Disease duration showed a differential pattern of correlation along the bundle thickness profile: we found that correlation was most significant across section III (r values ranging from −0.39 to −0.49, P < 0.05) and sections IV−V (r values ranging from −0.38 to −0.46, P < 0.05), while barely significant in section I (r values ranging from −0.38 to −0.39, P < 0.05), according to Witelson's classification.
We believe that the highly significant correlations, discrepant with respect to previous research ( Hasan et al., 2005 ; Sigal et al., 2012 ; Rimkus et al., 2013 ), might be largely explained by the fact that we assessed CC damage in a continuous fashion, without recurring to a priori subdivisions, and consequently to metrics averaged over pre-determined sections, which might have led to loss of space-variant information. 4.2 Regression findings Multiple regression analyses uncovered the differential pattern of contributions from the imaging characteristics of the entire CC to the global measures of disease severity.