Reporting of Coronary Artery Calcium on Abdominal CT Scans
Coronary artery calcium (CAC) is frequently visible on abdominal CT scans but is significantly under-reported by radiologists, and even when reported, ordering physicians often fail to act on this finding or inform patients appropriately.
Current State of CAC Detection and Reporting
Radiologist Reporting Practices
CAC is present in approximately 53% of non-cardiac CT examinations in patients without known coronary artery disease, yet radiologists report it in only about 69% of cases where it is actually present 1.
The 2016 Society of Cardiovascular Computed Tomography and Society of Thoracic Radiology guidelines explicitly recommend reporting CAC in all patients irrespective of scan indication or patient risk status 2.
On abdominal CT scans specifically, the heart and coronary arteries are typically visible in the upper portions of the scan, making CAC detection technically feasible 2.
Physician Awareness and Action
The gap between detection and clinical action is substantial:
Only 23% of ordering physicians were aware that incidental CAC was reported in their patients' radiology reports 1.
Among physicians surveyed, only 4% stated they would make medical management decisions based on incidental CAC findings 1.
When CAC was reported, there was only a 4-5% increase in statin and aspirin prescriptions, demonstrating minimal clinical impact under usual care conditions 1.
54% of physicians believed CAC on non-cardiac CT was analogous to coronary artery disease, but this knowledge did not translate into action 1.
Evidence for Clinical Importance
Prognostic Value
Visual CAC assessment on contrast-enhanced CT (including abdominal scans) has high diagnostic performance and prognostic utility, with hazard ratios of 4.5 for major adverse cardiac events 3.
The presence of moderate-to-large CAC on contrast-enhanced scans is 99% predictive of actual CAC presence and 88% predictive of CAC ≥100, making it highly reliable for identifying high-risk patients 4.
Impact of Systematic Notification
A randomized quality improvement project demonstrated that systematic notification of clinicians and patients about incidental CAC increased statin prescription rates from 7% to 51% within 6 months 5.
This represents a 7-fold increase in appropriate preventive therapy when notification systems are implemented 5.
Recommended Approach for Reporting
What Should Be Reported
CAC should be reported using visual assessment as none, mild, moderate, or severe 2:
- None: No visible calcium
- Mild: Minimal scattered calcium
- Moderate: Multiple areas of calcium
- Severe/Heavy: Extensive calcium throughout coronary arteries
This visual method correlates well with formal Agatston scores and mortality risk while being faster than quantitative scoring 2.
When to Report
CAC should be reported when it is likely to affect patient management, which essentially means all cases where it is present 2.
The 2016 guidelines recommend reporting CAC in all patients irrespective of scan indication, making this a standard practice expectation 2.
Clinical Pitfalls and Caveats
Contrast-Enhanced Scans
Visual CAC assessment on contrast-enhanced abdominal CT has excellent interobserver agreement (κ = 0.89) and maintains high diagnostic performance 3.
However, absence of visual CAC on contrast-enhanced scans may not be sufficient to "de-risk" patients, as 28% of contrast-enhanced scans with no visual CAC still had some calcium on dedicated cardiac CT 4.
The presence of moderate-to-large CAC on contrast-enhanced scans remains highly predictive (89% accuracy) regardless of contrast use 4.
Current Reality vs. Best Practice
The current standard of care involves significant under-reporting and under-recognition of incidental CAC, representing a major missed opportunity for cardiovascular disease prevention 1, 6.
Approximately 19 million non-gated chest CT scans are performed annually in the U.S., and systematic CAC reporting could identify millions of high-risk patients without additional radiation or cost 6.
Artificial intelligence algorithms are now available to automate CAC detection and quantification, which can improve reporting consistency and reduce the burden on radiologists 5, 6.
Patient Notification
Patients are rarely informed directly about incidental CAC findings under current usual care practices 1.
Systematic notification that includes patient-specific images and guideline recommendations significantly improves statin initiation rates 5.
The American Heart Association 2025 scientific statement emphasizes the need for streamlined care pathways involving multidisciplinary teams (radiology, cardiology, primary care) to ensure appropriate reporting, interpretation, and action 6.