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Echo planar

Nobuyuki Kosaka, Yasuhiro Fujiwara, Tetsuji Kurokawa, Tsuyoshi Matsuda, Masayuki Kanamoto, Naoyuki Takei, Kenji Takata, Jin Takahashi, Yoshio Yoshida, Hirohiko Kimura
OBJECTIVES: We evaluated the vascularity of retained products of conception (RPOC) using arterial spin-labeling magnetic resonance imaging (ASL-MRI) to clarify the clinical feasibility of this approach. MATERIALS AND METHODS: A pulsed-continuous ASL sequence with echo-planar imaging (EPI) acquisitions was used. Ten consecutive patients with RPOC were enrolled. All ASL images were evaluated visually and semiquantitatively and compared with the findings of Doppler ultrasound (US) and dynamic contrast-enhanced MRI (DCE-MRI)...
March 16, 2018: Magma
Naoki Ohno, Tosiaki Miyati, Shuto Suzuki, Hirohito Kan, Toshitaka Aoki, Yoshitaka Nakamura, Yuki Hiramatsu, Satoshi Kobayashi, Toshifumi Gabata
PURPOSE: To suppress olefinic signals and enable simultaneous and quantitative estimation of multiple functional parameters associated with water and lipid, we investigated a modified method using chemical shift displacement and recovery-based separation of lipid tissue (SPLIT) involving acquisitions with different inversion times (TIs), echo times (TEs), and b-values. MATERIALS AND METHODS: Single-shot diffusion echo-planar imaging (SSD-EPI) with multiple b-values (0-3000 s/mm2 ) was performed without fat suppression to separate water and lipid images using the chemical shift displacement of lipid signals in the phase-encoding direction...
March 12, 2018: Magnetic Resonance Imaging
Bei-Bei Wu, Ye Ma, Lei Xie, Jin-Zhuang Huang, Zong-Bo Sun, Zhi-Duo Hou, Rui-Wei Guo, Zhi-Rong Lin, Shou-Xing Duan, Shan-Shan Zhao, Yao-Xie, Dan-Miao Sun, Chun-Min Zhu, Shu-Hua Ma
BACKGROUND: Systemic lupus erythematosus (SLE) is associated with cognitive deficit but the exact neural mechanisms remain unclear. PURPOSE: To explore sequential brain activities using functional magnetic resonance imaging (fMRI) during the performance of a decision-making task, and to determine whether serum or clinical markers can reflect the involvement of the brain in SLE. SUBJECTS: Sixteen female SLE patients without overt clinical neuropsychiatric symptoms and 16 healthy controls were included...
March 14, 2018: Journal of Magnetic Resonance Imaging: JMRI
Lu-Ping Li, Jon Thacker, Wei Li, Huan Tan, Chi Wang, Orly Kohn, Stuart Sprague, Pottumarthi Prasad
BACKGROUND: Identification of patients with progressive chronic kidney disease (CKD) and those likely to respond to candidate therapeutics is urgently needed. Functional MRI measurements have shown promise. However, knowledge about the consistency of the measurements is essential to conduct longitudinal studies. PURPOSE/HYPOTHESIS: To investigate the consistency of repeated functional MRI measurements in healthy subjects. STUDY TYPE: Prospective, longitudinal study...
March 8, 2018: Journal of Magnetic Resonance Imaging: JMRI
Hyunjo Jeong, Shuzeng Zhang, Xiongbing Li
The practical implementation of nonlinear ultrasonic technique has been limited to the through-transmission setup for measuring the second harmonic component induced by the nonlinearity or microstructural changes of test material. A more practical technique such as the pulse-echo testing has been ruled out because a traction-free reflecting boundary destructively alters the nonlinear generation process. A focusing acoustic beam or rigid boundary condition was often employed for biomedical imaging and fluid nonlinearity in the pulse-echo inspection...
February 23, 2018: Ultrasonics
Máté Kiss, Petra Hermann, Zoltán Vidnyánszky, Viktor Gál
The original version of this article contained a mistake. The correct Affiliation 2 is Semmelweis University, János Szentágothai PhD School, MR Research Centre, Balassa Street 6, Budapest 1083, Hungary.
March 3, 2018: Neuroradiology
Elvis Dohmatob, Gael Varoquaux, Bertrand Thirion
In Echo-Planar Imaging (EPI)-based Magnetic Resonance Imaging (MRI), inter-subject registration typically uses the subject's T1-weighted (T1w) anatomical image to learn deformations of the subject's brain onto a template. The estimated deformation fields are then applied to the subject's EPI scans (functional or diffusion-weighted images) to warp the latter to a template space. Historically, such indirect T1w-based registration was motivated by the lack of clear anatomical details in low-resolution EPI images: a direct registration of the EPI scans to template space would be futile...
