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Magnetic Resonance Imaging

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https://www.readbyqxmd.com/read/28634048/activation-volume-vs-bold-signal-change-as-measures-of-fmri-activation-its-impact-on-gaba-fmri-activation-correlation
#1
Pallab K Bhattacharyya, Micheal D Phillips, Lael A Stone, Mark J Lowe
PURPOSE: To explore the relative robustness of functional MRI (fMRI) activation volume and blood oxygen level-dependent (BOLD) signal change as fMRI metric, and to study the effect of relative robustness on the correlation between fMRI activation and cortical gamma amino butyric acid (GABA) in healthy controls and patients with multiple sclerosis (MS). METHODS: fMRI data were acquired from healthy controls and patients with MS, with the subjects peforming self paced bilateral finger tapping in block design...
June 17, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28634047/the-study-of-the-intervertebral-disc-microstructure-in-matured-rats-with-diffusion-kurtosis-imaging
#2
Li Li, Wenzhen Zhu, Weiwei Chen, Jicheng Fang, Jing Li
OBJECTIVES: The aim of this study was to use DKI to detect the microstructural change of the discs in matured normal rats. METHODS: Total 24 normal SD rats (12 males/12 females) underwent DWI/DKI and T2 sequences with a 3T MRI scanner to get the values of ADC, FA, MD, Da, Dr, MK, Ka and Kr. The discs were categorized using a five-grade degeneration grading system in the T2-images. The height of the discs and the parameters in DWI/DKI were measured to compare between the different grades and sexes...
June 17, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28629956/effects-of-fat-saturation-on-short-t2-quantification
#3
Michael Carl, Amin Nazaran, Graeme M Bydder, Jiang Du
Ultrashort TE (UTE) sequences have the capability to image tissues with very short T2s that typically appear as low signal in clinical sequences. UTE sequences can also be used in multi-echo acquisitions which allow assessment of the T2s of these tissues. Here we study the accuracy of such T2 measurements when combined with fat saturation (FS).
June 16, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28629955/correlation-study-between-dki-and-conventional-dwi-in-brain-and-head-and-neck-tumors
#4
Silvia Minosse, Simona Marzi, Francesca Piludu, Antonello Vidiri
PURPOSE: To investigate the relationship between the Diffusion Kurtosis Imaging (DKI) parameters and conventional metrics provided by Diffusion-weighted imaging (DWI) in patients affected by Brain or Head and Neck (HN) cancer. METHODS: Ten patients affected by brain tumor and nine patients with HN tumor underwent a pre-treatment MR examination at 3 T. The largest tumor section was manually contoured by two expert neuroradiologists. The apparent diffusion coefficient (Dapp) and apparent diffusional kurtosis (Kapp) parameters were determined at the voxel level by using the DKI model, and compared to the apparent diffusion coefficient (ADC) and the tissue diffusion coefficient (Dmono) obtained from mono-exponential fitting methods...
June 16, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28629954/high-resolution-myelin-water-imaging-incorporating-local-tissue-susceptibility-analysis
#5
Zhe Wu, Hongjian He, Yi Sun, Yiping Du, Jianhui Zhong
Quantitative myelin water imaging (MWI) from signal T2* decay acquired with multiple Gradient-Recalled Echo (mGRE) sequence has been widely used since its first report. A recent study showed that with low resolution data (2mm isotropic voxels), direct application of complex fitting to a three-pool WM model with frequency shift terms could produce more stable parameter estimation for myelin water fraction mapping. MWI maps of higher spatial resolution resulting in more detailed tissue structures and reduced partial volume effects around white matter/gray matter (WM/GM) interface, however, is more desirable...
June 16, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28629953/3d-black-blood-mr-angiography-of-the-carotid-arteries-a-simple-sequence-for-plaque-hemorrhage-and-stenosis-evaluation
#6
Monica Sigovan, Clément Bidet, Sébastien Bros, Loic Boussel, Laura Mechtouff, Philip M Robson, Zahi A Fayad, Antoine Millon, Philippe Douek
OBJECTIVES: To evaluate the diagnostic performance of a new three-dimensional T1-weighted turbo-spin-echo sequence (3D T1-w TSE) compared to 3D contrast-enhanced angiography (CE-MRA) for stenosis measurement and compared to 2D T1-w TSE for intra-plaque hemorrhage (IPH) detection. METHODS: Eighty three patients underwent carotid MRI, using a new elliptic-centric phase encoding T1-weighted 3D TSE sequence in addition to the clinical protocol. Two observers evaluated image quality, presence of flow artifacts, and presence of intra-plaque hemorrhage, and computed the NASCET degree of stenosis for CE-MRA and for the new sequence...
