- Material and Methods: A total of 200 patients with suspected or known coronary artery disease (CAD) who have been referred for invasive coronary angiography (ICA) will prior to ICA undergo additional research CCTA with the newly developed coronary calcium subtraction protocol. Based on the coronary calcium scan (CS), coronary calcium score will be calculated according to the Agatston score. Conventional contrast enhanced CCTA studies will be analyzed for image quality and the presence and extent of coronary stenosis. Using a dedicated algorithm, subtraction will be performed on all datasets to obtain CCTA subtraction images. Subtracted images will be analyzed similar to the conventional CCTA images. ICA will serve as the gold standard. Image quality will be compared between conventional and subtracted CCTA. In addition, diagnostic accuracy in the evaluation of coronary stenosis as determined on ICA will be compared. Finally, factors influencing the performance of coronary calcium subtraction will be evaluated.