Multiparametric cardiovascular magnetic resonance imaging for the diagnosis of acute myocarditis: a single-center study

Background The Lake Louise Criteria (LLC) were updated in 2018 to improve accuracy in evaluating myocarditis. However, the diagnostic value of combining conventional magnetic resonance imaging (MRI) with contrast-enhanced whole-heart MRI (CE WH-MRI) in the diagnosis of acute myocarditis (AM) has not been determined. Purpose To assess the diagnostic accuracy of the updated LLC and test the incremental value of CE WH-MRI in diagnosis of AM. Material and Methods Between March 2020 and November 2023, a total of 37 patients with clinically suspected AM were prospectively recruited for this study. The cardiac MR (CMR) protocol for myocarditis and controls included T2-STIR, breath-hold steady-state free precession, native T1, T2, CE WH-MRI, late gadolinium enhancement (LGE), and post-contrast T1 mapping. Results For global native T1, the ideal cutoff value was 1308.5 ms (area under the curve [AUC]=0.879, sensitivity=82%, specificity=79%); for global T2, 43.2 ms (AUC=0.889, sensitivity=96%, specificity=75%), for ECV, 30.5% (AUC=0.946, sensitivity=97%, specificity=93%). The CE WH-MRI sequence detected 268 myocardial involvement (MI) segments, whereas 2D-LGE images identified 181 MI segments. Among 37 patients, 34 (91.9%) met the updated LLC definition for diagnosis, the AUC of updated LLC was 0.946. Conclusion The updated LLC, as a recommended criterion for the diagnosis of AM, had better diagnostic accuracy compared with CMR mapping imaging. Moreover, this study highlighted the additional diagnostic value of CE WH-MRI in the identification of AM. Then, multiparametric CMR imaging can provide a satisfactory diagnostic value to enhance the accuracy of diagnosing AM.