In Vivo Fibroblast Activation of Systemic Sarcoidosis: A 68Ga-FAPI-04 PET/CT Imaging Study.

A 47-year-old female with cardiac dysfunction and lymphadenopathy underwent 18FDG PET/CT and 68Ga-FAPI-04 imaging for tumor screening. Mild uptake in the left ventricular wall was detected on the oncology 18FDG PET/CT. True myocardiac-involvement could not be distinguished with physiological uptake. The following 68Ga-FAPI-04 showed intense heterogeneous uptake in the left ventricular wall, particularly in the septum and apex area, corresponding with the late gadolinium enhancement regions shown by cardiac MR. Intense uptake was also noted in the mediastinal and bilateral hilar lymph nodes. Endomyocardial biopsy demonstrated sarcoidosis.