective triggering, which was incorporated into a three-dimensional radial zero-echo-time sequence for respiratory navigated silent abdominal imaging. METHODS: A nonselective hard excitation radiofrequency pulse was used for the navigator sequence with a derated readout gradient, to avoid generation of high levels of acoustic noise. The acquired navigator signals were processed in real time and used for prospective triggering of the zero-echo-time sequence...
August 7, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28782150/mri-assessment-of-coronary-microvascular-endothelial-nitric-oxide-synthase-function-using-myocardial-t1-mapping
#9
Sophia X Cui, Frederick H Epstein
PURPOSE: Endothelial nitric oxide synthase (eNOS) plays a central role in regulating vascular tone, blood flow, and microvascular permeability. Endothelial dysfunction, including eNOS dysfunction, is an early biomarker of vascular disease. This study aimed to show that myocardial T1 mapping during nitric oxide synthase (NOS) inhibition could assess coronary microvascular eNOS function. METHODS: Wild-type mice, eNOS(-/-) mice, and wild-type mice fed a high-fat diet underwent T1 mapping at baseline and for 20 min after injection of N(G) -nitro-L-arginine methyl ester (LNAME), a NOS inhibitor...
August 7, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28782129/volumetric-mri-thermometry-using-a-three-dimensional-stack-of-stars-echo-planar-imaging-pulse-sequence
#10
Sumeeth V Jonathan, William A Grissom
PURPOSE: To measure temperature over a large brain volume with fine spatiotemporal resolution. METHODS: A three-dimensional stack-of-stars echo-planar imaging sequence combining echo-planar imaging and radial sampling with golden angle spacing was implemented at 3T for proton resonance frequency-shift temperature imaging. The sequence acquires a 188x188x43 image matrix with 1.5x1.5x2.75 mm(3) spatial resolution. Temperature maps were reconstructed using sensitivity encoding (SENSE) image reconstruction followed by the image domain hybrid method, and using the k-space hybrid method...
August 7, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28776754/quantitative-two-dimensional-ultrashort-echo-time-magnetization-transfer-2d-ute-mt-imaging-of-cortical-bone
#11
Ya-Jun Ma, Anthony Tadros, Jiang Du, Eric Y Chang
PURPOSE: To investigate quantitative 2D ultrashort echo time magnetization transfer (UTE-MT) imaging in ex vivo bovine cortical bone and in vivo human tibial cortical bone. METHODS: Data were acquired from five fresh bovine cortical bone samples and five healthy volunteer tibial cortical bones using a 2D UTE-MT sequence on a clinical 3T scanner. The 2D UTE-MT sequence used four or five MT powers with five frequency offsets. Results were analyzed with a two-pool quantitative MT model, providing measurements of macromolecular fraction (f), macromolecular proton transverse relaxation times (T2m ), proton exchange rates from water/macromolecular to the macromolecular/water pool (RM0m /RM0w ), and spin-lattice relaxation rate of water pool (R1w )...
August 3, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28771867/motion-corrected-k-space-reconstruction-for-interleaved-epi-diffusion-imaging
#12
Zijing Dong, Fuyixue Wang, Xiaodong Ma, Erpeng Dai, Zhe Zhang, Hua Guo
PURPOSE: To develop a new approach to correct for physiological and macroscopic motion in multishot, interleaved echo-planar diffusion imaging. THEORY: This work built on the previous SPIRiT (iterative self-consistent parallel imaging reconstruction) based reconstruction for physiological motion correction in multishot diffusion-weighted imaging to account for macroscopic motion. In-plane rotation, translation correction, data rejection, and weighted combination are integrated in SPIRiT-based reconstruction to correct for ghosting artifacts, blurring, altered b-matrix, and residual artifacts caused by motion...
August 3, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28771792/diaphragm-position-can-be-accurately-estimated-from-the-scattering-of-a-parallel-transmit-rf-coil-at-7-t
#13
Aaron T Hess, Elizabeth M Tunnicliffe, Christopher T Rodgers, Matthew D Robson
PURPOSE: To evaluate the use of radiofrequency scattering of a parallel transmit coil to track diaphragm motion. METHODS: Measurements made during radiofrequency excitation on an 8-channel parallel transmit coil by the directional couplers of the radiofrequency safety monitor were combined and converted into diaphragm position. A 30-s subject-specific calibration with an MRI navigator was used to determine a diaphragm estimate from each directional-coupler measure...
