Value of single photon emission computerized imaging in the treatment of patients undergoing carotid endarterectomy

The purpose of this study was to evaluate the clinical relevance of regional cerebral blood flow by single photon emission computerized imaging (SPECT) in patients undergoing carotid endarterectomy (CEA).

Eighty-four patients were included in this study; 74 were undergoing CEA. All 74 operative cases had SPECT scans before and after surgery. The first 30 patients undergoing CEA also had computed tomography scans for comparison. Findings were correlated during surgery with carotid stump pressures.

No deaths and no strokes occurred. Four complications were seen. In the first 30 patients with computed tomography scans, 20 had positive SPECT scans, whereas the computed tomography scan was negative. A 100% linear correlation was seen with operative stump pressures, and decreased regional cerebral blood flow was noted on SPECT scan before surgery (48 abnormal with mean 26 mm). These patients received shunts during CEA.

SPECT scans add useful physiologic data to anatomic images and provide factual or objective information that is valuable in treating patients undergoing CEA. A positive SPECT scan is predictive of poor collateral circulation and may possibly identify those "at risk," if they have no symptoms, and those who will require shunting during surgery. SPECT scans may facilitate case selection in severe bilateral carotid stenosis and deferment of operation in elderly patients at high risk. After surgery SPECT scans will document the value of successful CEA in reestablishing normal regional cerebral blood flow. Finally, SPECT scans have potential value for reevaluating patients who have complete carotid occlusion for external carotid/internal carotid artery bypass.