Head-to-head comparison of 18F-FAPI and 18F-FDG PET/CT in staging and therapeutic management of hepatocellular carcinoma

Background Fluorine 18 (F-18) fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) has limitations in staging hepatocellular carcinoma (HCC). The recently introduced F-18-labeled fibroblast-activation protein inhibitor (FAPI) has shown promising prospects in detection of HCC lesions. This study aimed to investigate the initial staging and restaging performance of F-18-FAPI PET/CT compared to F-18-FDG PET/CT in HCC.Methods This prospective study enrolled histologically confirmed HCC patients from March 2021 to September 2022. All patients were examined with F-18-FDG PET/CT and F-18-FAPI PET/CT within 1 week. The maximum standard uptake value (SUVmax), tumor-to-background ratio (TBR), and diagnostic accuracy were compared between the two modalities.Results A total of 67 patients (57 men; median age, 57 [range, 32-83] years old) were included. F-18-FAPI PET showed higher SUVmax and TBR values than F-18-FDG PET in the intrahepatic lesions (SUVmax: 6.7 vs. 4.3, P < 0.0001; TBR: 3.9 vs. 1.7, P < 0.0001). In diagnostic performance, F-18-FAPI PET/CT had higher detection rate than F-18-FDG PET/CT in intrahepatic lesions [92.2% (238/258) vs 41.1% (106/258), P < 0.0001] and lymph node metastases [97.9% (126/129) vs 89.1% (115/129), P = 0.01], comparable in distant metastases [63.6% (42/66) vs 69.7% (46/66), P > 0.05]. F-18-FAPI PET/CT detected primary tumors in 16 patients with negative F-18-FDG, upgraded T-stages in 12 patients and identified 4 true positive findings for local recurrence than F-18-FDG PET, leading to planning therapy changes in 47.8% (32/67) of patients.Conclusions F-18-FAPI PET/CT identified more primary lesions, lymph node metastases than F-18-FDG PET/CT in HCC, which is helpful to improve the clinical management of HCC patients.

Automated summary

This study compared the performance of F-18-FAPI PET/CT and F-18-FDG PET/CT in patients with HCC, showing that F-18-FAPI PET/CT performed better in detecting primary lesions and lymph node metastases compared to F-18-FDG PET/CT, which can help improve the clinical management of HCC patients.