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https://www.readbyqxmd.com/read/30334785/calibration-free-b0-correction-of-epi-data-using-structured-low-rank-matrix-recovery
#1
Arvind Balachandrasekaran, Merry Mani, Mathews Jacob
We introduce a structured low rank algorithm for the calibration-free compensation of field inhomogeneity artifacts in Echo Planar Imaging (EPI) MRI data. We acquire the data using two EPI readouts that differ in echo-time (TE). Using time segmentation, we reformulate the field inhomogeneity compensation problem as the recovery of an image time series from highly undersampled Fourier measurements. The temporal profile at each pixel is modeled as a single exponential, which is exploited to fill in the missing entries...
October 16, 2018: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/30328237/3d-chemical-shift-encoded-mri-for-volume-and-composition-quantification-of-abdominal-adipose-tissue-during-an-overfeeding-protocol-in-healthy-volunteers
#2
Angeline Nemeth, Bérénice Segrestin, Benjamin Leporq, Kevin Seyssel, Khuram Faraz, Valérie Sauvinet, Emmanuel Disse, Pierre-Jean Valette, Martine Laville, Hélène Ratiney, Olivier Beuf
BACKGROUND: Overweight and obesity are major worldwide health concerns characterized by an abnormal accumulation of fat in adipose tissue (AT) and liver. PURPOSE: To evaluate the volume and the fatty acid (FA) composition of the subcutaneous adipose tissue (SAT) and the visceral adipose tissue (VAT) and the fat content in the liver from 3D chemical-shift-encoded (CSE)-MRI acquisition, before and after a 31-day overfeeding protocol. STUDY TYPE: Prospective and longitudinal study...
October 16, 2018: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/30321565/post-mortem-high-resolution-diffusion-mri-for-large-specimen-imaging-at-11-7-tesla-with-3d-segmented-echo-planar-imaging
#3
Sophie Bernadette Sébille, Anne-Sophie Rolland, Marie-Laure Welter, Eric Bardinet, Mathieu David Santin
BACKGROUND: Diffusion weighted imaging (DWI) is the only in vivo technique allowing for the mapping of tissue fiber architecture. Post mortem DWI is an increasingly popular method, since longer acquisition times (compared to in vivo) allow higher spatial and angular resolutions to be achieved. However, DWI protocols must be adapted to post mortem tissue (e.g., tuning acquisition parameters to account for changes in T1/T2). NEW METHOD: In this work, we developed a framework to obtain high quality diffusion weighted images on post mortem large samples by using a combination of fast imaging with 3D diffusion-weighted segmented EPI (3D-DW seg-EPI), Gadolinium soaking and data denoising...
October 12, 2018: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/30320945/multipathway-multi-echo-mpme-imaging-all-main-mr-parameters-mapped-based-on-a-single-3d-scan
#4
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/30318790/pincer-type-mri-morphology-seen-in-over-a-third-of-asymptomatic-healthy-volunteers-without-femoroacetabular-impingement
#5
Susanne Bensler, Tobias J Dietrich, Veronika Zubler, Christian W A Pfirrmann, Reto Sutter
BACKGROUND: In daily routine, pincer femoroacetabular impingement (FAI) findings are often seen without a clinical diagnosis of pincer FAI. PURPOSE: To assess the presence of pincer FAI MRI findings in asymptomatic volunteers with negative impingement test versus patients with clinically confirmed FAI. STUDY TYPE: Case-control study. POPULATION: Sixty-three asymptomatic volunteers and 63 matched patients with FAI were included...
October 14, 2018: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/30318667/simultaneous-fat-free-isotropic-3d-anatomical-imaging-and-t-2-mapping-of-knee-cartilage-with-lipid-insensitive-binomial-off-resonant-rf-excitation-libre-pulses
#6
Roberto Colotti, Patrick Omoumi, Ruud B van Heeswijk, Jessica A M Bastiaansen
BACKGROUND: Improved knee cartilage morphological delineation and T2 mapping precision necessitates isotropic 3D high-resolution and efficient fat suppression. PURPOSE: To develop and assess an isotropic 3D lipid-insensitive T2 mapping technique of the knee for improved cartilage delineation and precise measurement of T2 relaxation times. STUDY TYPE: Prospective. PHANTOM/SUBJECTS: Phantoms (n = 6) used in this study were designed to mimic the T1 and T2 relaxation times of cartilage and fat...
