New MRI techniques in multiple sclerosis.

Early imaging investigations in multiple sclerosis (MS) described focal signs. Technological progress now suggests this concept should be revisited as more diffuse anomalies of the central nervous system are described, sometimes involving regions that appear normal with conventional imaging techniques, This integrative concept results largely from the contribution of magnetic resonance imaging techniques recently broadened to in vivo investigations. Technical developments in MRI now provide new contrast images (magnetization transfer, diffusion, anisotropic diffusion, functional MRI using the BOLD method) as well as new variants of conventional sequences designed to demonstrate specific aspects of the MS lesions: FLAIR sequence (a T2-weighted sequence), black holes (a particular aspect on T1-weighted images), cord atrophy (quantification of the axial section of the cord on T1-weighted sequences). Together these new methods should improve diagnostic sensitivity (FLAIR) or provide prognosis information not provided by conventional sequences (T2 or T2 weighted images with or without gadolinium injection).