A PET scan uses a small amount of a radioactive drug to show differences between healthy and diseased tissue.

A PET scan uses a small amount of a radioactive drug to show differences between healthy and diseased tissue.

Positron Emission Tomography, also called a PET scan, is a Nuclear Medicine exam that produces a 3D image of functional processes in the body.

Positron Emission Tomography (PET) scans use radio-active tracers injected intravenously (IV) to obtain images of the human body’s function and reveal information of health and disease. As the tracers journey through the body, the scanner records signals that the tracers emit and the targeted organs collect. A computer then interprets the signals and merges them with CT images, which reveal biological maps of organ function.

This type of imaging is some of the most advanced available to diagnose cancers and other diseases. PET scans are also utilized to examine the effects of cancer therapy by characterizing biochemical changes in the cancer. To determine if they are candidates for surgery, patients who have suspected or proven brain tumors, or who have seizure disorders that are not responsive to medical therapy can be evaluated using brain scans. Patients who have memory disorders of an undetermined cause are not candidates for surgery.

Patients lie on a table that moves slowly through the large opening of the PET scanner. Scan times usually average about 30 minutes, but vary depending on the region being assessed.


You should:

  • Wear comfortable clothes with no metal zippers or buttons
  • Avoid exercise and not engage in any form of strenuous or vigorous activity for 24 hours before your exam; for example, golfing, swimming, heavy lifting and housework

Any additional preparation for this test varies depending on the purpose of the scan. Expect a call from our preregistration staff who will instruct you on how to prepare for your exam.


  • Plan on being at the office for 1 ½ to 2 hours (registration, injection and scan duration are included in the time approximation)
  • You will receive an intravenous (IV) injection of the radio-active pharmaceutical
  • The radio-active tracer will take approximately 60 minutes to travel through your body and be absorbed by the tissue under study. During this time, you will be in a comfortable recliner and private room. You will be asked to rest quietly and avoid significant movement or talking, which may alter the localization of the administered substance
  • You will be positioned on the PET scanner table and asked to lie still during your exam
  • The table will move slowly through the large opening of the PET scanner
  • Scanning of the brain takes less than ten minutes. Scanning of the body takes between 15 and 25 minutes
  • Usually, there are no restrictions on daily routine after the test. You should drink plenty of liquids to flush the radio-active substance from your body

What will I experience during the procedure?

  • When given the intravenous injection, you will feel a slight prick. However, you will not feel the substance in your body
  • You will be made as comfortable as possible on the exam table before you are positioned in the PET scanner for the test
  • Your technologist can see, hear and speak with you at all times during your scan


The small amount of radiotracer in your body will lose its radio-activity over time through the natural process of radio-active decay. Following the test, it may also pass out of your body through your urine or stool during the first few hours or days. You should not feel any side effects and be able to return to your normal daily activities directly after the scan. We recommend that you hydrate thoroughly for 48 hours after the scan to help void the medications.

Keep your distance from children and pregnant women for approximately six hours after a PET scan.

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