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https://www.readbyqxmd.com/read/29887662/evaluation-of-inter-site-bias-and-variance-in-diffusion-weighted-mri
#1
Allison E Hainline, Vishwesh Nath, Prasanna Parvathaneni, Justin Blaber, Baxter Rogers, Allen Newton, Jeffrey Luci, Heidi Edmonson, Hakmook Kang, Bennett A Landman
An understanding of the bias and variance of diffusion weighted magnetic resonance imaging (DW-MRI) acquisitions across scanners, study sites, or over time is essential for the incorporation of multiple data sources into a single clinical study. Studies that combine samples from various sites may be introducing confounding due to site-specific artifacts and patterns. Differences in bias and variance across sites may render the scans incomparable, and, without correction, any inferences obtained from these data are misleading...
March 2018: Proceedings of SPIE
https://www.readbyqxmd.com/read/29887661/shard-spherical-harmonic-based-robust-outlier-detection-for-hardi-methods
#2
Vishwesh Nath, Kurt G Schilling, Allison E Hainline, Prasanna Parvathaneni, Justin A Blaber, Ilwoo Lyu, Adam W Anderson, Hakmook Kang, Allen T Newton, Baxter P Rogers, Bennett A Landman
High Angular Resolution Diffusion Imaging (HARDI) models are used to capture complex intra-voxel microarchitectures. The magnetic resonance imaging sequences that are sensitized to diffusion are often highly accelerated and prone to motion, physiologic, and imaging artifacts. In diffusion tensor imaging, robust statistical approaches have been shown to greatly reduce these adverse factors without human intervention. Similar approaches would be possible with HARDI methods, but robust versions of each distinct HARDI approach would be necessary...
March 2018: Proceedings of SPIE
https://www.readbyqxmd.com/read/29531965/empirical-estimation-of-intravoxel-structure-with-persistent-angular-structure-and-q-ball-models-of-diffusion-weighted-mri
#3
Vishwesh Nath, Kurt G Schilling, Prasanna Parvathaneni, Justin Blaber, Allison E Hainline, Zhaohua Ding, Adam Anderson, Bennett A Landman
The diffusion tensor model is nonspecific in regions where micrometer structural patterns are inconsistent at the millimeter scale (i.e., brain regions with pathways that cross, bend, branch, fan, etc.). Numerous models have been proposed to represent crossing fibers and complex intravoxel structure from in vivo diffusion weighted magnetic resonance imaging (e.g., high angular resolution diffusion imaging-HARDI). Here, we present an empirical comparison of two HARDI approaches-persistent angular structure MRI (PAS-MRI) and Q-ball-using a newly acquired reproducibility dataset...
January 2018: Journal of Medical Imaging
https://www.readbyqxmd.com/read/29520641/structural-connectome-with-high-angular-resolution-diffusion-imaging-mri-assessing-the-impact-of-diffusion-weighting-and-sampling-on-graph-theoretic-measures
#4
Giuseppina Caiazzo, Michele Fratello, Federica Di Nardo, Francesca Trojsi, Gioacchino Tedeschi, Fabrizio Esposito
PURPOSE: Advances in computational network analysis have enabled the characterization of topological properties of human brain networks (connectomics) from high angular resolution diffusion imaging (HARDI) MRI structural measurements. In this study, the effect of changing the diffusion weighting (b value) and sampling (number of gradient directions) was investigated in ten healthy volunteers, with specific focus on graph theoretical network metrics used to characterize the human connectome...
May 2018: Neuroradiology
https://www.readbyqxmd.com/read/29411435/empirical-single-sample-quantification-of-bias-and-variance-in-q-ball-imaging
#5
Allison E Hainline, Vishwesh Nath, Prasanna Parvathaneni, Justin A Blaber, Kurt G Schilling, Adam W Anderson, Hakmook Kang, Bennett A Landman
PURPOSE: The bias and variance of high angular resolution diffusion imaging methods have not been thoroughly explored in the literature and may benefit from the simulation extrapolation (SIMEX) and bootstrap techniques to estimate bias and variance of high angular resolution diffusion imaging metrics. METHODS: The SIMEX approach is well established in the statistics literature and uses simulation of increasingly noisy data to extrapolate back to a hypothetical case with no noise...
