Five-Year Persistent 18F-FAPI-74 Uptake in Radiation-induced Hepatic Fibrosis Following Proton Beam Therapy for Hepatocellular Carcinoma
Yuki Narita, Shinya Komori, Shinobu Adaniya, Toshimitsu Momose, Masao MurakamiA 79-year-old man underwent proton beam therapy (PBT) for hepatocellular carcinoma. During follow–up, MRI demonstrated stable T2-weighted hyperintensity in the irradiated region without interval enlargement or mass formation. Five years after PBT, a new hepatocellular carcinoma developed elsewhere in the liver. 18 F–FDG PET showed no apparent abnormal uptake in the irradiated region, whereas 18 F-fibroblast activation protein inhibitor–74 PET demonstrated persistent uptake. These findings may reflect chronic radiation–induced fibroinflammatory changes and suggest that fibroblast activation protein inhibitor–PET can visualize such changes even years after PBT.