نتایج جستجو برای: voxel model
تعداد نتایج: 2115264 فیلتر نتایج به سال:
Introduction: Dynamic and 4D MRI have been used to understand the functional and metabolic aspects of disease and its progression. Examples include dynamic contrast enhancement (DCE) for micro-vasculature of tumors and MR spectroscopic imaging (MRSI) for tissue bio-chemistry. The post-processing strategy for most of these protocols consists of obtaining parametric maps using voxel-by-voxel esti...
BACKGROUND 3D ultrasound volume reconstruction from B-model ultrasound slices can provide more clearly and intuitive structure of tissue and lesion for the clinician. METHODS This paper proposes a novel Global Path Matching method for the 3D reconstruction of freehand ultrasound images. The proposed method composes of two main steps: bin-filling scheme and hole-filling strategy. For the bin-f...
Fractional anisotropy (FA) and mean diffusivity (MD) are the most frequently used metrics to investigate white matter impairments in mental disorders. However, these two metrics are derived from intra-voxel analyses and only reflect the diffusion properties solely within the voxel unit. Local diffusion homogeneity (LDH) is a newly developed inter-voxel metric which quantifies the local coherenc...
The fluctuations in a brain region's activation levels over a functional magnetic resonance imaging (fMRI) time-course are used in functional connectivity (FC) to identify networks with synchronous responses. It is increasingly recognized that multi-voxel activity patterns contain information that cannot be extracted from univariate activation levels. Here we present a novel analysis method tha...
مقدمه: در سال های اخیر، با افزایش میانگین امید به زندگی در جهان، تشخیص بیماری آلزایمر از اهمیت بالایی برخوردار گردیده است. در صورت پیشرفت اختلال شناختی خفیف (mci یا mild cognitive impairment)، توانایی های ذهنی بیمار به صورت غیر قابل برگشت پذیر مختل و منجر به بیماری آلزایمر و دمانس می گردد. این اختلال، مورد توجه ویژه ی پژوهشگران زیادی قرار گرفته است؛ چرا که با تشخیص آن در مراحل اولیه، می توان شر...
This thesis involves the tracking of white matter and heart fibers, using diffusion tensor imaging data and high resolution MR scans. Dynamic programming is employed to generate fibers linking regions of interest in the brain and heart with paths that minimize an energy constraint. From the diffusion tensor data it is possible to determine the probability that a fiber passing through a particul...
We represent the sequence of fMRI (Functional Magnetic Resonance Imaging) brain volumes recorded during a cognitive stimulus by a graph which consists of a set of local meshes. The corresponding cognitive process, encoded in the brain, is then represented by these meshes each of which is estimated assuming a linear relationship among the voxel time series in a predefined locality. First, we def...
White matter structures composed of myelinated axons in the living human brain are primarily studied by diffusion-weighted MRI (dMRI). These long-range projections are typically characterized in a two-step process: dMRI signal is used to estimate the orientation of axon segments within each voxel, then these local orientations are linked together to estimate the spatial extent of putative white...
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