Multiparametric CMR in Myocarditis: A Comprehensive Review of Diagnostic Advances, Prognostic Value, and the Challenge of Genetic Mimics

Cardiac magnetic resonance (CMR) has revolutionized the diagnosis and risk stratification of myocarditis. Beyond its capacity in detecting functional abnormalities, CMR is now capable of tissue characterization with high sensitivity and specificity, allowing for the identification of myocardial edema, hyperemia, and necrosis/fibrosis. The introduction of the Lake Louise Criteria (LLC), updated in 2018 with the integration of parametric mapping techniques, has significantly improved diagnostic sensitivity and specificity. This review details the definition, stages, and etiologies of myocarditis, exploring the diagnostic journey from early techniques to the modern multiparametric approach. It underscores the prognostic value of CMR findings and highlights challenging scenarios such as genetic cardiomyopathies that mimic myocarditis. It then discusses CMR patterns in specific conditions like cardiac sarcoidosis, amyloidosis, and immune checkpoint inhibitor-induced myocarditis. Finally, future perspectives for CMR in myocarditis are addressed.