Diffusion Tensor Imaging

Abstract

Diffusion tensor imaging (DTI), or diffusion tensor magnetic resonance imaging (DT‐MRI), is a technique that measures the orientation dependence (i.e., anisotropy) of the diffusion process. This technique relies on diffusion‐induced MRI signal loss as a function of diffusion‐weighting gradient orientations. With DTI, the diffusion tensor at each spatial location can be characterized, and a series of parameters can be obtained to describe various aspects of the diffusion process in biological tissues. Typical parameters calculated from DTI include apparent diffusion coefficients (ADC), diffusion anisotropy indices, and the principal diffusion direction. These parameters (e.g., fractional anisotropy, or FA) can be used to reveal specific tissue structures, such as white‐matter fiber tracts in the brain, and detect their changes during disease progression and regression.