The emergence of new modalities such as Diusion Tensor Imaging (DTI) is of great interest for the characterization and the temporal study of Multiple Sclerosis (MS). DTI indeed gives information on water diusion within tissues and could therefore reveal alterations in white matter bers before being visible in conventional MRI. However, recent studies generally rely on scalar measures derived from the tensors such as FA or MD instead of using the full tensor itself. Therefore, a certain amount of information is left unused. In this article, we present a framework to study the benets of using the whole diusion tensor information to detect statistically signicant dierences between each individual MS patient and a database of control subjects. This framework, based on the comparison of the MS patient DTI and a mean DTI atlas built from the control subjects, allows us to look for dierences both in normally appearing white matter but also in and around the lesions of each patient. We present...