Prediction of hyperperfusion after carotid endarterectomy by brain SPECT analysis with semiquantitative statistical mapping method

Abstract

Background and Purpose - Hyperperfusion syndrome is a rare but disastrous complication after carotid endarterectomy (CEA). The aim of this study was to investigate the relationship between preoperative cerebral blood flow (CBF) abnormalities and postoperative hyperperfusion through the use of statistical brain mapping analysis. Methods - For 41 patients with unilateral carotid stenosis ≥70%, CBF and cerebral vasoreactivity (CVR) were investigated with resting and acetazolamide-challenge single photon emission CT before CEA. CBF 1 day after CEA was also measured. Three-dimensional stereotactic surface projection (3D-SSP) analysis of CBF changes was performed by use of a control database of 20 subjects. Results - Patients with reduced CVR (CVR <10%, n=15) were categorized into 2 groups based on the severity of CBF reduction relative to the control database by 3D-SSP analysis without normalization: type I (ipsilateral CBF decrease <20%, n=8) and type II (ipsilateral CBF decrease ≥20%, n=7). With thalamic normalization, the patients were also categorized into 2 groups: type A (ipsilateral Z score ≤2, n= 10) and type B (ipsilateral Z score >2, n=5). Severe CBF reduction (≥20% or Z score >2) was significantly associated with postoperative hyperperfusion (CBF increase ≥100%). However, 3D-SSP with thalamic normalization (Z score) demonstrated a higher predictive value (80%) and specificity (91%) for hyperperfusion than 3D-SSP without normalization (percent reduction) (57% and 73%, respectively). No patients with normal CVR (CVR ≥10%, n=26) demonstrated postoperative hyperperfusion. Conclusions - Objective evaluation of abnormalities of CBF and CVR with 3D-SSP could identify patients at risk for postoperative hyperperfusion.