Diffusion tensor MRI alterations of subcortical deep gray matter in clinically isolated syndrome

Background Abnormalities in the gray matter (GM) of the brain parenchyma are present early in the course of multiple sclerosis. Objectives To quantify white matter (WM) and subcortical deep GM (SDGM) alterations in patients with clinically isolated syndrome (CIS) using diffusion tensor imaging (DTI). Materials and methods 45 CIS patients and 52 healthy controls (HC) were scanned on 3 T MRI. Mean diffusivity (MD) and fractional anisotropy (FA) were calculated, in addition to the estimation of structural brain volume and lesion measurements. Results FA was significantly lower in CIS patients in the whole brain (p <0.001), total SDGM (p <0.001), normal appearing (NA) GM (p = 0.016), thalamus (p = 0.029) putamen (p = 0.036), caudate (p = 0.041) and accumbens nuclei (p = 0.041) compared to HC. No DTI MD or volumetric differences were detected in the brain parenchyma between CIS and HC groups. Normalized lateral ventricular volume was higher in CIS patients compared to HC (p = 0.033). A significant association was detected between the increased T2 lesion number and volume and decreased FA of the NAWM (p = 0.036), but not with FA of NAGM or SDGM structures. Conclusions Diffuse DTI alterations of GM structures, not associated with lesion formation, are present in CIS patients.