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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/29893997/changes-in-the-specific-absorption-rate-sar-of-radiofrequency-energy-in-patients-with-retained-cardiac-leads-during-mri-at-1-5t-and-3t
#1
Laleh Golestanirad, Amir Ali Rahsepar, John E Kirsch, Kenichiro Suwa, Jeremy C Collins, Leonardo M Angelone, Boris Keil, Rod S Passman, Giorgio Bonmassar, Peter Serano, Peter Krenz, Jim DeLap, James C Carr, Lawrence L Wald
PURPOSE: To evaluate the local specific absorption rate (SAR) and heating around retained cardiac leads during MRI at 64 MHz (1.5T) and 127 MHz (3T) as a function of RF coil type and imaging landmark. METHODS: Numerical models of retained cardiac leads were built from CT and X-ray images of 6 patients with retained cardiac leads. Electromagnetic simulations and bio-heat modeling were performed with MRI RF body and head coils tuned to 64 MHz and 127 MHz and positioned at 9 different imaging landmarks covering an area from the head to the lower limbs...
June 12, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29893995/on-the-relation-between-mr-spectroscopy-features-and-the-distance-to-mri-visible-solid-tumor-in-gbm-patients
#2
Nuno Pedrosa de Barros, Raphael Meier, Martin Pletscher, Samuel Stettler, Urspeter Knecht, Evelyn Herrmann, Philippe Schucht, Mauricio Reyes, Jan Gralla, Roland Wiest, Johannes Slotboom
PURPOSE: To improve the detection of peritumoral changes in GBM patients by exploring the relation between MRSI information and the distance to the solid tumor volume (STV) defined using structural MRI (sMRI). METHODS: Twenty-three MRSI studies (PRESS, TE 135 ms) acquired from different patients with untreated GBM were used in this study. For each MRSI examination, the STV was identified by segmenting the corresponding sMRI images using BraTumIA, an automatic segmentation method...
June 12, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29893992/removal-of-hyperpolarized-129-xe-gas-phase-contamination-in-spectroscopic-imaging-of-the-lungs
#3
Andrew D Hahn, Jeff Kammerman, Sean B Fain
PURPOSE: A novel technique is presented for retrospective estimation and removal of gas-phase hyperpolarized Xenon-129 (HP 129 Xe) from images of HP 129 Xe dissolved in the barrier (comprised of parenchymal lung tissue and blood plasma) and red blood cell (RBC) phases. The primary aim is mitigating RF pulse performance limitations on measures of gas exchange (e.g., barrier-gas and RBC-gas ratios). Correction for gas contamination would simplify technical dissemination of HP 129 Xe applications across sites with varying hardware performance, scanner vendors, and models...
June 12, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29893989/neurovascular-stent-artifacts-in-3d-tof-and-3d-pcmri-influence-of-stent-design-on-flow-measurement
#4
Pierre Bouillot, Olivier Brina, Bénédicte M A Delattre, Rafik Ouared, Alain Pellaton, Hasan Yilmaz, Paolo Machi, Karl-Olof Lovblad, Mohamed Farhat, Vitor Mendes Pereira, Maria Isabel Vargas
PURPOSE: The morphological and hemodynamic evaluations of neurovascular diseases treated with stents would benefit from noninvasive imaging techniques such as 3D time-of-flight MRI (3D-TOF) and 3D phase contrast MRI (3D-PCMRI). For this purpose, a comprehensive evaluation of the stent artifacts and their impact on the flow measurement is critical. METHODS: The artifacts of a representative sample of neurovascular stents were evaluated in vitro with 3D-TOF and 3D-PCMRI sequences...
June 12, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29851141/assessment-of-frequency-drift-on-cest-mri-and-dynamic-correction-application-to-gagcest-at-7-t
#5
Johannes Windschuh, Moritz Zaiss, Philipp Ehses, Jae-Seung Lee, Alexej Jerschow, Ravinder R Regatte
PURPOSE: To investigate the effect of a frequency drift of the static magnetic field on 3D CEST MRI based on glycosaminoglycans (GAGs) of articular cartilage at 7 T and to introduce a retrospective correction method that uses the phase images of the gradient-echo readout. METHODS: Repeated gagCEST and B0 measurements were performed in a glucose model solution and in vivo in the knee joint of 3 healthy volunteers at 7 T. Phase images of the modified 3D rectangular spiral centric-reordered gradient-echo CEST sequence were used to quantify and compensate the apparent frequency drift in repeated gagCEST measurements...
