Quantitative evaluation of 123I-MIBG imaging in patients with myocarditis: impairment of cardiac neuronal function revisited

Background 123 I-MIBG has been shown to visualize impaired cardiac neuronal function, but data of this imaging modality in patients with acute myocarditis are scarce. Nonetheless, an association with reduced cardiac function has been observed previously. The aim of this study was to establish and evaluate semi-quantitative and quantitative parameters in 123 I-MIBG scintigraphy and SPECT/CT in patients with acute myocarditis and identify associations with left ventricular ejection fraction (LVEF) and biomarkers. Methods Eight patients with acute myocarditis and a gender and age-matched control group who underwent 123 I-MIBG scintigraphy and SPECT/CT were retrospectively analysed. Semi-quantitative Heart-to-Mediastinum ( H / M ) ratio and washout rate were calculated, additionally SPECT/CT system calibration and a whole-heart-segmentation were used for absolute quantification of tracer uptake. ROC analysis for the prediction of acute myocarditis and correlation of imaging parameters with LVEF and serological biomarkers was performed. Results Seven patients (87.5%) showed visually decreased tracer uptake. Planar imaging parameters showed significant differences compared to the control group (e.g. H / M ratio 1.6 ± 0.3 vs. 2.3 ± 0.8, p < 0.05), as well as multiple quantitative parameters e.g. SUVmean (1.7 ± 0.5 vs. 3.0 ± 1.0; p < 0.01). Additionally, correlation between imaging parameters and LVEF (e.g. SUVmax r = 0.85, p < 0.01) and NT-proBNP (e.g. H / M r = − 0.88, p < 0.05) was observed. Conclusion 123 I-MIBG visualizes impairment of cardiac neuronal function in patients with acute myocarditis and is associated with reduced ejection fraction and elevated NT-proBNP. We could establish an absolute quantification approach that could offer novel diagnostic opportunities for disease assessment and risk stratification, which will be focused on further studies.