Positron Emission Tomography

Positron emission tomography is a form of radionuclide imaging that uses a special type of detector called a photomultiplier-scintillator detector to find the gamma rays. With positron emission tomography, tracers are also injected into the patient. The tracer are attracted to a natural body compound, usually glucose. Sometimes, however, the tracers attach to water or ammonia. The tracer is absorbed by the body, and then it settles in the affected areas of the heart or the blood vessels and is detected by the PET scanner.
The image produced by the scanner is displayed in different colors, each with varying degrees of brightness. The colors and brightness help the doctor or technician identify which areas of the body are damaged or abnormal. In most cases, this is done because the damaged areas will use up more glucose than normal, so it absorbs more of the tracer and is then displayed brighter on
They are used in diagnosing heart disease to evaluate the flow of blood to the heart and throughout the body, as well as determine whether there is a presence of coronary heart disease. It can also detect whether a person has had a previous heart attack based on damage done to the heart muscle.

Positron emission tomography is often used in conjunction with exercise stress tests to determine how efficiently the blood flows and the heart pumps in response to physical exertion.

What To Expect
If your doctor decides he would like you to undergo a PET scan, you will go to the hospital for an outpatient procedure conducted in the radiology department. A PET scan generally takes between two and three hours. First, you will change into a hospital gown and lie on a flat table, similar to the ones used in a traditional chest x-ray.

The radioactive tracer is injected into the veins through an IV. In addition, electrodes will be affixed to various parts of the body being studied, usually the chest. The tracer can take up to 30 minutes to be properly absorbed throughout the body.

The PET scanner then rotates around the table you are situated on. The tracer accumulates in areas of the heart that have been damaged, or in blood vessels that have narrowed due to plaque build-up. The scans then produce 3-d images onto a monitor. You will be required to hold still while the test is being performed and the images are being taken.

Is it Harmful?
A PET scan is considered a very safe and effective tool in diagnosing heart disease. Although radionuclide imaging utilizes radioactive material in the tracers, they are not considered dangerous to people. In fact, the amount of radioactive material used in the tracers is less than in a traditional x-ray. The tracer is easily flushed out of the system by drinking fluids.

However, even though it is a small amount, the radioactive material in the tracer should be avoided by women who are pregnant, might be pregnant, or are breastfeeding as there is a potential to harm a developing fetus. For this reason, doctors and technicians should be informed if you are pregnant, breastfeeding, or are potentially pregnant.

A doctor may order a PET scan to assist in diagnosing a variety of heart diseases and abnormalities. The PET scan is a painless, relatively simple procedure that provides accurate results. Once the results and received and analyzed, the doctor can help determine the best course of action to take from there.