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https://www.readbyqxmd.com/read/29044753/development-of-a-quantitative-intracranial-vascular-features-extraction-tool-on-3d-mra-using-semiautomated-open-curve-active-contour-vessel-tracing
#1
Li Chen, Mahmud Mossa-Basha, Niranjan Balu, Gador Canton, Jie Sun, Kristi Pimentel, Thomas S Hatsukami, Jenq-Neng Hwang, Chun Yuan
PURPOSE: To develop a quantitative intracranial artery measurement technique to extract comprehensive artery features from time-of-flight MR angiography (MRA). METHODS: By semiautomatically tracing arteries based on an open-curve active contour model in a graphical user interface, 12 basic morphometric features and 16 basic intensity features for each artery were identified. Arteries were then classified as one of 24 types using prediction from a probability model...
October 17, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29044721/body-diffusion-weighted-imaging-using-magnetization-prepared-single-shot-fast-spin-echo-and-extended-parallel-imaging-signal-averaging
#2
Eric K Gibbons, Shreyas S Vasanawala, John M Pauly, Adam B Kerr
PURPOSE: This work demonstrates a magnetization prepared diffusion-weighted single-shot fast spin echo (SS-FSE) pulse sequence for the application of body imaging to improve robustness to geometric distortion. This work also proposes a scan averaging technique that is superior to magnitude averaging and is not subject to artifacts due to object phase. THEORY AND METHODS: This single-shot sequence is robust against violation of the Carr-Purcell-Meiboom-Gill (CPMG) condition...
October 17, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29044690/apparent-diffusion-coefficients-of-the-five-major-metabolites-measured-in-the-human-brain-in-vivo-at-3t
#3
Dinesh K Deelchand, Edward J Auerbach, Małgorzata Marjańska
PURPOSE: To measure the apparent diffusion coefficients (ADC) of five main metabolites in the human brain at 3T with PRESS and STEAM, avoiding measurement biases because of cross-terms. Cross-terms arise from interactions between slice-selection and spoiler gradients in the localized spectroscopy sequence and the diffusion gradients. METHODS: Diffusion-weighted spectra were acquired from the prefrontal cortex in five healthy subjects using STEAM (echo time [TE]/mixing time [TM]/pulse repetition time [TR] = 21...
October 17, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29034514/measurement-of-murine-single-kidney-glomerular-filtration-rate-using-dynamic-contrast-enhanced-mri
#4
Kai Jiang, Hui Tang, Prasanna K Mishra, Slobodan I Macura, Lilach O Lerman
PURPOSE: To develop and validate a method for measuring murine single-kidney glomerular filtration rate (GFR) using dynamic contrast-enhanced MRI (DCE-MRI). METHODS: This prospective study was approved by the Institutional Animal Care and Use Committee. A fast longitudinal relaxation time (T1 ) measurement method was implemented to capture gadolinium dynamics (1 s/scan), and a modified two-compartment model was developed to quantify GFR as well as renal perfusion using 16...
October 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29034511/computationally-efficient-combination-of-multi-channel-phase-data-from-multi-echo-acquisitions-aspire
#5
Korbinian Eckstein, Barbara Dymerska, Beata Bachrata, Wolfgang Bogner, Karin Poljanc, Siegfried Trattnig, Simon Daniel Robinson
PURPOSE: To develop a simple method for combining multi-echo phase information from a number of coils in an array that requires no volume coil or additional scans and yields signal-to-noise ratio-optimal images that reflect only ΔB0-related phase. THEORY AND METHODS: Two SNR optimal coil combination methods were developed which retrieve the ΔB0-related phase by determining the coil-dependent phase offsets. The first variant, MCPC-3D-S, requires the unwrapping of one phase image; the second variant, ASPIRE, allows unwrapping to be avoided if two echoes j and k satisfy the echo time relation m⋅TEk=(m+1)⋅TEj, where m is an integer, making this a particularly fast and robust approach...