2018: Frontiers in Neuroscience
Ka-Loh Li, Daniel Lewis, Alan Jackson, Sha Zhao, Xiaoping Zhu
BACKGROUND: Previous studies have measured cerebral blood flow (CBF) with DSC-MRI using an "early time points" (ET) method based on microsphere theory. PURPOSE: To develop and assess a new ET method for absolute CBF estimation using low-dose high-temporal (LDHT) T1W-DCE-MRI. STUDY TYPE: Retrospective cohort study. SUBJECTS: Seven patients with sporadic vestibular schwannoma (VS) who underwent test-retest imaging; one patient with glioblastoma multiforme (GBM) imaged pretreatment; and 12 neurofibromatosis type 2 (NF2) patients undergoing bevacizumab treatment, imaged pre- and 90 days posttreatment...
February 23, 2018: Journal of Magnetic Resonance Imaging: JMRI
Felix Schyboll, Uwe Jaekel, Bernd Weber, Heiko Neeb
OBJECTIVE: Recent MRI studies have shown that the orientation of nerve fibres relative to the main magnetic field affects the R2 *(= 1/T2 *) relaxation rate in white matter (WM) structures. The underlying physical causes have been discussed in several studies but are still not completely understood. However, understanding these effects in detail is of great importance since this might serve as a basis for the development of new diagnostic tools and/or improve quantitative susceptibility mapping techniques...
February 20, 2018: Magma
Yuuki Yoshimura, Masahiro Kuroda, Irfan Sugiantoc, Babatunde O Bamgbosec, Kanae Miyahara, Yuichi Ohmura, Akira Kurozumi, Toshi Matsushita, Seiichiro Ohno, Susumu Kanazawa, Junichi Asaumi
Readout-segmented echo-planar imaging (RESOLVE) is a multi-shot echo-planar imaging (EPI) modality with k-space segmented in the readout direction. We investigated whether RESOLVE decreases the distortion and artifact in the phase direction and increases the signal-to-noise ratio (SNR) in phantoms image taken with 3-tesla (3T) MRI versus conventional EPI. We used a physiological saline phantom and subtraction mapping and observed that RESOLVE's SNR was higher than EPI's. Using RESOLVE, the combination of a special-purpose coil and a large-loop coil had a higher SNR compared to using only a head/neck coil...
February 2018: Acta Medica Okayama
Richard Nauber, Lars Büttner, Kerstin Eckert, Jochen Fröhlich, Jürgen Czarske, Sascha Heitkam
The flow field of moving foams is relevant for basic research and for the optimization of industrial processes such as froth flotation. However, no adequate measurement technique exists for the local velocity distribution inside the foam bulk. We have investigated the ultrasound Doppler velocimetry (UDV), providing the first two-dimensional, non-invasive velocity measurement technique with an adequate spatial (10mm) and temporal resolution (2.5Hz) that is applicable to medium scale foam flows. The measurement object is dry aqueous foam flowing upward in a rectangular channel...
January 2018: Physical Review. E
E S Beck, P Sati, V Sethi, T Kober, B Dewey, P Bhargava, G Nair, I C Cortese, D S Reich
BACKGROUND AND PURPOSE: Cortical lesions are common and often extensive in multiple sclerosis but are difficult to visualize by MRI, leaving important questions about their clinical implications and response to therapy unanswered. Our aim was to determine whether cortical lesions are better visualized using magnetization prepared 2 rapid acquisition gradient echoes (MP2RAGE) than T2*-weighted imaging on 7T MR imaging. MATERIALS AND METHODS: Brain MR imaging using T1-weighted MP2RAGE at 500-μm isotropic resolution, T2*-weighted gradient-echo, and T2*-weighted segmented echo-planar imaging sequences were collected for 13 patients with MS and 5 age-matched neurologically healthy controls on a 7T research system...
February 8, 2018: AJNR. American Journal of Neuroradiology
Jose R Teruel, Joshua M Kuperman, Anders M Dale, Nathan S White
BACKGROUND: Subject motion is known to produce spurious covariance among time-series in functional connectivity that has been reported to induce distance-dependent spurious correlations. PURPOSE: To present a feasibility study for applying the extended Kalman filter (EKF) framework for high temporal resolution motion correction of resting state functional MRI (rs-fMRI) series using each simultaneous multi-slice (SMS) echo planar imaging (EPI) shot as its own navigator...
