Characterization of gray-matter multiple sclerosis lesions using double inversion recovery, diffusion, contrast-enhanced, and volumetric MRI

Purpose: To investigate gray-matter (GM) lesions in relapsing-remitting multiple sclerosis (MS) using double-inversion recovery (DIR) MRI, determine GM lesions prevalence, spatial distribution and characterize their contrast-enhancement, diffusion characteristics and compare them to white-matter (WM) lesions. This is the first study, to our knowledge, to investigate GM MS lesions using double-inversion recovery MRI, to determine GM lesion prevalence and location, and characterize contrast-enhancement and diffusion characteristics, compared to WM lesion characteristics in the same patients. We also correlated GM lesion counts, volume and apparent diffusion coefficient (ADC) with total brain, WM, and GM volumes, as well as 25-foot walk test as a clinical disability. Materials and Methods: This retrospective study included 44 relapsing-remitting MS patients (12M/32F, 41 +/- 13 years) and 24 age-matched healthy controls (14M/10F, 36 +/- 13 years). Lesions were segmented based on DIR and grouped into GM, subcortical WM, and periventricular WM lesions. ADC was tabulated for contrast-enhancing and non-enhancing lesions. Unpaired two sample t-tests were used for comparison between groups. Linear regression was used to evaluate the relationship between number of GM lesions, number of total lesions, total GM lesion volume, and total WM lesion volume with brain volumes and clinical data. Results: GM MS lesions were present in the majority (86.4%, 38/44) of RRMS patients based on DIR, suggesting GM damage plays an important role in MS pathogenesis. The majority of the GM lesions were located in the frontal lobe. The percentage of lesions in GM that were contrast-enhanced was similar to those in WM, suggesting that blood-brain barrier integrity is likely affected similarly in GM and WM. Contrast-enhanced GM lesions showed higher ADC. GM lesion count and volume were correlated with global and regional brain atrophy, and with more severe disability group. Conclusion: This study characterized GM MS lesions using double-inversion recovery, contrast-enhanced and diffusion MRI. Understanding GM lesion pathophysiology using MRI in vivo, may prove useful for improving targeted therapy and monitoring disease progression.