MRI-Clinical Correlations in Multiple Sclerosis: Implications for Our Understanding of Neuronal Changes

This chapter discusses the main results obtained by the application of modern magnetic resonance (MR) technology to the study of multiple sclerosis (MS), with the ultimate goal of highlighting how they are changing the understanding of MS, which is now viewed as a diffuse condition affecting both white and gray matter of the central nervous system (CNS) and which causes irreversible clinical disability mainly through axonal or neuronal damage. Axonal or neuronal loss is an important feature of MS pathology, and it is likely to represent one of the main factors responsible for the accumulation of irreversible disability. The application of modern MR techniques to the in vivo study of MS is providing important insights into the pathophysiology of the disease, and it is establishing new markers to understand and monitor MS evolution. However, none of the quantitative MR-based techniques taken in isolation is likely to be able to provide a complete picture of the complexity of the MS process, and this should call for the definition of aggregates of MR measurements thought to reflect different aspects of MS pathology. This approach is likely to enhance our ability to monitor the disease and to improve the correlation between MRI metrics and disability.