Utility of 68Ga-FAPI-04 PET/CT in Adenoid Cystic Carcinoma Compared With 18F-FDG PET/CT: Two Case Reports.

68Ga-fibroblast activation protein inhibitor (FAPI) PET/CT is an emerging imaging modality with high sensitivity and high tumor-to-background ratio in various cancers including in the head and neck regions. The authors present 2 cases of adenoid cystic carcinoma who underwent 68Ga-FAPI-04 and 18F-FDG PET/CT. Locoregional recurrence has been detected more precisely in the first case with 68Ga-FAPI-04. In the second case, 68Ga-FAPI-04 outperformed 18F-FDG in the number of lesions and demonstrated intense FAP uptake on widespread metastases, which could provide a treatment option as a theranostic concept. These cases highlight that 68Ga-FAPI-04 PET/CT may be useful for detecting local recurrence and metastases and help select patients for radionuclide treatments targeting cancer-associated fibroblasts.