Role of Cardiac Ct With Late Iodine Enhancement in the Diagnosis of Acute Myocarditis

Background Cardiac Magnetic Resonance (CMR) is the gold standard for the diagnosis of acute myocarditis. However, its limited availability, particularly in smaller centers, restricts its clinical use. The role of cardiac Computed Tomography (CT) in myocardial tissue characterization has been poorly investigated. Purpose To evaluate the diagnostic accuracy of cardiac CT with Late Iodine Enhancement (LIE) compared with CMR for the diagnosis of acute myocarditis, especially in centers with limited access to CMR. Methods Seven patients with uncomplicated acute myocarditis were enrolled. Within 4–7 days from clinical diagnosis, all patients underwent cardiac CT including coronary artery assessment and myocardial tissue characterization using LIE. CMR was subsequently performed within 12–40 days to confirm the diagnosis. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy were calculated. Agreement between CT and CMR was assessed using Cohen’s kappa coefficient. Statistical analysis was performed both on a per–patient (global) and per–segment basis. Results All patients showed normal coronary arteries. CT demonstrated myocardial tissue abnormalities consistent with edema in 6 patients, all of which were confirmed by CMR. One patient showed no pathological segments on CT, a finding confirmed by CMR. Global analysis showed a sensitivity of 86%, specificity of 100%, PPV of 100%, NPV of 75% (Figure 1), and an overall diagnostic accuracy of 90%. Segmental analysis revealed perfect agreement between CT and CMR in 4 patients (67%), while in 2 patients (33%) CMR demonstrated a greater extent of myocardial edema. On a per–segment basis, CT showed a sensitivity of 69%, specificity of 86%, PPV of 75%, NPV of 83%, and an accuracy of 80% (Figure 2). Cohen’s kappa value was 0.565, indicating moderate agreement. ROC curve analysis showed an area under the curve (AUC) of 0.78 (Figure 3), indicating good discriminatory ability of CT for detecting pathological myocardial segments. Conclusions Cardiac CT with LIE is a promising and complementary imaging modality to CMR in the diagnosis of acute myocarditis. CT allows an integrated evaluation by excluding ischemic causes through coronary angiography and assessing myocardial edema using LIE. It may represent a valid alternative in centers where CMR is not available or in patients with contraindications to CMR.