Objective: 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.
Materials and methods: 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.
Results: 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.
Conclusion: 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.