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Echo Planar Imaging

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https://www.readbyqxmd.com/read/28926154/brain-functional-connectome-abnormalities-in-als-are-associated-with-disability-and-cortical-hyperexcitability
#1
Nimeshan Geevasinga, Mayuresh S Korgaonkar, Parvathi Menon, Mehdi Van den Bos, Lavier Gomes, Sheryl Foster, Matthew C Kiernan, Steve Vucic
OBJECTIVE: The present study utilized a multimodality approach encompassing connectome network combined with brain volume analysis, and assessment of cortical excitability to provide novel insights into amyotrophic lateral sclerosis (ALS) pathogenesis. METHODS: Magnetic resonance images (MRI) were acquired using a 3.0 Tesla GE Signa HDx scanner, using an 8-channel head coil. MR images for the resting state scan were acquired using echo planar imaging MR sequence, acquiring 40 contiguous axial/oblique slices...
September 19, 2017: European Journal of Neurology: the Official Journal of the European Federation of Neurological Societies
https://www.readbyqxmd.com/read/28921633/spontaneous-mechanical-and-electrical-activities-of-human-calf-musculature-at-rest-assessed-by-repetitive-single-shot-diffusion-weighted-mri-and-simultaneous-surface-electromyography
#2
Martin Schwartz, Günter Steidle, Petros Martirosian, Ander Ramos-Murguialday, Hubert Preißl, Alto Stemmer, Bin Yang, Fritz Schick
PURPOSE: Assessment of temporal and spatial relations between spontaneous mechanical activities in musculature (SMAM) at rest as revealed by diffusion-weighted imaging (DWI) and electrical muscular activities in surface EMG (sEMG). Potential influences of static and radiofrequency magnetic fields on muscular activity on sEMG measurements at rest were examined systematically. METHODS: Series of diffusion-weighted stimulated echo planar imaging were recorded with concurrent sEMG measurements...
September 17, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28921614/an-optimized-framework-for-quantitative-magnetization-transfer-imaging-of-the-cervical-spinal-cord-in-vivo
#3
Marco Battiston, Francesco Grussu, Andrada Ianus, Torben Schneider, Ferran Prados, James Fairney, Sebastien Ourselin, Daniel C Alexander, Mara Cercignani, Claudia A M Gandini Wheeler-Kingshott, Rebecca S Samson
PURPOSE: To develop a framework to fully characterize quantitative magnetization transfer indices in the human cervical cord in vivo within a clinically feasible time. METHODS: A dedicated spinal cord imaging protocol for quantitative magnetization transfer was developed using a reduced field-of-view approach with echo planar imaging (EPI) readout. Sequence parameters were optimized based in the Cramer-Rao-lower bound. Quantitative model parameters (i.e., bound pool fraction, free and bound pool transverse relaxation times [ T2F, T2B], and forward exchange rate [kFB ]) were estimated implementing a numerical model capable of dealing with the novelties of the sequence adopted...
September 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28913838/simultaneous-acquisition-of-perfusion-image-and-dynamic-mr-angiography-using-time-encoded-pseudo-continuous-asl
#4
Yuriko Suzuki, Michael Helle, Peter Koken, Marc Van Cauteren, Matthias J P van Osch
PURPOSE: Both dynamic magnetic resonance angiography (4D-MRA) and perfusion imaging can be acquired by using arterial spin labeling (ASL). While 4D-MRA highlights large vessel pathology, such as stenosis or collateral blood flow patterns, perfusion imaging provides information on the microvascular status. Therefore, a complete picture of the cerebral hemodynamic condition could be obtained by combining the two techniques. Here, we propose a novel technique for simultaneous acquisition of 4D-MRA and perfusion imaging using time-encoded pseudo-continuous arterial spin labeling...
September 14, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28905474/steer-prop-a-grase-propeller-sequence-with-interecho-steering-gradient-pulses
#5
Girish Srinivasan, Novena Rangwala, Xiaohong Joe Zhou
PURPOSE: This study demonstrates a novel PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction) pulse sequence, termed Steer-PROP, based on gradient and spin echo (GRASE), to reduce the imaging times and address phase errors inherent to GRASE. The study also illustrates the feasibility of using Steer-PROP as an alternative to single-shot echo planar imaging (SS-EPI) to produce distortion-free diffusion images in all imaging planes. METHODS: Steer-PROP uses a series of blip gradient pulses to produce N (N = 3-5) adjacent k-space blades in each repetition time, where N is the number of gradient echoes in a GRASE sequence...
