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Echo Planar Imaging

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https://www.readbyqxmd.com/read/29148118/role-of-the-combination-of-fa-and-t2-parameters-as-a-new-diagnostic-method-in-therapeutic-evaluation-of-parkinson-s-disease
#1
Yuan Fang, Tao Zheng, Lanxiang Liu, Dawei Gao, Qinglei Shi, Yanchao Dong, Dan Du
BACKGROUND: Simple diffusion delivery (SDD) has attained good effects with only tiny amounts of drugs. Fractional anisotropy (FA) and relaxation time T2* that indicate the integrity of fiber tracts and iron concentration within brain tissue were used to evaluate the therapeutic effect of SDD. PURPOSE: To evaluate therapeutic effect of SDD in the Parkinson's disease (PD) rat model with FA and T2* parameters. STUDY TYPE: Prospective case-control animal study...
November 17, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/29141638/diffusion-weighted-imaging-of-the-brains-of-dogs-with-idiopathic-epilepsy
#2
Antje Hartmann, Steffen Sager, Klaus Failing, Marion Sparenberg, Martin J Schmidt
BACKGROUND: Idiopathic epilepsy is one of the most common neurological disorders in dogs. Unfortunately, up to 30% of dogs with idiopathic epilepsy show no improvement under antiepileptic drug treatment. Diffusion-weighted imaging is used in human medicine to identify epileptogenic foci in the brain to allow for more invasive treatments such as deep brain stimulation or surgical removal. The aim of this study was to ass the feasibility of interictal diffusion-weighted MRI in dogs and to evaluate the distribution of diffusion in the brains of dogs with idiopathic epilepsy (IE) and to compare these values to previously published values from healthy beagle dogs...
November 15, 2017: BMC Veterinary Research
https://www.readbyqxmd.com/read/29134353/scan-time-reduction-in-diffusion-weighted-imaging-of-the-pancreas-using-a-simultaneous-multislice-technique-with-different-acceleration-factors-how-fast-can-we-go
#3
Jana Taron, Petros Martirosian, Thomas Kuestner, Nina F Schwenzer, Ahmed Othman, Jakob Weiß, Mike Notohamiprodjo, Konstantin Nikolaou, Christina Schraml
OBJECTIVES: To investigate the feasibility of simultaneous multislice-accelerated diffusion-weighted imaging (sms-DWI) of the pancreas with different acceleration factors and its influence on image quality, acquisition time and apparent diffusion coefficients (ADCs) in comparison to conventional sequences. METHODS: DWI of the pancreas was performed at 1.5T in ten healthy volunteers and 20 patients with sms-accelerated echo-planar DWI using two different sms-acceleration factors of 2 and 3 (sms2/3-DWI)...
November 13, 2017: European Radiology
https://www.readbyqxmd.com/read/29122668/estimation-of-physiological-sources-of-nonlinearity-in-blood-oxygenation-level-dependent-contrast-signals
#4
Daehun Kang, Yul-Wan Sung, Satoshi Shioiri
Blood oxygenation level-dependent (BOLD) contrast appears through a variation in the transverse relaxation rate of magnetic resonance signals induced by neurovascular coupling and is known to have nonlinear characteristics along echo time (TE) due to the intra-vasculature. However, the physiological causes of this nonlinearity are unclear. We attempted to estimate the physiological information related to the nonlinearity of BOLD signals by using a two-compartment model. For this purpose, we used a multi-echo gradient-echo echo-planar imaging sequence and developed a computational method to estimate the physiological information from the TE-dependent BOLD signals...
November 6, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/29120867/quantifying-the-ultrastructure-of-carotid-arteries-using-high-resolution-micro-diffusion-tensor-imaging-comparison-of-intact-versus-open-cut-tissue
#5
Syed Salman Shahid, Robert T Gaul, Christian Kerskens, Vittoria Flamini, Caitríona Lally
Diffusion magnetic resonance imaging (dMRI) can provide insights into the microstructure of intact arterial tissue. The current study employed high magnetic field MRI to obtain ultra-high resolution dMRI at an isotropic voxel resolution of 117 µm(3) in less than 2 h of scan time. A parameter selective single shell (128 directions) diffusion-encoding scheme based on Stejskel-Tanner sequence with echo-planar imaging (EPI) readout was used. EPI segmentation was used to reduce the echo time (TE) and to minimise the susceptibility-induced artefacts...
