The response of FDG uptake to immunosuppressive treatment on FDG PET/CT imaging for cardiac sarcoidosis


Background: Immunosuppression is used to treat cardiac sarcoidosis, despite limited data. FDG PET/CT is used for detecting cardiac inflammation in patients with CS, yet there is variability in interpretation of FDG PET/CT. Our aim was to compare quantitative and qualitative interpretation of FDG PET/CT for CS in defining the FDG response to immunosuppression. Methods and Results: Patients with CS (N = 43 total studies from 17 patients) had serial FDG PET/CT studies before/after immunosuppression. FDG uptake was analyzed qualitatively (visually; FDG-positive segments) and quantitatively (SUVmax; cardiac metabolic volume and activity (CMV, CMA); volume above SUV thresholds 2.7 and 4.1 g/mL). Complete resolution of FDG uptake was common using CMA (10/17), CMV (10/17), but a 2.7 g/mL SUV threshold (13/17) and SUVmax (14/17) were more likely to define partial responses. In six patients imaged after a reduction in immunosuppression, 4/6 had a rebound quantitative FDG uptake. Conclusions: Quantitative interpretation of FDG PET/CT in CS can detect changes in FDG uptake in response to immunosuppression. Further studies are needed to see if quantitative changes in FDG uptake are associated with improved outcomes.

Publication Title

Journal of Nuclear Cardiology