September 14, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28905414/high-spatio-temporal-resolution-in-functional-mri-with-3d-echo-planar-imaging-using-cylindrical-excitation-and-a-caipirinha-undersampling-pattern
#6
Wietske van der Zwaag, Olivier Reynaud, Mayur Narsude, Daniel Gallichan, José P Marques
PURPOSE: The combination of 3D echo planar imaging (3D-EPI) with a 2D-CAIPIRINHA undersampling scheme provides high flexibility in the optimization for spatial or temporal resolution. This flexibility can be increased further with the addition of a cylindrical excitation pulse, which exclusively excites the brain regions of interest. Here, 3D-EPI was combined with a 2D radiofrequency pulse to reduce the brain area from which signal is generated, and hence, allowing either reduction of the field of view or reduction of parallel imaging noise amplification...
September 14, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28893651/obstructive-sleep-apnea-is-associated-with-altered-midbrain-chemical-concentrations
#7
Paul M Macey, Manoj K Sarma, Janani P Prasad, Jennifer A Ogren, Ravi Aysola, Ronald M Harper, M Albert Thomas
Obstructive sleep apnea (OSA) is accompanied by altered structure and function in cortical, limbic, brainstem, and cerebellar regions. The midbrain is relatively unexamined, but contains many integrative nuclei which mediate physiological functions that are disrupted in OSA. We therefore assessed the chemistry of the midbrain in OSA in this exploratory study. We used a recently-developed accelerated 2D magnetic resonance spectroscopy (2D-MRS) technique, compressed sensing-based 4D echo-planar J-resolved spectroscopic imaging (4D-EP-JRESI), to measure metabolites in the midbrain of 14 OSA (mean age±SD:54...
September 8, 2017: Neuroscience
https://www.readbyqxmd.com/read/28884957/long-term-sequelae-of-hippocampal-lesions-in-patients-with-transient-global-amnesia-a-multiparametric-mri-study
#8
Xiaochuan Wang, Ran Zhang, Wenping Wei, Haibo Jiang, Zhongming Gao, Jianzhong Lin, Jiaxing Zhang
BACKGROUND: MRI signal diffusion-weighted imaging (DWI) hyperintensity in the hippocampus in patients with transient global amnesia (TGA) are resolved within several days after the onset of TGA. PURPOSE: To use multiparametric MRI to unravel the sequelae of TGA. STUDY TYPE: A prospective longitudinal study. POPULATION: Eight TGA patients. FIELD STRENGTH/SEQUENCE: A 3.0T Siemens Tim Trio MRI scanner with T1 -weighted MPRAGE, diffusion-weighted echo planar imaging, and multiecho gradient-recalled echo sequences...
September 7, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28867670/reduced-distortion-artifact-whole-brain-cbf-mapping-using-blip-reversed-non-segmented-3d-echo-planar-imaging-with-pseudo-continuous-arterial-spin-labeling
#9
Neville D Gai, Yi Yu Chou, Dzung Pham, John A Butman
PURPOSE: To implement and evaluate interleaved blip-up, blip-down, non-segmented 3D echo planar imaging (EPI) with pseudo-continuous arterial spin labeling (pCASL) and post-processing for reduced susceptibility artifact cerebral blood flow (CBF) maps. MATERIALS AND METHODS: 3D EPI non-segmented acquisition with a pCASL labeling sequence was modified to include alternating k-space coverage along phase encoding direction (referred to as "blip-reversed") for alternating dynamic acquisitions of control and label pairs...
September 1, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28864026/cardiac-cycle-induced-epi-time-series-fluctuations-in-the-brain-their-temporal-shifts-inflow-effects-and-t2-%C3%A2-fluctuations
#10
Olivia Viessmann, Harald E Möller, Peter Jezzard
The cardiac-induced arterial pressure wave causes changes in cerebral blood flow velocities and volumes that affect the signals in echo-planar imaging (EPI). Using single-echo EPI time series data, acquired fast enough to unalias the cardiac frequency, we found that the cardiac cycle-induced signal fluctuations are delayed differentially in different brain regions. When referenced to the time series in larger arterial structures, the cortical voxels are only minimally shifted but significant shifts are observed in subcortical areas...
