There is a rich and rapidly growing literature on the diagnostic utility of coronary CT angiography (CTA) and its performance relative to other modalities such as stress testing and invasive coronary angiography. Earlier studies of 16-slice coronary CTA showed wide variability in sensitivity (30%-95%) and some variability in specificity (86%-98%). With 40- and 64-slice coronary CTA, more of the chest is covered with each spin of the gantry, the breath hold is shorter, and there are fewer uninterpretable segments than with 16-slice coronary CTA. The very high negative predictive value is especially helpful in ruling out coronary artery disease in patients who have low to intermediate pretest likelihood of CAD.