February 13, 2018: Journal of Magnetic Resonance Imaging: JMRI
Ruibin Li, Guangyao Wu, Rui Wang
The aim of the present study was to investigate the significance and values of 3.0T diffusion weighted imaging (DWI) to differentially diagnose benign and malignant space-occupying liver lesions. A total of 91 patients with liver space-occupying lesions (145 lesions) were admitted into Zhongnan Hospital of Wuhan University (Wuhan, China) from November 2015 to May 2016. Routine scanning, DWI and high-resolution T2-weighted imaging using spin-echo echo-planar imaging were performed on all patients, to compare the apparent diffusion coefficient (ADC) values of three regions of interest in lesions with normal liver tissue...
February 2018: Oncology Letters
Olivier Chevallier, Nan Zhou, Jian He, Romaric Loffroy, Yì Xiáng J Wáng
Background It has been reported that intravoxel incoherent motion (IVIM) diffusion magnetic resonance imaging (MRI) scan-rescan reproducibility is unsatisfactory. Purpose To study IVIM MRI parameter reproducibility for liver parenchyma after the removal of motion-contaminated and/or poorly fitted image data. Material and Methods Eighteen healthy volunteers had liver scans twice in the same session to assess scan-rescan repeatability, and again in another session after an average interval of 13 days to assess reproducibility...
January 1, 2018: Acta Radiologica
Uten Yarach, Yi-Hang Tung, Kawin Setsompop, Myung-Ho In, Itthi Chatnuntawech, Renat Yakupov, Frank Godenschweger, Oliver Speck
PURPOSE: To develop a reconstruction pipeline that intrinsically accounts for both simultaneous multislice echo planar imaging (SMS-EPI) reconstruction and dynamic slice-specific Nyquist ghosting correction in time-series data. METHODS: After 1D slice-group average phase correction, the separate polarity (i.e., even and odd echoes) SMS-EPI data were unaliased by slice GeneRalized Autocalibrating Partial Parallel Acquisition. Both the slice-unaliased even and odd echoes were jointly reconstructed using a model-based framework, extended for SMS-EPI reconstruction that estimates a 2D self-phase map, corrects dynamic slice-specific phase errors, and combines data from all coils and echoes to obtain the final images...
February 9, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Viktor Pfaffenrot, Sascha Brunheim, Stefan H G Rietsch, Peter J Koopmans, Thomas M Ernst, Oliver Kraff, Stephan Orzada, Harald H Quick
PURPOSE: To design and evaluate an 8/15-channel transmit/receive (Tx/Rx) head-neck RF coil combination with region-specific B1+ shimming for whole-brain MRI with focus on improved functional MRI of the cerebellum at 7 T. METHODS: An 8-channel transceiver RF head coil was combined with a 7-channel receive-only array. The noise parameters and acceleration capabilities of this 8Tx/15Rx coil setup were compared with a commercially available 1Tx/32Rx RF head coil. Region-specific 8-channel B1+ shimming was applied when using the 8Tx/15Rx RF coil...
February 9, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Armin Rund, Christoph Stefan Aigner, Karl Kunisch, Rudolf Stollberger
PURPOSE: Joint design of minimum duration RF pulses and slice-selective gradient shapes for MRI via time optimal control with strict physical constraints, and its application to simultaneous multislice imaging. THEORY AND METHODS: The minimization of the pulse duration is cast as a time optimal control problem with inequality constraints describing the refocusing quality and physical constraints. It is solved with a bilevel method, where the pulse length is minimized in the upper level, and the constraints are satisfied in the lower level...
February 9, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Achim Seeger, Maximilian Schulze, Frank Schuettauf, Ulrike Ernemann, Till-Karsten Hauser
Objective The objective of this article is to evaluate advanced techniques of diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) measurements of the optic nerve in patients with optic neuritis. Methods In this prospective and institutional review board-approved trial, we examined 15 patients with acute visual loss and clinical signs of optic neuritis including thin-slice multi-shot segmented readout of long variable echo trains (rs-EPI, RESOLVE) DWI and reduced field-of view DWI using a parallel transmit system (rFOV-EPI)...
January 1, 2018: Neuroradiology Journal
Ahmed Abdel Khalek Abdel Razek
PURPOSE: To characterize salivary glands tumors with diffusion tensor imaging. METHODS: This study was conducted upon 53 patients (aged 18-81 years: mean 37 years) with salivary gland tumors that underwent diffusion tensor imaging was obtained using a single-shot echo-planar imaging sequence with parallel imaging at 1.5 tesla scanner. Forty-eight slices were obtained, with a thickness of 2.5 mm, with no gap and the total scan duration was 7-8 min. The fractional anisotropy (FA) and the mean diffusivity (MD) value of the salivary gland tumors was calculated and correlated with pathological findings...
February 7, 2018: Dento Maxillo Facial Radiology
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