The Accuracy of Photon-Counting CT Angiography of the Coronaries Compared to Invasive Coronary Angiography

To evaluate the diagnostic accuracy of photon-counting coronary CT angiography (PCCT-CCTA) for assessing coronary artery stenosis, using invasive coronary angiography (ICA) as the reference standard.

90 adult patients who underwent PCCT-CCTA followed by consecutive ICA were included in this retrospective single-center study. PCCT-CCTA examinations were performed in standard-resolution or ultra-high resolution. Image quality, coronary stenosis severity, and CAD-RADS 2.0 classifications were assessed by blinded experienced radiologists. ICA findings served as the reference standard. Statistical analyses included Wilcoxon signed-rank testing, Spearman correlation, ROC analysis, and calculation of overestimation, underestimation, and concordance rates.

The overall image quality was excellent (median Likert score 5). PCCT-CCTA demonstrated high sensitivity and negative predictive value for identifying patients requiring invasive therapy at a CAD-RADS score >3, but the specificity was low. PCCT-CCTA significantly differed from ICA in stenosis grading (p = 0.001) and showed a tendency to overestimate stenosis severity, particularly in mild to moderate lesions. The overall overestimation rate was 66.8%, the underestimation rate was 9.3%, and the concordance rate was 23.9%. Ultra-high resolution improved the detection of severe stenoses but did not eliminate overestimation. The CAD-RADS score demonstrated limited discriminatory performance for therapy prediction (AUC 0.581). No significant correlations were found between Agatston score, CAD-RADS 2.0 classification, and image quality.

PCCT-CCTA reliably identifies patients requiring invasive coronary therapy but tends to overestimate stenosis severity compared with ICA. Despite this limitation, PCCT-CCTA represents a valuable noninvasive gatekeeper for invasive coronary angiography.

· PCCT-CCTA reliably identifies patients requiring invasive coronary therapy.. · Ultra-high resolution improves severe stenosis detection but not specificity.. · Calcium score does not predict stenosis severity..

· Haag NP, Katz MS, Wiemer M et al. The Accuracy of Photon-Counting CT Angiography of the Coronaries Compared to Invasive Coronary Angiography. Rofo 2026; DOI 10.1055/a-2901-9309.