^<99m>Tc-HMPAO SPECT Study during Balloon Occlusron Test

Abstract

The authors have evaluated the cerebral blood flow (CBF) using single photon emission computed tomography (SPECT) during balloon occlusion of the internal carotid artery (ICA) as a preembolization test for permanent carotid ligation. Seventeen patients were studied. These Included 8 cases with aneurysm, 5 cases with direct carotid cavernous fistula (DCCF), 2 cases with arteriovenous fistula (AVF), I case with carotid basal plexus fistula and I case of parasellar tumor. The SPECT study during the balloon occlusion test was performed using technetium-99m hexamethyl-propyleneamine oxime (^<99m>Tc-HMPAO) intravenous injection method. The results showed that the SPECT study during the balloon occlusion test was a secure and useful examination, but it was necessary to be aware of the following : (1) As there were some cases whose blood pressure was unstable after the permanent carotid ligation, it was necessary to inject ^<99m>TC-HMPAO under induced hypotension. (2) In cases with DCCF, the steal phenomenon through the fistula is enhanced under proximal ICA occlusion. Therefore administration of ^<99m>TC-HMPAO should be done under complete occlusion of the fistula together with ICA. (3) For patients with preexisting reduction of regional CBF, a quantative analysis was required.