Carotid artery disease screening : assessment of criteria

Abstract

The Department of Radiology at St. Luke’s Hospital has provided a screening service for stroke related disease since April 1991. This consisted of Duplex Ultrasound screening (DUS) for Extracranial Carotid Artery Disease (ECAD) followed by angiography or intra-arterial digital subtraction angiography (lADSA) or digital intravenous angiography (DIVA) if ultrasound screening was positive for significant disease. The aim of this study was to evaluate in the local context, the various criteria for assessment already established overseas and to devise the best combination of these criteria to improve the detection of disease, thus improving the quality of the•local screening service. 504 patients have been screened for stroke related disease. Twelve patients (6M : 6F) with significant disease, who were considered for surgery, were referred for angiography, IADSA or DIVA. Comparison of these two modalities, DUS and vascular study, were made on 22 sides for the Multicentre Criteria (MCC), the Modified Seattle Criteria (MSC) and the Modified Washington Criteria (MWC). The accuracy, sensitivity, specificity, positive predictive value and negative predictive value were calculated for the MCC, the MSC and the MWC for peak systolic velocity. For the MCC the end diastolic velocity, the systolic velocity ratio and the diastolic velocity ratio were also compiled. The highest precision for extra cranial carotid artery disease screening can be achieved by a combination of the MCC or MSC for peak systolic velocity and with the systolic velocity ratio for the MCC.