Identification and Characterization of the Atherosclerotic Plaque Using Coronary CT Angiography

Coronary CT angiography (CTA) is the first diagnostic modality that allows simultaneous evaluation of the lumen and wall of these small, rapidly pulsating arteries. Catheter coronary angiography, by contrast, only evaluates the internal, patent lumen of these vessels, without providing direct information on the vessel wall or the extent of vascular parietal involvement by atherosclerosis. While it identifies areas of stenosis or obstruction, it does not show details of the plaque itself, unless heavy calcifications make the atherosclerotic plaque evident on the X-ray image. Intravascular ultrasonography (IVUS) is an excellent method to obtain high-resolution images of the vascular wall, with identification of the different layers and proper characterization of the atherosclerotic plaque; however, it is an invasive procedure, performed in the course of catheter coronary angiography, and does not simultaneously evaluate the vessel lumen. Coronary CTA is therefore the first non-invasive imaging technique that allows evaluation of the lumen and walls of the coronary arteries, a particular advantage in determining the atherosclerotic burden in these arteries. Since atherosclerosis is a disease of the vessel wall, obtaining proper and direct evidence of a coronary plaque is an important new diagnostic possibility. The technique provides morphological information and CT density measurements, with important prognostic and therapeutic implications.