Detection and quantification of carotid artery stenosis: efficacy of various Doppler velocity parameters

The purpose of this study was to evaluate and compare the accuracies of the different Doppler velocity parameters used to grade stenoses of the carotid artery.

Seven velocity parameters determined with Doppler spectra were compared with angiographic findings in 138 carotid bifurcations: the peak systolic and peak end-diastolic velocities in the internal and common carotid arteries, the ratios of peak systolic and peak end-diastolic velocities between the internal and common carotid arteries, and the ratio of peak systolic velocity in the internal carotid artery to peak end-diastolic velocity in the common carotid artery. A receiver-operating-characteristic (ROC) analysis was performed, with and without correction for the bias introduced by preferentially selecting patients for angiography, if the Doppler results indicated a lesion. Multiple regression analysis was performed to predict the percent stenosis and to predict the probability of a 70% or greater stenosis.

Of the Doppler parameters, the peak systolic velocity in the internal carotid artery and its ratio to the peak end-diastolic velocity in the common carotid artery were the most accurate and had equivalent test performance (ROC area = 0.94; after correction for verification bias, ROC area = 0.78). In multiple regression analysis, the peak systolic velocity in the internal carotid artery was the most significant parameter, although its ratio to the peak end-diastolic velocity in the common carotid artery had incremental value in detecting a 70% or greater stenosis, and the peak systolic velocity in the common carotid artery provided additional information for quantifying the stenosis.

The peak systolic velocity in the internal carotid artery is the best single velocity parameter for quantifying a stenosis and for detecting a 70% or greater stenosis.