18F-FDG PET for semiquantitative evaluation of acute allograft rejection and immunosuppressive therapy efficacy in rat models of liver transplantation.

UNLABELLED Acute allograft rejection remains a major complication after liver transplantation. We report a semiquantitative imaging method of detecting acute allograft rejection with (18)F-FDG PET. METHODS Syngeneic and allogeneic transplanted rats, with or without immunosuppressive treatment, were subjected to serial PET. Autoradiography of the liver was conducted in both the syngeneic and the allogeneic rats. RESULTS A significant increment of (18)F-FDG accumulation in liver allografts was observed by PET on day 2. The (18)F-FDG signal was concentrated in the area where inflammatory cells around the vessels were detected by autoradiography. Allotransplanted rats treated with an immunosuppressive agent displayed a marked decrease in hepatic (18)F-FDG uptake, compared with allotransplanted rats that were not treated. CONCLUSION (18)F-FDG PET may be a valid method for facilitating the development of protocols to diagnose graft rejection and to monitor the efficacy of immunosuppressive therapy.