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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/30329186/investigation-of-the-influence-of-macromolecules-and-spline-baseline-in-the-fitting-model-of-human-brain-spectra-at-9-4t
#1
Ioannis-Angelos Giapitzakis, Tamas Borbath, Saipavitra Murali-Manohar, Nikolai Avdievich, Anke Henning
PURPOSE: In this study, the influence of experimentally measured macromolecules and spline baseline on the quantification results of proton MRS data was investigated. METHODS: Proton MRS spectra from the left parietal lobe and the occipital lobe were acquired at 9.4T in the human brain using metabolite-cycled semi-LASER. Then, the left parietal lobe data, along with the occipital lobe, spectra were quantified and the influence of the inclusion of experimentally measured macromolecular basis sets in the fitting model was evaluated...
October 17, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/30329181/trajectory-optimized-nufft-faster-non-cartesian-mri-reconstruction-through-prior-knowledge-and-parallel-architectures
#2
David S Smith, Saikat Sengupta, Seth A Smith, E Brian Welch
PURPOSE: The non-uniform fast Fourier transform (NUFFT) involves interpolation of non-uniformly sampled Fourier data onto a Cartesian grid, an interpolation that is slowed by complex, non-local data access patterns. A faster NUFFT would increase the clinical relevance of the plethora of advanced non-Cartesian acquisition methods. METHODS: Here we customize the NUFFT procedure for a radial trajectory and GPU architecture to eliminate the bottlenecks encountered when allowing for arbitrary trajectories and hardware...
October 17, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/30329177/optimization-of-the-order-and-spacing-of-sequences-in-an-mri-exam-to-reduce-the-maximum-temperature-and-thermal-dose
#3
Giuseppe Carluccio, Christopher M Collins
PURPOSE: Evaluate the possibility to reduce specific energy absorption rate (SAR)-induced maximum temperature and thermal dose by rearranging the order and spacing of sequences without increasing duration of the MRI examination. METHODS: Using numerical simulations based on an actual SAR-intensive MRI examination, optimizations to reduce either maximum temperature or thermal dose were performed. For each permutation of groups of sequences having the same patient table position, temperature and thermal dose were computed very rapidly using recently published methods...
October 17, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/30325058/true-phase-quantitative-susceptibility-mapping-using-continuous-single-point-imaging-a-feasibility-study
#4
Hyungseok Jang, Xing Lu, Michael Carl, Adam C Searleman, Saeed Jerban, Yajun Ma, Annette von Drygalski, Eric Y Chang, Jiang Du
PURPOSE: In this study, we explore the feasibility of a new imaging scheme for quantitative susceptibility mapping (QSM): continuous single-point imaging (CSPI), which uses a pure phase encoding strategy to achieve true phase imaging and improve QSM accuracy. METHODS: The proposed CSPI is a modification of conventional SPI to allow acquisition of multiple echoes in a single scan. Immediately following a phase encoding gradient, the free induction decay is continuously sampled with extremely high temporal resolution to obtain k-space data at a fixed spatial frequency (i...
October 16, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/30325053/multi-modal-synergistic-pet-and-mr-reconstruction-using-mutually-weighted-quadratic-priors
#5
Abolfazl Mehranian, Martin A Belzunce, Colm J McGinnity, Aurelien Bustin, Claudia Prieto, Alexander Hammers, Andrew J Reader
PURPOSE: To propose a framework for synergistic reconstruction of PET-MR and multi-contrast MR data to improve the image quality obtained from noisy PET data and from undersampled MR data. THEORY AND METHODS: Weighted quadratic priors were devised to preserve common boundaries between PET-MR images while reducing noise, PET Gibbs ringing, and MR undersampling artifacts. These priors are iteratively reweighted using normalized multi-modal Gaussian similarity kernels...
October 16, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/30325052/electrical-properties-tomography-available-contrast-and-reconstruction-capabilities
#6
REVIEW
Ileana Hancu, Jiaen Liu, Yihe Hua, Seung-Kyun Lee
MR-based electrical properties tomography converts the MRI transmit/receive RF field measurements to tissue electrical property maps through dedicated reconstruction algorithms. Recent reports showed that despite limitations, electrical properties tomography holds promise for generating additional contrast for tumor detection and patient-specific modeling of tissue-RF field interactions. This review summarizes the available tissue electrical property contrasts and compares them with the capabilities of the most commonly used electrical properties tomography reconstruction method...
October 16, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/30320945/multipathway-multi-echo-mpme-imaging-all-main-mr-parameters-mapped-based-on-a-single-3d-scan
#7
Cheng-Chieh Cheng, Frank Preiswerk, W Scott Hoge, Tai-Hsin Kuo, Bruno Madore
PURPOSE: Quantitative parameter maps, as opposed to qualitative grayscale images, may represent the future of diagnostic MRI. A new quantitative MRI method is introduced here that requires a single 3D acquisition, allowing good spatial coverage to be achieved in relatively short scan times. METHODS: A multipathway multi-echo sequence was developed, and at least 3 pathways with 2 TEs were needed to generate T1 , T2 , T2 * , B1 + , and B0 maps. The method required the central k-space region to be sampled twice, with the same sequence but with 2 very different nominal flip angle settings...
