Reproducibility of Carotid Artery Doppler Frequency

Doppler sonography of 29 extracranial carotid arteries was performed twice within three days or less. Angiography revealed stenoses with from 10 to 95% diameter reduction in 25 internal carotid arteries whereas four vessels were found to be normal. The systolic peak frequency of the internal carotid artery read from the Doppler spectrum (n = 29) could be reproduced very well. This was shown by a linear regression nearest the line of identical values with a coefficient of correlation r = 0.97 (p < 0.001). Other values derived from the spectral analysis of the Doppler shift signal were not so well reproduced including the peak frequency ratio (systolic peak frequency of the internal carotid artery/systolic peak of the common carotid artery) (n = 22; r = 0.81; p < 0.001). The mean frequencies read from the zero-crossing detector recordings (n = 20) could not be reproduced as demonstrated by a linear regression far away from the line of identical measurements with a coefficient of correlation r = 0.43 (p < 0.05).