Table 2.

Four important diffusion tensor imaging (DTI) measurements.

Measurement	Formula
Fractional Anisotropy (FA)	$\sqrt{\frac{3}{2}}\sqrt{\frac{{\left({\lambda }_1-\overline{\mathsf{\lambda }}\right)}^2+{\left({\lambda }_2-\overline{\mathsf{\lambda }}\right)}^2+{\left({\lambda }_3-\overline{\mathsf{\lambda }}\right)}^2}{{\mathsf{\lambda }}_1^2+{\mathsf{\lambda }}_2^2+{\mathsf{\lambda }}_3^2}}$ where $\overline{\mathsf{\lambda }}$ = (${\lambda }_1$ + ${\lambda }_2$ + ${\lambda }_3$)/3
Mean Diffusivity (MD)	(λ1 + λ2 + λ3 )/3
Axial Diffusivity (AD)	λ1
Radial Diffusivity (RD)	(λ2 + λ3 )/2