Carotid artery assessment with continuous wave Doppler ultrasound, comparison of two methods with angiography.

A comparison of two non-invasive techniques of evaluation of the internal carotid artery in the neck with the results of angiography was carried out in 31 patients. The techniques were, spectral analysis of the doppler signals obtained from the common, internal and external arteries and, velocity waveform analysis of the common carotid analogue signal, in both methods a continuous wave doppler ultrasound velocimeter was used. With the spectral analysis technique sensitivity was 80% and specificity was 78% for a diagnosis of internal carotid stenosis of greater than 50% diameter reduction. For a diagnosis of 20% or greater, sensitivity was 82% and specificity 85%. Sensitivity may have been underestimated in this study because the angiographic technique used in 22 of the 31 patients was the intravenous digital subtraction method. In our hands velocity waveform analysis of the common carotid analogue signal while showing a similar sensitivity to the spectral analysis method had an unacceptably low specificity.