Registration of diffusion-weighted magnetic resonance images (DW-MRIs) is a key step for population studies, or construction of brain atlases, among other important tasks. Given the high dimensionality of the data, registration is usually performed by relying on scalar representative images, such as the fractional anisotropy (FA) and non-diffusion-weighted (b0) images, thereby ignoring much of ...

Diffusion MRI (dMRI) is the unique technique to infer the microstructure of the white matter in vivo and noninvasively, by modeling the diffusion of water molecules. Ensemble Average Propagator (EAP) and Orientation Distribution Function (ODF) are two important Probability Density Functions (PDFs) which reflect the water diffusion. Estimation and processing of EAP and ODF is the central problem...

The diffusion framework exhibits many promising properties for the purposes of junction analysis. In its most common form, images are diffused either isotropically or with respect to gradient information in an anisotropical fashion. This information is then collected into an orientational distribution function (ODF) and the resulting features are modeled as ’X’, ’Y’ or ’T’shaped junctions. Spec...

Introduction. Diffusion-weighted (DW) MRI provides important information regarding the arrangement of white matter fibres. However, imperfections in the DW gradients may cause errors in the estimation of diffusion parameters. The sources of the gradient errors are various and may arise from long-term eddy currents, background gradients, imaging gradients, and spatial non-linearity and non-unifo...

One of the most famous methods to predict the stiffness of short fiber composites is micromechanical modeling. In this study, a Representative Volume Element (RVE) of a beech wood flour natural composite has been designed and the orientation averaging approach has been utilized to predict its stiffness tensor. The novelty of this work is in finding the proper fiber orientation distribution func...

We present a Bayesian probabilistic model to estimate the brain white matter atlas from high angular resolution diffusion imaging (HARDI) data. This model incorporates a shape prior of the white matter anatomy and the likelihood of individual observed HARDI datasets. We first assume that the atlas is generated from a known hyperatlas through a flow of diffeomorphisms and its shape prior can be ...

Abstract Direct experimental evaluation of the anisotropic yield locus (YL) a given material, representing zeros material’s function in stress space, is arduous. It much more practical to determine YL by combining limited measurements strengths with predictions from numerical models based on microstructural features such as orientation distribution (ODF; also referred crystallographic texture)....

J. S. Campbell, P. Savadjiev, G. B. Pike, K. Siddiqi Montreal Neurological Institute, Montreal, Quebec, Canada, McGill Centre for Intelligent Machines, Montreal, Quebec, Canada Introduction High angular resolution diffusion (HARD) MRI can be used to infer multiple subvoxel fibre directions [1-2], and this information can be used to improve the precision of fibre tractography over that achieved ...

Though there are a variety of experimental techniques available for residual stress measurements, diffraction-based measurements have the unique advantage estimating individual components strain matrix in crystalline material. This is then converted to stresses with appropriate continuum elasticity model(s) and X-ray elastic constants. In particular, based on electron or neutron diffractions th...

Fiber tracking is winning more and more interest in the neuroscience research field and clinical practice, for its ability in revealing the structural connectivity; the quality of the fiber tracking depends in great extent, on fiber directions extraction The PSO algorithm could give good approximation of these directions. I. MATERIALS AND METHODS The diffusion tensor MRI (DTI) was introduced by...