Fig. 2

Contrast-enhanced CT and PET–CT during nivolumab treatment. a CT before nivolumab treatment. Liver metastases were 41 × 39 mm in segment 4 and 24 × 22 mm segment 8. b CT after 8 courses of nivolumab. The target lesion of liver metastasis achieved a therapeutic partial response. c CT after 18 courses of nivolumab. Liver metastases had shrunk to 24 × 22 mm in segment 4 and 11 × 9 mm in segment 8. d PET–CT at the time of recurrence and before nivolumab administration. No evidence of intrahepatic metastases other than two recurrent hepatic metastases was noted on CT. e PET–CT after 18 courses of nivolumab. No abnormal fluorodeoxyglucose (FDG) accumulation in liver metastases was shown, and no new metastases appeared