18F-fluorodeoxyglucose PET computed tomography in cardiac sarcoidosis: lessons from a 10-year review

AIMS: To determine the diagnostic performance and clinical usefulness of 18 F-fluorodeoxyglucose ( 18 F-FDG) PET computerised tomography (CT) in detecting cardiac inflammation in patients with suspected cardiac sarcoidosis; and to explore the role of interval and correlative imaging. MATERIAL AND METHODS: A 10-year (2015-2024) retrospective observational study was conducted at our teaching hospital. 397 18 F-FDG PET-CT scans performed in 296 patients with suspected or known cardiac sarcoidosis were reviewed. Assessment of diagnostic quality, patterns of myocardial and extracardiac FDG uptake, concordance with other modalities [cardiac MRI (CMR) and myocardial perfusion imaging (MPI)] were assessed. Separate subgroup analysis of patients undergoing repeat 18 F-FDG PET-CT scans was conducted. RESULTS: Images of excellent diagnostic quality 18 F-FDG PET-CT were obtained in 365/397 studies (91.9%). Cardiac inflammation was identified in 226 and scans were normal in 139 patients. Extracardiac sarcoidosis was present in 230 (63%) patients. MPI was abnormal in 50/98 patients (51%) and CMR was abnormal in 88/126 patients (70%). PET and MPI findings showed concordance in 53% patients but not considered significant ( P = 0.78). High concordance with CMR was noted in 85.7% patients ( P < 0.001). For treatment monitoring, follow-up 18 F-FDG PET-CT scans accurately assessed disease status in 66/70 patients (94.2%). CONCLUSION: We obtained excellent diagnostic quality of images in a high proportion of our patients (92%). Because of a high degree of concordance between 18 F-FDG PET-CT and CMR, we propose that either test can be used initially and the other test can be used in cases of clinical discordance. Interval 18 F-FDG PET-CT scans are immensely useful for treatment response monitoring.