Longitudinal evaluation of clinically early relapsing-remitting multiple sclerosis with diffusion tensor imaging

Abstract

Diffusion tensor imaging (DTI) parameters such as mean diffusivity (MD) and fractional anisotropy (FA) assess aspects of structural integrity within tissue. In relapsing-remitting (RR) multiple sclerosis (MS), abnormalities in normal appearing brain tissue (NABT) have been shown cross-sectionally. The evolution of these abnormalities over time is unclear. We present a longitudinal study investigating early RR MS subjects. The aims were to determine DTI changes over two years and assess the potential of DTI as a longitudinal quantitative marker at this stage of MS. Fifteen controls and 28 patients with RR MS (median disease duration 1.9 years; median EDSS 1.5) had DTI yearly for two years. NABT and whole brain tissue (NABT plus lesions) FA and MD histograms analysed. At baseline, differences in FA were noted between patients and controls (mean [p = 0.042] and peak height [p = 0.008]), while at two years differences in MD were observed (mean [p = 0.008] and peak location [p = 0.024]). However there were no significant DTI differences in longitudinal rates of change between patients and cohorts. In conclusion, although subtle NABT abnormalities were detected in early RR MS, the absence of longitudinal change suggests a limited role for global DTI assessment of NABT in following the early disease course.

Measuring Brain Tissue Integrity during 4 Years Using Diffusion Tensor Imaging

“…This finding is consistent with the findings of previous groups 29 , but is in contrast with previous shorter term studies that have shown tract specific longitudinal changes in NAWM DTI values. 8 The trends observed in NAWM changes over time in our study were similar to what would be pathophysiologically expected, with an increase in RD and decrease in AD over time indicating progressive demyelination with ongoing axon loss.…”

Characterization of functioning in multiple sclerosis using the ICF

“…This has also been demonstrated in previous studies related to clinical course, additional demographic and imaging features indicating differences in underlying pathogeneses [1,33]. Similar significant differences in EDSS between the three MS forms found have been reported previously where mean EDSS was 3, 2.75 in RR MS, 3.5 in PP MS and 4.0 in SP MS [28,29]. These EDSS differences emphasize how different the MS forms are with respect to functioning and participation.…”

DTI Measurements in Multiple Sclerosis: Evaluation of Brain Damage and Clinical Implications

“…Although abnormalities in RRMS patients were found throughout the brain, no longitudinal diffusion changes were observed in the follow-up [141], nor were any longitudinal FA changes observed in CIS patients when they were studied again after conversion to MS [139]. As these findings suggest that WM damage occurs early but progresses slowly, the information yielded by a global diffusion assessment of normal appearing brain tissue may be of limited value as a means of following disease progression, at least at disease onset.…”