Abstract
Multiple sclerosis is the second most common cause of disability in young adults. Conventional imaging so far failed to explain the extent of clinical disability even by careful examination of white matter lesion volume and their topographical distribution. The increasing availability of ultra-high field imaging allowed the improvement in understanding the dynamic lesional and extralesional pathology in different stages of the disease and their potential contribution to clinical and cognitive disability. The contribution of cortical lesions of different subtypes, the degree of microstructural damage in those lesions has been examined. This is in addition to the influence of white matter lesions and spinal cord pathology on the degree of disability in multiple sclerosis. Prognostic factors influencing long-term disability in patients with multiple sclerosis have also been a subject of interest for many years, particularly their significance in early decision-making with regard to disease-modifying treatment choice and early initiation. The frequency of iron rims in white matter lesions has been linked to increased disease severity in multiple sclerosis. Iron rim lesions’ potential evolution to slowly expanding lesions as well as the long-term prognostic impact of such lesions on the degree of clinical disability has also been examined in this chapter.