October 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29034509/3d-diffusion-weighted-129-xe-mri-for-whole-lung-morphometry
#6
Ho-Fung Chan, Neil J Stewart, Graham Norquay, Guilhem J Collier, Jim M Wild
PURPOSE: To obtain whole lung morphometry measurements from (129) Xe in a single breath-hold with 3D multiple b-value (129) Xe diffusion-weighted MRI (DW-MRI) with an empirically optimized diffusion time and compressed sensing for scan acceleration. METHODS: Prospective three-fold undersampled 3D multiple b-value hyperpolarized (129) Xe DW-MRI datasets were acquired, and the diffusion time (Δ) was iterated so as to provide diffusive length scale (LmD ) estimates from the stretched exponential model (SEM) that are comparable to those from (3) He...
October 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29034505/in-vivo-characterization-of-the-downfield-part-of-1-h-mr-spectra-of-human-brain-at-9-4-t-magnetization-exchange-with-water-and-relation-to-conventionally-determined-metabolite-content
#7
Nicole D Fichtner, Ioannis-Angelos Giapitzakis, Nikolai Avdievich, Ralf Mekle, Daniel Zaldivar, Anke Henning, Roland Kreis
PURPOSE: To perform exchange-rate measurements on the in vivo human brain downfield spectrum (5-10 ppm) at 9.4 T and to compare the variation in concentrations of the downfield resonances and of known upfield metabolites to determine potential peak labels. METHODS: Non-water-suppressed metabolite cycling was used in combination with an inversion transfer technique in two brain locations in healthy volunteers to measure the exchange rates and T1 values of exchanging peaks...
October 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29034502/ghost-reduction-in-echo-planar-imaging-by-joint-reconstruction-of-images-and-line-to-line-delays-and-phase-errors
#8
Julianna D Ianni, E Brian Welch, William A Grissom
PURPOSE: To correct line-to-line delays and phase errors in echo-planar imaging (EPI). THEORY AND METHODS: EPI-trajectory auto-corrected image reconstruction (EPI-TrACR) is an iterative maximum-likelihood technique that exploits data redundancy provided by multiple receive coils between nearby lines of k-space to determine and correct line-to-line trajectory delays and phase errors that cause ghosting artifacts. EPI-TrACR was efficiently implemented using a segmented FFT and was applied to in vivo brain data acquired at 7 T across acceleration (1×-4×) and multishot factors (1-4 shots), and in a time series...
October 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29030882/accelerated-multicontrast-volumetric-imaging-with-isotropic-resolution-for-improved-peri-infarct-characterization-using-parallel-imaging-low-rank-and-spatially-varying-edge-preserving-sparse-modeling
#9
Li Zhang, Peng Lai, Mihaela Pop, Graham A Wright
PURPOSE: To achieve consistent effectiveness in reconstruction of fine image features for cases of varying contrast-to-noise ratio (CNR) to facilitate translating accelerated multicontrast volumetric imaging with isotropic resolution toward clinical utility in peri-infarct characterization. THEORY AND METHODS: A low-rank and spatially varying edge-preserving constrained compressed sensing parallel imaging reconstruction method (CP-LASER) is developed to effectively preserve contrast of small-scale structures for highly accelerated multicontrast volumetric imaging in CNR-limited scenarios...
October 13, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29030880/direct-saturation-corrected-chemical-exchange-saturation-transfer-mri-of-glioma-simplified-decoupling-of-amide-proton-transfer-and-nuclear-overhauser-effect-contrasts
#10
Iris Yuwen Zhou, Enfeng Wang, Jerry S Cheung, Dongshuang Lu, Yang Ji, Xiaoan Zhang, Giulia Fulci, Phillip Zhe Sun
PURPOSE: Chemical exchange saturation transfer (CEST) MRI has shown promise in tissue characterization in diseases like stroke and tumor. However, in vivo CEST imaging such as amide proton transfer (APT) MRI is challenging because of concomitant factors such as direct water saturation, macromolecular magnetization transfer, and nuclear overhauser effect (NOE), which lead to a complex contrast in the commonly used asymmetry analysis (MTRasym). Here, we propose a direct saturation-corrected CEST (DISC-CEST) analysis for simplified decoupling and quantification of in vivo CEST effects...
