European Carotid Surgical Trial-based diameter measurement using B-mode ultrasound imaging to quantify low-grade carotid artery stenosis: the QUAMUS study

Background

Identification of carotid atherosclerotic lesions with no hemodynamic effect on Doppler ultrasound examination is a common situation. Although the use of B-mode ultrasound examination has been recommended to assess this type of lesion, there is no validated examination procedure to date for quantifying low-grade carotid stenosis.

Methods

We conducted a single-center prospective study (QUAntification Morphologique en UltraSonographie [QUAMUS] study) to assess the reproducibility of B-mode ultrasound quantification of low-grade internal carotid artery stenosis using the European Carotid Surgical Trial (ECST) measurement method. We included consecutive patients with <50% North American Symptomatic Carotid Endarterectomy Trial carotid stenosis identified by the University of Washington duplex criteria (ie, maximum systolic velocity of <125 cm/second at a Doppler angle of 50°-60°). The examination was carried out and interpreted independently, blindly, and successively by two operators according to a precise methodology based on the measurement of cross-sectional diameter in B-mode and calculation of the stenosis percentage according to the ECST method. The primary objective was to assess the measurement concordance of the stenosis percentage for a difference not exceeding 10% between the two operators. The secondary objective was to assess concordance in relation to examination quality.

Results

Among the 86 patients included, 159 atherosclerotic carotid arteries were eligible and 157 could be explored (feasibility of 98.74%). The conditions were considered as good by the two operators in 69.43% of cases and poor in 2.55%. The concordance of the stenosis percentage measurement for a maximum difference of 10% between the two operators was 89.17% (95% confidence interval, 83.23-93.56) with a Lin concordance correlation coefficient of 0.87 (95% confidence interval, 0.82-0.90). Under examination conditions estimated as good, average, and poor, the concordance was 95.37%, 78.95%, and 60.00%, respectively.

Conclusions

Our study shows that ECST-based B-mode ultrasound measurement of low-grade carotid stenosis is reliable and can be performed in routine practice in most patients with a measurement variation of <10% using a simple standardized examination procedure.