Coronary Artery Calcium Analysis and Reporting on Noncontrast Chest CT Scans: a Paradigm Shift in Prevention

Abstract

The quantification of coronary artery calcium (CAC) on gated noncontrast cardiac CT, as a screening test for subclinical coronary artery disease, has been consistently proven to be superior to risk factors and biomarkers for the prediction of long-term cardiovascular risk. Coronary artery calcium is also readily evaluable in every noncontrast (nongated) chest CT scan, yet there are no recommendations for reporting CAC in scans done for noncardiac indications. Lung CT scanning has been approved for lung cancer screening, and almost all the candidates are intermediate to high risk for coronary artery disease, which can be powerfully evaluated by the assessment of CAC at no additional radiation or cost. There are technical requirements for scanner detectors, slice thickness, and voltage which are easily satisfied. EKG gating provides the highest quality studies but will be more difficult to universally implement. Agatston scoring, ordinal scoring, and visual estimation of nongated scans offer alternatives and are supported by varying degrees of data. Similarly, newer reconstruction algorithms are available but are not yet widely used. Barriers to reporting include increased time and lack of increased reimbursement for CAC analysis, difficulties inherent to reporting abnormal results, and referring physician understanding and utilization of the results to alter patient education and management.