Characterization of Diffusion Anisotropy in DWI

Abstract

Diffusion-weighted magnetic resonance imaging (DWI) is unrivaled in its ability to quantify changes in biological tissue microstructure noninvasively. The quantification is based on the anisotropy of water diffusion and fiber pathways determined from DWI measurements. This chelator is devoted to the study of the characterization of diffusion anistropy. Two methods for characterizing diffusion anisotropy are introduced. One uses transition probability density function (PDF), and the other uses apparent diffusion coefficient (ADC) profiles. Techniques for estimating the PDF and ADC profiles from high angular resolution DWI are reviewed. In particular we presented a variational framework for the estimation of the PDF modeled as a mixture of two Gaussians. We also described a variational model for the estimation of the ADC profiles represented by a truncated spherical harmonic series, and the algorithm for the characterization of diffusion anisotropy using ADC profiles. These two models are distinguished by simultaneous smoothing and estimation. Experimental results indicate the effectiveness of these models in enhancing and revealing intravoxel information.