Understanding the Functions of PET/CT
A PET (Positron Emission Tomography) or CT (Computed Tomography) test can help locate tumors or cancer cells so your doctor can make a diagnosis and refer you to the Schwab Family Cancer Center at WMHS for further treatment.
This piece of equipment combines the functional information obtained from a PET scan with anatomical details from the CT scan into a single exam. The purpose of a PET scan is to detect changes in how cells function. These functional cell-level changes often occur before any physical changes are noticeable from cancer. By using a PET scan, a physician can make an early cancer diagnosis and get treatment started right away.
A CT scan combines X-rays with computers to enable the radiologist to see what’s happening inside of your body. Not only is a CT scan non-invasive, it quickly produces two-dimensional (2D) photos of your body anatomy for the radiologist’s reference. Later, the radiologist can convert the 2D photos into three-dimensional (3D) photos for a more in-depth evaluation.
When combining the metabolic cell activity provided by the PET and the anatomical view provided by the CT, the doctor can see metabolic changes as they occur within the proper anatomical context. This is only possible with combined PET/CT equipment.
Importance of a Combined PET/CT Exam
The PET/CT scan reduces diagnosis time as well as helps the doctor plan for treatment after forming an official diagnosis. With the results from the PET/CT exam, the doctor can predict the most likely outcomes of specific therapies. It also enables the doctor to monitor your progress during treatment and make adjustments as necessary.
What to Expect Before, During, and After a PET/CT Scan
Prior to receiving a PET/CT scan:
- Do not eat, drink, or chew gum for six hours before the exam because it could cause an incorrect reading
- If medications must be taken, use the minimum amount of plain water necessary to swallow them
- If medications must be taken with food, eat only a few soda crackers if it’s within six hours of the scheduled exam
- Please let the team know if you have diabetes
- Please let the team know if you have a fever
- Please inform the technician if you are pregnant, might be pregnant, or are breastfeeding
- Provide us with at least 24-hour notice if the test needs to be canceled or rescheduled since drugs are ordered for you specifically
During the PET/CT scan:
Once you arrive for a PET/CT scan, a nurse will review your medical history along with reports from past exams. You will then receive a small radiopharmaceutical injection to start the PET part of the exam and will rest for about 30 minutes as the radiopharmaceutical works its way throughout your body. This is a safe method of testing. The radiopharmaceutical loses its radioactive powers in less than two hours and within six hours of the exam, there are no or only trace amounts of radioactive properties left in your body. However, please wait up to eight hours before initiating close contact with others. This is especially important for pregnant women, infants, and children.
After 30 minutes of resting, you will lay on a padded table that moves slowly through a tube-shaped scanner. As it moves, the PET/CT collects details it needs to produce a diagnostic image. Because movement can change test results, you need to lie extremely still on the comfortable table. The technician will ask you to hold your breath for a couple of seconds during the CT scan to help control body movements. It’s common to hear a humming noise during the scan and will likely feel the table moving as the equipment captures images from different parts of the body. It typically takes 30 to 45 minutes for the entire exam, so plan to remain at WMHS for two to three hours.
Post PET/CT Scan
When the exam is over, you are free to leave immediately. The WMHS team will start preparing the results of the exam right away, and your physician will contact you directly to discuss it.