August 31, 2017: NeuroImage
https://www.readbyqxmd.com/read/28862352/geometric-distortion-correction-in-prostate-diffusion-weighted-mri-and-its-effect-on-quantitative-apparent-diffusion-coefficient-analysis
#11
Gabriel Nketiah, Kirsten M Selnaes, Elise Sandsmark, Jose R Teruel, Brage Krüger-Stokke, Helena Bertilsson, Tone F Bathen, Mattijs Elschot
PURPOSE: To evaluate the effect of correction for B0 inhomogeneity-induced geometric distortion in echo-planar diffusion-weighted imaging on quantitative apparent diffusion coefficient (ADC) analysis in multiparametric prostate MRI. METHODS: Geometric distortion correction was performed in echo-planar diffusion-weighted images (b = 0, 50, 400, 800 s/mm(2) ) of 28 patients, using two B0 scans with opposing phase-encoding polarities. Histology-matched tumor and healthy tissue volumes of interest delineated on T2 -weighted images were mapped to the nondistortion-corrected and distortion-corrected data sets by resampling with and without spatial coregistration...
September 1, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28845547/optimized-inversion-time-schedules-for-quantitative-t1-measurements-based-on-high-resolution-multi-inversion-epi
#12
Ouri Cohen, Jonathan R Polimeni
PURPOSE: Demonstrate an optimized multi-inversion echo-planar imaging technique to accelerate quantitative T1 mapping by judicious selection of inversion times for each slice. METHODS: Slice ordering is optimized to maximize discrimination between tissues with different T1 values. The optimized slice orderings are tested in the International Society for Magnetic Resonance in Medicine/National Institute of Standards and Technology phantom and compared with an unoptimized 21-measurement acquisition...
August 27, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28833542/echo-planar-spectroscopic-imaging-with-dual-readout-alternated-gradients-drag-epsi-at-7-t-application-for-2-hydroxyglutarate-imaging-in-glioma-patients
#13
Zhongxu An, Vivek Tiwari, Sandeep K Ganji, Jeannie Baxter, Michael Levy, Marco C Pinho, Edward Pan, Elizabeth A Maher, Toral R Patel, Bruce E Mickey, Changho Choi
PURPOSE: To develop echo-planar spectroscopic imaging (EPSI) with large spectral width and accomplish high-resolution imaging of 2-hydroxyglutarate (2HG) at 7 T. METHODS: We designed a new EPSI readout scheme at 7 T. Data were recorded with dual-readout alternated gradients and combined according to the gradient polarity. Following validation of its performance in phantoms, the new readout scheme, together with previously reported 2HG-optimized magnetic resonance spectroscopy (point-resolved spectroscopy echo time of 78 ms), was used for time-efficient and high-resolution imaging of 2HG and other metabolites in five glioma patients before treatment...
August 22, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28806768/design-and-fabrication-of-a-realistic-anthropomorphic-heterogeneous-head-phantom-for-mr-purposes
#14
Sossena Wood, Narayanan Krishnamurthy, Tales Santini, Shailesh Raval, Nadim Farhat, John Andy Holmes, Tamer S Ibrahim
OBJECTIVE: The purpose of this study is to design an anthropomorphic heterogeneous head phantom that can be used for MRI and other electromagnetic applications. MATERIALS AND METHODS: An eight compartment, physical anthropomorphic head phantom was developed from a 3T MRI dataset of a healthy male. The designed phantom was successfully built and preliminarily evaluated through an application that involves electromagnetic-tissue interactions: MRI (due to it being an available resource)...
2017: PloS One
https://www.readbyqxmd.com/read/28806322/reduced-field-of-view-diffusion-weighted-magnetic-resonance-imaging-of-the-prostate-at-3-tesla-comparison-with-standard-echo-planar-imaging-technique-for-image-quality-and-tumor-assessment
#15
Tsutomu Tamada, Justin M Ream, Ankur M Doshi, Samir S Taneja, Andrew B Rosenkrantz
OBJECTIVE: The purpose of this study was to compare image quality and tumor assessment at prostate magnetic resonance imaging (MRI) between reduced field-of-view diffusion-weighted imaging (rFOV-DWI) and standard DWI (st-DWI). METHODS: A total of 49 patients undergoing prostate MRI and MRI/ultrasound fusion-targeted biopsy were included. Examinations included st-DWI (field of view [FOV], 200 × 200 mm) and rFOV-DWI (FOV, 140 × 64 mm) using a 2-dimensional (2D) spatially-selective radiofrequency pulse and parallel transmission...