June 16, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28627463/pre-operative-assessment-of-residual-disease-in-locally-advanced-breast-cancer-patients-a-sequential-study-by-quantitative-diffusion-weighted-mri-as-a-function-of-therapy
#7
Khushbu Agarwal, Uma Sharma, Rani G Sah, Sandeep Mathur, Smriti Hari, Vurthaluru Seenu, Rajinder Parshad, Naranamangalam R Jagannathan
PURPOSE: The potential of diffusion weighted imaging (DWI) in assessing pathologic response and surgical margins in locally advanced breast cancer patients (n=38) undergoing neoadjuvant chemotherapy was investigated. METHODS: DWI was performed at pre-therapy (Tp0), after I (Tp1) and III (Tp3) NACT at 1.5T. Apparent diffusion coefficient (ADC) of whole tumor (ADCWT), solid tumor (ADCST), intra-tumoral necrosis (ADCNec) was determined. Further, ADC of 6 consecutive shells (5mm thickness each) including tumor margin to outside tumor margins (OM1 to OM5) was calculated and the data analyzed to define surgical margins...
June 13, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28619605/the-prognostic-value-of-proton-magnetic-resonance-spectroscopy-in-term-newborns-treated-with-therapeutic-hypothermia-following-asphyxia
#8
Paul E Sijens, Katharina Wischniowsky, Hendrik J Ter Horst
OBJECTIVE: The purpose of this study was to correlate brain metabolism assessed shortly after therapeutic hyperthermia by (1)H magnetic resonance spectroscopy (MRS), with neurodevelopmental outcome. METHODS: At the age of 6.0±1.8days, brain metabolites of 35 term asphyxiated newborns, treated with therapeutic hypothermia, were quantified by multivoxel proton MRS of a volume cranial to the corpus callosum, containing both gray and white matter. At the age of 30months the Bayley Scale of Infant Development-III was performed...
June 12, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28577902/directional-sensitivity-of-anomalous-diffusion-in-human-brain-assessed-by-tensorial-fractional-motion-model
#9
Boyan Xu, Gaolang Gong, Yang Fan, Bing Wu, Jia-Hong Gao
Anisotropic diffusion in the nervous system is most commonly modeled by apparent diffusion tensor, which is based on regular diffusion theory. However, the departure of diffusion-induced signal attenuation from a mono-exponential form implies that there is anomalous diffusion. Recently, a novel diffusion NMR theory based on the fractional motion (FM) model, which is an anomalous diffusion model, has been proposed. While the FM model has been applied to both healthy subjects and tumor patients, its anisotropy in the nervous system remains elusive...
June 1, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28549883/a-non-iterative-multi-scale-approach-for-intensity-inhomogeneity-correction-in-mri
#10
Maryjo M George, S Kalaivani, M S Sudhakar
Intensity inhomogeneity is the prime obstacle for MR image processing like automatic segmentation, registration etc. This complication has strong dependence on the associated acquisition hardware and patient anatomy which recommends retrospective correction. In this paper, a new method is developed for correcting the intensity inhomogeneity using a non-iterative multi-scale approach that doesn't necessitate segmentation and any prior knowledge on the scanner or subject. The proposed algorithm extracts bias field at different scales using a Log-Gabor filter bank followed by smoothing operation...
May 24, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28536087/workflow-sensitivity-of-post-processing-methods-in-renal-dce-mri
#11
Erik Hanson, Eli Eikefjord, Jarle Rørvik, Erling Andersen, Arvid Lundervold, Erlend Hodneland
OBJECTIVE: Estimation of renal filtration using dynamic contrast-enhanced imaging (DCE-MRI) requires a series of analysis steps. The possible number of distinct post-processing chains is large and grows rapidly with increasing number of processing steps or options. In this study we introduce a framework for systematic evaluation of the post-processing chains. The framework is later used to highlight the workflow processing chain sensitivity towards accuracy in estimation of glomerular filtration rate (GFR)...
May 20, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28526431/measurement-of-apt-using-a-combined-cert-arex-approach-with-varying-duty-cycles
#12
Zhongliang Zu, Hua Li, Junzhong Xu, Xiao-Yong Zhang, Moritz Zaiss, Ke Li, Mark D Does, John C Gore, Daniel F Gochberg
The goal is to develop an imaging method where contrast reflects amide-water magnetization exchange, with minimal signal contributions from other sources. Conventional chemical exchange saturation transfer (CEST) imaging of amides (often called amide proton transfer, or APT, and quantified by the metric MTRasym) is confounded by several factors unrelated to amides, such as aliphatic protons, water relaxation, and macromolecular magnetization transfer. In this work, we examined the effects of combining our previous chemical exchange rotation (CERT) approach with the non-linear AREX method while using different duty cycles (DC) for the label and reference scans...
May 17, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28526430/combination-of-integrated-dynamic-shimming-and-readout-segmented-echo-planar-imaging-for-diffusion-weighted-mri-of-the-head-and-neck-region-at-3tesla
#13
Sven S Walter, Wei Liu, Alto Stemmer, Petros Martirosian, Konstantin Nikolaou, Mike Notohamiprodjo, Sergios Gatidis
PURPOSE: To evaluate the performance of combined integrated slice-by-slice shimming and readout-segmented EPI (irsEPI) for diffusion-weighted MR imaging (DWI) of the neck at 3Tesla. METHODS: This study was approved by the local ethics committee. An anthropometric phantom of the head/neck region incorporating compartments with different diffusivities was constructed. In vivo measurements were performed in 10 healthy volunteers. DWI of the phantom and volunteers was performed on a 3Tesla MR scanner using single shot EPI (sEPI), a prototype single shot EPI with integrated slice-by-slice shimming (iEPI), readout segmented EPI (rsEPI) and a prototype readout segmented EPI with integrated shimming irsEPI...
