Positive 18 F-FDG and Negative 68 Ga-FAPI-04 Findings in a Patient With Gallbladder Adenocarcinoma.

Radiolabeled fibroblast activation protein inhibitor (FAPI) is considered as a potential alternative agent to 18 F-FDG for tumor-specific imaging. We report 18 F-FDG and 68 Ga-FAPI-04 PET/MR findings in a 67-year-old woman with gallbladder adenocarcinoma. The lesions showed intense 18 F-FDG uptake but limited 68 Ga-FAPI-04 uptake in PET/MR. This case emphasizes the necessity for nuclear clinicians to exercise caution when assessing gallbladder lesions with limited 68 Ga-FAPI-04 uptake, underscoring the continued relevance of 18 F-FDG in this diagnostic domain.