DTI measures the anisotropic diffusion of water molecules. In tissues like white matter, water molecules tend to diffuse more rapidly along the direction of fiber tracts than perpendicular to them. This anisotropic diffusion is quantified using tensors, which are mathematical constructs that describe the direction and magnitude of diffusion. The primary tensor metric used in DTI is fractional anisotropy (FA), which ranges from 0 (isotropic diffusion) to 1 (highly anisotropic diffusion).
