Objective: In moyamoya disease (MMD), blood flow to the internal carotid artery (ICA) system is supplied via the basal fine vascular network, leptomeningeal anastomoses, and transdural collateral vessels from the external carotid artery (ECA). After revascularization, there is a dramatic change in cerebral perfusion to the ECA system. Understanding this shift in blood supply is important for evaluating treatment efficacy and elucidating the postoperative pathophysiology. However, anatomical and quantitative methods for doing so have not yet been established. In the present study, selective intraarterial injection CT angiography (iaCTA) was performed in patients with MMD, and blood supply changes in each arterial system before and after revascularization surgery were evaluated.
Methods: This study included 10 hemispheres in 10 patients who underwent combined revascularization surgery for adult MMD. Digital subtraction angiography was performed before and 3 months after surgery, and selective iaCTA was performed from the ICA, ECA, and vertebral artery (VA) at the same times in a hybrid CT/digital subtraction angiography suite. The anatomical distribution of each vessel was determined and perfusion volume was measured quantitatively on contrast-enhanced axial CT images.
Results: Selective iaCTA clearly depicted the anatomical distribution of perfusion for each vessel. Conversion of blood supply from the ICA and VA to the ECA system was observed in the cerebral cortices and insulae but not in the basal ganglia. The mean volume of perfusion territories of the ECA (preoperative 0.9 cm3, postoperative 98.8 cm3); ICA (preoperative 225.7 cm3, postoperative 159.3 cm3); and VA (preoperative 244.0 cm3, postoperative 163.6 cm3) in the cerebral hemispheres changed significantly after revascularization. There was a correlation between increase in the ECA territory volume and decrease in the VA territory volume due to revascularization (R = -0.84, p < 0.005).
Conclusions: Selective iaCTA enabled clear visualization of anatomical changes in each vascular perfusion territory and quantitative measurement of each perfusion volume. Perfusion conversion to the ECA system after bypass surgery was observed in the cortical regions and in the insulae on the bypass operation sides, but not in the basal ganglia. Combined revascularization promoted the development of ECA-perfused territory, which correlated with a decrease in hemodynamic burden of the posterior cerebral artery.
Keywords: angiography; computed tomography; moyamoya disease; revascularization surgery; vascular disorders.