Measuring the degree of internal carotid artery stenosis

The use of ultrasonic methods to evaluate carotid disease differs from country to country. Most popular is the criterion of flow velocity in the stenosis, a criterion influenced by multiple other factors than narrowing of the artery. On the other side angiography does not reliably measure area reduction, responsible for the hemodynamic effect of a stenosis. Therefore correlations of velocity and the degree of stenosis as measured by angiography were never satisfying. In a recent international consensus a multiparametric approach has been proposed aiming to reduce possible errors. This article illustrates some of the possible errors measuring flow velocity with Doppler ultrasound and discusses the background for using multiple criteria. Ultrasound can be used for clinical decision making. This is possible in a clear cut high degree stenosis and in low degree disease. The advantage of Doppler ultrasound is to describe best the hemodynamic consequences of vessel narrowing. This may yield important additional information in combination with other imaging modalities.