May 17, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28526432/quantitative-susceptibility-mapping-using-principles-of-echo-shifting-with-a-train-of-observations-sequence-on-1-5t-mri
#14
Hirohito Kan, Nobuyuki Arai, Harumasa Kasai, Hiroshi Kunitomo, Yasujiro Hirose, Yuta Shibamoto
PURPOSE: To evaluate the accuracy of susceptibility estimated from the principles of echo shifting with a train of observations (PRESTO) sequence using a 1.5T MRI system, we conducted experiments on the human brain using the PRESTO sequence and compared our results with the susceptibility obtained from spoiled gradient-recalled echo (GRE) sequence with flow compensation using quantitative susceptibility mapping (QSM) reconstruction. MATERIALS AND METHODS: Experiments on the human brain were conducted on 12 healthy volunteers (27±4years) using PRESTO and spoiled GRE sequences on a 1...
May 16, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28522366/a-level-set-method-for-multiple-sclerosis-lesion-segmentation
#15
Yue Zhao, Shuxu Guo, Min Luo, Xue Shi, Michel Bilello, Shaoxiang Zhang, Chunming Li
In this paper, we present a level set method for multiple sclerosis (MS) lesion segmentation from FLAIR Images in the presence of intensity inhomogeneities. We use a three-phase level set formulation of segmentation and bias field estimation to segment MS lesions and normal tissue region (including GM and WM) and CSF and the background from FLAIR images. To save computational load, we derive a two-phase formulation from the original multi-phase level set formulation to segment the MS lesions and normal tissue regions...
May 15, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28479342/normalizing-data-from-gaba-edited-mega-press-implementations-at-3-tesla
#16
Ashley D Harris, Nicolaas A J Puts, S Andrea Wijtenburg, Laura M Rowland, Mark Mikkelsen, Peter B Barker, C John Evans, Richard A E Edden
Standardization of results is an important milestone in the maturation of any truly quantitative methodology. For instance, a lack of measurement agreement across imaging platforms limits multisite studies, between-study comparisons based on the literature, and inferences based on and the generalizability of results. In GABA-edited MEGA-PRESS, two key sources of differences between implementations are: differences in editing efficiency of GABA and the degree of co-editing of macromolecules (MM). In this work, GABA editing efficiency κ and MM-co-editing μ constants are determined for three widely used MEGA-PRESS implementations (on the most common MRI platforms; GE, Philips, and Siemens) by phantom experiments...
May 4, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28479341/towards-intrinsic-r2-imaging-in-the-prostate-at-3-and-7tesla
#17
Mariska P Luttje, Laurens D van Buuren, Peter R Luijten, Marco van Vulpen, Uulke A van der Heide, Dennis W J Klomp
PURPOSE: Hypoxia is an important marker for resistance to therapy. In this study, we quantify the macroscopic effects of R2* mapping in prostate cancer patients incorporating susceptibility matching and field strengths effects. MATERIALS AND METHODS: 91 patients were scanned without endorectal coil (ERC) at 3T. Only when rectal gas was absent, data was included for analysis. Another group of 10 patients was scanned using a susceptibility matched ERC. To assess the residual contamination of R2 and macroscopic field non-uniformities, a group of 10 patients underwent ultra-high resolution 7T MRI...
May 4, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28476308/magnetic-resonance-elastography-of-the-pancreas-measurement-reproducibility-and-relationship-with-age
#18
Arunark Kolipaka, Samuel Schroeder, Xiaokui Mo, Zarine Shah, Phil A Hart, Darwin L Conwell
PURPOSE: To determine magnetic resonance elastography (MRE)-derived stiffness of pancreas in healthy volunteers with emphasis on: 1) short term and midterm repeatability; and 2) variance as a function of age. METHODS: Pancreatic MRE was performed on 22 healthy volunteers (age range:20-64years) in a 3T-scanner. For evaluation of reproducibility of stiffness estimates, the scans were repeated per volunteer on the same day (short term) and one month apart (midterm)...
May 2, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28461132/a-non-contrast-cmr-index-for-assessing-myocardial-fibrosis
#19
Qian Yin, Dana Abendschein, David Muccigrosso, Robert O'Connor, Thomas Goldstein, Ridong Chen, Jie Zheng
PURPOSE: Safe, sensitive, and non-invasive imaging methods to assess the presence, extent, and turnover of myocardial fibrosis are needed for early stratification of risk in patients who might develop heart failure after myocardial infarction. We describe a non-contrast cardiac magnetic resonance (CMR) approach for sensitive detection of myocardial fibrosis using a canine model of myocardial infarction and reperfusion. METHODS: Seven dogs had coronary thrombotic occlusion of the left anterior descending coronary arteries followed by fibrinolytic reperfusion...
April 28, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28433503/mr-fingerprinting-reconstruction-with-kalman-filter
#20
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
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