October 14, 2018: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/30318501/three-dimensional-pseudo-continuous-arterial-spin-labeling-using-turbo-spin-echo-with-pseudo-steady-state-readout-a-comparison-with-other-major-readout-methods
#7
Suzuko Aoike, Hiroyuki Sugimori, Noriyuki Fujima, Yuriko Suzuki, Yukie Shimizu, Akira Suwa, Kinya Ishizaka, Kohsuke Kudo
We evaluated 3D pseudo-continuous arterial spin labeling (pCASL) using turbo spin echo with a pseudo-steady-state (PSS) readout in comparison with the other major readout methods of 3D spiral and 2D echo-planar imaging (EPI). 3D-PSS produced cerebral blood flow (CBF) values well correlated to those of the 3D spiral readout. By visual evaluation, the image quality of 3D-PSS pCASL was superior to that of 2D-EPI. The 3D-PSS technique was suggested useful as pCASL readout.
October 12, 2018: Magnetic Resonance in Medical Sciences: MRMS
https://www.readbyqxmd.com/read/30315340/incidence-of-echocardiographic-abnormalities-following-pediatric-svt-ablation-comparison-of-cases-utilizing-fluoroscopy-alone-to-cases-with-adjunctive-3d-electroanatomic-mapping
#8
Ari J Gartenberg, Robert H Pass, Scott Ceresnak, Lynn Nappo, Christopher M Janson
There are few data on the incidence of echocardiographic (echo) abnormalities following catheter ablation in children in the era of 3D mapping. Wide practice variation exists regarding routine post-ablation echo. We hypothesized a low incidence of clinically significant echo abnormalities following SVT ablation in otherwise healthy children. Single center data from 2009 to 2015 were reviewed; routine post-ablation echo was standard practice. Cases were categorized as utilizing fluoroscopy alone (FLUORO) or 3D mapping with a low fluoroscopic protocol (CARTO3)...
October 12, 2018: Pediatric Cardiology
https://www.readbyqxmd.com/read/30312836/traumatic-axonal-injury-revealed-by-postmortem-magnetic-resonance-imaging-a-case-report
#9
Yohsuke Makino, Nobutaka Arai, Yumi Hoshioka, Maiko Yoshida, Masatoshi Kojima, Takuro Horikoshi, Hiroki Mukai, Hirotaro Iwase
In forensic investigations, it is important to detect traumatic axonal injuries (TAIs) to reveal head trauma that might otherwise remain occult. These lesions are subtle and frequently ambiguous on macroscopic evaluations. We present a case of TAI revealed by pre-autopsy postmortem magnetic resonance imaging (PMMR). A man in his sixties was rendered unconscious in a motor vehicle accident. CT scans revealed traumatic mild subarachnoid hemorrhage. Two weeks after the accident he regained consciousness, but displayed an altered mental state...
October 1, 2018: Legal Medicine
https://www.readbyqxmd.com/read/30307075/quantitative-gd-dota-based-aerosol-deposition-mapping-in-the-lungs-of-asthmatic-rats-using-3d-ute-mri
#10
Hongchen Wang, Catherine Sebrié, Sébastien Judé, Anne Maurin, Stéphanie Rétif, Marilyne Le Mée, Felicia Julea, Rose-Marie Dubuisson, Georges Willoquet, Khaoula Bouazizi, Luc Darrasse, Geneviève Guillot, Xavier Maître, Ludovic de Rochefort
Asthma is a chronic respiratory disease, commonly treated with inhaled therapy. Better understanding of the mechanisms of aerosol deposition is required to improve inhaled drug delivery. Three-dimensional ultrashort echo time (UTE) MRI acquisitions at 1.5 T were combined with spontaneous nose-only inhalation of aerosolized gadolinium (Gd) to map the aerosol deposition and to characterize signal enhancement in asthmatic rat lungs. The rats were sensitized to ovalbumin (OVA) to develop asthmatic models and challenged before imaging by nebulization of OVA to trigger asthmatic symptoms...
