PET/CT is a nuclear medicine imaging technique that produces a 3-D image of functional processes in the body. It is often used to map brain and heart functioning, along with cancer diagnosis and treatment. PET/CT scans are performed on instruments that are combined PET and CT scanners. The combined PET/CT scans provide images that pinpoint the location of abnormal metabolic activity within the body. The combined scans have been shown to provide more accurate diagnoses than when the two scans are performed separately.