What to Expect during a PET Scan

How PET scans work

A small amount of radioactive glucose (a sugar) is injected into a vein. The PET scanner takes a picture of where glucose is being used in the brain.

PET scanning utilizes a radioisotope tracer that is an analog to glucose, called fluorodeoxyglucose (FDG). FDG accumulates within malignant cells because of their high rate of glucose metabolism. Once injected with this agent, the patient is imaged on the whole body PET scanner to reveal malignant lesions which may have been overlooked or difficult to characterize by conventional CT scan, X-ray, or MRI.

PET scan of the heart

A PET scan can also give information about the flow of blood through the coronary arteries to the heart muscle. This nuclear scan offers a higher resolution and imaging speed and is becoming more widely available for cardiac imaging.

PET scan of the brain

PET scans use injected radioactive material to help visualize active areas of the brain. A PET scan can be used to find malignant tumor cells or diagnose conditions like epilepsy. A small amount of radioactive glucose (a sugar) is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the brain. Malignant tumor cells show up brighter in the picture because they are more active and take up more glucose than normal cells do.

After the radioactive material is injected into a vein, it will take 3-90 minutes for the substance to accumulate in the brain tissue. During this waiting period, the individual will be asked to rest quietly and not talk or move around much. The actual scan takes 30-45 minutes. The amount of radioactive material used in the test is very small.

The benefit of PET scans in cancer diagnosis

Because disease is a biological process and PET is a biological imaging examination, PET can detect and stage most cancers, often before they are evident through other tests. Cancer cells show up brighter in the picture because they use more glucose than normal tissues. Clinical research data has proven that PET is superior to conventional imaging in the diagnosis, staging, and surveillance (restaging) of various types of cancers. Recently, the Centers for Medicare & Medicaid Services (CMS) expanded to include many more tumor types and reaffirmed its role in preexisting covered tumor types.