TY - JOUR T1 - <sup>68</sup>Ga-DOTATOC PET/CT to detect immune checkpoint inhibitor-related myocarditis. JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 48 LP - 48 VL - 62 IS - supplement 1 AU - Sarah Boughdad AU - Michel Obeid AU - MARIE MEYER AU - Solange Peters AU - Olivier Michielin AU - Pierre Monney AU - Mario Jreige AU - Christel Kamani AU - Niklaus Schaefer AU - John Prior Y1 - 2021/05/01 UR - http://jnm.snmjournals.org/content/62/supplement_1/48.abstract N2 - 48Objectives: Immune checkpoint inhibitor (ICI)-related myocarditis is a rare, but potentially lethal adverse event that can occur during the course of immunotherapy. Early diagnosis and treatment are keys to improve patients’ prognosis. Somatostatin receptor-based positron emission tomography computed tomography (PET/CT) showed promising results for the assessment of myocardial inflammation (Lapa et al. 2015), yet information regarding its use for the detection of ICI-related myocarditis, and especially at early stage, is limited. Thus, we investigated the value of 68Ga-DOTA(0)-Phe(1)-Tyr(3)-octreotide (68Ga-DOTATOC) PET-CT for detection and diagnosis of ICI-related myocarditis. Methods: Patients with clinically confirmed ICI-related myocarditis from July 2018 to October 2020 were retrospectively included in this single-center study. PET/CT images were acquired 90 minutes after injection of 2 MBq/kg of 68Ga-DOTATOC. Endomyocardial biopsy (EMB), serum cardiac Troponin I (cTnI), cardiac troponin T (cTnT), creatine kinase (CK), CK-MB, cardiac magnetic resonance imaging (CMR) reports and inflammatory cytokine markers were retrieved. The uptake of the left ventricle (LV) myocardium (SUVpeak myocardium) using a ratio with the LV activity (SUVmean LV cavity) on 68Ga-DOTATOC PET/CT was measured. Results: A total of 9 patients had ICI-associated myocarditis: 3 definite and 6 probable (Bonaca et al. 2019). Seven patients underwent 68Ga-DOTATOC PET/CT. All 7/7 (100%) patients with a 68Ga-DOTATOC PET/CT presented with pathological myocardial uptake of the left ventricle (LV) suggestive of ICI-related myocarditis (ratio SUVpeak myocardium/SUVmean LV cavity=2.9±0.8, range 2.2-4.4) above the cutoff value of 1.6 previously defined in our institution in a general cohort of patient with suspicion of myocarditis regardless the cause. All PET-positive patients except one patient previously treated with high-dose steroids and intravenous immunoglobulin during several days prior to the PET/CT had elevated serum cTnI. Interestingly, in 5/6 (83.3%) patients that presented with concomitant myositis and a pathological uptake was seen on 68Ga-DOTATOC PET/CT images in the skeletal muscles suggesting an additional advantage. Interestingly, there was no edema nor intramyocardial scars of inflammatory type in 4/7 patients who had CMR, despite elevated serum cTnI levels (range 88.7-1604.7 ng/ml) in 3 patients. Conclusion: 68Ga-DOTATOC PET/CT might help the diagnosis of ICI-related-myocarditis and concomitant myositis in addition to CMR, especially in the early stage of myocardial inflammation, as patients with elevated cTnI may not yet present with edema on CMR imaging. In addition, 68Ga-DOTATOC PET/CT imaging does not require an extensive carbohydrate-free diet in contrast to 18F-FDG PET/CT and is well-suited in the emergency setting. Nonetheless, these results need to be confirmed in a larger population of patients. ER -