However, a study with a larger sample size (134 patients with MDD vs. 54 healthy controls) showed that patients with MDD had no significant differences in FA, radial diffusivity (RD), mean diffusivity, and axonal diffusivity compared to healthy controls [ 26].
No regions showed reduced fractional anisotropy in the opposite comparison, i.e. in controls compared with subjects with PPAOS, or increased mean diffusivity in controls compared with PPAOS.
Patients showed large areas of reduced fractional anisotropy, as well as increased mean and axial diffusivities, compared with controls, despite the small amounts of cortical and white matter damage visible on standard imaging.
Diffusion tensor imaging measures, including fractional anisotropy (FA) and mean diffusivity (MD), were compared between groups and related to cognitive performance.
These patients showed statistically significant decrease in FA values and elevated mean diffusivity values as compared to age-matched controls [40].
It has previously been suggested that post-mortem diffusion-weighted MRI metrics may not reflect tissue microstructure to the same extent as they do in vivo (Shepherd et al., 2009 a, b ), which may be the source of lower fractional anisotropy and mean diffusivity values in our data compared to that seen in vivo (Miller et al., 2011).
Mean diffusivity was increased in chess players compared with that of controls in the left superior longitudinal fasciculus and the Elo score (a chess tournament ranking) was inversely related to mean diffusivity within the right superior longitudinal fasciculus.
We tested the diagnostic value of diffusion tensor-derived axial diffusivity (AD), mean diffusivity (MD) (=apparent diffusion coefficient) and radial diffusivity (RD) maps in comparison to T1w and T2w sequences.
Typical parameters related to diffusion are apparent diffusion coefficient (ADC), mean diffusivity (MD), mean kurtosis (MK), and fractional anisotropy (FA).
Widespread decreased fractional anisotropy (FA), and increased radial diffusivity (RaD) and mean diffusivity (MD) were observed in the ASD group compared to the TD group.
