The measurement of intima media thickness (IMT) of the common carotid artery has become very popular over the last decade. The IMT is regarded as a marker for atherosclerosis. A large number of studies are conducted with IMT as study endpoint.

In this study, with two ultrasound methods, it will be shown that IMT varies with blood pressure. In the first method, a sequence of 68 common carotid artery B-mode echo images covering 3 heartbeats was stored and analyzed with dedicated software. In each image the vessel diameter and the IMT of the far wall was determined. In the second method, the RF signal of M-mode echography of the same vessel segment of the same individual was used for wall tracking technique during 3 heartbeats. The time course of the diameter of the artery and the IMT of the far wall were determined.

During diastole IMT was thicker compared to systole. The cyclic variations of IMT and diameter were out of phase. Eliminating the time course revealed that IMT and diameter correlates highly and negatively. The difference of IMT could be as large as 10% of the average IMT value. Results were explainable with incompressible material during stretching.

These results underline the importance to define at what moment during the cardiac cycle the IMT measurement is done. More accurately the absolute blood pressure on the moment IMT is determined, is of great influence. Studies that omit this information contain a methodological flaw.