February 6, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29387938/post-mortem-inference-of-the-human-hippocampal-connectivity-and-microstructure-using-ultra-high-field-diffusion-mri-at-11-7-t
#6
Justine Beaujoin, Nicola Palomero-Gallagher, Fawzi Boumezbeur, Markus Axer, Jeremy Bernard, Fabrice Poupon, Daniel Schmitz, Jean-François Mangin, Cyril Poupon
The human hippocampus plays a key role in memory management and is one of the first structures affected by Alzheimer's disease. Ultra-high magnetic resonance imaging provides access to its inner structure in vivo. However, gradient limitations on clinical systems hinder access to its inner connectivity and microstructure. A major target of this paper is the demonstration of diffusion MRI potential, using ultra-high field (11.7 T) and strong gradients (750 mT/m), to reveal the extra- and intra-hippocampal connectivity in addition to its microstructure...
January 31, 2018: Brain Structure & Function
https://www.readbyqxmd.com/read/29074279/histological-validation-of-diffusion-mri-fiber-orientation-distributions-and-dispersion
#7
Kurt G Schilling, Vaibhav Janve, Yurui Gao, Iwona Stepniewska, Bennett A Landman, Adam W Anderson
Diffusion magnetic resonance imaging (dMRI) is widely used to probe tissue microstructure, and is currently the only non-invasive way to measure the brain's fiber architecture. While a large number of approaches to recover the intra-voxel fiber structure have been utilized in the scientific community, a direct, 3D, quantitative validation of these methods against relevant histological fiber geometries is lacking. In this study, we investigate how well different high angular resolution diffusion imaging (HARDI) models and reconstruction methods predict the ground-truth histologically defined fiber orientation distribution (FOD), as well as investigate their behavior over a range of physical and experimental conditions...
January 15, 2018: NeuroImage
https://www.readbyqxmd.com/read/28971011/structurofunctional-resting-state-networks-correlate-with-motor-function-in-chronic-stroke
#8
Benjamin T Kalinosky, Reivian Berrios Barillas, Brian D Schmit
PURPOSE: Motor function and recovery after stroke likely rely directly on the residual anatomical connections in the brain and its resting-state functional connectivity. Both structural and functional properties of cortical networks after stroke are revealed using multimodal magnetic resonance imaging (MRI). Specifically, functional connectivity MRI (fcMRI) can extract functional networks of the brain at rest, while structural connectivity can be estimated from white matter fiber orientations measured with high angular-resolution diffusion imaging (HARDI)...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28870572/high-angular-resolution-diffusion-imaging-abnormalities-in-the-early-stages-of-amyotrophic-lateral-sclerosis
#9
Francesca Trojsi, Giuseppina Caiazzo, Federica Di Nardo, Michele Fratello, Gabriella Santangelo, Mattia Siciliano, Cinzia Femiano, Antonio Russo, Maria Rosaria Monsurrò, Mario Cirillo, Gioacchino Tedeschi, Fabrizio Esposito
OBJECTIVE: Using magnetic resonance (MR) high angular resolution diffusion imaging (HARDI), we aimed at revealing possible microstructural alterations in the early stage of amyotrophic lateral sclerosis (ALS), still not completely elucidated. METHODS: We studied 22 patients with ALS, in stages 1 or 2 according to the King's staging system, compared to 18 healthy controls (HCs). Statistical mapping of HARDI-derived parameters and tractography measures were performed using the Q-ball imaging diffusion data model...
September 15, 2017: Journal of the Neurological Sciences
https://www.readbyqxmd.com/read/28845076/effects-of-b-value-and-number-of-gradient-directions-on-diffusion-mri-measures-obtained-with-q-ball-imaging
#10
Kurt G Schilling, Vishwesh Nath, Justin Blaber, Robert L Harrigan, Zhaohua Ding, Adam W Anderson, Bennett A Landman
High-angular-resolution diffusion-weighted imaging (HARDI) MRI acquisitions have become common for use with higher order models of diffusion. Despite successes in resolving complex fiber configurations and probing microstructural properties of brain tissue, there is no common consensus on the optimal b-value and number of diffusion directions to use for these HARDI methods. While this question has been addressed by analysis of the diffusion-weighted signal directly, it is unclear how this translates to the information and metrics derived from the HARDI models themselves...
