Evaluation of regional cerebral blood flow during carotid occlusion test with H215O PET: Matas maneuver and balloon occlusion

Abstract

We carried out carotid occlusion tests with regional cerebral flow (rCBF) study using H215O positron emission tomography (PET) for 7 cases of unruptured large internal carotid artery (ICA) aneurysms and 1 case of carotid stenosis. RCBF was measured with PET under Matas maneuver in 4 patients and under balloon occlusion test (BOT) in 4 patients. In the cases with Matas maneuver, we also performed conventional BOT to evaluate carotid stump pressure. H215O PET scan is an ideal examination for the rCBF study during an occlusion test for its excellent ability of absolute quantitative analysis and a brief scanning time. Measurement of rCBF with Matas maneuver is relatively simple and provides almost accurate information about a tolerance of a temporary or permanent occlusion of ICA, though it misgives us a possibility of an incomplete occlusion, the possibility of blood supply from the branches of external carotid artery and the shortness of the occlusion time compared to a BOT. On the contrary, measurement of rCBF with BOT enables the occlusion to be complete and enough long, while the examination becomes complicated and lengthy. It seems that we should select more accurate BOT with PET despite its complexity to detect the difficult cases that manifest intolerance on the permanent carotid occlusion and show false negative on conventional occlusion tests.