68Ga-FAPI-04 PET/CT for the Evaluation of Cholangiocarcinoma

Abstract

Purpose In this study, we evaluated and compared the diagnostic performances of 68Ga-FAPI-04 PET/CT and 18F-FDG PET/CT for primary and metastatic cholangiocarcinoma (CCA) lesions. We also investigated the performance of PET/MR for visualizing and characterizing CCA and liver metastasis lesions. Patients and Methods Forty-four patients with suspected CCA were recruited and underwent 68Ga-FAPI-04 and 18F-FDG PET/CT within 1 week, including 30 patients who underwent simultaneous abdominal 68Ga-FAPI-04 PET/MR scanning. The findings were confirmed by histopathology or radiographic follow-up. Results Compared with 18F-FDG PET/CT, 68Ga-FAPI-04 PET/CT showed higher sensitivity (94.3% vs 88.6%) and the same accuracy (86.4% vs 86.4%) in evaluating primary tumors. However, its specificity was lower (55.6% vs 77.8%). 68Ga-FAPI-04 PET was superior to 18F-FDG PET in both patient-based and lesion-based evaluations except for metastatic lesions in the liver and bone. For intrahepatic CCA, 68Ga-FAPI-04 PET/CT and 18F-FDG PET/CT (100% vs 100%) had similar detection rates, with similar uptake levels between tracers (P > 0.05). However, for extrahepatic CCA, 68Ga-FAPI-04 PET/CT had a higher detection rate (89.5% vs 78.9%), and 68Ga-FAPI-04 had a higher uptake (P < 0.05). PET/MR was more effective than PET/CT in terms of lesion conspicuity and diagnostic confidence for primary tumors and liver metastases. In addition, multisequence MRI identified more liver metastases than 68Ga-FAPI-04 PET/CT and 18F-FDG PET/CT. Conclusions Compared with 18F-FDG PET/CT, 68Ga-FAPI-04 PET/CT showed a higher sensitivity in detecting primary CCA tumors, involved lymph nodes, and peritoneal metastases. Compared with 68Ga-FAPI-04 PET/CT, PET/MR detected primary and liver metastatic lesions more accurately. For extrahepatic CCA, the combination of 68Ga-FAPI-04 PET/CT and abdominal PET/MRI may replace 18F-FDG PET/CT.