Check-up heart pet scan

I've had an ECG and exercise stress test, but my cardiologist now wants me to have a PET scan of my heart. What is this, asks MARION KERR

A positron emission tomography (PET) scan of the heart is a test that uses a radioactive substance to look for disease or reduced blood flow in the heart. The PET machine detects energy given off by the radioactive substance and changes it into three-

dimensional pictures. The images are sent to a computer, which are displayed on a monitor for the doctor or technician to read.

The heart scan can show the size, shape, position and some function of the heart, so your doctor can make sure it is working as well as it should. A PET scan can also show if the heart muscle is receiving enough blood flow, or if there is evidence of scar tissue.

This heart test is often used when other tests, such as echocardiogram (ECG) and stress ECGs, have not provided enough information.

What will the test involve?

Before the test you will not be able to eat for four to six hours. A small amount of radioactive material will be injected into a vein, usually on the inside of the elbow. You will then have to wait for about an hour as the radioactive substance travels through the blood and collects in the tissues of the heart. Once that time has elapsed, electrodes for an electrocardiogram (ECG) are placed on the chest, and you will lie on a table that slides into a tunnel in the centre of the PET scanner. You have to lie still during the scan, so that the machine can produce clear images of your heart.

Can other medical conditions affect the test?

Blood sugar or insulin levels may affect the test results in people with diabetes.

People with diabetes, who take metformin (Glucophage) or insulin injections, should tell the doctor or radiographer before receiving the injected contrast (dye) as extra precautions will have to be taken.

It is important to let your doctor and the radiologist know before the test if you have any other medical condition, are pregnant, breastfeeding or have any allergies.

You should also let them know about any prescription and over-the-counter medicines that you are taking, because they may interfere with the test.