Can non-calcified coronary artery plaques be detected on non-contrast CT calcium scoring studies?
Level 3 - non-randomized controlled study
Prospective diagnostic accuracy study comparing an index test against reference standards in a clinical cohort.
PubMed 21669351 · doi:10.1016/j.acra.2011.02.019
What was done
A prospective diagnostic study evaluated 106 patients (40 women, mean age 59 years) who underwent coronary calcium scoring, coronary CT angiography, and quantitative catheter angiography. Two blinded observers independently reviewed the non-contrast calcium scoring studies for signs of non-calcified plaque (hypoattenuation within the vessel wall and positive remodeling). Results were compared against coronary CT angiography and invasive catheter angiography.
What was found
The mean Agatston score was 515.8 ± 826.8. Interobserver agreement was substantial (κ = 0.69). Observer 1 and Observer 2 identified 38 and 35 lesions suggestive of non-calcified plaque in 21 and 17 patients, respectively. Coronary CT angiography confirmed non-calcified plaque in 86.8% (33/38) and 88.6% (31/35) of these lesions. The overall positive predictive value was 0.88, but overall sensitivity was low at 0.39.
Why it matters
Signs of non-calcified plaque observed on standard non-contrast calcium scoring scans are highly likely to be real, potentially identifying higher-risk patients without additional contrast-enhanced imaging. However, calcium scoring cannot rule out soft plaque.
Limits
The sample size was modest (106 patients) with a high baseline burden of calcification. The diagnostic sensitivity was poor (39%), meaning most non-calcified lesions went undetected on non-contrast scans. Specificity and negative predictive value were not reported in the abstract.
Cited by
- supports Coronary artery calcium (CAC) scoring only detects calcified arterial plaque and cannot identify soft (non-calcified) plaque.