November 9, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29116960/image-quality-and-geometric-distortion-of-modern-diffusion-weighted-imaging-sequences-in-magnetic-resonance-imaging-of-the-prostate
#6
Daniel Stocker, Andrei Manoliu, Anton S Becker, Borna K Barth, Daniel Nanz, Markus Klarhöfer, Olivio F Donati
PURPOSE: The aim of this study was to compare qualitative and quantitative image quality and geometric distortion of 4 magnetic resonance diffusion-weighted imaging (DWI) sequences of the prostate using comparable imaging parameters and similar acquisition times. METHODS AND MATERIALS: Axial T2-weighted turbo spin echo images and axial DWI echo-planar imaging (EPI) sequences, including single-shot spin-echo (ss-EPI), readout-segmented multishot (rs-EPI), selective excitation-reduced field of view (sTX-EPI), and prototype single-shot technique applying slice-specific shimming (iShim-EPI) sequences, were acquired at 3 T in 10 healthy volunteers (mean age, 26...
November 8, 2017: Investigative Radiology
https://www.readbyqxmd.com/read/29115686/inner-volume-echo-volumar-imaging-ivevi-for-robust-fetal-brain-imaging
#7
Rita G Nunes, Giulio Ferrazzi, Anthony N Price, Jana Hutter, Andreia S Gaspar, Mary A Rutherford, Joseph V Hajnal
PURPOSE: Fetal functional MRI studies using conventional 2-dimensional single-shot echo-planar imaging sequences may require discarding a large data fraction as a result of fetal and maternal motion. Increasing the temporal resolution using echo volumar imaging (EVI) could provide an effective alternative strategy. Echo volumar imaging was combined with inner volume (IV) imaging (IVEVI) to locally excite the fetal brain and acquire full 3-dimensional images, fast enough to freeze most fetal head motion...
November 8, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29112892/blipped-blipped-pure-phase-encoding-high-resolution-mri-with-low-amplitude-gradients
#8
Dan Xiao, Bruce J Balcom
MRI image resolution is proportional to the maximum k-space value, i.e. the temporal integral of the magnetic field gradient. High resolution imaging usually requires high gradient amplitudes and/or long spatial encoding times. Special gradient hardware is often required for high amplitudes and fast switching. We propose a high resolution imaging sequence that employs low amplitude gradients. This method was inspired by the previously proposed PEPI (π Echo Planar Imaging) sequence, which replaced EPI gradient reversals with multiple RF refocusing pulses...
October 31, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29112516/intravoxel-incoherent-motion-analysis-of-abdominal-organs-application-of-simultaneous-multislice-acquisition
#9
Valerie Doan Phi Van, Anton S Becker, Alexander Ciritsis, Caecilia S Reiner, Andreas Boss
PURPOSE: The aim of this study was to systematically evaluate the accuracy of quantitative intravoxel incoherent motion (IVIM) analysis of the upper abdomen applying simultaneous multislice (SMS) diffusion-weighted imaging (DWI) to reduce acquisition time. MATERIALS AND METHODS: Diffusion-weighted imaging of parenchymal abdominal organs was performed in 8 healthy volunteers at 3 T using a standard DWI sequence (acceleration factor 1 [AF1]) and an SMS-accelerated echo planar imaging sequence with acceleration factors 2 and 3 (AF2/AF3)...
November 6, 2017: Investigative Radiology
https://www.readbyqxmd.com/read/29106742/density-weighted-concentric-circle-trajectories-for-high-resolution-brain-magnetic-resonance-spectroscopic-imaging-at-7t
#10
Lukas Hingerl, Wolfgang Bogner, Philipp Moser, Michal Považan, Gilbert Hangel, Eva Heckova, Stephan Gruber, Siegfried Trattnig, Bernhard Strasser
PURPOSE: Full-slice magnetic resonance spectroscopic imaging at ≥7 T is especially vulnerable to lipid contaminations arising from regions close to the skull. This contamination can be mitigated by improving the point spread function via higher spatial resolution sampling and k-space filtering, but this prolongs scan times and reduces the signal-to-noise ratio (SNR) efficiency. Currently applied parallel imaging methods accelerate magnetic resonance spectroscopic imaging scans at 7T, but increase lipid artifacts and lower SNR-efficiency further...
