Ultrasound protocol and quality control procedures in the European Lacidipine Study on Atherosclerosis (ELSA).

The European Lacidipine Study on Atherosclerosis (ELSA) is a multinational interventional clinical trial aimed at determining the antiatherosclerotic effects of Lacidipine, a calcium antagonist, when compared to atenolol, a beta-blocker, on the carotid arteries of 2300 cardiovascular asymptomatic patients with moderately high blood pressure. Quantitative B-mode ultrasound imaging is being used to measure the intima-media thickness of a standardized section of the carotid arteries including the distal common, bifurcation, and proximal internal carotids. Prospective investigations of large samples of population using ultrasonographic endpoints rely heavily on the precision and reproducibility of the method. Therefore, specific quality control protocols are required to determine and monitor cross-sectional and longitudinal stability of the measurement reproducibility. In ELSA, the ultrasound methodology was specifically designed to include a set of procedures to quality control the critical components of measurement variation including instrumentation, and ultrasound operators, i.e. sonographers and readers. The ELSA clinical trial will provide the largest set of prospective quality control data on the use of quantitative B-mode ultrasound imaging.