How early can atherosclerosis be detected by coronary CT angiography? Insights from quantitative CT analysis of serial scans in the PARADIGM trial

Document Type

Journal Article

Publication Date



Journal of cardiovascular computed tomography




Artificial intelligence; Atherosclerosis; Coronary; Coronary CT angiography; Small plaque


BACKGROUND: Non-obstructing small coronary plaques may not be well recognized by expert readers during coronary computed tomography angiography (CCTA) evaluation. Recent developments in atherosclerosis imaging quantitative computed tomography (AI-QCT) enabled by machine learning allow for whole-heart coronary phenotyping of atherosclerosis, but its diagnostic role for detection of small plaques on CCTA is unknown. METHODS: We performed AI-QCT in patients who underwent serial CCTA in the multinational PARADIGM study. AI-QCT results were verified by a level III experienced reader, who was blinded to baseline and follow-up status of CCTA. This retrospective analysis aimed to characterize small plaques on baseline CCTA and evaluate their serial changes on follow-up imaging. Small plaques were defined as a total plaque volume <50 ​mm. RESULTS: A total of 99 patients with 502 small plaques were included. The median total plaque volume was 6.8 ​mm (IQR 3.5-13.9 ​mm), most of which was non-calcified (median 6.2 ​mm; 2.9-12.3 ​mm). The median age at the time of baseline CCTA was 61 years old and 63% were male. The mean interscan period was 3.8 ​± ​1.6 years. On follow-up CCTA, 437 (87%) plaques were present at the same location as small plaques on baseline CCTA; 72% were larger and 15% decreased in volume. The median total plaque volume and non-calcified plaque volume increased to 18.9 ​mm (IQR 8.3-45.2 ​mm) and 13.8 ​mm (IQR 5.7-33.4 ​mm), respectively, among plaques that persisted on follow-up CCTA. Small plaques no longer visualized on follow-up CCTA were significantly more likely to be of lower volume, shorter in length, non-calcified, and more distal in the coronary artery, as compared with plaques that persisted at follow-up. CONCLUSION: In this retrospective analysis from the PARADIGM study, small plaques (<50 ​mm) identified by AI-QCT persisted at the same location and were often larger on follow-up CCTA.