Reproducibility of measurements of intima-media thickness and distensibility in the common carotid artery

Objective: To assess reproducibility of ultrasonographic measurements of arterial distensibility nod intima-media thickness (IMT) bl the common carotid arteries. Design: Prospective study. Materials: Measurements of IMT non arterial distensibility were performed on-line in B-mode and M-mode, respectively. Blood pressure was assessed. From the measured variables stiffness indices were derived. Methods: Twenty-five personas were included in the IMT study, both healthy subjects and patients with atherosclerotic disease. Distensibility was measured in a randomly selected subgroup of 10 persons. Ail subjects were examined by two different sonographers an the same day and were re-examined after 1 or 2 weeks. Results: When data from both carotid arteries were combined, the interobserver coefficient of variation of IMT was on average 11.7%, of diastolic diameter 3.3%, of distension and relative distension 11.8%, of distensibility coefficient 12.3%, and of stiffness parameter beta 19%. Intraobserver variability was slightly lower than interobserver variability. Variability for measurements in the right common carotid artery only was higher than for measurements of both carotid arteries combined. Conclusions: Our study demonstrates that reproducibility of measurements of IMT and arterial distensibility of the common carotid artery, by B-mode and M-mode ultrasonography respectively, is acceptable when used in large studies.