October 11, 2018: NMR in Biomedicine
https://www.readbyqxmd.com/read/30302598/spatial-correlations-between-mri-derived-wall-shear-stress-and-vessel-wall-thickness-in-the-carotid-bifurcation
#11
Pim van Ooij, Merih Cibis, Ethan M Rowland, Meike W Vernooij, Aad van der Lugt, Peter D Weinberg, Jolanda J Wentzel, Aart J Nederveen
BACKGROUND: To explore the possibility of creating three-dimensional (3D) estimation models for patient-specific wall thickness (WT) maps using patient-specific and cohort-averaged WT, wall shear stress (WSS), and vessel diameter maps in asymptomatic atherosclerotic carotid bifurcations. METHODS: Twenty subjects (aged 75 ± 6 years [mean ± standard deviation], eight women) underwent a 1.5-T MRI examination. Non-gated 3D phase-contrast gradient-echo images and proton density-weighted echo-planar images were retrospectively assessed for WSS, diameter estimation, and WT measurements...
October 10, 2018: European radiology experimental
https://www.readbyqxmd.com/read/30301904/age-related-measurements-of-the-myelin-water-fraction-derived-from-3d-multi-echo-grase-reflect-myelin-content-of-the-cerebral-white-matter
#12
Tobias D Faizy, Dushyant Kumar, Gabriel Broocks, Christian Thaler, Fabian Flottmann, Hannes Leischner, Daniel Kutzner, Simon Hewera, Dominik Dotzauer, Jan-Patrick Stellmann, Ravinder Reddy, Jens Fiehler, Jan Sedlacik, Susanne Gellißen
Myelin Water Fraction (MWF) measurements derived from quantitative Myelin Water Imaging (MWI) may detect demyelinating changes of the cerebral white matter (WM) microstructure. Here, we investigated age-related alterations of the MWF in normal aging brains of healthy volunteers utilizing two fast and clinically feasible 3D gradient and spin echo (GRASE) MWI sequences with 3 mm and 5 mm isotropic voxel size. In 45 healthy subjects (age range: 18-79 years), distinct regions of interest (ROI) were defined in the cerebral WM including corticospinal tracts...
October 9, 2018: Scientific Reports
https://www.readbyqxmd.com/read/30291655/disrupted-functional-connectivity-and-activity-in-the-white-matter-of-the-sensorimotor-system-in-patients-with-pontine-strokes
#13
Jingjuan Wang, Zhipeng Yang, Miao Zhang, Yi Shan, Dongdong Rong, Qingfeng Ma, Hesheng Liu, Xi Wu, Kuncheng Li, Zhaohua Ding, Jie Lu
BACKGROUND: White matter (WM) blood oxygenation level-dependent (BOLD) signals are reported to be related to neural activity. However, sensitivity of WM BOLD signals to disease remains unclear. PURPOSE: To investigate WM BOLD signal changes, directional variations of resting-state correlations in sensorimotor system in patients with pontine strokes, and to determine the relationship between WM BOLD signals and motor deficits. STUDY TYPE: Prospective...
October 6, 2018: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/30291652/quantitative-mri-of-visually-intact-rotator-cuff-muscles-by-multiecho-dixon-based-fat-quantification-and-diffusion-tensor-imaging
#14
Pascal S Kälin, Florian A Huber, Qeumars M Hamie, Lydia S Issler, Nadja A Farshad-Amacker, Erika J Ulbrich, Roman Guggenberger
BACKGROUND: Quantitative MRI allows assessment of shoulder rotator cuff (RC) muscles by Dixon MR sequences with calculation of fractional fat content (FF%) maps and diffusion tensor imaging (DTI) including tractography. PURPOSE: To compare FF% and DTI derived parameters among visually intact RC muscles, to compare 2D with 3D DTI measurements and to establish normative values. STUDY TYPE: Prospective. SUBJECTS: Forty patients aged >18 years undergoing shoulder MR arthrography were included...
October 6, 2018: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/30291649/prospective-evaluation-of-an-r2-method-for-assessing-liver-iron-concentration-lic-against-ferriscan-derivation-of-the-calibration-curve-and-characterization-of-the-nature-and-source-of-uncertainty-in-the-relationship
#15
Kartik S Jhaveri, Stephan A R Kannengiesser, Richard Ward, Kevin Kuo, Marshall S Sussman
BACKGROUND: FerriScan is the method-of-choice for noninvasive liver iron concentration (LIC) quantification. However, it has a number of drawbacks including cost and expediency. PURPOSE/HYPOTHESIS: To characterize an R2*-based MRI technique that may potentially be used as an alternative to FerriScan. This was accomplished through the derivation of a calibration curve that characterized the relationship between FerriScan-derived LIC and R2*. The nature and source of uncertainty in this curve were investigated...