October 15, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/30320931/respiratory-and-cardiac-motion-corrected-simultaneous-whole-heart-pet-and-dual-phase-coronary-mr-angiography
#8
Camila Munoz, Radhouene Neji, Karl P Kunze, Stephan G Nekolla, Rene M Botnar, Claudia Prieto
PURPOSE: To develop a framework for efficient and simultaneous acquisition of motion-compensated whole-heart coronary MR angiography (CMRA) and left ventricular function by MR and myocardial integrity by PET on a 3T PET-MR system. METHODS: An acquisition scheme based on a dual-phase CMRA sequence acquired simultaneously with cardiac PET data has been developed. The framework is integrated with a motion-corrected image reconstruction approach, so that non-rigid respiratory and cardiac deformation fields estimated from MR images are used to correct both the CMRA (respiratory motion correction for each cardiac phase) and the PET data (respiratory and cardiac motion correction)...
October 15, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/30320925/magnetic-resonance-field-fingerprinting
#9
Gregor Körzdörfer, Yun Jiang, Peter Speier, Jianing Pang, Dan Ma, Josef Pfeuffer, Bernhard Hensel, Vikas Gulani, Mark Griswold, Mathias Nittka
PURPOSE: To develop and evaluate the magnetic resonance field fingerprinting method that simultaneously generates T1 , T2 , B0 , and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>B</mml:mi> <mml:mrow> <mml:mn>1</mml:mn> </mml:mrow> <mml:mo>+</mml:mo> </mml:msubsup> </mml:math> maps from a single continuous measurement. METHODS: An encoding pattern was designed to integrate true fast imaging with steady-state precession (TrueFISP), fast imaging with steady-state precession (FISP), and fast low-angle shot (FLASH) sequence segments with varying flip angles, radio frequency (RF) phases, TEs, and gradient moments in a continuous acquisition...
October 15, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/30311704/fully-convolutional-networks-for-automated-segmentation-of-abdominal-adipose-tissue-depots-in-multicenter-water-fat-mri
#10
Taro Langner, Anders Hedström, Katharina Mörwald, Daniel Weghuber, Anders Forslund, Peter Bergsten, Håkan Ahlström, Joel Kullberg
PURPOSE: An approach for the automated segmentation of visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) in multicenter water-fat MRI scans of the abdomen was investigated, using 2 different neural network architectures. METHODS: The 2 fully convolutional network architectures U-Net and V-Net were trained, evaluated, and compared using the water-fat MRI data. Data of the study Tellus with 90 scans from a single center was used for a 10-fold cross-validation in which the most successful configuration for both networks was determined...
October 12, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/30311694/a-framework-for-motion-correction-of-background-suppressed-arterial-spin-labeling-perfusion-images-acquired-with-simultaneous-multi-slice-epi
#11
Yuriko Suzuki, Thomas W Okell, Michael A Chappell, Matthias J P van Osch
PURPOSE: When using simultaneous multi-slice (SMS) EPI for background suppressed (BGS) arterial spin labeling (ASL), correction of through-plane motion could introduce artefacts, because the slices with most effective BGS are adjacent to slices with the least BGS. In this study, a new framework is presented to correct for such artefacts. METHODS: The proposed framework consists of 3 steps: (1) homogenization of the static tissue signal over the different slices to eliminate most inter-slice differences because of different levels of BGS, (2) application of motion correction, and (3) extraction of a perfusion-weighted signal using a general linear model...
October 12, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/30311689/whole-heart-spiral-simultaneous-multi-slice-first-pass-myocardial-perfusion-imaging
#12
Yang Yang, Craig H Meyer, Frederick H Epstein, Christopher M Kramer, Michael Salerno
PURPOSE: To develop and evaluate a simultaneous multislice (SMS) spiral perfusion pulse sequence with whole-heart coverage. METHODS: An orthogonal set of phase cycling angles following a Hadamard pattern was incorporated into a golden-angle (GA) variable density spiral perfusion sequence to perform SMS imaging at different multiband (MB) factors. Images were reconstructed using an SMS extension of L1-SPIRiT that we have termed SMS-L1-SPIRiT. The proposed sequence was evaluated in 40 subjects (10 each for MB factors of 1, 2, 3, and 4)...
October 12, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/30303564/lesion-segmentation-for-mr-spectroscopic-imaging-using-the-convolution-difference-method
#13
Andrew A Maudsley
PURPOSE: Delineation of lesion boundaries from volumetric MRSI metabolite ratio maps using a method that accounts for the spatial response function of the acquisition and variable spectral quality and is robust to signal heterogeneity within the lesion. METHODS: A novel method for lesion segmentation, termed convolution difference, has been developed that is robust to signal heterogeneity within the lesion and to differences in the spatial response function. Procedures are described for processing metabolite ratio maps and to exclude regions of inadequate spectral quality...
