Anatomy of the Coronary Arteries and Veins in CT Imaging

Abstract

The cardiologist and radiologist interpreting coronary computed tomography angiography (CTA) should be familiar with coronary artery anatomy. It has a standard logical structure with some common variations and only a few rare abnormalities. In a conventional selective coronary angiography, blood in the chambers and coronary veins does not interfere with the visualization of the coronary arteries. In addition, myocardium and other soft tissues are hardly seen because of their low absorption of X-rays. Invasive selective coronary angiograms use projections performed in various orientations so that the cardiologist can perceive the 3D anatomy of the coronary arteries. This is quite different for imaging techniques such as CTA. In CTA the contrast agent is intravenously injected, which results in enhancement of the myocardium and blood in the cavities, and projection techniques such as maximum intensity projection (MIP) are therefore of limited use. Overlap of structures that obscure coronary imaging can be avoided by multiplanar reformation (MPR) using thin slices in any desired orientation. However, in that case much of the 3D information is not used. With modern postprocessing tools, such as MIP or the volume-rendering technique (VRT), 3D impressions on a 2D surface can be created. These images look much like the gross anatomy of the heart, but they do not resemble the images known from invasive selective coronary angiography. In this chapter we will therefore review the normal coronary artery and venous anatomy as it may be seen on MPR and VRT images of CTA. We will also review the anomalies that may be encountered during investigations for coronary artery disease.