Infarct Pattern and Collateral Status in Adult Moyamoya Disease

Moyamoya disease (MMD) is an uncommon cerebrovascular disease that is characterized by progressive stenosis of the terminal portion of the internal carotid artery and its main branches. There have been many studies on the cerebral hemodynamics in patients with MMD, and based on their findings, current guidelines recommend revascularization surgery in patients with MMD with progressive ischemic symptoms or evidence of inadequate blood flow or cerebral perfusion reserve. The mechanism of ischemic stroke in MMD is not well understood, and the roles of therapeutic strategies, other than surgery, are unknown. Given the lack of systematic evidence on antiplatelet agents and anticoagulants for stroke prevention in patients with MMD, specific stroke prevention medications cannot be recommended outside of general treatment recommendations. However, pathological data showed collapse of the artery lumen and intraluminal thrombosis in patients with MMD. There is also some evidence that supports thromboembolism as the cause of infarction in patients with MMD. The present study aimed to explore the mechanism of ischemic stroke in patients with MMD. Thus, we evaluated the infarct pattern and collateral status, using multimodal magnetic resonance (MR) imaging, in patients with MMD. In this study, we investigated acute infarct pattern on diffusion-weighted imaging (DWI), microembolic signals on transcranial Doppler monitoring, and collateral status using our dynamic susceptibility contrast (DSC)–enhanced, MR perfusion–based collateral map to estimate the role of embolic and hemodynamic mechanisms in the development of stroke in adult patients with MMD.