Positron Emission Tomography (PET) Scan

Submitted on March 27, 2012

The Positron Emission Tomography scan which is often referred to as PET scan, is a new technique for scanning, which has been developed by medical research. It allows medical experts to measure in minute detail, the performance of distinct areas of many human organs like the human brain, and this can be done comfortably while the patient is conscious and alert.

Procedure to Conduct PET Scan

PET scans use a special camera and a special radioactive chemical, referred to as ‘tracer’. This tracer is in the form of a liquid and is injected into a vein of the arm. The tracer now moves through the vein and collects in the organ, where it gives off positrons, which are tiny positively charged particles. The camera takes pictures of the pattern of the positrons and records them on a computer.


The PET Scan is done to:

  • Find cancers such as lymphoma of the brain, breast, colon, lung or prostate. Early stages of cancer often show up with greater clarity in a PET scan than in an MRI or CT scan.
  • To find if a cancer has advanced or spread to other areas of the body, and help medical experts to choose the best treatment for it. PET scans make it possible to find out if a tumor can be removed by surgery.
  • To check flow of blood to the brain, which can help doctors to trace and treat nervous system problems like Parkinson’s disease, Alzheimer’s disease, Huntington’s disease, transient ischemic attack (TIA), stroke, schizophrenia, multiple sclerosis and amyotrophic sclerosis (ALS).
  • To find changes in the brain, that can cause epilepsy.
  • To find poor flow of blood to the heart, that can cause coronary artery disease.
  • To find damaged heart tissue after a heart attack.


You will be asked to:

  • Stop other medicines, smoking and drinking alcohol 24 hours before the test.
  • Stop any food 8 hours before the test.
  • The tracer will be given via intravenous and you will have to lie very still during the scan, while the doughnut-shaped camera of the scanner moves around you.
  • If it is for the brain, you may be asked to read or say something.
  • If it is for the heart, electrodes will be attached to your body.
  • The test may take 1 to 3 hours.
  • Drink lots of water after that to flush out the tracer.


  • Allergic reaction to the tracer is rare.
  • Tell your doctor if you are pregnant or breast-feeding.
  • Some people may be subject to panic attacks in enclosed places