Semiquantitative metrics of coronary artery disease burden: Intra-individual comparison between ultrahigh-resolution photon-counting detector CT and energy-integrating detector CT

BACKGROUND: Quantitative coronary stenosis and plaque volumes have demonstrated intra-individual differences between ultrahigh-resolution (UHR) photon-counting detector (PCD)-CT and energy-integrating detector (EID)-CT. This study aimed to assess the impact of UHR PCD-CT on semiquantitative scores of coronary artery disease (CAD) burden compared with EID-CT. METHODS: Patients undergoing coronary CT angiography (CCTA) on an EID-CT system for stable chest pain or pre-transcatheter aortic valve replacement evaluation were prospectively enrolled for UHR PCD-CT scan within 30 days. Both datasets were visually evaluated using five established semiquantitative scores: Segment Involvement Score (SIS), Segment Stenosis Score (SSS), Multivessel Aggregate Stenosis Score (MVAS), CCTA-adapted Leaman score (CT-LeSc), and Coronary Artery Disease Reporting and Data System (CAD-RADS). Additionally, the total number of detected plaques and high-risk features were reported (positive remodeling, spotty calcification, low-attenuation, and napkin-ring sign). RESULTS: The cohort comprised 46 patients (37 men, 68.4 ​± ​6.9 years). When assessing stenosis severity, PCD-CT showed lower SSS (3.5 [1.3-5.0] vs 6.5 [3.0-9.8], p ​< ​0.001), MVAS (5.5 [4.0-7.0] vs 7.0 [5.0-9.0], p ​< ​0.001), and CT-LeSc (10.4 [8.5-13.9] vs 11.2 [8.8-15.4], p ​= ​0.032). Furthermore, 52 ​% (24/46) of patients were reclassified to a lower CAD-RADS category compared to EID-CT. In terms of CAD extent, PCD-CT demonstrated higher SIS (8.0 [6.0-9.0] vs 7.0 [6.0-8.8], p ​= ​0.018) and plaque count (9.0 [7.0-13.8] vs 7.0 [7.0-9.8] p ​< ​0.001). Positive remodeling was less frequent in PCD-CT datasets (2.0 [1.0-4.3] vs 1.0 [0.0-3.0], p ​= ​0.012), with no significant differences in other high-risk features. CONCLUSION: The use of UHR PCD-CT detects less severe, but more extensive CAD compared to EID-CT. The effect of such CCTA-based differences on individual risk stratification needs further investigation.