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Magnetic Resonance Imaging

Yáo T Li, Hua Huang, Zhizheng Zhuo, Pu-Xuan Lu, Weitian Chen, Yì Xiáng J Wáng
OBJECTIVES: To investigate normative value and age-related change of brain magnetic resonance T1ρ relaxation at 1.5T. METHODS: This study was approved by the local ethical committee with participants' written consent obtained. There were 42 adults healthy volunteers, including 20 males (age: 41±16 (mean±standard deviation) years, range: 22-68years,) and 22 females (age: 39±15years, range: 21-62years). MRI was performed at 1.5T using 3D fluid suppressed turbo spin echo sequence...
March 16, 2017: Magnetic Resonance Imaging
Ying Teng, Lanlan Jiang, Yingting Fan, Yu Liu, Dayong Wang, Abuliti Abudula, Yongchen Song
The density driven convection phenomenon is expected to have a significant and positive role in CO2 geological storage capacity and safety. The onset and development of density-driven convective on the core scale is critical to understand the mass transfer mechanism. In this paper, laboratory experiments were conducted to investigate the density-driven convective in a vertical tube. The deuterium oxide (D2O)/manganese chloride (MnCl2) water solution in water or brine were as an analog for CO2-rich brine in original brine...
March 14, 2017: Magnetic Resonance Imaging
M Skorpil, P Brynolfsson, M Engström
OBJECTIVE: Multiparametric magnetic resonance imaging (MRI) and PI-RADS (Prostate Imaging - Reporting and Data System) has become the standard to determine a probability score for a lesion being a clinically significant prostate cancer. T2-weighted and diffusion-weighted imaging (DWI) are essential in PI-RADS, depending partly on visual assessment of signal intensity, while dynamic-contrast enhanced imaging is less important. To decrease inter-rater variability and further standardize image evaluation, complementary objective measures are in need...
March 9, 2017: Magnetic Resonance Imaging
Caroline Le Ster, Jérémy Lasbleiz, Stephan Kannengiesser, Raphaël Guillin, Giulio Gambarota, Hervé Saint-Jalmes
PURPOSE: Bone marrow is found either as red bone marrow, which mainly contains haematopoietic cells, or yellow bone marrow, which mainly contains adipocytes. In adults, red bone marrow is principally located in the axial skeleton. A recent study has introduced a method to simultaneously estimate the fat fraction (FF), the T1 and T2* relaxation times of water (T1w, T2*w) and fat (T1f and T2*f) in the vertebral bone marrow. The aim of the current study was to measure FF, T1w, T1f, T2*w and T2*f in five sites of bone marrow, and to assess the presence of regional variations...
March 2, 2017: Magnetic Resonance Imaging
Ouri Cohen, Matthew S Rosen
In MR Fingerprinting, the flip angles and repetition times are chosen according to a pseudorandom schedule. In previous work, we have shown that maximizing the discrimination between different tissue types by optimizing the acquisition schedule allows reductions in the number of measurements required. The ideal optimization algorithm for this application remains unknown, however. In this work we examine several different optimization algorithms to determine the one best suited for optimizing MR Fingerprinting acquisition schedules...
February 23, 2017: Magnetic Resonance Imaging
Mariya Doneva, Thomas Amthor, Peter Koken, Karsten Sommer, Peter Börnert
An iterative reconstruction method for undersampled magnetic resonance fingerprinting data is presented. The method performs the reconstruction entirely in k-space and is related to low rank matrix completion methods. A low dimensional data subspace is estimated from a small number of k-space locations fully sampled in the temporal direction and used to reconstruct the missing k-space samples before MRF dictionary matching. Performing the iterations in k-space eliminates the need for applying a forward and an inverse Fourier transform in each iteration required in previously proposed iterative reconstruction methods for undersampled MRF data...
February 18, 2017: Magnetic Resonance Imaging
Yao-Tien Chen
The study proposes a novel approach for segmentation and visualization plus value-added surface area and volume measurements for brain medical image analysis. The proposed method contains edge detection and Bayesian based level set segmentation, surface and volume rendering, and surface area and volume measurements for 3D objects of interest (i.e., brain tumor, brain tissue, or whole brain). Two extensions based on edge detection and Bayesian level set are first used to segment 3D objects. Ray casting and a modified marching cubes algorithm are then adopted to facilitate volume and surface visualization of medical-image dataset...
