Relevance of the skewness index in DTI exploration of multiple sclerosis

To this day, no parameter can really monitor the progression of multiple sclerosis (MS). In this study, an index the skewness (S) derived from parameters calculated in diffusion tensor imaging (DTI) has been tested on MS patients for its ability to monitor the disease course.

Eighteen patients underwent two examinations within 3 months consisting of a clinical evaluation (EDSS) and DTI acquisitions on a 1.5 T imager. Tensor was calculated thanks to"home-made" software. Mean diffusivity (MD) and fractional anisotropy (FA) histograms were described for normal-appearing white matter (NAWM) and gray matter (GM) of patients with S and also with usually indices peak position (pp) and peak height (ph) for the whole group of patients and for two separate groups according to their clinical status (EDSS < or = 3 and EDSS > 3 at month 0).

Although no significant clinical evolution is observed over 3 months, S in GM showed a significant shift for both MD/FA histograms towards abnormal values for the whole group of patients (p = 0.02/p = 0.04) and for the group with EDSS

S in GM could be an alternative marker to monitor the disease course before the repercussion on the clinical score.