[O-15]H2O positron emission tomography determination of cerebral blood flow reserve after intravenous acetazolamide during balloon test occlusion of the internal carotid artery

The purpose of this paper was to evaluate the effects of acetazolamide on cerebral blood flow (CBF) measured by [O-15] H2O positron emission tomography (PET) during balloon test occlusion (BTO) of the internal carotid artery (ICA). [O-15] H2O PET cerebral blood flow studies were completed in 20 patients undergoing BTO. CBF determinations were obtained without carotid occlusion as a baseline, following balloon occlusion, and as a third scan with balloon occlusion after an intravenous acetazolamide bolus. The balloon was left deflated between scans, and was only inflated immediately before and during the 90 second period of time needed for CBF determination. Significance was determined at the P<0.05 level. Two of twenty studies were technical failures. Prior to acetazolamide there was a significant decrease in CBF (P<0.0007) ipsilateral to the occlusion. After acetazolamide administration there was no statistically significant change in flow on the occluded side (P<0.3047); however, there was a significant increase in cerebral blood flow (P<0.0002) on the non-occluded sine. In this patient population, there was no acetazolamide-induced CBF decompensation (steal) phenomenon or haemodynamically significant risk in CBF ipsilateral to the occlusion.