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Magnetic Resonance Imaging

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https://www.readbyqxmd.com/read/28438714/the-effect-of-morphological-and-microstructural-integrity-of-the-corpus-callosum-on-cognition-fatigue-and-depression-in-mildly-disabled-ms-patients
#1
Jeroen Van Schependom, Jeroen Gielen, Jorne Laton, Georgios Sotiropoulos, Anne-Marie Vanbinst, Johan De Mey, Dirk Smeets, Guy Nagels
Aim To assess the value of callosal morphological and microstructural integrity in assessing different cognitive domains, fatigue and depression in mildly disabled multiple sclerosis (MS) patients. MATERIALS AND METHODS: We assessed 29 mildly disabled MS patients and 15 healthy controls using 3T magnetic resonance images (T1-weighted, FLAIR and DTI) and neuropsychological tests assessing different cognitive functions, depression and fatigue. We compared the added value of morphological measures (corpus callosum area corrected for total intracranial volume, index, circularity and the more detailed thickness profile) and diffusion features (fractional anisotropy and mean diffusivity) in multilinear models including standard clinical and whole-brain parameters in assessing neuropsychological scores...
April 21, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28438713/effects-of-arterial-input-function-selection-on-kinetic-parameters-in-brain-dynamic-contrast-enhanced-mri
#2
Vera C Keil, Burkhard Mädler, Jürgen Gieseke, Rolf Fimmers, Elke Hattingen, Hans H Schild, Dariusch R Hadizadeh
PURPOSE: Kinetic parameters derived from dynamic contrast-enhanced MRI (DCE-MRI) were suggested as a possible instrument for multi-parametric lesion characterization, but have not found their way into clinical practice yet due to inconsistent results. The quantification is heavily influenced by the definition of an appropriate arterial input functions (AIF). Regarding brain tumor DCE-MRI, there are currently several co-existing methods to determine the AIF frequently including different brain vessels as sources...
April 21, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28438712/empirical-consideration-of-the-effects-of-acquisition-parameters-and-analysis-model-on-clinically-feasible-q-ball-imaging
#3
Kurt Schilling, Vishwesh Nath, Justin A Blaber, Prasanna Parvathaneni, Adam W Anderson, Bennett A Landman
Q-ball imaging (QBI) is a popular high angular resolution diffusion imaging (HARDI) technique used to study brain architecture in vivo. Simulation and phantom-based studies suggest that QBI results are affected by the b-value, the number of diffusion weighting directions, and the signal-to-noise ratio (SNR). However, optimal acquisition schemes for QBI in clinical settings are largely undetermined given empirical (observed) imaging considerations. In this study, we acquire a HARDI dataset at five b-values with 11 repetitions on a single subject to investigate the effects of acquisition scheme and subsequent analysis models on the accuracy and precision of measures of tissue composition and fiber orientation derived from clinically feasible QBI at 3T...
April 21, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28438711/can-transverse-relaxation-rates-in-deep-gray-matter-be-approximated-from-functional-and-t2-weighted-flair-scans-for-relative-brain-iron-quantification
#4
Benjamín Garzón, Rouslan Sitnikov, Lars Bäckman, Grégoria Kalpouzos
Alterations in iron concentration in certain deep gray matter regions are known to occur in aging and several clinical conditions. In vivo measurements of R2(∗) transverse relaxation rates and quantitative susceptibility mapping (QSM) have been shown to be strongly correlated with iron concentration in tissue, but their calculation requires the acquisition of a multi-echo gradient recalled echo sequence (MGRE). In the current study, we examined the feasibility of approximating R2(∗) rates using metrics derived from fMRI-EPI and T2-weighted FLAIR images, which are widely available...
April 21, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28438710/a-purpose-built-neck-coil-for-black-blood-dante-prepared-carotid-artery-imaging-at-7t
#5
Konstantinos Papoutsis, Linqing Li, Jamie Near, Stephen Payne, Peter Jezzard
Atherosclerotic plaques in the bifurcation of the carotid arteries can pose a significant health risk due to possible plaque rupture and subsequent stroke. The assessment of plaques, and evaluation of the risk they pose, can be performed with Black-Blood (BB) vessel wall magnetic resonance imaging. However, resolution at standard clinical field strengths (up to 3T) is limited, hampering reliable assessment and diagnosis. The aim of this study was to investigate the benefits of 7T MRI using a BB application that has been successful at clinical field strengths...
April 21, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28438709/characterization-of-high-resolution-gradient-echo-and-spin-echo-epi-for-fmri-in-the-human-visual-cortex-at-7t
#6
Catarina Rua, Mauro Costagli, Mark R Symms, Laura Biagi, Graziella Donatelli, Mirco Cosottini, Alberto Del Guerra, Michela Tosetti
The increased signal-to-noise ratio (SNR) offered by functional Magnetic Resonance Imaging (fMRI) at 7T allows the acquisition of functional data at sub-millimetric spatial resolutions. However, simply reducing partial volume effects is not sufficient to precisely localize task-induced activation due to the indirect mechanisms that relate brain function and the changes in the measured signal. In this work T2* and T2 weighted Echo Planar Imaging (EPI) schemes based on Gradient Recalled Echo (GRE) and Spin Echo (SE) were evaluated in terms of temporal SNR, percent signal change, contrast to noise ratio (CNR), activation volume, and sensitivity and specificity to gray matter...
