Accuracy and Limitation of Plaque Detection by Coronary CTA: A Comparison With Optical Coherence Tomography

How good is a non-invasive CT scan at finding coronary plaque, compared with the invasive but exquisitely detailed optical coherence tomography? This study made a careful, section-by-section comparison to find out.

Measured against OCT as the reference, coronary CT angiography performed impressively: 92 percent sensitivity, 98 percent specificity, and a 99 percent negative predictive value — meaning a clean CT scan is highly reliable for ruling plaque out. Its weaknesses were specific and instructive: it missed the smallest sub-millimeter plaques (the earliest atherosclerosis), and it struggled to classify mixed plaque types. Notably, CT also outperformed OCT in one respect — detecting deep calcification that OCT’s limited tissue penetration can miss.

The conclusion is that CT and OCT are complementary, and that for non-invasive plaque assessment, CT angiography is highly accurate with a known and bounded blind spot at the very earliest, smallest lesions.

We rate the evidence moderate-to-strong. The sample is small, as such head-to-head imaging studies tend to be, but the methodology is rigorous and the practical message about CT’s strengths and limits is clear.