Intima–media thickness

Intima–media thickness (IMT), also called intimal medial thickness, is a measurement of the thickness of tunica intima and tunica media, the innermost two layers of the wall of an artery. The measurement is usually made by external ultrasound and occasionally by internal, invasive ultrasound catheters. Measurements of the total wall thickness of blood vessels can also be done using other imaging modalities.

Carotid IMT is used to detect the presence of atherosclerosis in humans and, more contentiously, to track the regression, arrest or progression of atherosclerosis. Ultrasound measurements of carotid IMT were first proposed and validated in vitro by Paolo Pignoli in 1984 and further details were subsequently published in a highly cited article. The use of IMT as a non-invasive tool to track changes in arterial walls has increased substantially since the mid-1990s. Although carotid IMT is predictive of future cardiovascular events, the usefulness of measuring change in carotid IMT over time is disputed, as meta-analyses have not found that change in carotid IMT is predictive of cardiovascular events. As such, the use of change in carotid IMT as a surrogate endpoint measure of drug efficacy in clinical trials, or in clinical management of cardiovascular disease, is debated.