CT Calcium Score Detection Capabilities
Yes, CT calcium scoring specifically detects and quantifies only calcified plaque in the coronary arteries, not non-calcified (soft) plaque. 1
What CT Calcium Scoring Actually Measures
CT calcium scoring uses non-contrast electrocardiogram-gated CT to detect and quantify calcium deposits in coronary arteries, which serve as a marker of coronary atherosclerosis. 1
The scan quantifies calcified plaque using the Agatston method, providing a numerical score that reflects the burden of calcified atherosclerotic plaque. 2
A calcium score of zero indicates absence of calcified plaque in the coronary tree, but this does NOT rule out the presence of non-calcified plaque. 2
Critical Limitation: Non-Calcified Plaque
Among patients with zero calcium scores, 14% still have non-obstructive disease, 2% have obstructive disease, 2% have visually assessed adverse plaques, and 13% have low-attenuation plaque burden >4%. 3
Non-calcified plaque cannot be reliably detected on standard calcium scoring studies, though some research suggests experienced observers may occasionally identify features suggestive of non-calcified plaque with 88% positive predictive value but only 39% sensitivity. 4
Zero calcium score is associated with good but not perfect prognosis and cannot rule out obstructive coronary artery disease, non-obstructive plaque, or adverse plaque phenotypes including low-attenuation plaque. 3
Clinical Implications
Calcium score should not be used in isolation and should be combined with at least a qualitative assessment of total plaque burden to ensure non-calcified plaque is accounted for. 2
For comprehensive plaque assessment including non-calcified plaque, coronary CT angiography (CCTA) with contrast is required, which can detect calcified, mixed, and non-calcified plaques. 5, 6
CT calcium scoring should be seen primarily as a marker of atherosclerosis and not of degree of stenosis. 1
When Non-Calcified Plaque Matters Most
In patients with high calcium scores and significant stenosis, mixed and non-calcified plaques are frequently present and associated with higher risk—sensitivity and positive predictive value of mixed (97.4%, 87.6%) and non-calcified plaques (97.8%, 95.7%) were significantly higher than calcified plaques (87.6%, 67.2%) for detecting significant stenosis. 5
Myocardial infarction occurred in 10% of patients who had zero calcium scores, emphasizing that absence of calcified plaque does not eliminate cardiovascular risk. 3