Interest in the use of computed tomography (CT) for cardiac evaluation has increased rapidly since the introduction of 64-slice scanners. Reflecting this, the installation base of CT scanners in US cardiology practices has tripled in the past 2 years.1 Reports of the high diagnostic performance of coronary CT angiography (CTA), and especially its high negative predictive value in populations with low-to-intermediate prevalence of coronary disease,2,3 have been tempered by a concern about its high radiation dose to patients and the attendant risk of cancer.4