Coronary Artery Calcium Score Without Contrast
Yes, coronary artery calcium (CAC) scoring is performed using non-contrast, ECG-gated cardiac CT and does not require intravenous contrast dye. 1, 2
Technical Basis
CAC scoring is fundamentally a non-contrast examination. The test uses electrocardiogram-gated multidetector CT to detect and quantify calcified plaques in coronary arteries based on their high CT density (>130 Hounsfield units) 1. This is one of the key advantages of the test—it provides robust atherosclerosis assessment without exposing patients to iodinated contrast agents and their associated risks (allergic reactions, contrast-induced nephropathy).
Radiation Exposure
The radiation dose is relatively low at approximately 0.37 ± 0.16 mSv 1, which is actually slightly lower than screening mammography (0.44–0.56 mSv). Modern CT technology with dose-reduction techniques has made this an increasingly safe test.
Clinical Context and Guidelines
Multiple international guidelines 3 recommend CAC scoring as a reasonable risk adjudicator for primary prevention, particularly in:
- Borderline risk patients (5.0% to <7.5% 10-year ASCVD risk)
- Intermediate risk patients where statin therapy decisions are uncertain 1
- Selective use in those with 3% to <10% 10-year risk per the 2026 PREVENT-ASCVD equations 4
The test is especially valuable because it provides prognostic information superior to traditional cardiovascular risk markers 1, 2.
Important Distinction: Contrast vs. Non-Contrast CT
Do not confuse CAC scoring with coronary CT angiography (CCTA). CCTA requires intravenous contrast to visualize coronary artery lumens and assess stenosis. CAC scoring only identifies and quantifies calcified plaque burden as a marker of total atherosclerotic burden—it does not assess stenosis severity 1.
Emerging Technology Note
Recent research 5, 6 explores deriving CAC scores from contrast-enhanced spectral CT using "virtual non-contrast" reconstructions, potentially eliminating the need for a separate non-contrast scan in patients already getting CCTA. However, this remains investigational and is not standard practice—the established clinical CAC score is obtained from dedicated non-contrast CT.
Additional Information From Non-Contrast Scans
Beyond the calcium score itself, the non-contrast cardiac CT can provide additional markers of cardio-metabolic health without protocol modifications, including epicardial fat, liver fat, bone density, and lung density 7. Clinicians should be aware of potential incidental findings.