An FDG PET scan uses a radiotracer to measure things like blood flow, oxygen use and sugar metabolism in your body. It shows how your tissues and organs are functioning at the molecular level. For cancer patients, PET scans are used for cancer staging, monitoring treatment or to check for recurrence. 

When you read results from a PET scan, you may notice a number called a standardized uptake value, or SUV. But what does it...