If the study doctor decides it is necessary (for example, if cramping occurs), you will receive a glucagon injection under the skin in order to relax the colon. Glucagon is a medication that helps to relax the colon and decrease cramping. If continued cramping occurs, the gas will be turned off which results in immediate relief. This is considered routine for the CT part of the PET/CT. Administering the gas for the CT is similar to the sensation that will be felt during the colonoscopy when the colon is also insufflated.