Book excerpt: Moyamoya disease (MMD) is a chronic cerebrovascular disease characterized by progressive stenosis of the arteries of the circle of Willis, and formation of a collateral vascular network at the base of the brain. Moyamoya syndrome is caused by numerous conditions, which lead to arterial occlusion of the circle of Willis and resultant collaterals reminiscent of moyamoya disease. Due to the diverse angioarchitecture and unknown influence factors, the hemodynamic disturbances of MMD/Moyamoya syndrome are complicated, and result in multimodal clinical manifestations including headache, cognitive impairment, seizures, TIA, infarction, and hemorrhage. Surgical revascularization has been proven as effective in decreasing incidence of long-term risk of stroke. However, occurrence of perioperative stroke and complications such as seizures and cerebral hyperperfusion syndrome are still unpredictable. In addition, many patients with cognitive impairment cannot benefit from surgical revascularization and the mechanism remains unclear. Thus, a series of studies focusing on the objective evaluation of MMD/Moyamoya syndrome are needed to help understand this complicated cerebrovascular disease and improve our treatment strategy. The goal of this Research Topic is to better understand the pathophysiological nature of MMD/Moyamoya syndrome through objective neuroimaging. We also aim to generate a reasonable and objective evaluation system for MMD/ Moyamoya syndrome and would like to understand the link between cognitive impairment and brain damage of MMD/Moyamoya syndrome though neuroimaging. Through these findings we also aim to improve the treatment strategy by understanding the pathophysiological link with relevant complications. Finally, we also aim to improve our understanding of the significance of perioperative management for patients with severe complications from the perspective of objective evaluation.