FIG 1. Average histograms from patients with multiple sclerosis (dashed line) and control volunteers (continuous line).

A, Mean diffusivity ().

B, Fractional anisotropy (FA).

FIG 2. Average histogram of fractional anisotropy (FA) from control volunteers (thick continuous line). This curve can be fitted by the superimposition of two theoretical gaussian curves, representing the distribution of fractional anisotropy values of gray (filled squares) and white (open triangles) matter. Height, mean, and SD of these curves can be estimated by minimizing the difference between the sum (dotted line) and the actual histogram. See the text for further details