October 13, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29030876/reproducibility-of-cmro2-determination-using-dynamic-17-o-mri
#11
Sebastian C Niesporek, Reiner Umathum, Jonathan M Lommen, Nicolas G R Behl, Daniel Paech, Peter Bachert, Mark E Ladd, Armin M Nagel
PURPOSE: To assess the reproducibility of (17) O MRI-based determination of the cerebral metabolic rate of oxygen consumption (CMRO2 ) in healthy volunteers. To assess the influence of image acquisition and reconstruction parameters on dynamic quantification of functional parameters such as CMRO2 . METHODS: Dynamic (17) O MRI data were simulated and used to investigate influences of temporal resolution (Δt) and partial volume correction (PVC) on the determination of CMRO2 ...
October 13, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29024066/a-comparison-of-exogenous-and-endogenous-cest-mri-methods-for-evaluating-in-vivo-ph
#12
Leila R Lindeman, Edward A Randtke, Rachel A High, Kyle M Jones, Christine M Howison, Mark D Pagel
PURPOSE: Extracellular pH (pHe) is an important biomarker for cancer cell metabolism. Acido-chemical exchange saturation transfer (CEST) MRI uses the contrast agent iopamidol to create spatial maps of pHe. Measurements of amide proton transfer exchange rates (kex ) from endogenous CEST MRI were compared to pHe measurements by exogenous acido-CEST MRI to determine whether endogenous kex could be used as a proxy for pHe measurements. METHODS: Spatial maps of pHe and kex were obtained using exogenous acidoCEST MRI and an endogenous CEST MRI analyzed with the omega plot method, respectively, to evaluate mouse kidney, a flank tumor model, and a spontaneous lung tumor model...
October 11, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29023982/medi-0-morphology-enabled-dipole-inversion-with-automatic-uniform-cerebrospinal-fluid-zero-reference-for-quantitative-susceptibility-mapping
#13
Zhe Liu, Pascal Spincemaille, Yihao Yao, Yan Zhang, Yi Wang
PURPOSE: To develop a quantitative susceptibility mapping (QSM) method with a consistent zero reference using minimal variation in cerebrospinal fluid (CSF) susceptibility. THEORY AND METHODS: The ventricular CSF was automatically segmented on the R2* map. An L2 -regularization was used to enforce CSF susceptibility homogeneity within the segmented region, with the averaged CSF susceptibility as the zero reference. This regularization for CSF homogeneity was added to the model used in a prior QSM method (morphology enabled dipole inversion [MEDI])...
October 11, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29023975/motion-robust-high-resolution-3d-free-breathing-pulmonary-mri-using-dynamic-3d-image-self-navigator
#14
Wenwen Jiang, Frank Ong, Kevin M Johnson, Scott K Nagle, Thomas A Hope, Michael Lustig, Peder E Z Larson
PURPOSE: To achieve motion robust high resolution 3D free-breathing pulmonary MRI utilizing a novel dynamic 3D image navigator derived directly from imaging data. METHODS: Five-minute free-breathing scans were acquired with a 3D ultrashort echo time (UTE) sequence with 1.25 mm isotropic resolution. From this data, dynamic 3D self-navigating images were reconstructed under locally low rank (LLR) constraints and used for motion compensation with one of two methods: a soft-gating technique to penalize the respiratory motion induced data inconsistency, and a respiratory motion-resolved technique to provide images of all respiratory motion states...
October 11, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29023969/calculating-potential-error-in-sodium-mri-with-respect-to-the-analysis-of-small-objects
#15
Robert W Stobbe, Christian Beaulieu
PURPOSE: To facilitate correct interpretation of sodium MRI measurements, calculation of error with respect to rapid signal decay is introduced and combined with that of spatially correlated noise to assess volume-of-interest (VOI) (23) Na signal measurement inaccuracies, particularly for small objects. METHODS: Noise and signal decay-related error calculations were verified using twisted projection imaging and a specially designed phantom with different sized spheres of constant elevated sodium concentration...
