Positron Emission Tomography, also called PET imaging or a PET scan, uses small amounts of radioactive material to diagnose or treat a variety of diseases. PET scans have become particularly useful in helping to diagnose and treat cancer.
How it works
Before you have a PET scan, a small amount of radioactive material is either injected into your vein, or you will be asked to swallow or inhale it in the form of gas. The material accumulates in the organ or area of your body where there is more chemical activity present. This energy is detected by a PET scanner or probe. The scanner is able to produce images with details on the structure and function of the organs and tissues affected by the chemical activity.
PET and PET/CT scans are used to:
- Diagnose cancer
- See if a cancer has spread
- Find out if a treatment plan, such as cancer therapy, is working
- See if a cancer has returned after treatment
- Look at blood flow to the heart muscle
- Determine the impact of a heart attack
- Identify areas of the heart muscle that surgery could help
- Evaluate brain abnormalities and other central nervous system disorders
A PET scan can provide your doctors with useful information not obtained using any other test. A PET scan provides:
- More precise information than exploratory surgery
- Information about molecular changes that signal a possible disease earlier than any other diagnostic tool
The MRI scanner
A PET scanner is a large machine with a round, doughnut shaped hole in the middle. You will lie on a narrow examination table that slides in and out of the machine or tunnel. The X-ray tube and electronic X-ray detectors will rotate around you. These detectors will record the emission of energy from the radioactive material in your body. A computer captures the data provided by the scanner and produces images your doctor will study. A technologist will operate the scanner from a separate room, but will be in constant contact with you during the entire test.
What to expect when you have a PET scan
Before your exam
Based on the type of PET scan you have, your doctor will give you specific instructions on how to prepare. If you have diabetes, you will have special instructions to follow so please make sure your doctor is aware of your condition.
- If you are claustrophobic, talk to your doctor well in advance of the exam about giving you something to help you relax.
- You may be asked not to eat anything for several hours before a whole body PET/CT scan.
- You should not drink any liquids containing sugars or calories for several hours before the scan. You'll be encouraged to drink water.
- You will need to tell the technologist about medications, vitamins or herbal supplements you are taking, and any allergies, recent illnesses or other medical conditions you may have.
- Metal objects including jewelry, eyeglasses, dentures and hairpins should be left at home or removed before the test.
- You may be asked to remove hearing aids and removable dental work.
- You may be asked to wear a gown during the exam.
Starting the exam
You will be positioned on an MRI exam table. the radioactive material will be injected through an IV or you will be asked to swallow or inhale it in the form of a gas. If it is injected, you may feel a slight cold sensation as the material moves up your arm. When swallowed, the material has little taste. When inhaled, it is not noticeable and you should feel no differently. You will be asked to remain still while the substance travels through your body.
During the exam
Total scanning time is about 30 minutes. Additional tests involving other drugs used to help spot chemical activity may be used. This may add as much as three hours to the testing time. More images may be needed for a better view of the area the doctor wants to view. You should NOT worry that an extended exam means anything abnormal was found.
After the exam
- Unless you have taken medication to relax you, you should be able to resume normal activities after your scan. The small amount of radioactive material used to identify chemical activity loses its radioactivity during the first few days after the test. You will be given instructions for drinking lots of water and taking other precautions.
- Our radiologists will conduct the exam and study your scan within the next 48 hours so that your physician can plan treatment right away.
- Your referring doctor will discuss the test results with you.