Electron-beam computed tomographic (CT) scanning has been established as a noninvasive imaging modality for the diagnosis of coronary arterial disease. major clinical applications are the detection and quantification of coronary calcium (1-3) and noninvasive CT angiography of the coronary arteries (4-6). Current limitations of electron-beam CT imaging include the limited reproducibility of coronary calcium quantification, the inability to deduct noncalcified atherosclerotic plaques, and the limited spatial resolution of three-dimensional (3D) depictions of the coronary arteries (7). Because of the restriction to transverse, nonspiral scanning in electrocardiographically (ECG) synchronized cardiac investigations, acquisition of 3D images by using electron-beam CT can provide only limited z resolution within a single breath-hold scan.