October 11, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29019349/do-workers-health-surveillance-examinations-fulfill-their-occupational-preventive-objective-analysis-of-the-medical-practice-of-occupational-physicians-in-catalonia-spain
#16
Mari Cruz Rodríguez-Jareño, Emilia Molinero, Jaume de Montserrat, Antoni Vallès, Marta Aymerich
OBJECTIVES: Although routine workers' health examinations are extensively performed worldwide with important resource allocation, few studies have analyzed their quality. The objective of this study has been to analyze the medical practice of workers' health examinations in Catalonia (Spain) in terms of its occupational preventive aim. MATERIAL AND METHODS: A cross-sectional study was carried out by means of an online survey addressed to occupational physicians who were members of the Catalan Society of Safety and Occupational Medicine...
October 6, 2017: International Journal of Occupational Medicine and Environmental Health
https://www.readbyqxmd.com/read/29017897/patients-conceptions-of-terms-related-to-sexual-interest-desire-and-arousal
#17
John D DeLamater, Kevin P Weinfurt, Kathryn E Flynn
BACKGROUND: Measurement of sexual function typically uses self-report, which, to work as intended, must use language that is understood consistently by diverse respondents. Commonly used measures employ multiple terms, primarily (sexual) interest, desire, and arousal, that might not be understood in the same way by laypeople and professionals. AIM: To inform self-reported measurement efforts for research and clinical settings by examining how US men and women recruited from a health care setting understand and interpret different terms...
October 7, 2017: Journal of Sexual Medicine
https://www.readbyqxmd.com/read/29017802/big-data-and-total-hip-arthroplasty-how-do-large-databases-compare
#18
Nicholas A Bedard, Andrew J Pugely, Michael A McHugh, Nathan R Lux, Kevin J Bozic, John J Callaghan
BACKGROUND: Use of large databases for orthopedic research has become extremely popular in recent years. Each database varies in the methods used to capture data and the population it represents. The purpose of this study was to evaluate how these databases differed in reported demographics, comorbidities, and postoperative complications for primary total hip arthroplasty (THA) patients. METHODS: Primary THA patients were identified within National Surgical Quality Improvement Programs (NSQIP), Nationwide Inpatient Sample (NIS), Medicare Standard Analytic Files (MED), and Humana administrative claims database (HAC)...
September 13, 2017: Journal of Arthroplasty
https://www.readbyqxmd.com/read/28994492/quality-of-clinical-brain-tumor-mr-spectra-judged-by-humans-and-machine-learning-tools
#19
Sreenath P Kyathanahally, Victor Mocioiu, Nuno Pedrosa de Barros, Johannes Slotboom, Alan J Wright, Margarida Julià-Sapé, Carles Arús, Roland Kreis
PURPOSE: To investigate and compare human judgment and machine learning tools for quality assessment of clinical MR spectra of brain tumors. METHODS: A very large set of 2574 single voxel spectra with short and long echo time from the eTUMOUR and INTERPRET databases were used for this analysis. Original human quality ratings from these studies as well as new human guidelines were used to train different machine learning algorithms for automatic quality control (AQC) based on various feature extraction methods and classification tools...
October 10, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28994487/scan-rescan-of-axcaliber-macromolecular-tissue-volume-and-g-ratio-in-the-spinal-cord
#20
Tanguy Duval, Victoria Smith, Nikola Stikov, Eric C Klawiter, Julien Cohen-Adad
PURPOSE: Recent MRI techniques have been introduced that can extract microstructural information in the white matter, such as the density or macromolecular content. Translating quantitative MRI to the clinic raises many challenges in terms of acquisition strategy, modeling of the MRI signal, artifact corrections, and metric extraction (template registration and partial volume effects). In this work, we investigated the scan-rescan repeatability of several quantitative MRI techniques in the human spinal cord...
October 10, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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