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Magnetic Resonance Imaging

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https://www.readbyqxmd.com/read/28782677/the-value-of-eswan-in-diagnosis-and-differential-diagnosis-of-prostate-cancer-preliminary-study
#1
Jian-Ying Xin, Shan-Shan Gao, Jin-Gang Liu, Cheng-Feng Sun, Yu Han, Xi-He Sun, Xi-Zhen Wang, Bin Wang
OBJECTIVE: To evaluate the value of enhanced T2 star-weighted angiography (ESWAN) in diagnosis and differential diagnosis of prostate cancer by comparing the multiple indices of ESWAN in benign prostatic hyperplasia (BPH), prostate cancer (PCa) and the normal peripheral zone (PZ). METHODS: Traditional MRI and ESWAN were performed on forty-nine clinically-diagnosed PCa patients, sixty BPH patients, and forty-six normal adult males. The ESWAN indices (magnitude value, phase value, R2* value and T2* value) measured on different regions of interest (ROIs) were analyzed...
August 3, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28782676/transverse-relaxation-of-cerebrospinal-fluid-depends-on-glucose-concentration
#2
A Daoust, S Dodd, G Nair, N Bouraoud, S Jacobson, S Walbridge, D S Reich, A Koretsky
PURPOSE: To evaluate the biophysical processes that generate specific T2 values and their relationship to specific cerebrospinal fluid (CSF) content. MATERIALS AND METHODS: CSF T2s were measured ex vivo (14.1T) from isolated CSF collected from human, rat and non-human primate. CSF T2s were also measured in vivo at different field strength in human (3 and 7T) and rodent (1, 4.7, 9,4 and 11.7T) using different pulse sequences. Then, relaxivities of CSF constituents were measured, in vitro, to determine the major molecule responsible for shortening CSF T2 (2s) compared to saline T2 (3s)...
August 3, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28757459/radiofrequency-magnetic-resonance-coils-and-communication-antennas-simulation-and-design-strategies
#3
Giulio Giovannetti, Gianluigi Tiberi
Coils simulation and design is a fundamental task to maximize Signal-to-Noise Ratio in Magnetic Resonance applications. In the meantime, in the last years the issue of accurate communication antennas analysis has grown. Coil design techniques take advantage of computer simulations in dependence on the magnetic field wavelength and coil sizes. In particular, since at high frequencies coils start to behave as antennas, modern Magnetic Resonance coil development exploits numerical methods typically employed for antennas simulation...
July 27, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28755862/ketamine-changes-the-local-resting-state-functional-properties-of-anesthetized-monkey-brain
#4
Jia-Sheng Rao, Zuxiang Liu, Can Zhao, Rui-Han Wei, Wen Zhao, Peng-Yu Tian, Xia Zhou, Zhao-Yang Yang, Xiao-Guang Li
OBJECTIVE: Ketamine is a well-known anesthetic. 'Recreational' use of ketamine common induces psychosis-like symptoms and cognitive impairments. The acute and chronic effects of ketamine on relevant brain circuits have been studied, but the effects of single-dose ketamine administration on the local resting-state functional properties of the brain remain unknown. In this study, we aimed to assess the effects of single-dose ketamine administration on the brain local intrinsic properties...
July 26, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28754270/fast-acceleration-of-asl-based-time-resolved-magnetic-resonance-angiography-by-acquisition-of-control-and-labeled-images-in-the-same-shot-fast-actress-an-optimization-study
#5
Hiroyuki Sugimori, Noriyuki Fujima, Yuriko Suzuki, Hiroyuki Hamaguchi, Kinya Ishizaka, Kohsuke Kudo
PURPOSE: To establish an optimized sequence design for fast acceleration of arterial spin labeling (ASL)-based time-resolved magnetic resonance angiography (MRA) by acquisition of control and labeled images in the same shot (fast ACTRESS) and a scan time of <1min, for the evaluation of intracranial vessels. MATERIALS AND METHODS: Ten healthy volunteers with no unilateral symptomatic arterial stenosis, who underwent 3-tesla MRI, were investigated. Imaging parameters for the fast ACTRESS sequence were set with an acquisition time of 45s...
