Diffusion-weighted imaging in moyamoya disease.

Moyamoya disease is characterized by progressive intracranial vascular stenoses of the circle of Willis, resulting in successive ischemic events. We report serial diffusion-weighted imaging studies in a case of moyamoya disease. A 4-year-old right-handed patient presented with multiple infarcts in the right and left hemispheres. Each new infarct was unambiguously recognized as bright on diffusion-weighted imaging. Previous infarcts, readily detected on other magnetic resonance imaging sequences, were not bright on diffusion-weighted imaging. The patient subsequently underwent bilateral synangiosis. In this case, the diffusion-weighted images were helpful in assessing the extent of infarcts, determining the age of the lesion, and correlation with new clinical findings. We emphasize the usefulness of diffusion-weighted imaging for following the clinical course of children with moyamoya disease, in whom new focal deficits are highly suspicious of new infarcts.