Coronary artery disease (CAD) is a leading cause of mortality and morbidity in most developed countries [1]. CAD is a common and sometimes disabling disorder, although medication therapy, percutaneous coronary intervention and coronary artery bypass grafting have developed recently. Medical doctors need to prevent from developing acute coronary syndrome. The development of non-invasive cardiac imaging tools (particularly, cardiac computed tomography, echocardiography and so on) for the diagnostic and prognostic assessments of patients is evolving evidence for various treatment strategies. Cardiac catheterization is golden standard for the diagnosis of CAD. Although the risk of adverse events for invasive coronary angiography is generally considered to be low, potential life-threatening complications can arise, including not only coronary artery dissection, but also arrhythmia, stroke, hemorrhage, myocardial infarction (MI), and death [2]. Non-invasive imaging devices for CAD have been developing, such as echocardiography, scintigraphy, computed tomography (CT) and magnetic resonance imaging (MRI) and so on. Particularly, the development of cardiac CT is remarkable in the last 10 years. Prior report suggested a hierarchial model of efficacy to assess the contribution of diagnostic imaging to the patient management process. Level 1 is technical quality of the images. Level 2 is diagnostic accuracy, sensitivity, and specificity associated with interpretation of the images. Level 3 is whether the information produces change in the referring physician’s diagnostic thinking. Level 4 is efficacy, which concerns effect on the patient management plan. Level 5 is effect of the information on patient outcomes. Level 6 is societal costs and benefits of a diagnostic imaging technology [3]. CT imaging was introduced in 1972 [4]. The ability to obtain cross-sectional images of the computer-assisted tomography, Sir Geoffrey N. Hounsfield and Allan M. Cormack were awarded the Nobel prize in Medicine in 1979. Since a 4 detector row cardiac CT angiography was launched in 1998. Cardiac CT has experienced rapid improvement of imaging qualities with the ongoing evolution of cardiac CT. The diagnostic accuracy of the 64 detector cardiac CT to detect coronary stenoses is available. Cardiac CT is useful for the diagnosis and risk stratification of CAD. Cardiac CT presently has not been considered a routine replacement for invasive coronary angiography,