July 25, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28751204/rapid-acquisition-of-magnetic-resonance-imaging-of-the-shoulder-using-three-dimensional-fast-spin-echo-sequence-with-compressed-sensing
#6
Seung Hyun Lee, Young Han Lee, Ho-Taek Song, Jin-Suck Suh
PURPOSE: To evaluate the feasibility of 3D fast spin-echo (FSE) imaging with compressed sensing (CS) for the assessment of shoulder. MATERIALS AND METHODS: Twenty-nine patients who underwent shoulder MRI including image sets of axial 3D-FSE sequence without CS and with CS, using an acceleration factor of 1.5, were included. Quantitative assessment was performed by calculating the root mean square error (RMSE) and structural similarity index (SSIM). Two musculoskeletal radiologists compared image quality of 3D-FSE sequences without CS and with CS, and scored the qualitative agreement between sequences, using a five-point scale...
July 24, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28751203/simple-algorithm-for-the-correction-of-mri-image-artefacts-due-to-random-phase-fluctuations
#7
Lionel M Broche, P James Ross, Gareth R Davies, David J Lurie
PURPOSE: Fast Field-Cycling (FFC) MRI is a novel technology that allows varying the main magnetic field B0 during the pulse sequence, from the nominal field (usually hundreds of millitesla) down to Earth's field or below. This technique uses resistive magnets powered by fast amplifiers. One of the challenges with this method is to stabilise the magnetic field during the acquisition of the NMR signal. Indeed, a typical consequence of field instability is small, random phase variations between each line of k-space resulting in artefacts, similar to those which occur due to homogeneous motion but harder to correct as no assumption can be made about the phase error, which appears completely random...
July 24, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28751202/r1%C3%AF-dispersion-and-sodium-imaging-in-human-calf-muscle
#8
Ping Wang, He Zhu, Hakmook Kang, John C Gore
PURPOSE: To evaluate the magnitude of chemical exchange effects and R1ρ dispersion in muscle and their relationship to tissue sodium levels with aging. METHODS: Seven healthy volunteers (aged 24 to 87years, median age 47) underwent MRI to assess tissue sodium levels and water T1ρ values at different spin-locking frequencies in calf muscles. T1ρ values at each locking field were computed based on a three-parameter mono-exponential model to fit signals obtained at different locking times, and R1ρ (=1/T1ρ) rates were compared at different locking fields...
July 24, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28739393/rat-brain-digital-stereotaxic-white-matter-atlas-with-fine-tract-delineation-in-paxinos-space-and-its-automated-applications-in-dti-data-analysis
#9
Shengxiang Liang, Shang Wu, Qi Huang, Shaofeng Duan, Hua Liu, Yuxiao Li, Shujun Zhao, Binbin Nie, Baoci Shan
PURPOSE: To automatically analyze diffusion tensor images of the rat brain via both voxel-based and ROI-based approaches, we constructed a new white matter atlas of the rat brain with fine tracts delineation in the Paxinos and Watson space. MATERIALS AND METHODS: Unlike in previous studies, we constructed a digital atlas image from the latest edition of the Paxinos and Watson. This atlas contains 111 carefully delineated white matter fibers. A white matter network of rat brain based on anatomy was constructed by locating the intersection of all these tracts and recording the nuclei on the pathway of each white matter tract...
