Quantification of carotid artery stenosis with various Doppler velocity parameters

Abstract

Purpose: To assess the Doppler indices best suited for detecting a stenosis of the internal carotid artery.

Material and method: 358 patients (234 men, 124 women, mean age 59 years, range 25-83 years) were examined via duplex carotid sonography (US) and arteriography. Flow indices and B-mode real-time results of stenoses were compared with arteriographic findings.

Results: The accuracy of US in differentiating a 50% or more severe ICA stenosis was 93% and the correlation coefficient between angiographic and US stenosis was 0.94. Peak systolic velocity of the internal carotid artery (vpICA) and its ratio to the systolic (vpICA/vpCCA) and diastolic velocity of the common carotid artery were most accurate at 70% stenosis. The vpICA/vpCCA ratio was even slightly more accurate in cases of less severe stenosis. B-mode real-time measurement of diameter stenosis was most accurate at the < 30% level. There was large variation in the flow values of the ICA, mostly due to the variability of flow in the common carotid artery. The vpCCA was low in wide and higher in medium-sized or narrow common carotid arteries. Contralateral ICA stenosis also affected the flow and thus on the vpICA/vpCCA ratio and the differentiation between significant and non-significant stenosis.

Conclusions: At duplex US, B-mode real-time measurement is suitable for screening small carotid plaques and flow indices, especially vpICA and vpICA/vpCCA in severe stenoses.