PET (Positron Emission Tomography) is a diagnostic tool which combines the functional information of a PET scan with the structural information of a CT scan. It shows the chemical function of an organ or tissue. A radioactive glucose is injected via a vein and is then absorbed by tissue into your body. The PET scanner then detects the activity within your organs and how they function which will help your Doctor plan the appropriate treatment for you.
CT imaging is a highly advanced form of x-ray which shows the anatomical detail inside the body and detects alterations of structure caused by diseases.