Inclusion criteria • Adults at least 20 years old • Subject who requested a coronary CT angiography to assess clinical disease Exclusion criteria • Subjects suspected of having myocardial infarction, unstable angina pectoris, or coronary artery disease • Subjects who experienced heart attack within 40 days prior to the CT scan • Subjects with a diagnosed complicated heart anomaly • BMI > 35 kg/m2 • Serum creatinine ≥ 1.5 mg/dl • Pregnant subjects • Subjects with a history of hypersensitivity reaction to contrast agents • Subjects with contraindications to the use of nitroglycerine • Subjects who plan to participate or enroll in other randomized clinical trials for cardiovascular disease. • Subjects with contraindications to the use of adenosine (e.g., bronchial asthma, 2–3 degree AV block, sick sinus syndrome, SBP less than 90 mmHg, recent prescribed history of dipyridamole, or hypersensitivity to adenosine) |