February 17, 2017: Magnetic Resonance Imaging
Qun He, Yajun Ma, Shujuan Fan, Hongda Shao, Vipul Sheth, Graeme M Bydder, Jiang Du
In this paper, we aimed to investigate the feasibility of direct visualization of myelin, including myelin lipid and myelin basic protein (MBP), using two-dimensional ultrashort echo time (2D UTE) sequences and utilize phase information as a contrast mechanism in phantoms and in volunteers. The standard UTE sequence was used to detect both myelin and long T2 signal. An adiabatic inversion recovery UTE (IR-UTE) sequence was used to selectively detect myelin by suppressing signal from long T2 water protons. Magnitude and phase imaging and T2* were investigated on myelin lipid and MBP in the forms of lyophilized powders as well as paste-like phantoms with the powder mixed with D2O, and rubber phantoms as well as healthy volunteers...
February 17, 2017: Magnetic Resonance Imaging
Michinobu Nagao, Yuzo Yamasaki, Satoshi Kawanami, Takeshi Kamitani, Koji Sagiyama, Taiki Higo, Tomomi Ide, Atsushi Takemura, Umiko Ishizaki, Kenji Fukushima, Yuji Watanabe, Hiroshi Honda
PURPOSE: Quantification of myocardial oxygenation (MO) in heart failure (HF) has been less than satisfactory. This has necessitated the use of invasive techniques to measure MO directly or to determine the oxygen demand during exercise using the cardiopulmonary exercise (CPX) test. We propose a new quantification method for MO using blood-oxygen-level-dependent (BOLD) myocardial T2* magnetic resonance imaging (M-T2* MRI), and investigate its correlation with CPX results. METHODS: Thirty patients with refractory HF who underwent cardiac MRI and CPX test for heart transplantation, and 24 healthy, age-matched volunteers as controls were enrolled...
February 17, 2017: Magnetic Resonance Imaging
Naoki Ohno, Hirohito Kan, Tosiaki Miyati, Toshitaka Aoki, Shota Ishida, Toshifumi Gabata
PURPOSE: To obtain water and lipid diffusion-weighted images (DWIs) simultaneously, we devised a novel method utilizing chemical shift displacement-based separation of lipid tissue (SPLIT) imaging. MATERIALS AND METHODS: Single-shot diffusion echo-planar imaging without fat suppression was used and the imaging parameters were optimized to separate water and lipid DWIs by chemical shift displacement of the lipid signals along the phase-encoding direction. Using the optimized conditions, transverse DWIs at the maximum diameter of the right calf were scanned with multiple b-values in five healthy subjects...
February 16, 2017: Magnetic Resonance Imaging
Xinqiang Yan, Xiaoliang Zhang, John C Gore, William A Grissom
Traveling-wave MRI, which uses relatively small and simple RF antennae, has robust matching performance and capability for large field-of-view (FOV) imaging. However, the power efficiency of traveling-wave MRI is much lower than conventional methods, which limits its application. One simple approach to improve the power efficiency is to place passive resonators around the subject being imaged. The feasibility of this approach has been demonstrated in previous works using a single small resonant loop. In this work, we aim to explore how much the improvements can be maintained in human imaging using an array design, and whether electric dipoles can be used as local elements...
February 9, 2017: Magnetic Resonance Imaging
Lina Carlbom, Jan Weis, Lars Johansson, Olle Korsgren, Håkan Ahlström
OBJECTIVE: To investigate the feasibility of using (31)P-MRS for objective non-invasive quality assessment of human pancreas grafts prior to transplantation or islet isolation. MATERIALS AND METHODS: Pancreata from 5 human donors, 3 males and 2 females, aged 49-78years, with body mass index (BMI) 22-31kg/m(2), were included. Pancreata were perfused with histidine-tryptophan-ketoglutarate solution during procurement and stored in hypothermic condition (4°C) for 21-44h...
February 8, 2017: Magnetic Resonance Imaging
Xiang Feng, Andreas Deistung, Michael G Dwyer, Jesper Hagemeier, Paul Polak, Jessica Lebenberg, Frédérique Frouin, Robert Zivadinov, Jürgen R Reichenbach, Ferdinand Schweser
Accurate and robust segmentation of subcortical gray matter (SGM) nuclei is required in many neuroimaging applications. FMRIB's Integrated Registration and Segmentation Tool (FIRST) is one of the most popular software tools for automated subcortical segmentation based on T1-weighted (T1w) images. In this work, we demonstrate that FIRST tends to produce inaccurate SGM segmentation results in the case of abnormal brain anatomy, such as present in atrophied brains, due to a poor spatial match of the subcortical structures with the training data in the MNI space as well as due to insufficient contrast of SGM structures on T1w images...
