Tissue Structure Analysis Using Anomalous Diffusion Signal Decay Models in Magnetic Resonance Imaging

Abstract

Diffusion magnetic resonance imaging plays a significant role in the study of tissue structures, such as by providing important biological information on prostate cancer and brain tissue complexity. Diffusion MRI contains information describing the isotropy and anisotropy of the diffusion assuming the existence of the Gaussian diffusion, which is referred to as mono-exponential signal decay. Because of the structural heterogeneity and complexity of biological tissues, diffusion is not always Gaussian. Hence, the diffusion signal decay is no longer mono-exponential. In order to investigate the deviation from mono-exponentiality decay many non-Gaussian diffusion models have been developed, such as the bi-exponential, stretched exponential, kurtosis, and fractional order calculus (FROC) models, as well as neurite orientation dispersion and density imaging (NODDI), combined hindered and restricted models of water diffusion (CHARMED), and anomalous diffusion imaging. The goal of this thesis is to show the ability of the anomalous diffusion signal decay models to characterize cellular microstructure on both the prostate and the structured brain tissue.