vivo assessment of cervical cord damage in MS patients: A longitudinal diffusion tensor MRI study

Cervical cord damage is likely to contribute to the accumulation of disability in multiple sclerosis (MS) and can be quantified in vivo using MRI.We used conventional and diffusion tensor (DT) MRI to: (a) define the temporal evolution of intrinsic tissue injury and atrophy in the cervical cord from MS patients, (b) investigate how these two aspects of cord damage are interrelated and (c) assess the correlation of cord MRI metrics with concomi-tant brain damage and disability. Conventional and DT MRI of the brain and cervical cord were obtained from 42 MS patients and 9 healthy controls at baseline and after amean follow-up of 2.4 years. At each time-point, we measured: cervical cord lesion number, cross-sectional area, mean diffusivity (MD) and fractional anisotropy (FA). BrainT2 lesion volume, grey matter MD, normal appearing white matter (NAWM) MD and FA, as well as longitudinal normalized percentage brain volume changes were also measured. In MS patients, cervical cord cross-sectional area (P _ 0.001) and FA (P ^ 0.01) decreased, and cervical cord MD increased (P _ 0.001) during follow-up. Cord FA decrease, but not cord cross-sectional area and MD, was sig-nificantly higher (P ^ 0.05) in primary progressive MS patients than in those with either relapsing^remitting or secondary progressive MS. At baseline and follow-up, moderate correlations were found between intrinsic cord diffusivity abnormalities and cord cross-sectional area (r values ranging from 0.34 to 0.58), but not between their changes over time.No cross-sectional and longitudinal correlations were found between these MRImetrics an