A positron emission tomography (PET) scan is an imaging test that uses a radioactive drug called a tracer to show both typical and atypical metabolic activity in your tissues and organs. The tracer is most often injected into a vein within your hand or arm, and it collects into areas of your body that have higher levels of metabolic or biochemical activity, often pinpointing the location of the disease. The PET images are typically combined with CT or MRI and are called PET-CT or PET-MRI scans. A PET scan can often detect the atypical 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) .
PET scans are used to diagnose a variety of conditions, including cancer, heart disease, and brain disorders. They can be used to check certain brain disorders, such as tumors, Alzheimers disease, and seizures. PET scans can measure vital functions, such as blood flow, oxygen use, and blood sugar (glucose) metabolism, and identify organs and tissues that aren’t working as they should.
During a PET scan, a small amount of radioactive tracer is given through a vein, and the tracer travels through your blood and collects in organs and tissues, which helps the radiologist see certain areas more clearly. The scan usually takes about 15 to 30 minutes to produce detailed images of metabolic activity in your tissues and organs. The amount of radiation used in a PET scan is about the same amount as used in most CT scans, and the radiation is gone from your body in about 2 to 10 hours.
