Diagnostic Value of Cardiovascular Magnetic Resonance T1 and T2 Mapping in Acute Myocarditis: A Systematic Literature Review

Background and Objectives: Over the past decade, there has been increasing attention paid to advanced and innovative cardiovascular magnetic resonance (CMR) modalities, such as T1 and T2 mapping, which play a major role in diagnosing diffuse myocardial disease. There is little data summarizing the current evidence regarding the diagnostic accuracy of T1 and T2 mapping, and extracellular volume (ECV) in acute myocarditis. The aim of our study was to select, analyze, and systematically review the recent scientific literature on the diagnostic value of CMR T1 and T2 parametric mapping in clinically suspected acute myocarditis. Materials and Methods: The literature search was performed in the PubMed database. Articles published in the years 2014-2024 were included in the analysis. At the initial stage, 458 articles were reviewed, and 13 exploratory research studies were further analyzed and presented in this systematic literature review. Results: The analysis included 686 patients with clinically suspected myocarditis and 372 subjects in the control group. The average age of patients with suspected myocarditis was 40.25 years; 26% of them were women. Prolonged native myocardial T1 relaxation time provides diagnostic accuracy in the setting of suspected acute myocarditis ranging from 69 to 99%, with sensitivity from 64 to 98% and specificity from 87 to 100%. Diagnostic accuracy of prolonged T2 relaxation time ranges from 47 to 87%, with sensitivity being from 48% to 94% and specificity from 60% to 92%. ECV alone showed moderate diagnostic performance, with diagnostic accuracy ranging from 62% to 76%, sensitivity from 47% to 73%, and specificity from 76% to 90%. T1 and T2 mapping and ECV, combined with the late gadolinium enhancement (LGE) technique, increases the probability of detecting myocardial inflammatory changes at various stages of the disease, improving the diagnostic accuracy to 96%. Conclusions: New quantitative CMR techniques, i.e., T1 and T2 mapping, have an advantage over conventional CMR sequences in detecting inflammatory myocardial structural changes and play an important role in diagnosing acute myocarditis. Incorporating these sequences in daily clinical practice increases the diagnostic value of CMR in acute myocarditis and becomes an alternative to endomyocardial biopsy, which has been considered the gold standard until now.