Clinical Value of 18F-FAPI PET/CT in assessing early-stage fibrosis of liver after liver transplantation: preliminary experience

Abstract Aims: To investigate the clinical usefulness and performance of 18F-FAPI PET/CT in assessing early-stage liver fibrosis in liver transplantation (LT) recipients.Methods: A prospective study including 17 LT recipients and 12 chronic Hepatitis B (CHB) patients was performed. All patients received liver biopsy, transient elastography (TE), and 18F-FAPI PET/CT. The maximum standardized uptake values (SUVmax) of the liver parenchyma were recorded on 18F-FAPI PET/CT images. The receiver operating characteristic (ROC) curve analysis was applied to determine the diagnostic efficacy of 18F-FAPI PET/CT in early-stage liver fibrosis (S1 ~ S2) compared with the diagnostic performance of TE.Results: Of 29 patients, 15(51.7%) had fibrosis stage 0 (S0), 10(34.5%) had stage 1 (S1), and 4(13.8%) had stage 2 (S2) respectively. The SUVmax of patients with early-stage liver fibrosis were significantly higher than those without liver fibrosis in LT recipients and CHB patients (p=0.004, p=0.02). In LT recipients, a SUVmax cut-off value of 2.0 detected early-stage liver fibrosis with an AUROC of 0.92 (P=0.006) and a Liver Stiffness measurements (LSM) score cut-off value of 8.2 kPa detected early-stage liver fibrosis with an AUROC of 0.80 (P=0.012). In CHB patients, a SUVmax cut-off value of 2.7 detected early-stage liver fibrosis with an AUROC of 0.94 (P<0.001) and a LSM scores cut-off value of 8.4 kPa detected early-stage liver fibrosis with an AUROC of 0.91 (P<0.001).Conclusions: 18F-FAPI PET/CT could be applied to evaluate early-stage liver fibrosis in LT recipients and CHB patients accurately. Compared with TE, 18F-FAPI PET/CT was comparable in detecting early-stage liver fibrosis with the additional advantages in whole-liver evaluation.