Imaging of coronary atherosclerosis: intravascular ultrasound

Atherosclerosis is the main cause of coronary heart disease, which is today the leading cause of death worldwide and will continue to be the first in the world in 2030. In the formation of atherosclerotic coronary lesions, a critical primary step is the accumulation and oxidation of low-density lipoprotein (LDL) particles. Oxidized-LDL favours leucocyte recruitment and their activation, as well as cell death. This leads to generation of complex atherosclerotic plaques. These plaques have a high content of necrotic core, a thin inflamed fibrous cap (intense accumulation of macrophages) and scarce presence of smooth muscle cells (i.e. thin-capped fibroatheroma). At early stages of the formation of the atheroma, the remodelling of the vessel wall usually prevents plaque from encroaching on the lumen, thereby masking the presence of atheroma on angiography. In contrast, greyscale intravascular ultrasound can fully assess the extension of the disease axially and longitudinally. This intravascular imaging technique has played a vital role in advancing our understanding of the pathophysiology of coronary artery disease, and in the development of novel cardiovascular drugs and device therapies. This intravascular imaging technology and its clinical and research applications are discussed in more detail below.