Combined Non-invasive Coronary Angiography and Myocardial Perfusion Imaging Using 320 Detector Computed Tomography

Inclusion Criteria: * Male or female patients, age 45-85. Women of child bearing potential must demonstrate a negative pregnancy test within 24 hours of the study MDCT. * Suspected or diagnosed coronary artery disease with a clinical indication for coronary angiography; and planned coronary angiography within the next 60 days. * Able to understand and willing to sign the Informed Consent Form. Exclusion Criteria: * Known allergy to iodinated contrast media. * History of contrast-induced nephropathy. * History of multiple myeloma or previous organ transplantation. * Elevated serum creatinine (\> 1.5 mg/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. * Previous coronary artery bypass or other cardiac surgery. * Coronary artery intervention within the last 6 months. * Known or suspected intolerance or contraindication to beta-blockers including: * Known allergy to beta-blockers * History of moderate to severe bronchospastic lung disease (including moderate to severe asthma). * Severe pulmonary disease (chronic obstructive pulmonary disease). * Presence of any other history or condition that the investigator feels would be problematic. * SPECT preformed in non-validated center within 60 days prior to screening. * SPECT performed within the previous 6 months of screening but \> 60 days. * SPECT studies performed within 60 days of screening that include rest and stress studies performed using 2 day protocols. * BMI greater than 40