In this study, participants will have a full-body PET/CT procedure performed like they normally would, but the difference will be that gas will be pumped into the colon before the scan. This is so the colon will be opened up (inflated) so the study doctor will be able to more easily look for any lesions. The procedure is called gas insufflation. (In standard PET/CT scanning of the colon, gas insufflation is not used.)