Association Between Pericoronary Fat Attenuation Index and High-Risk Plaque Features Assessed by Photon-Counting CT.

PURPOSE: To evaluate the correlation between pericoronary fat attenuation index (pFAI) and the presence, characteristics, and number of high-risk plaque (HRP) features identified using photon-counting computed tomography coronary computed tomography angiography (PCCT-CCTA) in patients with suspected coronary artery disease (CAD). PATIENTS AND METHODS: This was a single-center prospective cross-sectional study. We prospectively enrolled 119 consecutive patients with suspected CAD who underwent PCCT-CCTA at a local hospital between August and September, 2025. pFAI was measured from coronary computed tomography angiography (CCTA) images, and its correlation with individual HRP features and their cumulative number was investigated. RESULTS: A total of 119 patients with suspected CAD were prospectively enrolled (mean age: 58.9±11.3 years; 62.1% male). pFAI was significantly higher in the HRP group than in the non-HRP group (-90.1±7.5 HU vs. -98.4±6.7 HU, P<0.001). Patients with ≥2 high-risk features exhibited significantly higher pFAI scores than those without HRP features. The pFAI was not significantly increased in patients with only one HRP feature (P=0.408). Furthermore, pFAI was significantly higher in patients with spotty calcification (SC), positive remodeling (PR), or napkin-ring sign (NRS) (all P<0.05), but no significant increase in pFAI was found in patients with low-attenuation plaque (LAP). Multivariable analysis identified non-calcified plaque (NCP) volume, SC, and PR as independent factors associated with pFAI (all P < 0.05). CONCLUSION: The pFAI was significantly elevated in patients with HRP. Coronary arterial inflammation plays a pivotal role in HRP formation. The PCCT is a powerful tool for detecting HRP and assessing coronary arterial inflammation.