EXPERIMENTAL DESIGN: A prospective cohort analysis comparing the quantification of coronary atherosclerosis by Computed Tomographic angiography to that of invasive Catheterization. Subjects will be patients who are scheduled for non-urgent cardiac cath based on a clinical need to evaluate the coronary anatomy. Cath may be scheduled after a positive stress test or on the basis of concerning symptoms. If a patient consents to participation they will be scheduled for CTA no less than 3 and no more than 30 days prior to Cath. Comparison of lesions detected by the two imaging modalities in the proximal, mid and distal coronary arteries will be made. Grades of disease used will be the following 1). less than 50% 2). 50-75% 3). greater than 75% 4) Uninterpretable. Sensitivity and specificity will be calculated for CTA; in addition PPV and NPV will also be calculated. The 2 readers of the CTA will be blinded to the invasive angiography results. The 2 readers of the invasive angiography, who are blinded to the CTA results will be the standard of comparison. Analysis of data will be performed on a segmental, vessel, and patient basis.