Mean diffusivity and fractional anisotropy histograms of patients with multiple sclerosis

diffusion tensor MR imaging provides quantitative indices with increased specificity to the most destructive aspects of multiple sclerosis. In this study, we obtained brain mean diffusivity (D ¯) and fractional anisotropy histograms of patients with multiple sclerosis to compare them with those of healthy volunteers and to investigate the correlation between diffusion tensor MR imaging histogram-derived measures and the level of disability and quantities derived from conventional MR imaging. METHODS: Dual-echo and diffusion tensor MR images were obtained from 78 patients with relapsing-remitting, secondary progressive, or primary progressive multiple sclerosis and from 20 healthy control volunteers. After obtaining mean diffusivity (D ¯ ) and fractional anisotropy images and image coregistration, D ¯ and fractional anisotropy histograms were created. From each histogram, the following measures were derived: the average D ¯ and fractional anisotropy, the histogram peak heights, and the histogram peak locations. RESULTS: All the D ¯ and fractional anisotropy histogram-derived measures were different be-tween patients and controls at a significance level of P,.001. No differences were found in any of the considered quantities among the three multiple sclerosis phenotypes. In patients with re