November 6, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29103481/comparison-between-multi-shot-gradient-echo-epi-and-balanced-ssfp-in-unenhanced-3t-mra-of-thoracic-aorta-in-healthy-volunteers
#11
Yuji Iyama, Takeshi Nakaura, Yasunori Nagayama, Seitaro Oda, Daisuke Utsunomiya, Masafumi Kidoh, Hideaki Yuki, Kenichiro Hirata, Tomohiro Namimoto, Mika Kitajima, Kosuke Morita, Yoshinori Funama, Atsushi Takemura, Shinichi Tokuyasu, Tomoyuki Okuaki, Yasuyuki Yamashita
PURPOSE: The purpose of this study was to compare scan time and image quality between magnetic resonance angiography (MRA) of the thoracic aorta using a multi-shot gradient echo planar imaging (MSG-EPI) and MRA using balanced steady-state free precession (b-SSFP). MATERIALS AND METHODS: Healthy volunteers (n=17) underwent unenhanced thoracic aorta MRA using balanced steady-state free precession (b-SSFP) and MSG-EPI sequences on a 3T MRI. The acquisition time, total scan time, signal-to-noise ratio (SNR) of the thoracic aorta, and the coefficient of variation (CV) of thoracic aorta were compared with paired t-tests...
November 2017: European Journal of Radiology
https://www.readbyqxmd.com/read/29090483/a-1-minute-full-brain-mr-exam-using-a-multicontrast-epi-sequence
#12
Stefan Skare, Tim Sprenger, Ola Norbeck, Henric Rydén, Lars Blomberg, Enrico Avventi, Mathias Engström
PURPOSE: A new multicontrast echo-planar imaging (EPI)-based sequence is proposed for brain MRI, which can directly generate six MR contrasts (T1 -FLAIR, T2 -w, diffusion-weighted (DWI), apparent diffusion coefficient (ADC), T2*-w, T2 -FLAIR) in 1 min with full brain coverage. This could enable clinical MR clinical screening in similar time as a conventional CT exam but with more soft-tissue information. METHODS: Eleven sequence modules were created as dynamic building blocks for the sequence...
October 31, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29084089/value-of-t1-weighted-magnetic-resonance-imaging-in-cholesteatoma-detection
#13
Atsushi Fukuda, Shinya Morita, Taisuke Harada, Keishi Fujiwara, Kimiko Hoshino, Yuji Nakamaru, Akihiro Homma
OBJECTIVE: To reveal the usefulness of T1-weighted (T1W) imaging on diagnostic magnetic resonance (MR) imaging for cholesteatoma. STUDY DESIGN: A retrospective case review. SETTING: Tertiary referral center. PATIENTS: Fifty-three patients (57 ears) suspected to have cholesteatomas and treated (6-82 yr of age). INTERVENTION: Preoperative MR imaging, including non-echo planar (non-EP) diffusion-weighted (DW) and T1W imaging...
December 2017: Otology & Neurotology
https://www.readbyqxmd.com/read/29074632/improved-spatiotemporal-resolution-of-dynamic-susceptibility-contrast-perfusion-mri-in-brain-tumors-using-simultaneous-multi-slice-echo-planar-imaging
#14
A Chakhoyan, K Leu, W B Pope, T F Cloughesy, B M Ellingson
DSC perfusion MR imaging in brain tumors requires a trade-off between spatial and temporal resolution, resulting in less spatial coverage to meet the temporal resolution requirements for accurate relative CBV estimation. DSC-MR imaging could potentially benefit from the advantages associated with simultaneous multi-slice imaging, including increased spatiotemporal resolution. In the current article, we demonstrate how simultaneous multi-slice EPI can be used to improve DSC-MR imaging spatiotemporal resolution in patients with glioblastoma...
October 26, 2017: AJNR. American Journal of Neuroradiology
https://www.readbyqxmd.com/read/29044896/support-vector-machine-for-breast-cancer-classification-using-diffusion-weighted-mri-histogram-features-preliminary-study
#15
Igor Vidić, Liv Egnell, Neil P Jerome, Jose R Teruel, Torill E Sjøbakk, Agnes Østlie, Hans E Fjøsne, Tone F Bathen, Pål Erik Goa
BACKGROUND: Diffusion-weighted MRI (DWI) is currently one of the fastest developing MRI-based techniques in oncology. Histogram properties from model fitting of DWI are useful features for differentiation of lesions, and classification can potentially be improved by machine learning. PURPOSE: To evaluate classification of malignant and benign tumors and breast cancer subtypes using support vector machine (SVM). STUDY TYPE: Prospective. SUBJECTS: Fifty-one patients with benign (n = 23) and malignant (n = 28) breast tumors (26 ER+, whereof six were HER2+)...
