Accuracy of photon-counting detector CT-based iodine maps for myocardial late enhancement detection

Objectives: To evaluate the diagnostic accuracy of iodine maps from photon-counting detector (PCD) CT in detecting myocardial late enhancement compared to late gadolinium enhancement (LGE)-MRI. Materials and methods: In this retrospective analysis of a prospective cohort, patients underwent cardiac MRI with LGE followed by late iodine enhancement (LIE)-CT using dual-source PCD-CT. LIE-CT was performed 5 min post-intravenous administration of 100 mL iopromide (370 mg I/mL) using an ECG-triggered sequential protocol with full spectral capabilities (120 kVp, 144 × 0.4 mm collimation). Iodine maps were reconstructed with a quantitative kernel (Qr40) and iterative reconstruction. Two radiologists independently rated image quality on a four-point scale (1: “poor” to 4: “excellent”). Diagnostic performance was assessed per-patient and per-segment using LGE-MRI as reference, and inter-reader agreement was analyzed using Cohen’s kappa (κ). Results: The study included 27 patients (52% female; mean age 52.9 ± 17.2 years). Twelve (44%) had positive LGE, with 87/459 (19%) myocardial segments affected. Image quality was rated as good, with no significant differences between readers (median 3 [2–4] vs 3 [3–4]; p = 0.058). Per-patient sensitivities were 100% and 91.7%, specificities 73.3% and 80.0%, and accuracies 85.2%, respectively. Per-segment sensitivities, specificities, and accuracies were 74.7%, 94.9%, and 91.1% (reader 1) and 66.7%, 96.4%, and 90.7% (reader 2). Substantial inter-reader agreement was observed (κ = 0.70 per patient, 0.63 per segment). Conclusion: Iodine maps from PCD-CT demonstrate high diagnostic accuracy for assessing myocardial late enhancement, with substantial inter-reader agreement. These findings suggest that PCD-CT may serve as a valuable alternative to LGE-MRI. Key Points: Question Can PCD CT iodine maps detect myocardial late enhancement with accuracy comparable to LGE-MRI? Findings PCD-CT iodine maps achieved high accuracy (85.2% per patient, > 90% per segment) with substantial inter-reader agreement. Clinical relevance PCD-CT iodine maps offer a valuable alternative to LGE-MRI for myocardial late enhancement assessment, especially for patients with contraindications to MRI.