Relationship between pericoronary fat attenuation index and quantitative plaque components in newly identified coronary plaques

Purpose: This study investigates the correlation between fat attenuation index (FAI) and plaque components before and after coronary plaque formation in humans. Methods: This retrospective study included 249 patients who developed newly identified coronary plaques after two coronary computed tomography angiography (CCTA) examinations, with the first yielding normal results. Vessels with newly identified plaques were categorized into the new plaque group, while others formed the no new plaque group. A control group of 50 patients with consistently normal CCTA results was also included. The new plaque group was further divided into stable FAI and progressive FAI groups based on changes in FAI. Results: Before plaque formation, baseline FAI was highest in the new plaque group [(−80 (−84，-77) HU]. Baseline FAI was positively correlated with plaque volume, necrotic core volume, fibrofatty volume, and necrotic core percentage at both patient and vessel levels while showing a negative association with fibrous volume percentage (P < 0.05). After plaque formation, the percentage of necrotic core volume and diabetes mellitus were independent determinants of FAI increase in the patient level [OR: 1.31 (95 % CI: 1.12–––1.53) and OR: 3.07 (95 % CI: 1.14–––8.28), respectively]. At the vessel level, the percentage of necrotic core volume and fibrous volume were independent determinants of FAI increase [OR: 1.33 (95 % CI: 1.16–––1.53) and OR: 0.98 (95 % CI: 0.96–––0.99), respectively]. Conclusion: FAI was found to interact with the volume and components of newly formed coronary plaques, especially the necrotic core. A higher baseline FAI was associated with necrotic core formation, and the development of necrotic cores further increased FAI. Conversely, the formation of fibrous components appeared to mitigate the increase in FAI.