A simple and reproducible method for assessing intimal-medial thickness of the common carotid artery

Intimal-medial thickness (IMT) of the inner arterial wall is a marker for early changes of atherosclerosis. In order to assess the IMT of the common carotid artery (CCA), two observers (A and B) examined the far wall of both CCAs of three groups of 10 healthy volunteers on two occasions, separated by a period of 2 weeks. Each observer examined one group, then both examined a third group (A, B and interobserver groups). The distance between the two echogenic lines representing the IMT of the arterial wall of the distal CCA was measured within 1 cm proximal to the carotid bulb. The maximal IMT at this site in the right and left CCAs was measured three times on each side and a mean value calculated. The mean of the absolute value of differences between both assessments was 0.027 mm for observer A, 0.027 mm for observer B and 0.0480 mm between observers. The calculated coefficient of variation was 5.02% for observer A, 5.70% for observer B and 8.98% between observers. The coefficient of repeatability was, 0.074 mm for observer A, 0.070 mm for observer B and 0.128 mm between observers. This method for estimating the IMT provides a reproducible and reliable measurement suitable for routine practice.