Performance of native and contrast-enhanced T1 mapping to detect myocardial damage in patients with suspected myocarditis: a head-to-head comparison of different cardiovascular magnetic resonance techniques.

Myocardial T1 mapping is a novel technique that has proven to be superior to standard imaging for differentiation between healthy individuals in acute myocarditis. Aim of this study was comparison of T1 mapping with a clinical biomarker. We retrospectively investigated 171 patients undergoing cardiovascular magnetic resonance (CMR) examination with suspected myocarditis by performing native and contrast enhanced T1-mapping. Additionally, T2w and T1w images and late gadolinium enhancement sequences (LGE) were utilized for myocardial evaluation; Lake Louise Criteria comprise T1w, T2w and LGE imaging in a score. Reference for positive myocarditis diagnosis was a ten-fold increase of troponin level above normal (0.14 ng/ml). Native T1 and extracellular volume (ECV) showed good association with relevant troponin elevations. Area under the curve (AUC) was 81% (p = 0.0001) for native T1 with an optimal threshold of 979 ms and 86% (p < 0.0001) for ECV with an optimal cutoff of 32.4%. AUC for T2w imaging (T2-signal intensity ratio to skeletal muscle) was 77% (p = 0.0003). AUC for T2w imaging (T2-signal intensity compared to remote myocardium) was 69% (p = 0.012). Additionally, we found positive correlation for native T1 and ECV with the Lake Louise Criteria (r = 0.44, p = 0.0001 for native T1 and r = 0.45, p = 0.0001 for ECV). Correlated to troponin as biomarker, ECV and native T1 mapping perform at least equally well in comparison to established CMR-techniques LGE, T2w imaging and the combined Lake Louise Criteria in detecting acute myocardial damage. Normal ECV values rule out myocardial damage with very high certainty. T1 mapping qualifies for further prospective evaluations to evolve as a separate biomarker.