Background:
Coronary computed tomography angiography (CCTA) is a key non-invasive imaging modality for the diagnostic workup of coronary artery disease (CAD), particularly in patients with low to moderate pre-test probability.
Photon-counting computed tomography (PCCT) represents a novel detector technology with improved spatial resolution and dose efficiency compared with conventional and dual-source CT (DSCT). However, real-world data that compare the diagnostic performance between these modalities remain limited.
Methods:
A total of 420 consecutive patients who underwent coronary CT angiography between 2019 and 2024 and were referred to invasive coronary angiography (ICA) within 5 months were retrospectively analyzed. 210 scans were acquired with DSCT and 210 with PCCT. For each major coronary vessel (LM, LAD, CX, RCA and bypass grafts), CT results were categorized as true positive (TP), false positive (FP), false negative (FN), or true negative (TN) according to invasive findings. Diagnostic metrics including accuracy, sensitivity, and specificity were calculated per vessel and compared between modalities using χ² tests. In addition, dose-length product (DLP, mGy·cm) was systematically assessed to evaluate radiation exposure and compared using multivariable linear regression adjusted for BMI.
Results:
On a per-patient basis, PCCT was associated with a significantly lower rate of false-positive findings compared to DSCT (14.8% vs 27.6%, p=0.002). A total of 1,679 vessels were analyzed (842 DSCT, 837 PCCT). In vessel-specific analysis, PCCT demonstrated superior diagnostic accuracy compared to DSCT in the left anterior descending artery (LAD: 82.7% vs 73.7%, p=0.031) with a significant reduction in the false-positive rate (13.5% vs 22.0%). The diagnostic accuracy for the other main vessels showed no statistically significant differences: circumflex artery (CX: 80.4% vs 78.9%, p=0.53), right coronary artery (RCA: 82.9% vs 88.3%, p=0.10), and left main (LM: 96.2% vs 97.6%, p=0.40). Bypass grafts (n=19) could not be statistically compared due to insufficient sample size.
Radiation dose was significantly lower with PCCT compared to DSCT (mean DLP 262±190 vs 375±385 mGy·cm; p<0.001). After adjustment for BMI, PCCT remained an independent predictor of lower radiation exposure (β=–110 mGy·cm; p<0.001), whereas BMI itself was positively associated with DLP (+8 mGy·cm per BMI unit; p< 0.001).
Conclusion:
In this real-world cohort, coronary angiography with Photon-counting CT in comparison to Dual Source CT demonstrated lower radiation exposure and a lower false-positive rate per patient, mainly driven by superior diagnostic accuracy for the LAD.
