Tract Based Spatial Statistics (TBSS) whole-brain group comparisons of white matter microstructural integrity (assessed via radial diffusivity) showing the contrast of persons with MS (PwMS) > healthy controls (HC), with lighter colors indicating the largest differences between groups. Analysis is restricted to those white matter voxels that constitute the skeleton (green) of the brain’s connectional architecture, whereby this skeleton can be matched across subjects. PwMS had a large network of impaired white matter integrity (reflected by higher radial diffusivity values), most notably within interhemispheric callosal fibers. The reverse contrast of HC > PwMS yielded no significant differences. Results are multiple comparison-corrected and controlled for age, gender, brain volume, and EDSS..