Audible interpretation of carotid Doppler signals. An improved technique to define carotid artery disease.

Direct interrogation of the common, internal, and external carotid arteries with a bidirectional Doppler detector was performed on 199 vessels in 101 patients. Audible interpretations of normal, disturbed (stenotic), or absent (occluded) flow signals were made by vascular technologists and the results were compared with independently assessed carotid arteriograms. The sensitivity in detecting severe (greater than or equal to 50%) stenosis or occlusion was 9.2%, with correct differentiation of these two conditions in 84% of vessels. Nonobstructive (less than 50%) stenoses were detected in 30% of cases. The specificity in identifying normal carotid arteries was 91%. The predictive values of normal, abnormal, and absent flow signals were 95%, 90%, and 90%, respectively. Direct carotid Doppler signal analysis is more accurate than indirect periorbital Doppler screening in defining carotid stenosis or occlusion.