Fractional Anisotropy (FA) is a measure derived from diffusion tensor imaging (DTI), a specialized form of MRI. FA quantifies the degree of anisotropy of water diffusion in tissues. In simpler terms, it measures how directionally dependent the movement of water molecules is within a given tissue. High FA values indicate highly directional water movement, often associated with structured tissues like white matter in the brain, while low FA values suggest more isotropic diffusion, common in less organized tissues.
