Usefulness of Dual and Fully Automated Measurements of Cerebral Blood Flow during Balloon Occlusion Test of the Internal Carotid Artery

BackgroundThis study was conducted to show the reliability of fully automated quantification of regional cerebral blood flow (rCBF) in balloon occlusion test (BOT) of the internal carotid artery (ICA). We also shows the usefulness of ratio of rCBF during BOT to rCBF at rest (BOT/rest ratio = rCBF during BOT/rCBF at rest) rather than asymmetry index (AI) during BOT (AI = occluded-side rCBF/contralateral rCBF).MethodsIn the last 2 years, we performed the BOT on 10 consecutive patients (4 with intracranial aneurysms and 6 with head and neck tumors). During the BOT, mean stump pressure (MSTP) of the ICA was monitored. We measured cerebral blood flow (CBF) with technetium-99m hexamethylpropylene amine oxime single-photon emission computed tomography at rest and during BOT. rCBF was determined using 3-dimensional stereotaxic region of interest template (3DSRT) which automatically divided CBF into 12 segments. We defined hypoperfusion segment as BOT/rest ratio <0.9 or AI <0.9.ResultsWhen the BOT/rest ratio was used as a hypoperfusion parameter, the number of hypoperfusion segments was significantly greater in patients with an MSTP ≤50 mm Hg than in patients with an MSTP >50 mm Hg. However, only AI during BOT did not reflect MSTP significantly.ConclusionsThe evaluation of CBF changes in BOT using 3DSRT and the BOT/rest ratio were useful because of objective comparison.