Electron beam computed tomography (EBCT) has been regarded as the state-of-the-art investigation for detecting and quantitating coronary artery calcification. However, EBCT is expensive, and the asymmetric gantry geometry makes it less useful for routine scanning; thus, EBCT is not readily available to the general population. Recent reports have shown that "volumetric" (also known as "helical" or "spiral") scanners, which are much more commonly available than EBCT, can detect coronary artery calcifications. Updated software available to the NIH which will allow for EKG gating of volumetric scans should improve the quality of the images, and thus improve the ability to accurately quantitate coronary calcification by volumetric scanners. We would like to compare the results of volumetric scans with that of standard EBCT in order to characterize similarities and differences between the two scanning techniques. We propose to obtain EBCT and volumetric CT scans of the coronary arteries in a group of patients with known or suspected coronary artery disease and to calculate the calcium score by each method. Our primary analysis will be a comparison of the sensitivities of the two methods.