Incidental findings at FDG PET/CT in carriers of cardiovascular implantable electronic devices

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: None. BACKGROUND: FDG-PET/CT clinical use for cardiovascular implantable electronic device (CIED) infection is of relevant importance, since it provides information about presence and extension of the infection. However, asymptomatic patients with incidental FDG uptake on CIED are challenging. PURPOSE: The primary objective of this observational study was to assess the diagnostic role of FDG PET/CT in patients without a suspicious of CIED infection. The secondary objective was to identify qualitative and semiquantitative predictors of CIED infection. METHODS: From 2017 to 2019 all FDG-PET/CT scans of CIED patients were analysed, the indications were a suspicious of CIED or non-cardiovascular infection, or oncological follow up. Four expert nuclear medicine physicians blindly reviewed all scans, focusing on FDG uptake in pocket and/or in extracardiac lead parts. They reported standardized uptake values (SUV), liver and blood pool target-to-background ratios, metabolic tumour volume (MTV). 6 months follow up after PET/CT scan was performed for eventual CIED extraction because of infection. RESULTS: 320 FDG-PET/CT scans were considered. Median age was 74 [33-94] years, 219/320 (68%) males. 122/320 (38%) scans presented FDG uptake around pocket and/or extracardiac lead parts; and 65/320 (20%) scans reported suspicious uptake. We identified these cut-off criteria as predictors of CIED extraction: TARGET SUV max >2.6 (sensitivity 71%, specificity 89%), LIVER-TARGET SUV max >1.3 (sensitivity 68%, specificity 89%). Both these values also demonstrated to be good predictors of CIED infection after 6 months follow up (p<0,001). CONCLUSION: FDG-PET/CT uptake in asymptomatic CIED patients is underestimated and may be related to subtle CIED infection. By introducing high-specific SUV cut-off values, a considerable impact on patient management is expected.