Keynote: Late enhancement photon-counting detector CT can accurately identify pathological myocardial segments in ventricular arrhythmia, closely matching unipolar electroanatomical mapping, especially in ischaemic cardiomyopathy.
Keywords: Photon-counting detector CT, late enhancement, ventricular arrhythmia, electroanatomical mapping, myocardial extracellular volume, atlas maps
Photon-counting detector CT (PCD-CT) technology has emerged as a promising advancement in cardiac imaging, offering high spectral resolution, reduced noise, and improved contrast-to-noise ratio compared with conventional energy-integrating detector CT (EID-CT). This study by Mergen et al., published in Insights into Imaging (August 2025), evaluates the feasibility of late enhancement (LE) PCD-CT for left ventricular myocardial characterisation in patients with ventricular arrhythmias, using invasive electroanatomical mapping (EAM) as the reference.
Twenty patients (mean age 64 ± 8 years) with ventricular arrhythmias—60% with ischaemic cardiomyopathy and 40% with non-ischaemic cardiomyopathy—underwent LE PCD-CT before EAM and radiofrequency catheter ablation (RFCA). Notably, 80% of participants had cardiac implantable electronic devices (CIEDs), a group for whom MRI is often contraindicated or yields suboptimal image quality.
LE PCD-CT scans, acquired five minutes after contrast administration, enabled calculation of myocardial extracellular volume (ECV) directly from iodine maps, avoiding the need for separate unenhanced scans and registration. The authors introduced atlas maps—a novel visualisation combining colour-coded ECV data with myocardial wall thickness—to identify fibrosis, scar, and myocardial thinning in a single display.
In ischaemic cardiomyopathy, LE PCD-CT demonstrated good agreement with unipolar EAM (κ = 0.655) and moderate agreement with bipolar EAM (κ = 0.547). In non-ischaemic cardiomyopathy, agreement was moderate with unipolar mapping (κ = 0.455) and fair with bipolar mapping (κ = 0.255). Agreement was consistently stronger with unipolar mapping, reflecting its greater sensitivity for mid-myocardial and epicardial pathology.
Image quality was high overall, with only 3% of myocardial segments in ischaemic and 2% in non-ischaemic cases excluded due to beam-hardening artefacts from CIEDs. In ischaemic cases, myocardial thinning was the predominant abnormality, whereas elevated ECV dominated in non-ischaemic disease.
These findings suggest that LE PCD-CT can characterise pathological myocardial segments with a level of agreement comparable to MRI-EAM correlations reported in prior literature, but with advantages for patients with CIEDs. By integrating anatomical, functional, and tissue characterisation data in one scan, LE PCD-CT could improve pre-procedural substrate mapping and RFCA planning.
Limitations include the retrospective design, single-centre setting, small cohort size, and absence of a direct MRI comparison. Nonetheless, the study supports further investigation of PCD-CT as a non-invasive alternative or adjunct to MRI in the management of arrhythmias. The novel atlas mapping approach, merging fibrosis and wall-thickness information, may enhance clinical interpretation and procedural guidance in future workflows.
Reference: Mergen, V., Reiner, M.F., Klambauer, K. et al. Myocardial characterisation using late enhancement photon-counting detector CT in ventricular arrhythmia: comparison with electroanatomical mapping. Insights Imaging 16, 187 (2025). https://doi.org/10.1186/s13244-025-02069-4
Disclaimer
This summary is provided for general informational and educational purposes only and does not constitute medical advice, diagnosis, or treatment. The information presented is based on the referenced study by Mergen et al. (2025) and should not be interpreted as conclusive evidence or as a substitute for professional medical judgement. Clinical decisions should be made by qualified healthcare professionals, taking into account individual patient circumstances, the full peer-reviewed publication, and other relevant clinical data. The described techniques, including late enhancement photon-counting detector CT and atlas mapping, may not be widely available and could be subject to further validation. The inclusion of trade names, technologies, or specific methodologies does not imply endorsement.