A positron emission tomography (PET) scan is usually used in combination with other tests, such as X-rays or magnetic resonance imaging (MRI) scans, to investigate or diagnose health conditions. PET scans can also be used to find out how well a treatment is working.
The main advantage of a PET scan compared with other types of scans, such as an X-ray or MRI scan, is that it can show how well a certain part of the body is working, rather than simply showing what it looks like.
This can show how certain conditions have affected the functions of the body and enable healthcare professionals to track accurately how far a condition, such as cancer, has spread.
Cancer
One of the most common uses of a PET scan is to investigate confirmed cases of cancer. A PET scan can usually provide three important pieces of information:
- how far a particular cancer has spread (this is known as staging - the higher the stage, the further the cancer has spread)
- how well a particular cancer is responding to treatment
- whether any cancerous cells remain after a course of treatment has been completed
Neurological conditions
A less common use of PET scans is to help diagnose a number of conditions that can affect the brain and nervous system (neurological conditions).
For example, a PET scan can be used to help plan brain surgery in cases of epilepsy that have not responded to medication.
The PET scanner can sometimes locate damage to the brain that is responsible for triggering seizures (seizures occur when the normal electrical activity of the brain becomes disrupted). The damaged areas of the brain can be removed using surgery.
PET scans can also help to diagnose dementia (a group of symptoms that are related to a decline in brain function) and Parkinson’s disease (a long-term neurological condition that affects around 120,000 people in the UK).
Heart disease
A PET scan is very effective in tracking the blood flow in and around the heart, so it is often used to determine whether someone could benefit from different types of heart surgery, such as a:
- heart transplant - where a diseased heart is replaced with a healthy heart taken from a donor who has died
- coronary artery bypass graft - where a blood vessel that is taken from another part of the body is used to bypass a blocked or narrowed section of artery
- angioplasty - where a blocked or narrowed section of artery is widened using a small metal tube called a stent
Medical research
PET scans can also be used to look at how the body works and to help understand what happens when something goes wrong with the way the body functions.
For example, researchers are currently using PET scanners to study the brain function of people with autism.
