Hepatic Metastasis From Duodenal Ampullary Carcinoma With Intense FAP Activity But Without FDG Uptake

A 58-year-old man with 3 years postduodenal ampullary carcinoma surgery underwent a routine abdominal CT 1 week ago, revealing occupancy of the S7 segment of the liver, suggesting a probability of metastasis. Serum CA19-9 and CEA levels were within the reference range. The patient, with informed consent, was then enrolled in a clinical trial of comparison of 18 F-FDG and 68 Ga-FAPI-04 PET/CT in hepatic lesions. Compared with the absence of tracer uptake on 18 F-FDG PET/CT, 18 Ga-FAPI-04 PET/CT showed high tracer uptake and prominent tumor-to-background contrast. The final pathology confirmed an infiltrating adenocarcinoma, originating from the primary duodenal ampullary carcinoma.