COLOR-FLOW DUPLEX SCANNING OF CAROTID ARTERIES - NEW VELOCITY CRITERIA-BASED ON RECEIVER OPERATOR CHARACTERISTIC ANALYSIS FOR THRESHOLD STENOSES USED IN THE SYMPTOMATIC AND ASYMPTOMATIC CAROTID TRIALS

Purpose: Duplex scanning has become the standard for noninvasive evalu ation of carotid arteries. However, current ultrasound criteria for in ternal carotid artery (ICA) stenosis (16% to 49%, 50% to 79%, 80% to 9 9%) may not be applicable to the categories (30% to 49%, 50% to 69%, 7 0% to 99%) used in ongoing symptomatic and asymptomatic carotid endart erectomy trials. This study was undertaken to determine new velocity c riteria consistent with these categories. Methods: From January 1, 198 9 through October 30, 1992, 5871 color-flow duplex scans were obtained in our laboratories. After inadequate arteriograms and patients with a contralateral ICA occlusion were excluded, 770 peak systolic velocit y (PSV) and 229 end-diastolic velocity (EDV) measurements were availab le for comparison with arteriography. ICA PSV and EDV were subjected t o receiver operator characteristic curve analysis to determine optimum criteria for identifying stenoses of 30%, 50%, and 70%. Results: For 70% to 99% carotid artery stenosis, PSV greater than 130 plus EDV grea ter than 100 provided the best sensitivity (81%), specificity (98%), p ositive predictive value (89%), negative predictive value (96%), and o verall accuracy (95%). For 50% to 69% stenosis, a PSV greater than 130 and EDV of 100 or less cm/sec proved to be the best combination: sens itivity (92%), specificity (97%), positive predictive value (93%), neg ative predictive value (99%), and accuracy (97%). Stenoses in the 30% to 49% range were less accurately identified. Conclusion: These redefi ned criteria may prove useful for analyzing duplex ultrasound velocity data in reference to the classification of ICA stenosis used in recen t clinical trials of the safety and efficacy of carotid endarterectomy .