May 31, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29845659/assessment-of-renal-fibrosis-in-murine-diabetic-nephropathy-using-quantitative-magnetization-transfer-mri
#6
Feng Wang, Daisuke Katagiri, Ke Li, Keiko Takahashi, Suwan Wang, Shinya Nagasaka, Hua Li, C Chad Quarles, Ming-Zhi Zhang, Akira Shimizu, John C Gore, Raymond C Harris, Takamune Takahashi
PURPOSE: Renal fibrosis is a hallmark of progressive renal disease; however, current clinical tests are insufficient for assessing renal fibrosis. Here we evaluated the utility of quantitative magnetization transfer MRI in detecting renal fibrosis in a murine model of progressive diabetic nephropathy (DN). METHODS: The db/db eNOS-/- mice, a well-recognized model of progressive DN, and normal wild-type mice were imaged at 7T. The quantitative magnetization transfer data were collected in coronal plane using a 2D magnetization transfer prepared spoiled gradient echo sequence with a Gaussian-shaped presaturation pulse...
May 30, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29845651/chemical-exchange-saturation-transfer-fingerprinting-for-exchange-rate-quantification
#7
Zhengwei Zhou, Pei Han, Bill Zhou, Anthony G Christodoulou, Jaime L Shaw, Zixin Deng, Debiao Li
PURPOSE: There is an increased interest to determine the exchange rate using CEST to provide pH information. However, current CEST quantification methods require lengthy scan times and do not address magnetization transfer effects. The purpose of this work was to apply the magnetic resonance fingerprinting (MRF) concept to CEST to achieve more efficient and accurate exchange rate quantification. METHODS: The proposed CEST fingerprinting method used varying saturation powers and saturation times to create unique signal evolutions for different exchange rates...
May 30, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29845645/revealing-sub-voxel-motions-of-brain-tissue-using-phase-based-amplified-mri-amri
#8
Itamar Terem, Wendy W Ni, Maged Goubran, Mahdi Salmani Rahimi, Greg Zaharchuk, Kristen W Yeom, Michael E Moseley, Mehmet Kurt, Samantha J Holdsworth
PURPOSE: Amplified magnetic resonance imaging (aMRI) was recently introduced as a new brain motion detection and visualization method. The original aMRI approach used a video-processing algorithm, Eulerian video magnification (EVM), to amplify cardio-ballistic motion in retrospectively cardiac-gated MRI data. Here, we strive to improve aMRI by incorporating a phase-based motion amplification algorithm. METHODS: Phase-based aMRI was developed and tested for correct implementation and ability to amplify sub-voxel motions using digital phantom simulations...
May 30, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29845640/cest-asl-and-magnetization-transfer-contrast-how-similar-pulse-sequences-detect-different-phenomena
#9
REVIEW
Linda Knutsson, Jiadi Xu, André Ahlgren, Peter C M van Zijl
Chemical exchange saturation transfer (CEST), arterial spin labeling (ASL), and magnetization transfer contrast (MTC) methods generate different contrasts for MRI. However, they share many similarities in terms of pulse sequences and mechanistic principles. They all use RF pulse preparation schemes to label the longitudinal magnetization of certain proton pools and follow the delivery and transfer of this magnetic label to a water proton pool in a tissue region of interest, where it accumulates and can be detected using any imaging sequence...
May 30, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29802643/golden-ratio-stack-of-spirals-for-flexible-angiographic-imaging-proof-of-concept-in-congenital-heart-disease
#10
Grzegorz Tomasz Kowalik, Jennifer Anne Steeden, David Atkinson, Javier Montalt-Tordera, Kristian Havmand Mortensen, Vivek Muthurangu
PURPOSE: In this study, a golden ratio stack of spiral (GRASS) sequence that used both golden step and golden angle ordering was implemented. The aim was to demonstrate that GRASS acquisitions could be flexibly reconstructed as both cardiac-gated and time-resolved angiograms. METHODS: Image quality of time-resolved and cardiac-gated reconstructions of the GRASS sequence were compared to 3 conventional stack of spirals (SoS) acquisitions in an in silico model. In 10 patients, the GRASS sequence was compared to conventional breath hold angiography (BH-MRA) in terms of image quality and for vessel measurement...
