Magnetic Resonance Imaging (MRI) provides a powerful tool for assessing disease activity in Multiple Sclerosis (MS), and its role as a surrogate marker for monitoring treatment efficacy is now becoming established.
The most commonly used MRI parameters in treatment trials are:
- Monthly Gadolinium-enhanced MRI, with the number of
- Annual Lesion Load quantification, in which
We evaluated clinical/MRI correlations and the relationship between these two
markers of disease activity in 73 patients with Clinically Definite MS.
Quantification of T2 lesion load was performed at study entry and exit, with a median study duration of 11 months (range, 9 to 14 months). Monthly post-Gadolinium T1-weighted images were acquired between these time points.
Lesion load at study entry was significantly correlated with the baseline Expanded
Disability Status Scale (EDSS) score, but no significant longitudinal correlation was demonstrated.
The number of enhancing lesions on the entry scan was predictive of subsequent relapse rate over the study duration and also correlated with the subsequent enhancing lesion activity over the study period.
A significant correlation was found between change in lesion load and disease activity on the monthly scans.
Our results suggest that annual Lesion Load quantification provides an efficient measure of ongoing disease activity, and this supports its application as a surrogate marker of disease evolution in Phase III Treatment Trials.