Quantification of brain gray matter damage in different MS phenotypes by use of diffusion tensor MR imaging

BACKGROUND AND PURPOSE: Increasing evidence exists that cerebral gray matter (GM) from patients with multiple sclerosis (MS) is not spared. This study was performed to quantify in vivo the extent of cerebral GM pathologic abnormality in patients with relapsing-remitting (RR), secondary progressive (SP), and primary progressive MS, by using diffusion tensor (DT) MR imaging. METHODS: Dual-echo and DT MR imaging of the brain were performed in 102 patients with MS and 30 healthy volunteers. After GM segmentation using a technique based on diffusion anisotropy thresholding, average diffusivity ((D) over bar) histograms of the cerebral GM were produced for all participants. RESULTS: All (D) over bar histogram-derived metrics of the GM were significantly different between control volunteers and the whole MS population. No significant difference was found for any of the (D) over bar histogram-derived metrics between control volunteers and patients with RRMS, whereas significant differences were found for (D) over bar and (D) over bar histogram peak location between control volunteers and patients with PPMS. All the (D) over bar histogram-derived metrics differed significantly between patients with RRMS and patients with SPMS. Patients with SPMS also had significantly lower (D) over bar than did patients with PPMS. All (D) over bar histogram-derived metrics of the GM were strongly correlated with the T2 lesion volume. CONCLUSIONS: This study confirms the presence of brain GM changes in patients with MS. It also shows that the extent of such changes is greater during the progressive forms of the disease.