May 25, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29802641/chemical-exchange-rotation-transfer-cert-on-human-brain-at-3-tesla
#11
Eugene C Lin, Hua Li, Zhongliang Zu, Elizabeth A Louie, Christopher L Lankford, Richard D Dortch, Mark D Does, John C Gore, Daniel F Gochberg
PURPOSE: To test the ability of a novel pulse sequence applied in vivo at 3 Tesla to separate the contributions to the water signal from amide proton transfer (APT) and relayed nuclear Overhauser enhancement (rNOE) from background direct water saturation and semisolid magnetization transfer (MT). The lack of such signal source isolation has confounded conventional chemical exchange saturation transfer (CEST) imaging. METHODS: We quantified APT and rNOE signals using a chemical exchange rotation transfer (CERT) metric, MTRdouble ...
May 25, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29802635/reproducibility-of-2d-glucest-in-healthy-human-volunteers-at-7-t
#12
Ravi Prakash Reddy Nanga, Catherine DeBrosse, Dushyant Kumar, David Roalf, Brendan McGeehan, Kevin D'Aquilla, Arijitt Borthakur, Hari Hariharan, Damodara Reddy, Mark Elliott, John A Detre, Cynthia Neill Epperson, Ravinder Reddy
PURPOSE: To investigate the reproducibility of gray and white matter glutamate contrast of a brain slice among a small group of healthy volunteers by using the 2D single-slice glutamate CEST (GluCEST) imaging technique. METHODS: Six healthy volunteers were scanned multiple times for within-day and between-day reproducibility. One more volunteer was scanned for within-day reproducibility at 7T MRI. Glutamate CEST contrast measurements were calculated for within subjects and among the subjects and the coefficient of variations are reported...
May 25, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29802629/simultaneous-t-1-and-t-2-mapping-of-the-carotid-plaque-simple-with-t-2-and-inversion-recovery-prepared-3d-radial-imaging
#13
Haikun Qi, Jie Sun, Huiyu Qiao, Xihai Zhao, Rui Guo, Niranjan Balu, Chun Yuan, Huijun Chen
PURPOSE: To propose a technique that can produce different T1 and T2 contrasts in a single scan for simultaneous T1 and T2 mapping of the carotid plaque (SIMPLE). METHODS: An interleaved 3D golden angle radial trajectory was used in conjunction with T2 preparation with variable duration (TEprep ) and inversion recovery pulses. Sliding window reconstruction was adopted to reconstruct images at different inversion delay time and TEprep for joint T1 and T2 fitting...
May 25, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29774599/deep-convolutional-neural-network-for-segmentation-of-knee-joint-anatomy
#14
Zhaoye Zhou, Gengyan Zhao, Richard Kijowski, Fang Liu
PURPOSE: To describe and evaluate a new segmentation method using deep convolutional neural network (CNN), 3D fully connected conditional random field (CRF), and 3D simplex deformable modeling to improve the efficiency and accuracy of knee joint tissue segmentation. METHODS: A segmentation pipeline was built by combining a semantic segmentation CNN, 3D fully connected CRF, and 3D simplex deformable modeling. A convolutional encoder-decoder network was designed as the core of the segmentation method to perform high resolution pixel-wise multi-class tissue classification for 12 different joint structures...
May 17, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29774597/assessment-of-the-generalization-of-learned-image-reconstruction-and-the-potential-for-transfer-learning
#15
Florian Knoll, Kerstin Hammernik, Erich Kobler, Thomas Pock, Michael P Recht, Daniel K Sodickson
PURPOSE: Although deep learning has shown great promise for MR image reconstruction, an open question regarding the success of this approach is the robustness in the case of deviations between training and test data. The goal of this study is to assess the influence of image contrast, SNR, and image content on the generalization of learned image reconstruction, and to demonstrate the potential for transfer learning. METHODS: Reconstructions were trained from undersampled data using data sets with varying SNR, sampling pattern, image contrast, and synthetic data generated from a public image database...
