FA
Also written as: FA — Fractional Anisotropy
Fractional anisotropy, a scalar measure of the degree of directional water diffusion in brain tissue.
Full Definition
Fractional anisotropy (FA) is a normalized measure ranging from 0 to 1 that quantifies the degree of anisotropic diffusion within a voxel. Higher FA values indicate more directional diffusion, typically associated with intact white matter fiber bundles, while lower values suggest more isotropic diffusion found in gray matter or damaged white matter. FA is one of the most commonly reported DTI metrics and is sensitive to various pathological processes including demyelination, axonal damage, and edema.
Usage
Usage note: Always specify as diffusion metric; avoid confusion with other medical FA abbreviations
In Context
- "FA values in the genu of the corpus callosum showed significant reduction in patients with traumatic brain injury." — TBI research results
- "The FA map demonstrated preserved anisotropy in major white matter tracts despite the presence of lesions." — Multiple sclerosis assessment