October 16, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/29044762/density-weighted-concentric-rings-k-space-trajectory-for-1-h-magnetic-resonance-spectroscopic-imaging-at-7%C3%A2-t
#16
Mark Chiew, Wenwen Jiang, Brian Burns, Peder Larson, Adam Steel, Peter Jezzard, M Albert Thomas, Uzay E Emir
It has been shown that density-weighted (DW) k-space sampling with spiral and conventional phase encoding trajectories reduces spatial side lobes in magnetic resonance spectroscopic imaging (MRSI). In this study, we propose a new concentric ring trajectory (CRT) for DW-MRSI that samples k-space with a density that is proportional to a spatial, isotropic Hanning window. The properties of two different DW-CRTs were compared against a radially equidistant (RE) CRT and an echo-planar spectroscopic imaging (EPSI) trajectory in simulations, phantoms and in vivo experiments...
October 18, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/29034502/ghost-reduction-in-echo-planar-imaging-by-joint-reconstruction-of-images-and-line-to-line-delays-and-phase-errors
#17
Julianna D Ianni, E Brian Welch, William A Grissom
PURPOSE: To correct line-to-line delays and phase errors in echo-planar imaging (EPI). THEORY AND METHODS: EPI-trajectory auto-corrected image reconstruction (EPI-TrACR) is an iterative maximum-likelihood technique that exploits data redundancy provided by multiple receive coils between nearby lines of k-space to determine and correct line-to-line trajectory delays and phase errors that cause ghosting artifacts. EPI-TrACR was efficiently implemented using a segmented FFT and was applied to in vivo brain data acquired at 7 T across acceleration (1×-4×) and multishot factors (1-4 shots), and in a time series...
October 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28987676/value-of-diffusion-tensor-imaging-in-differentiating-malignant-from-benign-parotid-gland-tumors
#18
Koji Takumi, Yoshihiko Fukukura, Hiroto Hakamada, Junichi Ideue, Yuichi Kumagae, Takashi Yoshiura
PURPOSE: To evaluate whether diffusion tensor imaging (DTI) can be used to differentiate malignant parotid gland tumors from the benign ones. MATERIALS AND METHODS: The study population comprised 59 parotid gland tumors (24 Warthin's tumors, 19 pleomorphic adenomas, seven other benign tumors, and nine malignant tumors). Single-shot echo-planar DTI was performed with motion-probing gradients along 30 noncollinear directions (b=1000s/mm(2)) at 3.0T. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values for benign and malignant tumors were compared using the Mann-Whitney U test...
October 2017: European Journal of Radiology
https://www.readbyqxmd.com/read/28986646/differentiation-of-benign-and-malignant-solid-pancreatic-masses-using-magnetic-resonance-elastography-with-spin-echo-echo-planar-imaging-and-three-dimensional-inversion-reconstruction-a-prospective-study
#19
Yu Shi, Feng Gao, Yue Li, Shengzhen Tao, Bing Yu, Zaiyi Liu, Yanqing Liu, Kevin J Glaser, Richard L Ehman, Qiyong Guo
OBJECTIVES: To determine the diagnostic performance of MR elastography (MRE) and compare it with serum CA19-9 in differentiating malignant from benign pancreatic masses, with emphasis on differentiating between pancreatic ductal adenocarcinoma (PDAC) and mass-forming pancreatitis (MFP). METHODS: We performed a prospective, consecutive, 24-month study in 85 patients with solid pancreatic masses confirmed by histopathologic examinations. The mass stiffness and stiffness ratio (calculated as the ratio of mass stiffness to the parenchymal stiffness) were assessed...
October 6, 2017: European Radiology
https://www.readbyqxmd.com/read/28983969/a-high-performance-gradient-insert-for-rapid-and-short-t2-imaging-at-full-duty-cycle
#20
Markus Weiger, Johan Overweg, Manuela Barbara Rösler, Romain Froidevaux, Franciszek Hennel, Bertram Jakob Wilm, Alexander Penn, Urs Sturzenegger, Wout Schuth, Menno Mathlener, Martino Borgo, Peter Börnert, Christoph Leussler, Roger Luechinger, Benjamin Emanuel Dietrich, Jonas Reber, David Otto Brunner, Thomas Schmid, Laetitia Vionnet, Klaas P Pruessmann
PURPOSE: The goal of this study was to devise a gradient system for MRI in humans that reconciles cutting-edge gradient strength with rapid switching and brings up the duty cycle to 100% at full continuous amplitude. Aiming to advance neuroimaging and short-T2 techniques, the hardware design focused on the head and the extremities as target anatomies. METHODS: A boundary element method with minimization of power dissipation and stored magnetic energy was used to design anatomy-targeted gradient coils with maximally relaxed geometry constraints...
October 5, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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