The results suggested that the differences between the TLR (ΔTLR, %) of pre-treatment 18F-FDG PET and post-treatment 18F-FDG PET were promising imaging biomarkers for pathological response and prognosis of primary unresectable HCC after treated with the PD-1 blockade in combination with Lenvatinib as conversion therapy. Here, PDCD1 is linked to hepatocellular carcinoma.