Purpose of review: Patients with multiple sclerosis have benefited from an increasingly large number of choices for anti-inflammatory, disease-modifying therapy. One cannot reliably predict how an individual patient will respond to a particular therapy. MRI has become an integral component of therapy selection and monitoring in multiple sclerosis.
Recent findings: Number of lesions at baseline and new lesions on therapy have implications for long-term prognosis. To achieve best therapeutic outcomes, patients with accumulating lesions may benefit from a change in their therapy. For patients with established stable disease, MRI may be done less frequently.
Summary: Practitioners should be obtaining brain MRI scans to supplement their clinical evaluations and assess for subclinical disease activity. In certain circumstances, changing therapy may be warranted based upon MRI alone, despite the appearance of clinical stability. The appearance of two to five T2-weighted lesions or one to two gadolinium-enhancing lesions represents a threshold of concern.