High inter- and intra-observer agreement in mapping sequences compared to classical Lake Louise Criteria assessment of myocarditis by inexperienced observers

Abstract

To investigate the observer agreement for the assessment of chronic myocarditis by native T1 and T2 relaxation times, post-contrast T1 relaxation time, and extracellular volume (ECV) fraction, compared to Lake Louise Criteria: oedema ratio (OR) and early gadolinium enhancement ratio (EGEr). Data were collected retrospectively on 71 consecutive patients who underwent cardiac magnetic resonance imaging as part of a complete diagnostic work-up according to current guidelines for suspected myocarditis. Thirteen cases were excluded due to previous myocardial infarction or technical issues. To test for intra- and interobserver agreement, the determination of the myocardial native T1 and T2 relaxation times, post-contrast T1 relaxation time, ECV, OR and EGEr was undertaken by two medical school graduates after comprehensive training. Bland-Altman analysis and intraclass correlation coefficient (ICC) were assessed. The final analysis included 27 patients with chronic myocarditis, 21 patients with dilated cardiomyopathy and/or hypertensive heart disease, and 10 patients with unremarkable investigations in the control group. Excellent interobserver agreement was obtained for native T1 and T2 relaxation times, post-contrast T1 relaxation time and ECV, with ICC of 0.982/0.977/0.991/0.994, p < 0.001. Interobserver agreement was lower for OR and EGEr, with ICC of 0.841 and 0.818, p < 0.001, respectively. Mapping parameters (cut-off values: T1 1,070 ms, T2 54 ms, ECV 30%) yield good performance in the diagnosis of chronic myocarditis with the best sensitivity/specificity/accuracy of 93%/80%/88% for ECV, followed by 70%/80%/74% for T2, and 52%/88%/69% for T1. mapping parameters show excellent agreement between observers in the assessment of myocarditis.