68 Ga-FAPI-04 Versus 18 F-FDG PET/CT in Duodenal Synovial Sarcoma.

A previously healthy 18-year-old man with a 9-month history of upper abdominal pain and significant weight loss underwent gastroscopy, revealing an ulcerative lesion in the duodenal bulb. Enrolled in a clinical trial, both 18 F-FDG and 68 Ga-FAPI-04 PET/CT demonstrated similar metabolic activity, though 68 Ga-FAPI-04 offered superior lesion delineation. Pathology confirmed synovial sarcoma. This case highlights the potential utility of 68 Ga-FAPI-04 as a radiopharmaceutical for evaluating rare gastrointestinal synovial sarcomas.