April 21, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28433503/mr-fingerprinting-reconstruction-with-kalman-filter
#7
Xiaodi Zhang, Zechen Zhou, Shiyang Chen, Shuo Chen, Rui Li, Xiaoping Hu
Magnetic resonance fingerprinting (MR fingerprinting or MRF) is a newly introduced quantitative magnetic resonance imaging technique, which enables simultaneous multi-parameter mapping in a single acquisition with improved time efficiency. The current MRF reconstruction method is based on dictionary matching, which may be limited by the discrete and finite nature of the dictionary and the computational cost associated with dictionary construction, storage and matching. In this paper, we describe a reconstruction method based on Kalman filter for MRF, which avoids the use of dictionary to obtain continuous MR parameter measurements...
April 19, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28414052/spiral-mr-fingerprinting-at-7t-with-simultaneous-b1-estimation
#8
Guido Buonincontri, Rolf F Schulte, Mirco Cosottini, Michela Tosetti
Magnetic resonance fingerprinting is an efficient, new approach for quantitative imaging with MR. We aimed to extend this technique to cases with B1+ inhomogeneities within the imaging volume. Previous approaches have used abrupt changes in flip angles to estimate the B1+ field simultaneously with T1 and T2, using a Cartesian approach in a small-animal scanner at 4.7T. Here, we evaluated whether a similar approach would be suitable for imaging human brains using spiral readouts with a 7T scanner. We found that our modified scheme could significantly reduce the adverse effects of B1+ inhomogeneities even in extreme cases, reducing both the bias and the variance in T2 estimations by an order of magnitude when compared to literature methods...
April 13, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28412455/effects-of-rf-pulse-profile-and-intra-voxel-phase-dispersion-on-mr-fingerprinting-with-balanced-ssfp-readout
#9
Su-Chin Chiu, Te-Ming Lin, Jyh-Miin Lin, Hsiao-Wen Chung, Cheng-Wen Ko, Martin Büchert, Michael Bock
PURPOSE: To investigate possible errors in T1 and T2 quantification via MR fingerprinting with balanced steady-state free precession readout in the presence of intra-voxel phase dispersion and RF pulse profile imperfections, using computer simulations based on Bloch equations. MATERIALS AND METHODS: A pulse sequence with TR changing in a Perlin noise pattern and a nearly sinusoidal pattern of flip angle following an initial 180-degree inversion pulse was employed...
April 13, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28391061/rf-slice-profile-effects-in-magnetic-resonance-fingerprinting
#10
Taehwa Hong, Dongyeob Han, Min-Oh Kim, Dong-Hyun Kim
The radio frequency (RF) slice profile effects on T1 and T2 estimation in magnetic resonance fingerprinting (MRF) are investigated with respect to time-bandwidth product (TBW), flip angle (FA) level and field inhomogeneities. Signal evolutions are generated incorporating the non-ideal slice selective excitation process using Bloch simulation and matched to the original dictionary with and without the non-ideal slice profile taken into account. For validation, phantom and in vivo experiments are performed at 3T...
April 5, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28377304/longitudinal-mri-evaluation-of-neuroprotective-effects-of-pharmacologically-induced-hypothermia-in-experimental-ischemic-stroke
#11
Silun Wang, Xiaohuan Gu, Ramesh Paudyal, Ling Wei, Thomas A Dix, Shan P Yu, Xiaodong Zhang
Pharmacologically induced hypothermia (PIH) shows promising neuroprotective effects after stroke insult. However, the dynamic evolution of stroke infarct during the hypothermic therapy has not been understood very well. In the present study, MRI was utilized to longitudinally characterize the infarct evolution in a mouse model of ischemic stroke treated by PIH using the neurotensin agonist HPI201. Adult male C57BL/6 mice underwent permanent occlusion of the right middle cerebra artery (MCA). Each animal received a vehicle or HPI201 intraperitoneal injection...
April 2, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28377305/the-influence-of-spatial-patterns-of-capillary-networks-on-transverse-relaxation
#12
F T Kurz, C H Ziener, M Rückl, A Hahn, V J F Sturm, K Zhang, L R Buschle, M Bendszus, S Heiland, H P Schlemmer, W R Bauer, T Kampf
Tissue-inherent relaxation parameters offer valuable information about the arrangement of capillaries: in an external field, capillaries act as magnetic perturbers to generate local inhomogeneous fields due to the susceptibility difference of deoxygenated blood and the surrounding tissue. These field inhomogeneities influence the free induction decay in a characteristic way, and, conversely, the above tissue parameters can be recovered by multi-parametric fits of adequate theoretical models to experimentally sampled free induction decays...