October 10, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/30303562/on-the-accuracy-and-precision-of-planet-for-multiparametric-mri-using-phase-cycled-bssfp-imaging
#14
Yulia Shcherbakova, Cornelis A T van den Berg, Chrit T W Moonen, Lambertus W Bartels
PURPOSE: In this work we demonstrate how sequence parameter settings influence the accuracy and precision in T1 , T2 , and off-resonance maps obtained with the PLANET method for a single-component signal model. In addition, the performance of the method for the particular case of a two-component relaxation model for white matter tissue was assessed. METHODS: Numerical simulations were performed to investigate the influence of sequence parameter settings on the accuracy and precision in the estimated parameters for a single-component model, as well as for a two-component white matter model...
October 10, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/30303553/combined-imaging-and-shimming-with-the-dynamic-multi-coil-technique
#15
S Umesh Rudrapatna, Fabian Fluerenbrock, Terence W Nixon, Robin A de Graaf, Christoph Juchem
PURPOSE: Spatial encoding and shimming in MRI have traditionally been performed using dedicated coils that generate orthogonal spherical harmonic fields. The recently introduced multi-coil hardware has proven that MRI-relevant magnetic fields can also be created by a generic set of localized coils producing non-orthogonal fields. As a step towards establishing a purely multi-coil-based MRI field generation system, the feasibility of performing conventional Cartesian k-space encoding and echo-planar imaging (EPI), as well as concurrent encoding and shimming is demonstrated in this study...
October 10, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/30303550/mapping-connectomes-with-diffusion-mri-deterministic-or-probabilistic-tractography
#16
Tabinda Sarwar, Kotagiri Ramamohanarao, Andrew Zalesky
PURPOSE: Human connectomics necessitates high-throughput, whole-brain reconstruction of multiple white matter fiber bundles. Scaling up tractography to meet these high-throughput demands yields new fiber tracking challenges, such as minimizing spurious connections and controlling for gyral biases. The aim of this study is to determine which of the two broadest classes of tractography algorithms-deterministic or probabilistic-is most suited to mapping connectomes. METHODS: This study develops numerical connectome phantoms that feature realistic network topologies and that are matched to the fiber complexity of in vivo diffusion MRI (dMRI) data...
October 10, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/30298692/prospective-motion-correction-improves-high-resolution-quantitative-susceptibility-mapping-at-7t
#17
Hendrik Mattern, Alessandro Sciarra, Falk Lüsebrink, Julio Acosta-Cabronero, Oliver Speck
PURPOSE: Recent literature has shown the potential of high-resolution quantitative susceptibility mapping (QSM) with ultra-high field MRI for imaging the anatomy, the vasculature, and investigating their magnetostatic properties. Higher spatial resolutions, however, translate to longer scans resulting, therefore, in higher vulnerability to, and likelihood of, subject movement. We propose a gradient-recalled echo sequence with prospective motion correction (PMC) to address such limitation...
October 9, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/30298595/simultaneous-perfusion-and-permeability-assessments-using-multiband-multi-echo-epi-m2-epi-in-brain-tumors
#18
Junjie Wu, Amit M Saindane, Xiaodong Zhong, Deqiang Qiu
PURPOSE: To study a multiband multi-echo EPI (M2-EPI) sequence for dynamic susceptibility contrast (DSC) perfusion imaging with leakage correction and vascular permeability measurements, and to evaluate the benefits of increased temporal resolution provided by this acquisition strategy on the accuracy of perfusion and permeability estimations. METHODS: A novel M2-EPI sequence was developed, and a pharmacokinetic model accounting for contrast agent extravasation was used to produce perfusion maps and additional vascular permeability maps...
October 9, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/30298547/background-field-removal-for-susceptibility-mapping-of-human-brain-with-large-susceptibility-variations
#19
Jinsheng Fang, Lijun Bao, Xu Li, Peter C M van Zijl, Zhong Chen
PURPOSE: In quantitative susceptibility mapping (QSM) of human brain, the background field induced by air-tissue interface varies significantly with respect to the rotation angle between the head and the static field, which may result in substantial error in the estimated magnetic susceptibility values. The goal of this study was to develop a strategy to better remove such orientation dependent background field. METHODS: An improved background field removal method is proposed based on the sophisticated harmonic artifact reduction for phase data using a region adaptive kernel (R-SHARP), named iRSHARP...
October 9, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/30298524/redesign-of-the-laplacian-kernel-for-improvements-in-conductivity-imaging-using-mri
#20
Jaewook Shin, Jun-Hyeong Kim, Dong-Hyun Kim
PURPOSE: To develop an electrical property tomography reconstruction method that achieves improvements over standard method by redesigning the Laplacian kernel. THEORY AND METHODS: A decomposition property of the governing PET equation shows the possibility of redesigning the Laplacian kernel for conductivity reconstruction. Hence, the discrete Laplacian operator used for electrical property tomography reconstruction is redesigned to have a Gaussian-like envelope, which enables manipulation of the spatial and spectral response...
October 9, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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