Carotid duplex scan versus angiography in evaluation of carotid artery disease

Angiography is presently felt to be the most accurate means of evaluating the carotid artery bifurcation, and is required preoperatively by most vascular surgeons. Arterial digital subtraction angiography (DSA) is the method commonly used. Angiography, however, is expensive and invasive, with significant morbidity and mortality. Duplex scanning (DS) has gained acceptance as a screening technique and has recently been advocated as the sole preoperative study in several centers because it is non-invasive and has an accuracy that is equal to or better than angiography. This study preoperatively evaluated 41 carotid arteries in 38 patients by arterial digital subtraction angiography and duplex scanning, and the results were compared to the surgical specimen. One artery was excluded because of an inadequate duplex scan, leaving 40 arteries studied by both techniques. Forty arteries (100%) studied by duplex scans corresponded with the surgical specimen, whereas only 31 arteries (77.5%) studied by DSA corresponded with the surgical specimen. Nine arteries (22.5%) studied by DSA had stenosis at the time of surgery significantly greater than predicted by DSA. Three arteries (7%) were felt to be normal by DSA, but had approximately 80 per cent stenosis by DS and at surgery. Our findings indicate that duplex scanning at our institution is more accurate than arterial DSA in determining percent diameter stenosis and plaque morphology of carotid arteries.