Cerebral hyperperfusion following carotid endarterectomy (CEA) occurs in patients with preoperative impairments in cerebral hemodynamics. The aim of the present study was to determine whether late images/early images on preoperative brain 123I-iomazenil (IMZ) single-photon emission computed tomography (SPECT), which correlate with oxygen extraction fraction images on positron emission tomography, could identify patients at risk for cerebral hyperperfusion following endarterectomy for unilateral cervical internal carotid artery (ICA) stenosis.
In 80 patients, preoperative brain SPECT scans were initiated immediately after (early images) and 180 min after (late images) administration of 123I-IMZ. A region of interest (ROI) was automatically placed in the middle cerebral artery territory in both the cerebral hemispheres using a three-dimensional stereotaxic ROI template. Transcranial regional cerebral oxygen saturation (rSO2) was monitored using near-infrared spectroscope throughout carotid endarterectomy, and a patient was defined as having cerebral hyperperfusion when a ratio of rSO2 at the end of the surgery to rSO2 before ICA clamping was ≥ 1.1.
Cerebral hyperperfusion was observed on intraoperative rSO2 monitoring in eight patients (10%). Preoperative increase in affected side-to-contralateral side asymmetry on late/early 123I-IMZ value was the only significant independent predictor of cerebral hyperperfusion (95% confidence interval [CI], 1.606 to 8.710; P = 0.0010). The preoperative late/early 123I-IMZ asymmetry corresponded to an 88% sensitivity and 89% specificity, with 47% positive- and 98% negative-predictive values for the development of cerebral hyperperfusion.
Preoperative late/early 123I-IMZ images can identify patients at risk for cerebral hyperperfusion following endarterectomy for unilateral cervical ICA stenosis.