Coronary Plaque Quantification with Ultrahigh-Spatial-Resolution Photon-counting Detector CT: Intraindividual Comparison with Energy-integrating Detector CT

= .13). Total, calcified, and fibrotic plaque volumes demonstrated excellent agreement between repeated measurements and between readers for both PCD CT and EID CT (all intraclass correlation coefficients [ICCs] > 0.90). Whereas low-attenuation plaque volume had strong intrareader (ICC, 0.84; 95% CI: 0.57, 0.94) and interreader (ICC, 0.92; 95% CI: 0.81, 0.97) agreements for PCD CT, EID CT showed only moderate (ICC, 0.62; 95% CI: 0.11, 0.86) and poor (ICC, 0.47; 95% CI: 0.01, 0.79) intrareader and interreader reproducibility. Conclusion Compared with EID CT, PCD CT UHR imaging reduced segmented coronary plaque volume by nearly one-third and improved reproducibility of low-attenuation plaque measurements. © RSNA, 2025