A PET scan is also recommended. A PET (Positron Emission Tomography) scan is a medical technique that monitors the activity in the brain and other organs by tracking the movement of a special radioactive solution through the body. The radioactive solution is either inhaled as a mist or injected into a vein. The radioactive solution is usually made from simple sugar that has radioactive particles attached to it. After the solution is injected into a vein or inhaled, the PET scanner takes pictures of the radioactive solution as it moves through the body and collects in various organs. By watching how the solution travels through the body and studying where the solution collects, researchers can learn the extent of disease in certain organs in the body.