July 21, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28739392/large-improvement-of-rf-transmission-efficiency-and-reception-sensitivity-for-human-in-vivo-31-p-mrs-imaging-using-ultrahigh-dielectric-constant-materials-at-7t
#10
Byeong-Yeul Lee, Xiao-Hong Zhu, Sebastian Rupprecht, Michael T Lanagan, Qing X Yang, Wei Chen
In vivo(31)P MRS provides a unique and important imaging tool for studying high-energy phosphate metabolism and bioenergetics noninvasively. However, compared to (1)H MRS, (31)P MRS with a relatively low gyromagnetic ratio (γ) has a lower and limited sensitivity even at ultrahigh field. The proof of concept has been recently demonstrated that the use of high dielectric constant (HDC) materials between RF coil and object sample could increase MRI signal and reduce required RF transmission power for reaching the same RF pulse flip angle in the region of interest...
July 21, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28735732/assessment-of-mri-issues-for-a-new-cerebral-spinal-fluid-shunt-gravitational-valve-gv
#11
Daniel Moghtader, Hans-Joachim Crawack, Christoph Miethke, Zinah Dörlemann, Frank G Shellock
PURPOSE: A gravitational valve (GV) may be used to treat hydrocephalus, offering possible advantages that include avoidance of over drainage and long-term complications. Because a GV is made from metal, there are potential safety and other problems related to the use of MRI. The objective of this investigation was to evaluate MRI-related issues (i.e., magnetic field interactions, heating, and artifacts) for a newly developed, metallic GV. METHODS: Tests were performed on the GV (GAV 2...
July 20, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28734956/fast-carotid-artery-mr-angiography-with-compressed-sensing-based-three-dimensional-time-of-flight-sequence
#12
Bo Li, Hao Li, Li Dong, Guofu Huang
OBJECTIVE: In this study, we sought to investigate the feasibility of fast carotid artery MR angiography (MRA) by combining three-dimensional time-of-flight (3D TOF) with compressed sensing method (CS-3D TOF). MATERIALS AND METHODS: A pseudo-sequential phase encoding order was developed for CS-3D TOF to generate hyper-intense vessel and suppress background tissues in under-sampled 3D k-space. Seven healthy volunteers and one patient with carotid artery stenosis were recruited for this study...
July 20, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28734955/predicting-the-nodal-status-in-gastric-cancers-the-role-of-apparent-diffusion-coefficient-histogram-characteristic-analysis
#13
Song Liu, Yujuan Zhang, Jie Xia, Ling Chen, Wenxian Guan, Yue Guan, Yun Ge, Jian He, Zhengyang Zhou
PURPOSE: To explore the application of histogram analysis in preoperative T and N staging of gastric cancers, with a focus on characteristic parameters of apparent diffusion coefficient (ADC) maps. MATERIALS AND METHODS: Eighty-seven patients with gastric cancers underwent diffusion weighted magnetic resonance imaging (b=0, 1000s/mm(2)), which generated ADC maps. Whole-volume histogram analysis was performed on ADC maps and 7 characteristic parameters were obtained...
July 20, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28734954/sparse-mri-reconstruction-using-multi-contrast-image-guided-graph-representation
#14
Zongying Lai, Xiaobo Qu, Hengfa Lu, Xi Peng, Di Guo, Yu Yang, Gang Guo, Zhong Chen
Accelerating the imaging speed without sacrificing image structures plays an important role in magnetic resonance imaging. Under-sampling the k-space data and reconstructing the image with sparsity constraint is one efficient way to reduce the data acquisition time. However, achieving high acceleration factor is challenging since image structures may be lost or blurred when the acquired information is not sufficient. Therefore, incorporating extra knowledge to improve image reconstruction is expected for highly accelerated imaging...
July 19, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28729016/learning-based-structurally-guided-construction-of-resting-state-functional-correlation-tensors
#15
Lichi Zhang, Han Zhang, Xiaobo Chen, Qian Wang, Pew-Thian Yap, Dinggang Shen
Functional magnetic resonance imaging (fMRI) measures changes in blood-oxygenation-level-dependent (BOLD) signals to detect brain activities. It has been recently reported that the spatial correlation patterns of resting-state BOLD signals in the white matter (WM) also give WM information often measured by diffusion tensor imaging (DTI). These correlation patterns can be captured using functional correlation tensor (FCT), which is analogous to the diffusion tensor (DT) obtained from DTI. In this paper, we propose a noise-robust FCT method aiming at further improving its quality, and making it eligible for further neuroscience study...
