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

Abstract

Abstract Background Fluorine 18 ( 18 F) fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) has limitations in staging hepatocellular carcinoma (HCC). The recently introduced 18 F-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 18 F-FAPI PET/CT compared to 18 F-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 18 F-FDG PET/CT and 18 F-FAPI PET/CT within 1 week. The maximum standard uptake value (SUV max ), 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. 18 F-FAPI PET showed higher SUV max and TBR values than 18 F-FDG PET in the intrahepatic lesions (SUV max : 6.7 vs. 4.3, P < 0.0001; TBR: 3.9 vs. 1.7, P < 0.0001). In diagnostic performance, 18 F-FAPI PET/CT had higher detection rate than 18 F-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]. 18 F-FAPI PET/CT detected primary tumors in 16 patients with negative 18 F-FDG, upgraded T-stages in 12 patients and identified 4 true positive findings for local recurrence than 18 F-FDG PET, leading to planning therapy changes in 47.8% (32/67) of patients. Conclusions 18 F-FAPI PET/CT identified more primary lesions, lymph node metastases than 18 F-FDG PET/CT in HCC, which is helpful to improve the clinical management of HCC patients. Trial registration Clinical Trials, NCT05485792 . Registered 1 August 2022, Retrospectively registered.