PET Scans

What is a PET scan?

Developed in 1975, the PET scan is a diagnostic tool that allows doctors to picture of how the cells in your body are working and to detect abnormalities. You may not have heard as much about PET scans as you have about MRIs and CT scans. This is because the machines are extraordinarily expensive and there are not many of them in the country, furthermore, they are not available in the  Canadian public healthcare system.

The abbreviation PET stands for Positron Emission Tomography and refers to the tiny particles (positrons) that appear during the procedure. During a PET scan, you are injected with a small amount of a radioactive substance. Your body then emits positrons and your body’s reaction to these positrons can be photographed from different angles. When all these photographs are put together on a computer (tomography) the result is a 3-D image of how your body is performing.

How does a PET scan differ from other diagnostic procedures?

Unlike other scans, a PET scan is able to take pictures of how your body actually works, not just what it looks like. Because of this, PET scans can often detect disease sooner and much more accurately than other non-invasive diagnostic tests.

Sometimes PET scans are used in combination with a CT-scan – the latter being used to provide information about size, shape and location of various body structures.

How is a PET scan most useful?

An PET scan can help doctors detect:

• Cancer – It may be useful for identifying any of the following cancers: breast, colorectal, gastro-esophageal, head & neck, liver, lung, lymphoma, melanoma, pancreatic, testicular and uterine/cervical.
• Brain disorder – It may be useful for identifying Alzheimer’s, Parkinson’s, epilepsy and for assessing damage done by a stroke.
• Heart disease - By assessing myocardial perfusion (the flow of blood to the heart) a PET scan can help diagnose coronary artery disease. It can also assess myocardial viability, indicating in the case of severe heart disease whether bypass surgery or a transplant is the better choice.

Why do I have to wait so long for my PET scan?

The technology is expensive and requires not just the machinery, but the ability to make or get access to the right radioactive material. This means that there are not many PET scan facilities in Canada – a number of provinces do not have even one machine. As well, there is a shortage of trained and experienced staff to operate the scanners. As a result, there is a waiting list in Canada to receive scans. If your case is urgent or the required wait is unacceptable to you, Timely Medical Alternatives can help you find a private clinic to expedite the test you need.

How is the procedure performed?

When you go for your appointment at the PET scan clinic, you will be given an injection of a very small amount of a radioactive drug. After receiving the injection, you will be asked to avoid moving or talking, to allow the drug to spread through your body.

You will be lying on a narrow table that will slide into the middle of the PET scanner (the machine is often described as looking like a large donut) during the procedure. The exam typically takes 30 to 45 minutes. Again, you will be asked to keep very still.

How should I prepare for the procedure?

You should wear comfortable, loose fitting clothing. Any specific information you will require will be given at the time of scheduling.

Who interprets the results and how do I get them?

A radiologist at the PET scan clinic will analyze the images and send a report with his or her interpretation to your doctor.