Cerebral hemodynamics and metabolism in moyamoya disease--a positron emission tomography study

We studied the cerebral blood flow (CBF), cerebrovascular response to hypercapnia, oxygen extraction fraction (OEF), metabolic rate for oxygen (CMRO2), blood volume (CBV) and transit time (TT: CBV/CBF) in Moyamoya disease using positron emission tomography (PET). The subjects consisted of 23 patients with Moyamoya disease, including eight pediatric and 15 adult patients. Among them, ten patients were examined both before and after surgery. The pediatric patients showed a marked increase in the CBV and a prolonged TT, especially in the striatum. The adult patients also showed a prolonged TT, but it was less prominent than that observed in pediatric patients, while the CBF remained at the level of the normal controls. The cerebrovascular response to hypercapnia was markedly impaired in both the pediatric and adult patients, which thus indicates a decrease in the hemodynamic reserve capacity. After surgery, the CBV, TT and cerebrovascular response to hypercapnia all improved, mainly in the temporal cortex where extracranial-intracranial (EC-IC) bypass surgery had been performed. In the striatum, the CBV also decreased, while the TT was shortened after surgery. A PET study was thus found to be useful for evaluating the cerebral hemodynamics in Moyamoya disease and monitoring the effect of surgery.