October 6, 2018: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/30277274/3d-high-resolution-imaging-of-2-hydroxyglutarate-in-glioma-patients-using-drag-epsi-at-3t-in-vivo
#16
Zhongxu An, Vivek Tiwari, Jeannie Baxter, Michael Levy, Kimmo J Hatanpaa, Edward Pan, Elizabeth A Maher, Toral R Patel, Bruce E Mickey, Changho Choi
PURPOSE: To develop 3D high-resolution imaging of 2-hydroxyglutarate (2HG) at 3T in vivo. METHODS: Echo-planar spectroscopic imaging with dual-readout alternated-gradients (DRAG-EPSI), which was recently reported for 2D imaging of 2HG at 7T, was tested for 3D imaging of 2HG at 3T. The frequency drifts and acoustic noise induced by DRAG-EPSI were investigated in comparison with conventional EPSI. Four patients with IDH-mutant gliomas were enrolled for 3D imaging of 2HG and other metabolites...
September 14, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/30273963/a-circular-echo-planar-sequence-for-fast-volumetric-fmri
#17
Christoph Rettenmeier, Danilo Maziero, Yongxian Qian, V Andrew Stenger
PURPOSE: To demonstrate a circular EPI (CEPI) sequence as well as a generalized EPI reconstruction for fast fMRI with parallel imaging acceleration. METHODS: The CEPI acquisition was constructed using variable readout lengths and maximum ramp sampling as well as blipped-CAIPI z-gradient encoding for simultaneous multislice (SMS) and 3D volumetric imaging. A signal equation model with constant and linear phase terms was used to iteratively reconstruct images with low ghosting...
October 1, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/30272567/robust-selective-weighted-field-mapping-using-multi-echo-gradient-echo-based-mri
#18
Chemseddine Fatnassi, Habib Zaidi
In 3D gradient echo (GRE) and echo planar imaging (EPI), strong macroscopic field gradients are observed at air/tissue interfaces. The respective field gradients lead to an apparent increase in intravoxel dephasing, and, subsequently, to signal loss or image distortion. We propose an analytical approximation and a consequent method to compute low and high resolution field maps over all field map regimes (small and large echo spacing). A number of approaches which compute field maps from reconstructed phase data rely upon optimized linear least square fit and complex division approaches owing to the simplicity of their implementation...
October 1, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/30257059/multiple-point-magnetic-resonance-acoustic-radiation-force-imaging
#19
Henrik Odéen, Joshua de Bever, Lorne W Hofstetter, Dennis L Parker
PURPOSE: To implement and evaluate an efficient multiple-point MR acoustic radiation force imaging pulse sequence that can volumetrically measure tissue displacement and evaluate tissue stiffness using focused ultrasound (FUS) radiation force. METHODS: Bipolar motion-encoding gradients were added to a gradient-recalled echo segmented EPI pulse sequence with both 2D and 3D acquisition modes. Multiple FUS-ON images (FUS power > 0 W) were interleaved with a single FUS-OFF image (FUS power = 0 W) on the TR level, enabling simultaneous measurements of volumetric tissue displacement (by complex subtraction of the FUS-OFF image from the FUS-ON images) and proton resonance frequency shift MR thermometry (from the OFF image)...
September 26, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/30257041/three-dimensional-diffusion-imaging-with-spiral-encoded-navigators-from-stimulated-echoes-3d-dispense
#20
Qinwei Zhang, Bram F Coolen, Aart J Nederveen, Gustav J Strijkers
PURPOSE: To introduce a new method for motion-insensitive 3D multishot diffusion imaging using 3D spiral-encoded navigators from stimulated echoes (3D-DISPENSE). METHODS: The 3D-DISPENSE sequence contains a 3D stack-of-spiral navigator generated between the diffusion preparation and the turbo spin-echo image acquisition from the twin pathway of a stimulated echo. Unlike normal navigator methods, 3D-DISPENSE separates the navigator acquisition from the imaging readout without compromising the image SNR...
September 26, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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