February 2017: Proceedings of SPIE
https://www.readbyqxmd.com/read/28777598/primordial-black-holes-from-supersymmetry-in-the-early-universe
#11
Eric Cotner, Alexander Kusenko
Supersymmetric extensions of the standard model generically predict that in the early Universe a scalar condensate can form and fragment into Q balls before decaying. If the Q balls dominate the energy density for some period of time, the relatively large fluctuations in their number density can lead to formation of primordial black holes (PBH). Other scalar fields, unrelated to supersymmetry, can play a similar role. For a general charged scalar field, this robust mechanism can generate black holes over the entire mass range allowed by observational constraints, with a sufficient abundance to account for all dark matter in some parameter ranges...
July 21, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28744187/spatiotemporal-relationship-of-brain-pathways-during-human-fetal-development-using-high-angular-resolution-diffusion-mr-imaging-and-histology
#12
Lana Vasung, Marina Raguz, Ivica Kostovic, Emi Takahashi
In this study, we aimed to identify major fiber pathways and their spatiotemporal relationships within transient fetal zones in the human fetal brain by comparing postmortem high-angular resolution diffusion MR imaging (HARDI) in combination with deterministic streamline tractography and histology. Diffusion weighted imaging was performed on postmortem human fetal brains [N = 9, age = 18-34 post-conceptual weeks (PCW)] that were grossly normal with no pathologic abnormalities. After HARDI was performed, the fibers were reconstructed using Q-ball algorithm and deterministic streamline tractography...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/28736471/comparison-of-multi-fiber-reproducibility-of-pas-mri-and-q-ball-with-empirical-multiple-b-value-hardi
#13
Vishwesh Nath, Kurt G Schilling, Justin A Blaber, Zhaohua Ding, Adam W Anderson, Bennett A Landman
Crossing fibers are prevalent in human brains and a subject of intense interest for neuroscience. Diffusion tensor imaging (DTI) can resolve tissue orientation but is blind to crossing fibers. Many advanced diffusion-weighted magnetic resolution imaging (MRI) approaches have been presented to extract crossing-fibers from high angular resolution diffusion imaging (HARDI), but the relative sensitivity and specificity of approaches remains unclear. Here, we examine two leading approaches (PAS and q-ball) in the context of a large-scale, single subject reproducibility study...
February 11, 2017: Proceedings of SPIE
https://www.readbyqxmd.com/read/28694526/intrapatient-functional-clonality-deconvoluted-by-coupling-intracellular-flow-cytometry-and-next-generation-sequencing-in-human-leukemia
#14
Q Zhang, M C Ball, Y Zhao, M Balasis, C Letson, A Vedder, A F List, P K Epling-Burnette, R S Komrokji, E Padron
The interplay between tumor heterogeneity and microenvironmental factors is a critical mechanism for clonal selection in leukemia. Evidence of unique clonal capacities to engraft within patient-derived xenograft (PDX) models suggests that intrapatient genetic architecture may be defined by functional differences at the clonal level. However, methods to detect functional differences assigned to genetically defined clones remain limited. Here, we describe a scalable method to directly measure the functional properties of clones within the same leukemia patient by coupling intracellular flow cytometry and next-generation sequencing (NGS)...
February 2018: Leukemia: Official Journal of the Leukemia Society of America, Leukemia Research Fund, U.K
https://www.readbyqxmd.com/read/28438712/empirical-consideration-of-the-effects-of-acquisition-parameters-and-analysis-model-on-clinically-feasible-q-ball-imaging
#15
Kurt G 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...
