MRI and MR angiography in moyamoya disease.

The role of radiological imaging in moyamoya disease includes screening of the disease based on clinical findings, evaluation of the changes in vasculature and brain parenchyma, and clinical follow-up. The imaging findings in moyamoya disease are classified as primary and secondary. The primary findings essentially consist of occlusion of the circle of Willis and collateral formation, including moyamoya vessel formation. The secondary findings include cerebral infarction, white matter lesions, atrophy, and hemorrhage. For the visualization of the primary and secondary findings as well as postoperative results, MRI and MR angiography are the most reliable methods and play important roles because of their excellent diagnostic yield and noninvasiveness.