February 7, 2017: Magnetic Resonance Imaging
Angshul Majumdar
This technical note addresses the problem of causal online reconstruction of dynamic MRI, i.e. given the reconstructed frames till the previous time instant, we reconstruct the frame at the current instant. Our work follows a prediction-correction framework. Given the previous frames, the current frame is predicted based on a Kalman estimate. The difference between the estimate and the current frame is then corrected based on the k-space samples of the current frame; this reconstruction assumes that the difference is sparse...
February 4, 2017: Magnetic Resonance Imaging
R Nicolas, H Gros-Dagnac, F Aubry, P Celsis
The blood oxygen level-dependent (BOLD) effect is extensively used for functional MRI (fMRI) but presents some limitations. Diffusion-weighted fMRI (DfMRI) has been proposed as a method more tightly linked to neuronal activity. This work proposes a protocol of DfMRI acquired for several b-values and diffusion directions that is compared to gradient-echo BOLD (GE-BOLD) and to repeated spin-echo BOLD (SE-BOLD, acquisitions performed with b=0s/mm(2)), which was also used to ensure the reproducibility of the response...
February 3, 2017: Magnetic Resonance Imaging
Li Min Chen, Pai-Feng Yang, Feng Wang, Arabinda Mishra, Zhaoyue Shi, Ruiqi Wu, Tung-Lin Wu, George H Wilson, Zhaohua Ding, John C Gore
Functional MRI (fMRI) has evolved from simple observations of regional changes in MRI signals caused by cortical activity induced by a task or stimulus, to task-free acquisitions of images in a resting state. Such resting state signals contain low frequency fluctuations which may be correlated between voxels, and strongly correlated regions are deemed to reflect functional connectivity within synchronized circuits. Resting state functional connectivity (rsFC) measures have been widely adopted by the neuroscience community, and are being used and interpreted as indicators of intrinsic neural circuits and their functional states in a broad range of applications, both basic and clinical...
February 2, 2017: Magnetic Resonance Imaging
Jung Hwan Kim, David Ress
Functional magnetic resonance imaging (fMRI) often relies on a hemodynamic response function (HRF), the stereotypical blood oxygen level dependent (BOLD) response elicited by a brief (<4s) stimulus. Early measurements of the HRF used coarse spatial resolutions (≥3mm voxels) that would generally include contributions from white matter, gray matter, and the extra-pial compartment (the space between the pial surface and skull including pial blood vessels) within each voxel. To resolve these contributions, high-resolution fMRI (0...
January 28, 2017: Magnetic Resonance Imaging
Murat Aksoy, Julian Maclaren, Roland Bammer
Head motion is an unsolved problem in magnetic resonance imaging (MRI) studies of the brain. Real-time tracking using a camera has recently been proposed as a way to prevent head motion artifacts. As compared to navigator-based approaches that use MRI data to detect and correct motion, optical motion correction works independently of the MRI scanner, thus providing low-latency real-time motion updates without requiring any modifications to the pulse sequence. The purpose of this study was two-fold: 1) to demonstrate that prospective optical motion correction using an optical camera mitigates artifacts from head motion in three-dimensional pseudo-continuous arterial spin labeling (3D PCASL) acquisitions and 2) to assess the effect of latency differences between real-time optical motion tracking and navigator-style approaches (such as PROMO)...
January 27, 2017: Magnetic Resonance Imaging
Stephen J Riederer, Eric A Borisch, Adam T Froemming, Roger C Grimm, Akira Kawashima, Lance A Mynderse, Joshua D Trzasko
PURPOSE: To assess whether acquisition with 32 receiver coils rather than the vendor-recommended 12 coils provides significantly improved performance in 3D dynamic contrast-enhanced MRI (DCE-MRI) of the prostate. MATERIALS: The study was approved by the institutional review board and was compliant with HIPAA. 50 consecutive male patients in whom prostate MRI was clinically indicated were prospectively imaged in March 2015 with an accelerated DCE-MRI sequence in which image reconstruction was performed using 12 and 32 coil elements...
January 27, 2017: Magnetic Resonance Imaging
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