April 1, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28366758/fast-single-image-super-resolution-using-estimated-low-frequency-k-space-data-in-mri
#13
Jianhua Luo, Zhiying Mou, Binjie Qin, Wanqing Li, Feng Yang, Marc Robini, Yuemin Zhu
PURPOSE: Single image super-resolution (SR) is highly desired in many fields but obtaining it is often technically limited in practice. The purpose of this study was to propose a simple, rapid and robust single image SR method in magnetic resonance (MR) imaging (MRI). METHODS: The idea is based on the mathematical formulation of the intrinsic link in k-space between a given (modulus) low-resolution (LR) image and the desired SR image. The method consists of two steps: 1) estimating the low-frequency k-space data of the desired SR image from a single LR image; 2) reconstructing the SR image using the estimated low-frequency and zero-filled high-frequency k-space data...
March 31, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28366757/feasibility-of-in-vivo-semi-laser-renal-magnetic-resonance-spectroscopy-mrs-pilot-study-in-healthy-volunteers
#14
Kartik Jhaveri, Lijun Guo, Timothy DeVito
PURPOSE: To evaluate the feasibility of semi-LASER renal magnetic resonance spectroscopy (MRS) in healthy volunteers and establish signature chemical composition of normal renal tissue towards future application for renal carcinoma characterization and grading. MATERIALS AND METHODS: 14 healthy volunteers were recruited after informed consent. Single voxel (1)H spectra were acquired on a 3T MRI system using a semi-LASER sequence, employing outer-volume suppression and VAPOR water suppression with multiple averages in multiple breath-holds...
March 31, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28366759/mri-ductography-of-contrast-agent-distribution-and-leakage-in-normal-mouse-mammary-ducts-and-ducts-with-in-situ-cancer
#15
Erica Markiewicz, Xiaobing Fan, Devkumar Mustafi, Marta Zamora, Suzanne D Conzen, Gregory S Karczmar
High resolution 3D MRI was used to study contrast agent distribution and leakage in normal mouse mammary glands and glands containing in situ cancer after intra-ductal injection. Five female FVB/N mice (~19weeks old) with no detectable mammary cancer and eight C3(1) SV40 Tag virgin female mice (~15weeks old) with extensive in situ cancer were studied. A 34G, 45° tip Hamilton needle with a 25μL Hamilton syringe was inserted into the tip of the nipple and approximately 15μL of a Gadodiamide was injected slowly over 1min into the nipple and throughout the duct on one side of the inguinal gland...
March 30, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28363761/t1%C3%AF-mapping-improvement-using-stretched-type-adiabatic-locking-pulses-for-assessment-of-human-liver-function-at-3t
#16
Tomoyuki Okuaki, Yukihisa Takayama, Akihiro Nishie, Tetsuo Ogino, Makoto Obara, Hiroshi Honda, Tosiaki Miyati, Marc Van Cauteren
PURPOSE: The purpose of this study is to investigate the performance of stretched-type adiabatic spin lock pulses for homogeneous spin locking with a flexible spin lock time (TSL) setting. METHODS: T1ρ values were obtained from 61 patients and five normal volunteers who were categorized using the Child-Pugh classification and scanned using each spin lock pulse type. The pulses used were the block and two kinds of hyperbolic secant (HS); HS8_10, and HS8_5. Visual scoring was categorized using a four point scale (1:Severe, 2:Moderate, 3:Mild and 4:None) to evaluate the homogeneity of the T1ρ map and the source images obtained by each spin lock pulse...
March 28, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28359912/diffusion-tensor-imaging-and-tractography-of-the-white-matter-in-normal-aging-the-rate-of-change-differs-between-segments-within-tracts
#17
J Mårtensson, J Lätt, F Åhs, M Fredrikson, H Söderlund, H B Schiöth, J Kok, B Kremer, Danielle van Westen, E-M Larsson, M Nilsson
Knowledge concerning the normal aging of cerebral white matter will improve our understanding of abnormal changes in neurodegenerative diseases. The microstructural basis of white matter maturation and aging can be investigated using diffusion tensor imaging (DTI). Generally, diffusion anisotropy increases during childhood and adolescence followed by a decline in middle age. However, this process is subject to spatial variations between tracts. The aim of this study was to investigate to what extent age-related variations also occur within tracts...
March 27, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28323127/bi-phase-age-related-brain-gray-matter-magnetic-resonance-t1%C3%AF-relaxation-time-change-in-adults
#18
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 18, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28315390/quantifying-the-dynamic-density-driven-convection-in-high-permeability-packed-beds
#19
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
https://www.readbyqxmd.com/read/28286063/motion-corrected-dwi-with-integrated-t2-mapping-for-simultaneous-estimation-of-adc-t2-relaxation-and-perfusion-in-prostate-cancer
#20
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
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