Overview

A positron emission tomography (PET) scan is an imaging test that can help reveal the metabolic or biochemical function of your tissues and organs. The PET scan uses a radioactive drug (tracer) to show both normal and abnormal metabolic activity. A PET scan can often detect the abnormal metabolism of the tracer in diseases before the disease shows up on other imaging tests, such as computerized tomography (CT) and magnetic resonance imaging (MRI).

The tracer is most often injected into a vein within your hand or arm. The tracer will then collect into areas of your body that have higher levels of metabolic or biochemical activity, which often pinpoints the location of the disease. The PET images are typically combined with CT or MRI and are called PET-CT or PET-MRI scans.