Diffusion Tensor Imaging Abnormalities in Multiple Sclerosis Cortical Lesions and Normal-Appearing Grey Matter and their Associations with Disability (P6.108)

OBJECTIVE: To compare mean diffusivity (MD) and fractional anisotropy (FA) in cortical lesions and cortical normal-appearing grey matter (cNAGM) in different multiple sclerosis (MS) subtypes, and assess associations with disability. BACKGROUND: MS cortical pathology can be substantial and contribute significantly to disability. However, it is not clear whether or not microstructural abnormalities in cortical lesions or cNAGM are similar, or contribute equally to disability, in different MS subtypes. DESIGN/METHODS: Cross-sectional case-control study. In total, 46 people with relapsing-remitting (RR), 26 secondary-progressive (SP) and 20 primary-progressive (PP) MS, and 36 healthy controls were included in this study. Expanded Disability Status Scale (EDSS), MS functional composite (MSFC), and Symbol Digit Modalities Test (SDMT) scores were obtained. Phase-sensitive inversion recovery images (1x1x1mm3, to identify cortical lesions), T1-weighted volumetric scans (0.5x0.5x2mm3, to segment cortical GM), and high angular resolution diffusion tensor imaging (2x2x2mm3, to measure FA and MD) were acquired on a 3T system. RESULTS: In cNAGM, mean FA was lower and MD higher in MS than controls (both p<0.001). In contrast, in MS cortical lesions, mean FA was higher and MD lower compared with cNAGM (both p<0.001). In cNAGM, MD was borderline higher in SPMS than RRMS (p=0.056) or PPMS (p=0.057), while mean MD in cortical lesions was higher in SPMS compared with RRMS (p=0.010) or PPMS (p=0.010). Mean FA in cortical lesions or cNAGM did not differ between different MS subtypes. Both MSFC (rho=-0.206, p=0.049) and SDMT (rho=-0.303, p=0.004) scores correlated with MD in cNAGM. EDSS did not correlate with FA or MD in cortical lesions or cNAGM. CONCLUSIONS: Mean diffusivity abnormalities are greater in cortical lesions in SPMS compared with RRMS or PPMS, with a similar trend in cNAGM. Compared with cortical lesions, diffusivity changes in cNAGM are more consistently associated with clinical outcome measures. Study Supported by: University Basel, MAGNIMS/ECTRIMS Disclosure: Dr. Yaldizli has nothing to disclose. Dr. Pardini has nothing to disclose. Dr. Sethi has nothing to disclose. Dr. Muhlert has nothing to disclose. Dr. Liu has nothing to disclose. Dr. Yousry has received research support from Biogen Idec, British Heart Foundation, GlaxoSmithKline, Medical Research Council, MS Society of Great Britain and Northern Ireland, and NIHR Comprehensive. Dr. Tozer has received research support from Biogen Idec and Novartis. Dr. Samson has nothing to disclose. Dr. Wheeler-Kingshott has received personal compensation for activities with Biogen Idec as an advisory board member. Prof. Miller has received honoraria through payments to his employer, UCL Institute of Neurology, for Advisory Committee and/or Consultancy advice in multiple sclerosis studies from Biogen Idec,;, Dr. Chard has received personal compensation for activities with Serono and Ismar Healthcare NV.