Colour duplex scanning versus angiography: a retrospective assessment of carotid stenosis

A retrospective study was performed to investigate the reliability of colour duplex scanning as a screening method in detecting carotid artery disease. The results of this technique and digital subtraction arteriography of 100 carotid bifurcations in 50 patients undergoing carotid endarterectomy were compared. In accordance with suggested standard reports dealing with cerebrovascular disease, the diameter reduction was classified in one of five categories: < 20%, 20-59%, 60-79%, 80-99% and total occlusion. In 78% the gradings determined using digital subtraction arteriography and duplex scanning correlated perfectly, and in 99% of the studied bifurcations the difference was not more than one grade. The sensitivity and specificity of colour duplex scanning in detecting a stenosis with a diameter reduction of more than 60% was 98% and 87.7%, respectively. The best non-invasive method to identify carotid bifurcation disease is duplex scanning. Although the role of duplex scanning as an alternative to angiography is currently evolving, the authors still advocate carotid angiography when surgery is considered.