The use of common carotid waveform analysis in the diagnosis of carotid occlusive disease.

Abstract

Duplex scanning with spectral analysis of the pulsed Doppler signal are currently used to detect and classify disease at the carotid bifurcation. Although the sensitivity of the test exceeds 90%, the method has a lower specificity which ranges between 8 and 50%. The poor specificity is due to the difficulty in distinguishing flow disturbances normally present at the carotid bifurcation from those produced by minimal amount of disease. In order to improve the ability of the method to predict normalcy, new features measured from the low common carotid waveform are evaluated on 150 sides. The difference of frequency from the systolic peak (a) to the point of first zero slope after peak systole (b) was used to define the ratio (a-b)/a. A ratio greater than 0.5 was associated with 76% of the normal sides and only 7% of the diseased sides. A ratio below 0.5 was associated with 83% of the diseased sides. This ratio, when used alone, can improve the specificity of the method to 76%.