PET/CT With 68Ga-FAPI Detects More Biliary Tract Cancer than 18F-FDG

Gallium 68–labeled fibroblast-activation protein inhibitor (⁶⁸Ga-FAPI) PET/CT showed potential to more accurately stage biliary tract cancer than Fluorine 18 fluorodeoxyglucose (¹⁸F-FDG) PET/CT in a study published in Radiology.

The single-center prospective clinical study was performed at the Affiliated Hospital of Southwest Medical University between June 2020 and June 2021. Eighteen patients with primary or recurrent biliary tract cancer underwent both ⁶⁸Ga-FAPI and ¹⁸F-FDG PET/CT. Using the paired-sample t test, the maximum standardized uptake value (SUV_max) of the primary tumor and nodal and distant metastases between ¹⁸F-FDG and ⁶⁸Ga-FAPI PET/CT were compared.

The sensitivity of ⁶⁸Ga-FAPI PET/CT was higher than ¹⁸F-FDG PET/CT in primary tumors (100% versus 81%), nodal metastases (98% vs 83%), and distant metastases (100% vs 79%). With ⁶⁸Ga-FAPI, 10 participants had new oncologic findings and five had upgraded tumor staging or restaging. In inflammatory processes secondary to tumor-related obstruction, ⁶⁸Ga-FAPI PET/CT demonstrated higher sensitivity than ¹⁸F-FDG PET/CT (88% vs 13%).

Two experienced nuclear medicine physicians, both of whom had more than 10 years of experience in nuclear oncology, evaluated both the ⁶⁸Ga-FAPI PET/CT and ¹⁸F-FDG PET/CT studies in random order.

⁶⁸Ga-FAPI PET/CT visualized 99 distant metastases in 12 participants  while ¹⁸F-FDG PET/CT missed 21 distant metastatic lesions in seven participants. 65 of the 99 distant metastases were localized in the liver. Also, ⁶⁸Ga-FAPI PET/CT demonstrated a higher detection efficacy for metastatic lymph nodes compared with 18F-FDG PET/CT.

The authors conclude that ⁶⁸Ga-FAPI PET/CT is superior to ¹⁸F-FDG PET/CT for detecting the primary tumor and nodal and distant metastases in participants with biliary tract cancer. In addition to upgrade staging or restaging five patients, ⁶⁸Ga-FAPI PET/CT showed good detection efficacy for inflammatory and reactive processes secondary to tumor-related obstruction of the proximal bile and/or pancreatic duct.