Inclusion Criteria:

• * Patients aged 21-85 years
• * Clinical history suggestive of CHD who are referred by their primary cardiologist for further evaluation via Computed tomography angiography (CTA) will be asked to participate.
• * Women of child bearing potential must demonstrate a negative pregnancy test within 24 hours of the study CTA.
• * Ability to understand and willingness to sign the Informed Consent Form.

Exclusion Criteria:

• * Known allergy to iodinated contrast media.
• * History of multiple myeloma or previous organ transplantation
• * Elevated serum creatinine (\> 1.5mg/dl) OR calculated creatinine clearance of \< 60 ml/min (using the Cockcroft-Gault formula
• * Atrial fibrillation or uncontrolled tachyarrhythmia, or advanced atrioventricular block (second or third degree heart block)
• * Evidence of severe symptomatic heart failure (NYHA Class III or IV);
• * Known or suspected moderate or severe aortic stenosis
• * History of prior percutaneous coronary intervention (PCI) in one or more vessel or history of coronary arterial bypass grafting (CABG)
• * Suspected acute coronary syndrome
• * Presence of any other history or condition that the investigator feels would be problematic