Both tests evaluate coronary artery plaque, but they reveal very different information. Understanding these differences can help you make an informed decision about your cardiovascular screening.
Last updated: January 28, 2026
A calcium score (coronary artery calcium or CAC test) uses a quick CT scan to measure the amount of calcified plaque in your coronary arteries. It produces a single number the Agatston score that correlates with cardiovascular risk.
A Cleerly scan uses coronary CT angiography (CCTA) with artificial intelligence analysis to provide a comprehensive assessment of all plaque types, degree of artery narrowing, and specific characteristics that indicate plaque vulnerability.
The calcium score asks: "Is there calcified plaque present?" Cleerly asks: "What is the complete picture of your coronary artery disease?"
| Feature | Calcium Score (CAC) | Cleerly Scan |
|---|---|---|
| Plaque Detection | Calcified plaque only | All types: calcified, fibrous, and soft |
| Soft Plaque | Not detected | Detected (often most dangerous) |
| Stenosis Measurement | No | Yes, with percentage narrowing |
| Contrast Dye | Not required | Required (IV contrast) |
| Radiation Exposure | Low (~1 mSv) | Moderate (~3-5 mSv) |
| Typical Cost | $75-$300 | $1,000-$1,500 |
| Test Duration | 5-10 minutes | 15-30 minutes |
| Best For | Initial screening, intermediate risk | Comprehensive assessment, unclear cases |
A calcium score of zero is often celebrated as a "clean bill of health." However, this interpretation can be dangerously misleading. Zero calcification only means no hardened plaque was detected it says nothing about soft, non-calcified plaque that may be accumulating.
Soft plaque is particularly concerning because it's more prone to rupture. When soft plaque ruptures, it triggers the blood clot formation that causes heart attacks. This is why some "surprise" heart attacks occur in individuals with previously reassuring calcium scores.
At GRN Labs, we view these imaging tests as one component of a broader vascular assessment. Imaging shows the structural result of years of endothelial dysfunction but by the time plaque is visible, the process has been underway for decades. Our approach focuses on functional markers like ADMA levels and nitric oxide capacity that indicate dysfunction before structural damage becomes apparent.
A calcium score is appropriate and cost-effective for:
The additional investment in a Cleerly scan may be worthwhile if:
Both calcium scoring and Cleerly provide anatomical information they show what's happening structurally. But arterial plaque is the end result of a process that begins at the endothelial level, years before any imaging can detect it.
This is why a comprehensive vascular assessment should include functional markers. Biomarkers like ADMA, ApoB, and hs-CRP indicate whether the process is actively progressing, even when imaging appears normal. The Vascular Age Calculator provides a starting point for understanding your functional vascular status.
Want to understand your complete vascular picture beyond what imaging alone reveals?
Start the Protocol →This content is for informational purposes only and does not constitute medical advice. The information provided should not be used for diagnosis or treatment. Consult with a qualified healthcare provider for personalized recommendations about cardiac imaging and cardiovascular risk assessment.