Carotid artery intima-media thickness (IMT) measurements are now recognized as a surrogate measure of atherosclerosis. The measurement is performed on high-resolution ultrasound images of the carotid artery at the level of the carotid bifurcation. Increased IMT values indicate a higher likelihood of having had a stroke or myocardial infarction. In epidemiological studies, IMT measurements made in asymptomatic individuals also predict future cardiovascular events.
Intima-media thickness measurements have also been used in clinical trials as a means of gauging the effects of interventions that modify cardiovascular risk factors, low-density lipoprotein cholesterol for example. A positive response to the intervention is defined as a measurable difference in IMT values of the treated group as compared with a control group.
The technique has also shown the possibility of identifying certain high-risk individuals with evidence of more advanced atherosclerosis or with a high risk for cardiovascular events. This paper reviews the basic history of the development of carotid artery IMT measurements and discusses some technical aspects of the measurement.