July 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/26683657/multi-shell-hybrid-diffusion-imaging-hydi-at-7-tesla-in-tgf344-ad-transgenic-alzheimer-rats
#16
Madelaine Daianu, Russell E Jacobs, Tara M Weitz, Terrence C Town, Paul M Thompson
Diffusion weighted imaging (DWI) is widely used to study microstructural characteristics of the brain. Diffusion tensor imaging (DTI) and high-angular resolution imaging (HARDI) are frequently used in radiology and neuroscience research but can be limited in describing the signal behavior in composite nerve fiber structures. Here, we developed and assessed the benefit of a comprehensive diffusion encoding scheme, known as hybrid diffusion imaging (HYDI), composed of 300 DWI volumes acquired at 7-Tesla with diffusion weightings at b = 1000, 3000, 4000, 8000 and 12000 s/mm2 and applied it in transgenic Alzheimer rats (line TgF344-AD) that model the full clinico-pathological spectrum of the human disease...
2015: PloS One
https://www.readbyqxmd.com/read/26654181/identifying-preoperative-language-tracts-and-predicting-postoperative-functional-recovery-using-hardi-q-ball-fiber-tractography-in-patients-with-gliomas
#17
Eduardo Caverzasi, Shawn L Hervey-Jumper, Kesshi M Jordan, Iryna V Lobach, Jing Li, Valentina Panara, Caroline A Racine, Vanitha Sankaranarayanan, Bagrat Amirbekian, Nico Papinutto, Mitchel S Berger, Roland G Henry
OBJECT Diffusion MRI has uniquely enabled in vivo delineation of white matter tracts, which has been applied to the segmentation of eloquent pathways for intraoperative mapping. The last decade has also seen the development from earlier diffusion tensor models to higher-order models, which take advantage of high angular resolution diffusion-weighted imaging (HARDI) techniques. However, these advanced methods have not been widely implemented for routine preoperative and intraoperative mapping. The authors report on the application of residual bootstrap q-ball fiber tracking for routine mapping of potentially functional language pathways, the development of a system for rating tract injury to evaluate the impact on clinically assessed language function, and initial results predicting long-term language deficits following glioma resection...
July 2016: Journal of Neurosurgery
https://www.readbyqxmd.com/read/26444579/resolving-power-for-the-diffusion-orientation-distribution-function
#18
Jens H Jensen, Joseph A Helpern
PURPOSE: The diffusion orientation distribution function (dODF) is primarily used for white matter fiber tractography. Here the resolving power of the dODF is investigated for a simple diffusion model of two intersecting axonal fiber bundles. METHODS: The resolving power for the dODF is evaluated using the Sparrow criterion. This is determined for the exact dODF and also for q-space imaging (QSI), q-ball, and kurtosis approximations. RESULTS: Based on theoretical and numerical calculations, the resolving power is found to depend on the eigenvalues of the diffusion model and on the degree of radial weighting for the dODF...
August 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/26410325/fiber-tracking-of-brain-white-matter-based-on-graph-theory
#19
Meng Lu
Brain white matter tractography is reconstructed via diffusion-weighted magnetic resonance images. Due to the complex structure of brain white matter fiber bundles, fiber crossing and fiber branching are abundant in human brain. And regular methods with diffusion tensor imaging (DTI) can't accurately handle this problem. the biggest problems of the brain tractography. Therefore, this paper presented a novel brain white matter tractography method based on graph theory, so the fiber tracking between two voxels is transformed into locating the shortest path in a graph...
2015: Technology and Health Care: Official Journal of the European Society for Engineering and Medicine
https://www.readbyqxmd.com/read/26406103/brain-white-matter-fiber-estimation-and-tractography-using-q-ball-imaging-and-bayesian-model
#20
Meng Lu
Diffusion tensor imaging allows for the non-invasive in vivo mapping of the brain tractography. However, fiber bundles have complex structures such as fiber crossings, fiber branchings and fibers with large curvatures that tensor imaging (DTI) cannot accurately handle. This study presents a novel brain white matter tractography method using Q-ball imaging as the data source instead of DTI, because QBI can provide accurate information about multiple fiber crossings and branchings in a single voxel using an orientation distribution function (ODF)...
2015: Bio-medical Materials and Engineering
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