PET Scan

What is PET Scan?

A Positron Emission Tomography (PET) scan is an imaging test that uses a harmless injection of a very small amount of radiopharmaceuticals, which are marked by a radioactive substance, to produce images of the body. It helps doctors diagnose and determine the severity of various diseases and conditions. PET scans will usually provide clear images that help in identifying or monitoring diseases such as cancer, heart disease and brain disorders.


Before the PET scan, the patient is typically asked to drink plenty of water and avoid strenuous physical activities. For the scan, the patient is also required to wear comfortable clothes and remove any other metal articles, such as jewellery, glasses or dental fillings.


The PET scan procedure usually takes between 30 minutes and an hour. The patient is given an intravenous (IV) injection of a radioactive substance, followed by a 60-minute waiting period. This waiting period allows the substance enough time to circulate throughout the body so that it can produce clear images of the body's organs and tissues. The patient usually lies on a table, which enters the scanner where the images are taken. This step usually takes around 20 minutes.

Types of PET Scan

  • Cardiac PET Scan: This type of scan is used to diagnose cardiac diseases such as coronary artery disease, cardiomyopathy, and congestive heart failure.
  • Brain PET Scan: This type of scan is useful for diagnosing brain disorders, such as stroke, epilepsy, or Alzheimer's disease.
  • Oncologic PET Scan: This type of scan is used to diagnose and monitor cancer.

Risks of PET Scan

PET scans use small doses of radiation, but the risks are very low, and the actual amount of radiation used is equivalent to a few years of natural exposure. The only risk associated with PET scans is increased exposure to radiation, and this risk is usually very minor.

Why is PET scan done?

The main purpose of a PET scan is to identify and diagnose diseases and conditions. The test is able to assess how healthy a body organ is, assess how well the body is functioning, and provide details about the size, shape, and structure of the organ or tissue. It is also used to detect cancerous tumors, locate areas of inflammation, or to identify changes in the brain caused by a stroke or other medical condition.

When is PET Scan done?

PET scans are typically recommended when other tests such as CT scans and MRIs fail to produce an accurate diagnosis. PET scans are also useful for monitoring a patient's response to treatment. This type of scan is not usually recommended as a routine diagnostic tool, as it may be too expensive or unnecessary for most people.