The diagnostic value of 18 F-FAPI-04 PET/CT in unresectable hepatocellular carcinoma: a head-to-head comparison with 18 F-FDG PET/CT

Abstract

Purposes: This study aimed to evaluate the diagnostic value of 18F-FAPI-04 PET/CT in unresectable hepatocellular carcinoma(uHCC) and with a comparative analysis against 18F-FDG PET/CT. Methods: Patients with uHCC who underwent paired 18F-FDG and 18F-FAPI-04 PET/CT for pre-treatment staging or post-treatment restaging were retrospectively included. The two tracers were compared in terms of their ability to detect intrahepatic and extrahepatic lesions, including sensitivity, maximum standardized uptake value (SUVmax), and tumour-to-background ratio (TBR). Results: Eighty-five patients (mean age: 53.9 ± 10.0 years) were included. In patient-based analysis, 18F-FAPI-04 showed higher intrahepatic lesion detection sensitivity (98.8% vs. 85.9%, P = 0.003) and lesion uptake than 18F-FDG (median maximum SUVmax:9.1 vs. 7.6, P = 0.028). Contrast enhanced CT/MRI(CECT/MR) demonstrated comparable sensitivity to 18F-FAPI-04 PET and superior to 18F-FDG PET (96.5% vs. 85.9%, P = 0.004). In lesion-based analysis, 18F-FAPI-04 demonstrated significantly higher sensitivity (89.5% vs. 57.1%, P < 0.001), intrahepatic lesion SUVmax, (median:6.5 vs. 3.7, P < 0.001) and TBR (median:3.4 vs. 1.7, P < 0.001) than 18F-FDG, but lower sensitivity than CECT/MR (89.5% vs. 96.2%, P < 0.001). Among organ transplant recipients, 18F-FDG showed superior sensitivity to 18F-FAPI-04 for detecting intrahepatic lesions (87.5% vs. 37.5%, P = 0.002). 18F-FDG had a higher detection rate of portal vein tumour thrombosis (PVTT) (95.7% vs. 43.5%, P = 0.002), lymph node metastasis (95.7% vs. 82.8%, P = 0.004), and lung metastasis (69.3% vs. 58.4%, P = 0.007).18F-FAPI-04 was significantly better than 18F-FDG in detecting peritoneal metastasis (100% vs. 69.6%, P = 0.016). According to 18F-FAPI-04 PET/CT, Barcelona Clinic Liver Cancer (BCLC) and China Liver Cancer (CNLC) staging were changed in 16 (18.8%) and 22 (25.9%) patients, respectively. Conclusions: 18F-FAPI-04 exhibits significant diagnostic advantages in uHCC patients, particularly in the detection of intrahepatic lesions, peritoneal metastases, and better contrast compared with 18F-FDG. Among organ transplant recipients,18F-FDG may offer higher sensitivity than 18F-FAPI-04 for intrahepatic lesion detection. 18F-FDG outperforms 18F-FAPI-04 in identifying PVTT. The rational selection of these two tracers may improve the accuracy of clinical staging.