Clinical Value of 18F-FAPI PET/CT in assessing early-stage fibrosis of graft 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 conducted. All patients received liver biopsy, transient elastography (TE), and 18F-FAPI PET/CT. On 18F-FAPI PET/CT scans, the liver parenchyma's maximum standardized uptake values (SUVmax) were noted. 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 S0, 10(34.5%) had S1, and 4(13.8%) had S2 respectively. The SUVmax of patients with early-stage liver fibrosis was 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 diagnosed 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 an LSM scores cut-off value of 8.4 kPa diagnosed early-stage liver fibrosis with an AUROC of 0.91 (P < 0.001). Conclusions As a non-invasive method, 18F-FAPI PET/CT could be applied to evaluate early-stage liver fibrosis in LT recipients and CHB patients properly. 18F-FAPI PET/CT provided a diagnostic accuracy higher than TE for staging of early-stage liver fibrosis with the additional advantages in whole-liver evaluation.