Validation of Coronary Calcium Subtraction to Improve Diagnostic Accuracy of Coronary CT Angiography

Prospective International Study of Coronary Substraction Using 320 Row-detector CT

Coronary calcium hampers accurate evaluation of the coronary arteries with coronary computed tomography angiography (CCTA). A novel approach to potentially overcome this limitation is coronary calcium subtraction.

The primary hypothesis of the study is:

- Coronary calcium subtraction CCTA will improve diagnostic accuracy as compared to conventional CCTA on a per-patient basis

CCTA is a very important clinical method for the clinical evaluation of patients with chest pain of potential cardiac ischemic origin. However Coronary calcification and/or previously implanted coronary stents may limit the diagnostic accuracy of CCTA. A novel approach - coronary calcium subtraction - has been developed to potentially overcome this limitation.

• Study Objective: To assess diagnostic accuracy using coronary calcium subtraction coronary CT angiography (CCTA) as compared to conventional CCTA.
• 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.

Inclusion Criteria:

• Age > 55 Years
• Scheduled for invasive coronary angiography
• Logistically possible to perform CCTA before invasive evaluation

Exclusion Criteria:

• Known Iodine-contrast allergy
• Estimated GFR below 50 ml/min
• Atrial fibrillation or other persistence cardiac arrythmia
• Contraindication to betablockers (bronchospasm, LVEF less than 40%)
• Implanted PM or ICD
• Previous mechanical heart valve surgery
• Inability to maintain breath-hold for at least 5 sec
• Patient-related condition resulting the inability of the patient to understand the informed consent form of the study