Anatomy of an emerging diagnostic test: computed tomographic coronary angiography.

The study by Mollet et al on CT coronary angiography in this issue of Circulation is important for several reasons.1 The 64-multislice technology for acquiring tomographic x-rays of the coronary vessels during the arterial phase of a bolus of iodinated contrast introduces several technical advances: improved spatial resolution (thinner slices), improved temporal resolution (less time needed to acquire an image means less time for the vessel to move), and improved spatial coverage of the heart (reduction of registration errors). Unlike previous studies, the authors attempted to analyze the entire length of all of the major arteries, not just those in which image quality was optimal. All patients had the definitive end point comparison to invasive angiography, which was not prompted by the results of the CT examination. The authors report sensitivity for the detection of significant obstructive disease of 99% and a specificity of 95%, confirming a slight propensity of CT to generate false-positive lesions in the presence of vessel wall calcification. Although the results were excellent, it is clear that this study and others have struggled with the question as to how to best evaluate CT angiography.