A 71-year-old female patient with a newly diagnosed colon cancer underwent whole-body FDG PET scan on suspicion of hepatic metastasis due to a small indeterminate lesion on contrast-enhanced CT. The small hepatic lesion was successfully diagnosed by histopathologic examination as liver metastasis under the help of an unconventionally delayed PET approach with more postponed time interval and prolonged emission time. In addition, FDG accumulation from colonic wall to lumen was demonstrated by dual-time-point PET images. Based on our incidental findings, we proposed the hypothesis to explain the mechanism of colonic FDG accumulation.