FAP and rheumatoid arthritis: We imaged the arthritic joints in RA patients with [68 Ga]Ga-fibroblast activation protein inhibitor-04 ([68 Ga]Ga-FAPI-04), a recently introduced FAP-targeted PET agent, and found markedly increased uptake of [68 Ga]Ga-FAPI-04 in the arthritic joints of patients with RA.