A positron emission tomography (PET) scan is a nuclear imaging technique that allows a physician to view a patient’s organs and how they are functioning. This minimally invasive imaging test produces three-dimensional images of the chemical activity within the heart, brain, breasts, ovaries and other organs. This activity is displayed as colors that are more intense or less intense, depending upon the status of the organ or tissue.

PET scans are ordered by physicians to help with the diagnosis and management of cancers, certain brain disorders and heart disease. They are especially helpful in:

• Determining the presence and extent of coronary artery disease (CAD) or damage to the heart after a heart attack.
  
  
• Revealing the existence and monitoring the spread of cancer.
  
  
• Pinpointing neurological conditions such as clinical depression and Alzheimer’s disease by monitoring the brain’s activity.

PET scanning is not as readily available as more conventional nuclear imaging because of its greater cost and the need for a cyclotron, a machine used to create high-speed beams of atomic or subatomic particles. However, most large medical facilities have the ability to administer the test. Before the test, patients are encouraged to:

• Wear comfortable, loose clothing
  
  
• Refrain from eating or drinking, typically for at least six hours before the test
  
  
• Discuss current medications with their physician

During the test, patients may feel the prick of a needle when an intravenous (I.V.) line is inserted in their arm to administer a small amount of radioactive material. Otherwise, the test is painless, and the amount of radioactivity is minimal, roughly the same as patients are exposed to during a CAT scan (computed axial tomography). The test takes at least an hour to complete. Afterward, patients may drive themselves home and resume their usual activities. They are typically instructed to drink plenty of water to flush the radioactive material from their body.