Object: The dynamic process of neovascularization seen in patients with moyamoya disease who have received bypass surgery has not been sufficiently elucidated. Magnetic resonance angiography (MRA)is expected to disclose this process since it can be conducted frequently because of its non-invasive nature. In this study, we prospectively investigated postoperative neovascularization using repeated MRA.
Methods: We studied 14 pediatric patients (23 sides) who have received both direct bypass surgery of the superficial temporal artery (STA) to middle cerebral artery and indirect surgery of encephalo-duro-arterio-myo-synangiosis during the past 3 years. MRA was performed using a 1.5-T machine, image sequences of 512 x 256 resolution, and the time-of-flight method. MRA was prospectively performed preoperatively and repeated 1, 3, and 6 months after surgery.
Conclusions: A tendency toward a decrease in moyamoya vessels and the development of the STA was observed 1 month after the surgery. Development of the deep temporal artery and the middle meningeal artery was observed 3 months after the surgery. The progression of stenotic change was apparently accelerated after the surgery. A reciprocal relation between neovascularization artificially induced by bypass surgery and moyamoya vessels, which are supposed to compensate for the stenotic change of the internal carotid artery, was disclosed.