MRI

In brief: Brain MRI shows tissue injury and other structural findings. It complements vascular and perfusion imaging rather than replacing them.

Diffusion-weighted imaging can identify acute infarction. Other sequences show old infarcts, hemorrhage products, white-matter injury, cortical changes, and alternative diagnoses. Susceptibility imaging may reveal prior microbleeds or hemorrhage.

Use in moyamoya disease

Specialized heavy T2-weighted sequences can assess the outer diameter of involved arteries, which may help distinguish moyamoya from atherosclerotic narrowing in the appropriate context. Imaging protocols vary by center. [1]

Use in multiple sclerosis

Brain and spinal cord MRI help identify lesions in characteristic central nervous system locations, assess interval activity, and evaluate alternative diagnoses. Specialists consider lesion morphology, distribution, enhancement, and change over time rather than treating every white-matter spot as MS.

Consensus recommendations emphasize standardized three-dimensional FLAIR, purposeful spinal imaging, comparable follow-up protocols, and selective use of gadolinium for a defined clinical question. [2]

Clinical detail

MRI appearance should be interpreted with the clinical question. In moyamoya, a normal routine brain MRI does not by itself exclude significant hemodynamic impairment. In an MS evaluation, nonspecific lesions do not establish the diagnosis and a normal study may change, but does not independently settle, the differential diagnosis.