Statistical issues related to the use of MRI data in multiple sclerosis.

Since magnetic resonance imaging (MRI) of the brain has proved to be the most important paraclinical tool for diagnosing multiple sclerosis (MS) and monitoring its evolution, methodological and statistical issues related to the use of MRI markers in MS have been the focus of several studies in the past 10 years. While many of these methodological issues have been addressed using standard procedures available from other areas of application of medical statistics, in some cases statistical procedures that are not standard have been developed specifically for MRI variables in MS. Two of the major achievements in the statistical methods applied to the use of MRI variables in MS in the past 10 years were the identification of a parametric model to describe the distribution of MRI lesion counts across patients and the study of the relationships between MRI markers and clinical variables, with the aim to validate MRI parameters as surrogates for clinical progression.