May 17, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29774594/in-vivo-characterization-of-3d-skull-and-brain-motion-during-dynamic-head-vibration-using-magnetic-resonance-elastography
#16
Ziying Yin, Yi Sui, Joshua D Trzasko, Phillip J Rossman, Armando Manduca, Richard L Ehman, John Huston
PURPOSE: To introduce newly developed MR elastography (MRE)-based dual-saturation imaging and dual-sensitivity motion encoding schemes to directly measure in vivo skull-brain motion, and to study the skull-brain coupling in volunteers with these approaches. METHODS: Six volunteers were scanned with a high-performance compact 3T-MRI scanner. The skull-brain MRE images were obtained with a dual-saturation imaging where the skull and brain motion were acquired with fat- and water-suppression scans, respectively...
May 17, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29770503/a-novel-phase-unwrapping-method-by-using-phase-jump-detection-and-local-surface-fitting-application-to-dixon-water-fat-mri
#17
Junying Cheng, Jijing Guan, Yingjie Mei, Lin Xu, Xiaoyun Liu, Qianjin Feng, Wufan Chen, Yanqiu Feng
PURPOSE: This study aims to develop an accurate and robust phase-unwrapping method that works effectively under severe noise, rapid-varying phase, and disconnected regions for water-fat Dixon MRI. METHODS: The proposed method first segments the phase map into blocks by automatically detecting phase jumps, and then clusters the pixels near phase jumps into residual pixels. Thereafter, the proposed method sequentially performs intrablock, interblock, and residual-pixel unwrapping using the local surface fitting approach...
May 16, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29770495/prostate-dce-mri-with-b1-correction-using-an-approximated-analytical-approach
#18
Xinran Zhong, Thomas Martin, Holden H Wu, Krishna S Nayak, Kyunghyun Sung
PURPOSE: To develop and evaluate a practical B1+ correction method for prostate dynamic contrast-enhanced (DCE) MRI analysis. THEORY: We proposed a simple analytical B1+ correction method using a Taylor series approximation to the steady-state spoiled gradient echo signal equation. This approach only requires B1+ maps and uncorrected pharmacokinetic (PK) parameters as input to estimate the corrected PK parameters. METHODS: The proposed method was evaluated using a prostate digital reference object (DRO), and 82 in vivo prostate DCE-MRI cases...
May 16, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29770492/accelerated-3d-grase-imaging-improves-quantitative-multiple-post-labeling-delay-arterial-spin-labeling
#19
Markus Boland, Rüdiger Stirnberg, Eberhard D Pracht, Johanna Kramme, Roberto Viviani, Julia Stingl, Tony Stöcker
PURPOSE: To investigate the impact of accelerated, single-shot 3D-GRASE acquisition on quantitative arterial spin labeling (ASL) with multiple and single post-labeling delay (PLD) in terms of perfusion-weighted SNR per unit scan time (TSNRPW ) and quantification accuracy. METHODS: Five subjects were scanned on a 3T MRI scanner using the pseudo-continuous arterial spin labeling (PCASL) technique with a 3D-GRASE imaging sequence capable of parallel imaging acceleration...
May 16, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29770490/functional-magnetic-resonance-electrical-impedance-tomography-fmreit-sensitivity-analysis-using-an-active-bidomain-finite-element-model-of-neural-tissue
#20
Rosalind J Sadleir, Fanrui Fu, Munish Chauhan
PURPOSE: A direct method of imaging neural activity was simulated to determine typical signal sizes. METHODS: An active bidomain finite-element model was used to estimate approximate perturbations in MR phase data as a result of neural tissue activity, and when an external MR electrical impedance tomography imaging current was added to the region containing neural current sources. RESULTS: Modeling-predicted, activity-related conductivity changes should produce measurable differential phase signals in practical MR electrical impedance tomography experiments conducted at moderate resolution at noise levels typical of high field systems...
May 16, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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