Increased carotid intima-media thickness (C-IMT) is a non-invasive marker of early arterial alterations which is associated with increased cardiovascular risk. The aim of this study is to validate a new real-time automatic system to measure C-IMT. Results are compared with the manual measurements, which are still largely accepted as the gold standard.

Ultrasound scans of the distal common carotid artery (right/left) were obtained from 120 patients with cardiovascular risk factors and 30 healthy controls. The C-IMT was measured on the far wall, 1 cm above the bifurcation. The dataset was analysed by two operators both automatically and manually. The first operator repeated the analysis twice.

The agreement between automatic and manual measurements was evaluated by Bland-Altman plots: a bias of −0.020mm and an interval of agreement of 0.027mm were obtained. Intra-observer variability was computed on the repeated measurements of the first operator. Bias was not significantly different from zero for both manual and automatic measurements, whereas the interval of agreement was 0.077mm in manual analysis and 0.012mm in automatic analysis. Coefficients of variation of 2.8% and 0.4% were obtained, respectively. Inter-observer variability showed a little bias (−0.032mm) only for manual analysis, whereas the interval of agreement was 0.075mm in manual analysis and 0.021mm in automatic analysis with coefficients of variation of 4.5% and 0.6%, respectively.

In conclusion, the new real-time automatic system represents a more feasible and reproducible method than the manual approach when used to estimate C-IMT in clinical studies and practice.