Abstract
The present study attempts to assess regional cerebral blood flow imaging under intravascular balloon occlusion testing, using single-photon emission computed tomography (SPECT) and 99m Tc-hexamethyl-propyleneamine oxime (99mTc-HM-PAO) for the surgery of large cerebral aneurysms.
The balloon occlusion test was performed on 4 patients, two with ruptured large internal carotid aneurysms, one with an unruptured giant internal carotid aneurysm, and one with a vertebral dissecting aneurysm. During the balloon occlusion test of the internal carotid artery and the vertebral artery, 99mTc-HM-PAO (20mCi) was injected intravenously 1 to 2 minutes before deflation of the balloon, and the stump pressure was monitored simultaneously. SPECT images were obtained using HEADTOME SET 031. The hypoperfusion area on the SPECT image was estimated into three grades: mild, moderate, and marked, in comparison with the unaffected area.
99mTc-HM-PAO SPECT showed a marked hypoperfusion area in the ipsilateral cerebral hemisphere at 5 mmHg of stump pressure in one patient with a ruptured large internal carotid aneurysm, and a moderate hypoperfusion area in the basal ganglia even at 70 mmHg of stump pressure in another patient with a ruptured large internal carotid aneurysm. In one patient with an unruptured giant internal carotid aneurysm, 99mTc-HM-PAO SPECT showed no hypoperfusion area at 50 mmHg of the stump pressure. In one patient with a dissecting aneurysm of the vertebral artery, 99mTc-HM-PAO SPECT showed a mild hypoperfusion area in the left posterior inferior cerebellar arterial territory. No patient showed neurological deterioration during the balloon occlusion test.
In conclusion, preoperative 99mTc-HM-PAO SPECT study during the balloon occlusion test might be a useful tool for planning the surgery of a large cerebral aneurysm, in which temporary clipping or permanent occlusion of major cerebral arteries is considered.
