Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 52 for “"Tractography"”.
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A stochastic tractography system and applications
… Diffusion Tensor Imaging (DTI) and stochastic tractography allow us to investigate white matter architecture non-invasively through measurements of water self diffusion throughout the brain. Many comparative studies of white matter architecture utilize spatially localized comparisons of …
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Validation of MRtrix tractography for clinical use
Tractography is a technique which uses non-invasive diffusion magnetic resonance imaging (dMRI) to model the structural connections of the brain in vivo. Since it is not known to what extent the exact positions of white matter tracts vary between individuals, and how scan parameters affect the …
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Imaging 3D tissue fiber organization using optical polarization tractography
Optical polarization tractography (OPT) is a new imaging technology developed based on an advanced Jones matrix implementation of polarization-sensitive optical coherence tomography (PSOCT). OPT can acquire high-resolution, three-dimensional (3D), depth-resolved images of fiber organization in …
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Diffusion Tensor Imaging: Evaluation of Tractography Algorithm Performance Using Ground Truth Phantoms
… directions of anisotropic water diffusion. DTI tractography estimates are a macroscopically sampled description of underlying microscopic structure, and are therefore of limited validity. The under-sampling of underlying white matter structure in DTI data gives rise to Intra-Voxel Orientational …
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Diffusion Tensor Imaging and Quantitative Tractography of Skeletal Muscle for Microstructural Tissue Characterization
… is exploring the feasibility of using DTI and tractography to accurately represent muscle structure in the presence of imaging noise. Noise produces a random perturbation of the diffusion tensor, which can shift the eigenvectors and produce incorrect results. Various tractography algorithms are …
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Finding the missing connection: diffusion-based tractography reconstruction of the acoustic radiation and other applications
Magnetic resonance diffusion-based tractography techniques have offered a real breakthrough in brain studies. These methods allow, for the first time, to explore the anatomical organization of white matter pathways in humans, in-vivo and non-invasively. As any other method, diffusion-based …
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Vehicle-pedestrian interaction using naturalistic driving video through tractography of relative positions and pedestrian pose estimation
… clicked human data. We have obtained correct tractography results for over 82% of the videos. For pose estimation, we have used flexible mixture model for capturing co-occurrence between pedestrian body segments. Based on existing single-frame human pose estimation model, we have introduced …
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Cerebral white matter analysis using diffusion imaging
In this thesis we address the whole-brain tractography segmentation problem. Diffusion magnetic resonance imaging can be used to create a representation of white matter tracts in the brain via a process called tractography. Whole brain tractography outputs thousands of trajectories that each …
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Validation of dMRI techniques for mapping brain pathways
Diffusion magnetic resonance imaging (dMRI) tractography is the only non-invasive tool for studying the connectional architecture of the brain in vivo. By measuring the diffusion of water molecules dMRI provides unique information about white matter pathways and their integrity, making it an …
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Machine Learning for Tract Segmentation in dMRI data
… of the brain as a set of streamlines, called tractography. A streamline is a vectorial representation of thousands of neuronal axons expressing structural connectivity. An important task is to group the same functional streamlines into one tract segmentation. This work is extremely helpful for …
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Simulation of tongue muscle deformation
… by high resolution diffusion tensor imaging with tractography. DTI tractography displayed the complete fiber anatomy of the tongue, consisting of a core region of orthogonally aligned fibers encased within a longitudinal sheath, which merge with the externally connected styloglossus, hyoglossus, …
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A comparison of methods for the registration of tractographic fibre images
Diffusion tensor imaging (DTI) and tractography have opened up new avenues in neuroscience and are allowing previously unexplored areas of neuroanatomy and function to be researched.
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New perspectives on the multimodal validation of the human brain white matter anatomy.
… of white matter connections. Diffusion MRI-based tractography has transformed neuroscience by enabling non-invasive mapping of these white matter connections in the living human brain, fueling both basic research and clinical practices. Yet, tractography remains an indirect measure, prone to …
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Brain Connectivity in Autism Spectrum Disorder
… consisted in the creation of a diffusion tensor tractography atlas of the normal human brain derived from 40 healthy adults. The atlas was then used to localise the findings from a metaanalysis of published voxel-based morphometry studies investigating white matter abnormalities in ASD. This …
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Deep Learning for Brain Structural Connectivity Analysis: From Tissue Segmentation to Tractogram Alignment
… to investigate the structures of WM through tractography techniques, obtaining a virtual representation of the WM pathways called tractogram. Since the tractogram is a collection of digital fibers representing the neuronal axons connecting the brain's cortical areas, it is the fundamental …
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Structural organization in 9-year-old HIV-infected children and HIV-exposed children
… methods, such as voxel wise analysis (VWA) and tractography. Within this cohort, we've previously reported white matter alterations using VWA at ages 5 and 7 years in the inferior/superior longitudinal fasciculus (ILF/SLF), inferior fronto-occipital fasciculus (IFOF), forceps minor, superior …
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Neuroimaging investigation of the motor control disorder, dystonia with special emphasis on laryngeal dystonia
… anisotropy (FA) and probabilistic diffusion tractography analyses were used to investigate the questions of whether LD patients exhibited altered connectivity between BG and brainstem regions and whether FA and tractography could be used to predict differences in clinical presentations of …
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Learning motion patterns using hierarchical Bayesian models
… matter in the brain in vivo. Using methods of tractography segmentation, one can connect local diffusion measurements to create global fiber trajectories, which can then be clustered into anatomically meaningful bundles. This is similar to clustering trajectories of objects in visual …
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Three dimensional mapping of lingual myoarchitecture
… diffusion spectrum imaging (DSI), DSI with tractography, q-ball imaging, diffusion tensor imaging (DTI), and ADC and FA mapping. Each imaging method was evaluated in three ways: 1) finite element simulation using 2D structures to model the diffusion environment in an idealized situation, 2) …
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Generative models of brain connectivity for population studies
… model to merge information from DWI tractography and resting-state fMRI correlations. Our formulation captures the interaction between hidden templates of anatomical and functional connectivity within the brain. We also present an intuitive extension to population studies and …
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