Detection of acute myocarditis by ECG-triggered PET imaging of somatostatin receptors compared to cardiac magnetic resonance: preliminary results.

Somatostatin receptors are overexpressed by inflammatory cells but not by cardiac cells, under normal conditions. This study assesses the detection of acute myocarditis by the ECG-triggered digital-PET imaging of somatostatin receptors ( ⁶⁸ Ga-DOTATOC-PET), as compared to Cardiac Magnetic Resonance (CMR) imaging, which is the reference diagnostic method in this setting.
Methods: Fourteen CMR-defined acute myocarditis patients had a first 15-minutes ECG-triggered ⁶⁸ Ga-DOTATOC PET recording, 4.4 ± 3.0 days from peak troponin, and 10 had a second 4.3 ± 0.3 months later. Myocardial/blood SUVmax ratio was analyzed relative to the normal upper limit of 2.18, which had been previously determined from oncology ⁶⁸ Ga-DOTATOC-PET recordings of patients with a similar age range as the myocarditis patients.
Results: An increased myocardial ⁶⁸ Ga-DOTATOC uptake relative to blood activity was invariably observed during the acute phase. SUVmax ratio exceeded 2.18 in all patients during the acute phase but also in 3/10 patients at 4-months, at a time when there were no more signs of active inflammation on CMR. A residual myocardial ⁶⁸ Ga-DOTATOC uptake was still observed on all gated-PET cine loops at 4-months.
Conclusion: These preliminary results suggest that ⁶⁸ Ga-DOTATOC ECG-triggered digital-PET may be as sensitive as CMR at detecting myocarditis during the acute phase and more sensitive at later stages.
(© 2022. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.)