August 3, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28766824/ekg-based-detection-of-deep-brain-stimulation-in-fmri-studies
#14
Eric Fiveland, Radhika Madhavan, Julia Prusik, Renee Linton, Marisa Dimarzio, Jeffrey Ashe, Julie Pilitsis, Ileana Hancu
PURPOSE: To assess the impact of synchronization errors between the assumed functional MRI paradigm timing and the deep brain stimulation (DBS) on/off cycling using a custom electrocardiogram-based triggering system METHODS: A detector for measuring and predicting the on/off state of cycling deep brain stimulation was developed and tested in six patients in office visits. Three-electrode electrocardiogram measurements, amplified by a commercial bio-amplifier, were used as input for a custom electronics box (e-box)...
August 2, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28762243/quantitative-susceptibility-mapping-report-from-the-2016-reconstruction-challenge
#15
Christian Langkammer, Ferdinand Schweser, Karin Shmueli, Christian Kames, Xu Li, Li Guo, Carlos Milovic, Jinsuh Kim, Hongjiang Wei, Kristian Bredies, Sagar Buch, Yihao Guo, Zhe Liu, Jakob Meineke, Alexander Rauscher, José P Marques, Berkin Bilgic
PURPOSE: The aim of the 2016 quantitative susceptibility mapping (QSM) reconstruction challenge was to test the ability of various QSM algorithms to recover the underlying susceptibility from phase data faithfully. METHODS: Gradient-echo images of a healthy volunteer acquired at 3T in a single orientation with 1.06 mm isotropic resolution. A reference susceptibility map was provided, which was computed using the susceptibility tensor imaging algorithm on data acquired at 12 head orientations...
July 31, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28758248/ratio-adjustable-power-splitters-for-array-compressed-parallel-transmission
#16
Xinqiang Yan, Zhipeng Cao, William A Grissom
PURPOSE: To implement and validate low-loss ratio-adjustable power splitters (RAPS) for array-compressed parallel transmission (acpTx). METHODS: In acpTx, a small number of transmit channels drive a larger number of transmit coils, which are connected via an array compression network that implements optimized coil-to-channel combinations. Previous networks comprised a bank of power splitters, followed by attenuators to implement the amplitudes of the compression weights for each coil, but this resulted in high power dissipation in the network...
July 31, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28758241/in-vivo-phase-imaging-of-human-epiphyseal-cartilage-at-7-t
#17
Barbara Dymerska, Klaus Bohndorf, Paul Schennach, Alexander Rauscher, Siegfried Trattnig, Simon D Robinson
PURPOSE: To assess the potential clinical utility of in vivo susceptibility-weighted imaging and quantitative susceptibility mapping of growth cartilage in the juvenile human knee at 7 T. METHODS: High-resolution gradient-echo images of the knees of six healthy children and adolescents aged 6 to 15 were acquired with a 28-channel coil at 7 T. Phase images from the coils were combined using a short echo-time reference scan method (COMPOSER). RESULTS: Veins oriented perpendicular to the static B0 field appeared doubled in susceptibility-weighted imaging, but not quantitative susceptibility mapping...
July 31, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28758240/effects-of-imaging-gradients-in-sequences-with-varying-longitudinal-storage-time-case-of-diffusion-exchange-imaging
#18
Samo Lasič, Henrik Lundell, Daniel Topgaard, Tim B Dyrby
PURPOSE: To illustrate the potential bias caused by imaging gradients in correlation MRI sequences using longitudinal magnetization storage (LS) and examine the case of filter exchange imaging (FEXI) yielding maps of the apparent exchange rate (AXR). METHODS: The effects of imaging gradients in FEXI were observed on yeast cells. To analyze the AXR bias, signal evolution was calculated by applying matrix exponential operators. RESULTS: A sharp threshold for the slice thickness was identified, below which the AXR is increasingly underestimated...
July 31, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28752556/3d-multi-echo-radial-imaging-of-23-na-3d-merina-for-time-efficient-multi-parameter-tissue-compartment-mapping
#19
Yasmin Blunck, Sonal Josan, Syeda Warda Taqdees, Bradford A Moffat, Roger J Ordidge, Jon O Cleary, Leigh A Johnston
PURPOSE: This work demonstrates a 3D radial multi-echo acquisition scheme for time-efficient sodium ((23) Na) MR-signal acquisition and analysis. Echo reconstructions were used to produce signal-to-noise ratio (SNR)-enhanced (23) Na-images and parameter maps of the biexponential observed transverse relaxation time ( T2*) decay. METHODS: A custom-built sequence for radial multi-echo acquisition was proposed for acquisition of a series of 3D volumetric (23) Na-images...
July 28, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28748645/in-memoriam-sir-peter-mansfield-1933-2017
#20
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July 26, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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