What a Pet Scan is and How They Work

by GregP_WN

When you are diagnosed with cancer, one of the first few tests you will likely have is a PET Scan or Positron Emission Tomography scan. It is a nuclear medicine functional imaging technique that is used to observe metabolic processes in the body. 

Pet Scan Ct Scan Comparison

These scans produce a color image that highlight where cancer may be located in the body, making it much easier for Doctors to know where to treat, how much to treat and to stage your cancer. In the two photos above, you can see the difference in a CT Scan on the left and a PET Scan on the right.

A PET Scan is similar to a CT scan in the machine is very similar looking. One difference is that you are given an injection of a glucose solution that when circulated around your body cancer cells will take up this glucose more rapidly than the healthy cells in your body. This uptake is visible on the PET Scan and will show up on the scan as a bright color. PET scanners work by detecting the radiation given off by a substance called a radiotracer as it collects in different parts of your body. In most PET scans a radiotracer called fluorodeoxyglucose (FDG) is used, which is similar to naturally occurring glucose (a type of sugar) so your body treats it in a similar way.

Pet Scan

This injection is given to you about an hour before your scan. You will be in an exam room, given the shot or IV, then you wait for 45 to 60 minutes before the technician will come get you for the scan. You will most likely not feel anything from the injection or from the scan. If you have had a CT scan before, the scan portion of this procedure is just like that. A PET Scan will measure oxygen use, blood flow, and metabolism. The metabolism part is what makes cancerous cells show up. These type of scans are also very valuable in scans of the brain. 

Depending on the organ in the body that is being scanned the tracer may be injected, inhaled or swallowed.

Related Question About PET Scans

You may be given a PET Scan in the beginning of your diagnosis and staging, then depending on the type of cancer, it may be repeated periodically throughout your treatment to gauge how well the treatment is working. After treatment is concluded, often PET Scans will be given to check for recurrences for a period of time. 

In the animated video below, you will see how a PET Scan works

The risk to you from having a PET Scan is minimal compared to the benefits and advantages of having one. However, you are given radioactive tracer solution, but the radiation level is too low to harm any body functions, and since it is attached to glucose, your body can eliminate the radiation quickly. Radiation is not safe for someone who is pregnant. If you are pregnant or think you may be, or if you are breastfeeding you should not have the scan.

You will be told not to eat or drink anything prior to the scan, up to 8 hours before. You should heed this warning, if you arrive for the scan and you have eaten or had anything to drink other than a small amount of water, you will be sent home without having the scan. Since the scan uses glucose to mark spots where cancer may be, any food or drink will disturb the actions of the glucose in the injections and give false readings. 

If you have never had a CT or PET Scan before, it can be a daunting procedure. You are placed on a skinny table and asked to lie perfectly still. The table will slide you through a large circle, or doughnut looking device that actually takes the images. During the scan you will be asked to hold your breath at times, the table will move slowly at times while the machine is taking several images. The machine will make some buzzing sounds as it works. If you have ever had an MRI, it is NOT as loud as that machine.

A PET Scan is a very valuable tool for diagnosing and treating cancer. Don't be afraid of them, the benefit far outways any negatives of having the test. For more information and to get first-hand experience descriptions of having it done, drop by the Pet Scan experience pages at WhatNext. There are hundreds of descriptions listed from people that have had them. 

Have you had a PET Scan done? Comment below on your experience and let others know if it was simple or harsh, and what side effects or problems, if any, you had during your scan. 

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