Abstract
Moyamoya disease is a complex phenomenon with many potential etiologies and can present with a variety of clinical manifestations. Imaging plays a crucial role in the diagnosis of Moyamoya disease, and the radiologist may be the first to suggest the disease. Either invasive or noninvasive angiography can be used to establish the diagnosis, based on defined radiologic criteria. Once the diagnosis is established, cerebral perfusion imaging before and after a vasodilatory challenge can be used to assess cerebrovascular reserve. The definitive treatment for Moyamoya disease is surgical revascularization with a goal to increase cerebral blood flow to tissues at risk. There are a variety of surgical options for revascularization in broad categories of either direct or indirect bypasses. Noninvasive imaging plays a key role in the evaluation of patients following surgical re-vascularization to assess the effectiveness of surgery as well as for complications. Noncontrast CT or MR imaging can be used to evaluate for early postoperative complications. CTA can be used to assess the patency of bypass grafts. Perfusion imaging can be performed to assess the degree of improvement in cerebral perfusion. Learning Objectives: Describe the imaging appearance of Moyamoya disease, identify typical postoperative findings after surgical revascularization, and recognize the complications of Moyamoya disease and its treatments. © 2020, American Society of Neuroradiology. All rights reserved.