Ultrasound assessment of atherosclerotic vessel wall changes: reproducibility of intima-media thickness measurements in carotid and femoral arteries.

Abstract

Ultrasonography is widely used in cardiovascular research to quantify early atherosclerotic vessel wall changes. In this article, we examined the short- and long-term reproducibility of this technique in the common carotid artery, carotid bifurcation, common femoral artery, and superficial femoral artery. Furthermore, we assessed the effect of progressed atherosclerosis on reproducibility. Repeated ultrasound examinations were performed by one observer on 15 healthy individuals and 18 patients suffering from coronary heart disease. Intima-media thickness was determined by B-mode ultrasonography. The examinations were repeated by the same observer after a short time interval (short-term) and after a few weeks (long-term) and expressed as the mean difference between the measurements and the coefficient of variation (CV). The reproducibility of the intima-media thickness determination turned out to be best in the common carotid artery and the superficial femoral artery when performed in healthy controls (CV 5.6% and 5.5%, respectively). Reproducibility was less in patients with clinical atherosclerosis; this especially affected the reliability of the superficial femoral artery measurement (CV in healthy controls was 5.5%; in coronary heart disease patients, 17.5 %). The reliability of the intima-media thickness measurements in the common carotid artery (CV in healthy controls was 5.6%; in coronary heart disease patients, 9.5%) proved to be least affected by progressed atherosclerosis. A longer time interval between measurements did not affect the reproducibility of intima-media thickness measurements in healthy controls, whereas in the patients it led to some decrease of reproducibility and to a major decrease in reproducibility of the superficial femoral artery measurements (CV changed from 12.7% to 17.5%). Ultrasonography is a reliable and accurate technique to determine intima-media thickness in superficial arteries. In studies in which the intima-media thickness determination is used as a marker for generalized and coronary atherosclerosis, the common carotid artery should always be included, whereas the benefit of inclusion of other arteries depends on age and the expected extent of atherosclerosis in the individuals studied.