Cerebral blood flow and metabolism measurement using positron emission tomography before and during internal carotid artery test occlusions: feasibility of rapid quantitative measurement of CBF and OEF/CMRO(2)

Abstract

Balloon test occlusion (BTO) of the internal carotid artery (ICA) combined with cerebral blood flow (CBF) study is a sensitive test for predicting the outcome of permanent ICA occlusion. However, false negative results sometimes occur using single photon emission tomography (SPECT). We have recently developed a rapid positron emission tomography (PET) protocol that measures not only the CBF but also the cerebral oxygen metabolism before and during BTO in succession. We measured acute changes in regional CBF and OEF/CMRO(2) before and during BTO in three cases with large or giant cerebral aneurysms using the rapid PET protocol. Although no patients showed ischemic symptoms during BTO, PET studies exhibited mildly to moderately decreased CBF (9∼34%) compared to the values obtained before BTO in all cases. The average OEF during BTO was significantly increased (21% and 43%) than that of before BTO in two cases. The two cases were considered to be non-tolerant for permanent ICA occlusion and treated without ICA sacrifice. Measurement of the CBF and OEF/CMRO(2) using a rapid PET protocol before and during BTO is feasible and can be used for accurate assessment of tolerance prediction in ICA occlusion.

Figure 1

A) Right ICA angiogram shows a large paraclinoid aneurysm. The right ICA is completely occluded by a balloon during BTO. B) During BTO of the right ICA, a moderate decrease in CBF in the right MCA territory is demonstrated by PET study. The CMRO₂ was symmetrical (C) and the OEF in the right MCA territory is markedly increased (D). This patient was considered to be non-tolerant for permanent ICA occlusion.

Figure 1

A) Right ICA angiogram shows a large paraclinoid aneurysm. The right ICA is completely occluded by a balloon during BTO. B) During BTO of the right ICA, a moderate decrease in CBF in the right MCA territory is demonstrated by PET study. The CMRO₂ was symmetrical (C) and the OEF in the right MCA territory is markedly increased (D). This patient was considered to be non-tolerant for permanent ICA occlusion.

Figure 2

A) left ICA angiogram shows a large paraclinoid aneurysm. The left ICA is completely occluded by a balloon during BTO. B) During BTO of the left ICA, a mild decrease in CBF in the left MCA territory is demonstrated by PET study. The CMRO₂ was symmetrical (C) and the OEF in the left MCA territory is mildly increased (D). This patient was considered to be non-tolerant for permanent ICA occlusion.

Figure 2

A) left ICA angiogram shows a large paraclinoid aneurysm. The left ICA is completely occluded by a balloon during BTO. B) During BTO of the left ICA, a mild decrease in CBF in the left MCA territory is demonstrated by PET study. The CMRO₂ was symmetrical (C) and the OEF in the left MCA territory is mildly increased (D). This patient was considered to be non-tolerant for permanent ICA occlusion.

Figure 3

A) 3D-CT angiogram shows a giant cavernous aneurysm. B) During BTO of the right ICA, a mild global decrease in CBF in the bilateral hemispheres is demonstrated by PET study. The CMRO₂ was symmetrical (C) and the OEF in the right MCA territory is slightly increased (D). This patient was considered to be tolerant for permanent ICA occlusion and treated with coil embolization with ICA occlusion (E).

Figure 3

A) 3D-CT angiogram shows a giant cavernous aneurysm. B) During BTO of the right ICA, a mild global decrease in CBF in the bilateral hemispheres is demonstrated by PET study. The CMRO₂ was symmetrical (C) and the OEF in the right MCA territory is slightly increased (D). This patient was considered to be tolerant for permanent ICA occlusion and treated with coil embolization with ICA occlusion (E).