August 12, 2017: Journal of Computer Assisted Tomography
https://www.readbyqxmd.com/read/28804779/language-mapping-using-t2-prepared-bold-functional-mri-in-the-presence-of-large-susceptibility-artifacts-initial-results-in-patients-with-brain-tumor-and-epilepsy
#16
Jun Hua, Xinyuan Miao, Shruti Agarwal, Chetan Bettegowda, Alfredo Quiñones-Hinojosa, John Laterra, Peter C M Van Zijl, James J Pekar, Jay J Pillai
At present, presurgical functional mapping is the most prevalent clinical application of functional magnetic resonance imaging (fMRI). Signal dropouts and distortions caused by susceptibility effects in the current standard echo planar imaging (EPI)-based fMRI images are well-known problems and pose a major hurdle for the application of fMRI in several brain regions, many of which are related to language mapping in presurgical planning. Such artifacts are particularly problematic in patients with previous surgical resection cavities, craniotomy hardware, hemorrhage, and vascular malformation...
June 2017: Tomography: a Journal for Imaging Research
https://www.readbyqxmd.com/read/28801939/assessment-of-advanced-hepatic-mr-elastography-methods-for-susceptibility-artifact-suppression-in-clinical-patients
#17
Jin Wang, Kevin J Glaser, Tianhui Zhang, Qungang Shan, Bingjun He, Jun Chen, Meng Yin, Bogdan Dzyubak, Jennifer L Kugel, Scott A Kruse, Roger C Grimm, Sudhakar K Venkatesh, Richard L Ehman
PURPOSE: To assess the success rate, image quality, and the ability to stage liver fibrosis of a standard 2D gradient-recalled echo (GRE) and four different spin-echo (SE) magnetic resonance elastography (MRE) sequences in patients with different liver iron concentrations. MATERIALS AND METHODS: A total of 332 patients who underwent 3T MRE examinations that included liver fat and iron quantification were enrolled, including 136 patients with all five MRE techniques...
August 11, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28799090/prostate-cancer-detection-among-readers-with-different-degree-of-experience-using-ultra-high-b-value-diffusion-weighted-imaging-is-a-non-contrast-protocol-sufficient-to-detect-significant-cancer
#18
D Hausmann, N Aksöz, J von Hardenberg, T Martini, N Westhoff, S Buettner, S O Schoenberg, P Riffel
AIM: To evaluate the accuracy of a T2-weighted (T2w) - and a parallel transmit zoomed b = 2000 s/mm2 (b2000) - diffusion-weighted imaging sequence among three readers with different degrees of experience for prostate cancer (Pca) detection. METHODS: Ninety-three patients with suspected Pca were enrolled. For b2000 a two-dimensional spatially-selective RF pulse using an echo-planar transmit trajectory was applied, and the field of view (FOV) was reduced to one-third...
August 10, 2017: European Radiology
https://www.readbyqxmd.com/read/28797739/mb-swift-functional-mri-during-deep-brain-stimulation-in-rats
#19
Lauri J Lehto, Djaudat Idiyatullin, Jinjin Zhang, Lynn Utecht, Gregor Adriany, Michael Garwood, Olli Gröhn, Shalom Michaeli, Silvia Mangia
Recently introduced 3D radial MRI pulse sequence entitled Multi-Band SWeep Imaging with Fourier Transformation (MB-SWIFT) having virtually zero acquisition delay was used to obtain functional MRI (fMRI) contrast in rat's brain at 9.4 T during deep brain stimulation (DBS). The results demonstrate that MB-SWIFT allows functional images free of susceptibility artifacts, and provides an excellent fMRI activation contrast in the brain. Flip angle dependence of the MB-SWIFT fMRI signal and elimination of the fMRI contrast while using saturation bands, indicate a blood flow origin of the observed fMRI contrast...
August 7, 2017: NeuroImage
https://www.readbyqxmd.com/read/28796443/relative-cerebral-blood-volume-is-a-potential-biomarker-in-late-delayed-radiation-induced-brain-injury
#20
Ying Xie, Haiwei Huang, Junjie Guo, Dongxiao Zhou
PURPOSE: To assess whether relative cerebral blood volume (rCBV) can provide information to reliably evaluate the stages of late delayed radiation-induced brain injury. MATERIALS AND METHODS: Forty patients diagnosed with late delayed radiation-induced brain injury were enrolled. The patients were examined using a 1.5T magnetic resonance imaging (MRI) system equipped with an 8-channel head coil. An echo planar imaging (EPI) sequence was used in perfusion-weighted imaging (PWI)...
August 10, 2017: Journal of Magnetic Resonance Imaging: JMRI
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