Since the introduction of coronary CT angiography (CCTA) there has been an enormous growth in the quantity of evidence to support the role of CCTA in the diagnosis of patients with suspected coronary artery disease (CAD). But what is the level of diagnostic accuracy of CCTA today? Have we attained sufficient reliable evidence to fully appreciate the role of CCTA in cardiologic practice?

Hierarchical model of diagnostic efficacy

The technical details and potential clinical applications of CCTA have been reported in two recent reviews in ‘Education in Heart’.1 ,2 In this current state-of-the-art exposition of CCTA for patients with suspected CAD it appears useful to arrange the available evidence according to a hierarchical model of efficacy of diagnostic imaging first described by Fryback and Thornburg in 1991.3 Efficacy is defined as: “the probability of benefit to individuals in a defined population from medical technology (CCTA) applied for a given medical problem under ideal conditions”.3

The model consists of six levels of efficacy: level 1—technical efficacy; level 2—diagnostic accuracy efficacy; level 3—diagnostic thinking accuracy; level 4—therapeutic efficacy; level 5—patient outcome efficacy; level 6—societal efficacy. The goal of the model not only involves the traditional view of the assessment of diagnostic imaging to generate optimal quality images and hence optimal diagnosis, but rather is a comprehensive assessment of patient and societal benefits of CCTA.3

This review is an update of the current position of CCTA in the diagnosis of patients with suspected CAD.

Technical efficacy

The spatial resolution of 64-slice (or more) CCTA in the laboratory setting is 0.3–0.4 mm³ (isotropic spatial resolution allowing undistorted reconstruction of images in any plane), but in the clinical setting this is 0.5–0.6 mm³. The spatial resolution of CCTA is still limited compared to the 0.1–0.2 mm of invasive coronary angiography (ICA). The temporal resolution …