July 17, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28716683/trimmed-autocalibrating-k-space-estimation-based-on-structured-matrix-completion
#16
Mark Bydder, Stanislas Rapacchi, Olivier Girard, Maxime Guye, Jean-Philippe Ranjeva
PURPOSE: Parallel imaging allows the reconstruction of undersampled data from multiple coils. This provides a means to reject and regenerate corrupt data (e.g. from motion artefact). The purpose of this work is to approach this problem using the SAKE parallel imaging method. THEORY AND METHODS: Parallel imaging methods typically require calibration by fully sampling the center of k-space. This is a challenge in the presence of corrupted data, since the calibration data may be corrupted which leads to an errors-in-variables problem that cannot be solved by least squares or even iteratively reweighted least squares...
July 15, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28716681/mri-magic-angle-effect-in-femorotibial-cartilages-of-the-red-kangaroo
#17
Tonima S Ali, Namal Thibbotuwawa, YuanTong Gu, Konstantin I Momot
OBJECTIVE: Kangaroo knee cartilages are robust tissues that can support knee flexion and endure high levels of compressive stress. This study aimed to develop a detailed understanding of the collagen architecture in kangaroo knee cartilages and thus obtain insights into the biophysical basis of their function. DESIGN: Cylindrical/square plugs from femoral and tibial hyaline cartilage and tibial fibrocartilage were excised from the knees of three adult red kangaroos...
July 15, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28716679/modified-brisque-as-no-reference-image-quality-assessment-for-structural-mr-images
#18
Li Sze Chow, Heshalini Rajagopal
An effective and practical Image Quality Assessment (IQA) model is needed to assess the image quality produced from any new hardware or software in MRI. A highly competitive No Reference - IQA (NR - IQA) model called Blind/Referenceless Image Spatial Quality Evaluator (BRISQUE) initially designed for natural images were modified to evaluate structural MR images. The BRISQUE model measures the image quality by using the locally normalized luminance coefficients, which were used to calculate the image features...
July 15, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28716678/cancer-recurrence-monitoring-using-hyperpolarized-1-13-c-pyruvate-metabolic-imaging-in-murine-breast-cancer-model
#19
Peter J Shin, Zihan Zhu, Roman Camarda, Robert A Bok, Alicia Y Zhou, John Kurhanewicz, Andrei Goga, Daniel B Vigneron
The purpose of this work was to study the anatomic and metabolic changes that occur with tumor progression, regression and recurrence in a switchable MYC-driven murine breast cancer model. Serial (1)H MRI and hyperpolarized [1-(13)C]pyruvate metabolic imaging were used to investigate the changes in tumor volume and glycolytic metabolism over time during the multistage tumorigenesis. We show that acute de-induction of MYC expression in established tumors results in rapid tumor regression and significantly reduced glycolytic metabolism as measured by pyruvate-to-lactate conversion...
July 15, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28716682/air-mrf-accelerated-iterative-reconstruction-for-magnetic-resonance-fingerprinting
#20
Christopher C Cline, Xiao Chen, Boris Mailhe, Qiu Wang, Josef Pfeuffer, Mathias Nittka, Mark A Griswold, Peter Speier, Mariappan S Nadar
Existing approaches for reconstruction of multiparametric maps with magnetic resonance fingerprinting (MRF) are currently limited by their estimation accuracy and reconstruction time. We aimed to address these issues with a novel combination of iterative reconstruction, fingerprint compression, additional regularization, and accelerated dictionary search methods. The pipeline described here, accelerated iterative reconstruction for magnetic resonance fingerprinting (AIR-MRF), was evaluated with simulations as well as phantom and in vivo scans...
July 14, 2017: Magnetic Resonance Imaging
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