The "Coronary Evaluation Using Multidetector Spiral Computed Tomography Angiography using 64 Detectors" or "CorE-64" study was designed to evaluate the diagnostic accuracy of multislice spiral CT angiography using 64 detector rows for identifying coronary artery stenosis in patients with suspected or known coronary artery disease. The study was designed as a prospective, multi-center, international, blinded study examining the diagnostic accuracy of 64-slice CT in comparison with CCA. The primary hypothesis of the study is that 64-slice CT coronary angiography will be able to detect significant coronary artery disease in a patient with acceptable diagnostic accuracy as compared to CCA. Significant CAD is defined as ≥ 50% stenosis as determined by quantitative analysis of CCA (QCA). The diagnostic parameters is per-patient sensitivity and specificity compared with CCA, with both point estimates and continuous measurements of diagnostic accuracy. Eligible patients will first undergo MDCT (calcium scanning and MDCTA)prior to clinically indicated conventional coronary angiography. Patients with CAC 600 or less will be included in the primary analysis. Patients will be followed for clinical events including revascularization.