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The diagnostic accuracy of duplex ultrasonography for evaluating carotid bifurcation
J L Ballard1, K Fleig, M De Lange
1Division of Vascular Surgery, Loma Linda University Medical Center, California 92354.
Background:
In many medical centers the standard preoperative study for patients undergoing carotid endarterectomy is four-vessel carotid arteriography, but duplex scanning of the carotid bifurcation is also reported to be highly accurate for detecting stenotic or occluded carotid arteries.
Methods:
The diagnostic accuracy of duplex ultrasonography was evaluated in a study of 774 carotid bifurcations, in 400 patients comparing the degree of predicted internal carotid artery (ICA) stenosis found using that technique, with that found by contrast arteriography. Agreement between the predicted degree of ICA stenosis and the arteriographic measurement was evaluated using the Spearman rank order correlation. Accuracy statistics for duplex scanning as a diagnostic modality were assessed using 2 x 2 tables.
Results:
The Spearman rank order correlation coefficient was 0.74 (P = 0) for the symptomatic group, 0.65 (P = 0) for the asymptomatic group, and 0.68 (P = 0) for the total group. The accuracy of duplex ultrasonography for detecting all grades of ICA stenosis ranged from 80% to 97%.
Conclusions:
Duplex ultrasonography of the carotid bifurcation is a reliable diagnostic tool and can be used as the sole preoperative study for selected patients with extracranial cerebrovascular disease. Our current algorithm is discussed in conjunction with a critical analysis of this large database.