Are noninvasive tests sufficiently accurate to identify patients in need of carotid arteriography?

Noninvasive studies were performed on 1771 patients with suspected extracranial cerebrovascular disease. Of these, 328 underwent arteriography, providing 604 arteriograms for comparison with carotid phonoangiography (CPA), 516 for comparison with pulse-delay oculoplethysmography (OPG), and 571 for comparison with pulsed Doppler ultrasonic arteriograms (UAs). The UA was the most sensitive test, detecting 92% of the internal carotid stenoses of 60% or more and 72% of those between 20% and 59%. When the results of three tests were combined, the sensitivity was 80% and the specificity was 61% for any recognizable disease at the carotid bifurcation. Ninety percent of stenoses of 20% or more and 95% of stenoses of 40% or more were detected by the combination. The UA identified 86% to 93% of patients with operable disease, and combined studies identified 88% to 95%. Carotid endarterectomies were performed on 112 patients. The UA was positive in 91% to 96% of the patients undergoing surgery, and combined testing was positive in 96%. This study suggests that noninvasive tests are capable of identifying most patients in need of carotid endarterectomy.