The PET scan uses a safe, mildly radioactive drug to show up areas of your body where cells are more active than normal. Cancer tends to be more active than normal cells because it is rapidly dividing and requires a lot of energy to do so. You will drink radioactive sugar which is used to help diagnose cancer. It can also help to find out where and whether cancer has spread. Some cancers may not show up on a PET Scan. Usually a CT scan of almost the entire body is also performed and fused with the PET scan portion for more precise identification of abnormal areas. This is called and ordered a CT-PET scan. The SUV is a number reported for those areas that show up on the PET scan. It represents the degree of uptake. An SUV greater than 6 correlates with malignant (cancerous) tumors.