Comparable Diagnostic Value of 99m Tc-FAPI-46 SPECT/CT and 18 F-FDG PET/CT in Cholangiocarcinoma: A Case Report.

We describe a 51-year-old man with cholangiocarcinoma of the common bile duct. Initially deemed nonmetastatic, he was a candidate for curative surgery and liver transplantation. However, during laparotomy, peritoneal seeding was discovered, necessitating omentectomy and lesion resection. Following chemotherapy, the patient underwent 18 F-FDG PET/CT for re-staging, revealing uptake in the primary tumor and a right iliac bone metastasis. Subsequently, FAPI-based scintigraphy using 99m Tc-FAPI-46 as a novel conventional imaging agent demonstrated comparable uptake in both lesions. This case highlights the diagnostic potential of 99m Tc-FAPI-46 SPECT/CT as an alternative to 18 F-FDG PET/CT and 68 Ga-FAPI in cholangiocarcinoma, particularly in resource-limited settings.