The Role Of Noninvasive 320-Row Multidetector Computer Tomography

Inclusion Criteria: * Male or female, 18 years and older * Able to understand and willing to sign the Informed Consent Form * Undergoing vascular surgery or intermediate risk surgery (these include intraperitoneal, intrathoracic, carotid endarterectomy , head and neck, orthopedics or prostate) AND * One or more of the following clinical predictors according to the Revised Cardiac Risk Index: 1. history of ischemic heart disease (CABG, MI, Stent, positive stress test, Q-waves on ECG) 2. Diabetes (requiring insulin) 3. history of congestive heart failure (NYHA I- II) 4. history of cerebrovascular disease, any of : 1. history of carotid stenosis 2. history of ischemic cerebrovascular disease (stroke or TIA) 5. Aortic or peripheral vascular disease OR 6. Risk of CAD with 3 or more of the following 1. Age ≥ 70 years 2. Hypertension (medicated) 3. Cholesterol (medicated) 4. Diabetes (medicated-oral hypoglycemic) 5. Family history of coronary artery disease \- Exclusion Criteria: 1. Lack of consent for participation 2. Pregnancy 3. History of an allergic response to iodinated contrast medium 4. History of an allergic response, or other contraindication to beta blockers 5. eGFR \< 45 mL/min 6. Hemodynamically unstable/compromised 7. Urgent surgery 8. Atrial fibrillation \> 80 bpm 9. Uncontrolled tachyarrhythmia 10. Atrioventricular block (second and third degree) 11. Moderate to severe aortic stenosis 12. Not able to hold breath for 5 - 10 seconds 13. History of multiple myeloma or organ transplant 14. Severe pulmonary disease including COPD, PAH, asthma 15. Congestive heart failure presented as NYHA functional class III - IV 16. Severe anemia 17. Increased intracranial pressure 18. Closed angle glaucoma 19. Absolute contraindication to Nitroglycerin 20. Presence of medical condition or history that investigator feels would be problematic 21. Acute myocardial infarction (within 4-6 weeks) -