Postoperative FLAIR Imaging Changes

ypass surgery is widely accepted as effective treatment to improve cerebral hemodynamics and to prevent both further ischemic and hemorrhagic stroke in moyamoya disease (MMD). For these 10 years, there is increasing evidence that the hyperintense signal develops in the brain surface on fluid-attenuated inversion recovery (FLAIR) images following bypass surgery. This novel, unique phenomenon is specific for moyamoya disease and does not occur in patients with atherosclerotic carotid artery diseases. This phenomenon can be observed between 3 and 14 days after surgery and completely disappears thereafter. Even now, its pathophysiology and underlying mechanisms are not fully understood. In this chapter, therefore, the authors precisely review recent knowledge on the hyperintense signal on FLAIR image after surgical revascularization for moyamoya disease and discuss future perspective.