Fractional Anisotropy (FA) is a scientific term, most commonly used in neuroscience, representing an index of white matter integrity.
Here's a breakdown:
-
Fractional Anisotropy (FA): A scalar value between 0 and 1 that quantifies the degree of anisotropy in a diffusion process. Anisotropy refers to direction-dependent properties.
-
Context: Diffusion Tensor Imaging (DTI): FA is derived from Diffusion Tensor Imaging (DTI), a magnetic resonance imaging (MRI) technique that measures the diffusion of water molecules in biological tissues. In the brain, water diffuses more readily along the direction of nerve fibers (axons) in white matter.
-
White Matter Integrity: FA provides information about the organization, density, and myelination of nerve fibers in white matter. Higher FA values generally indicate more coherent and aligned fiber tracts, while lower FA values suggest disruptions or damage.
-
Applications: FA is used to study various neurological conditions, including:
- Traumatic Brain Injury (TBI): FA can detect white matter damage after a TBI, even when conventional MRI scans appear normal.
- Multiple Sclerosis (MS): FA can reveal demyelination and axonal damage in MS.
- Neurodevelopmental Disorders: FA is used to study brain development in conditions like autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD).
- Neurodegenerative Diseases: FA can help assess white matter changes in Alzheimer's disease and Parkinson's disease.
- Stroke: FA helps in evaluating white matter damage after stroke.
In summary, Fractional Anisotropy (FA) serves as a valuable biomarker for assessing white matter integrity in various neurological and psychiatric conditions, providing insights into brain structure and function.
