Popcorn type calcification: A feature of calcified nodules observed by coronary computed tomography angiography

Calcified nodule is one of the most difficult lesions to treat in interventional cardiology. Optical coherence tomography (OCT)/optical frequency domain imaging (OFDI) enables detailed assessment of calcified plaques, including calcified nodule (CN). In contrast, coronary CT angiography (CCTA) is a non-invasive modality widely used to detect coronary artery stenosis and calcification; however, its role in identifying CN remains unclear.

To compare the subsequent characteristics of calcifications observed on CCTA and OFDI.

We retrospectively analyzed patients who underwent preprocedural CCTA and percutaneous coronary intervention with OCT/OFDI between March 2016 and August 2024. Calcifications on OCT/OFDI were classified as CN, nodular calcification (NC), or sheet calcification (SC). On CCTA, calcifications were categorized as "popcorn type" (irregular morphology) or "linear type" (regular morphology). Each culprit lesion was also evaluated using the Agatston score. Imaging findings were compared across groups.

A total of 216 lesions from 192 patients were analyzed in this study. Popcorn-type calcification on CCTA was more common in CN than in NC and SC (91.3%, 44.3%, and 3.8%, respectively; p < 0.001), whereas linear-type calcification was less prevalent in CN than in NC and SC (8.7%, 55.6%, and 96.2%, respectively; p < 0.001). Popcorn-type calcification identified CN or NC with 64% sensitivity, 96% specificity, 86% positive predictive value, and 88% negative predictive value. The median calcium score (IQR) for the culprit coronary artery was the highest in CN, followed by NC and SC (1105, 660, and 537, respectively; P < 0.001).

Popcorn-type calcification on CCTA may be associated with CN on OCT/OFDI.