A positron emission tomography (PET) scan is an imaging test that can help reveal the metabolic or biochemical function of your tissues and organs. The PET scan uses a radioactive drug (tracer) to show both normal and abnormal metabolic activity. A PET scan can often detect the abnormal metabolism of the tracer in diseases before the disease shows up on other imaging tests, such as computerized tomography (CT).
The tracer is most often injected into a vein within your hand or arm. The tracer will then collect into areas of your body that have higher levels of metabolic or biochemical activity, which often pinpoints the location of the disease.
A PET scan is an effective way to help identify a variety of conditions, including cancer, heart disease and brain disorders. Your doctor can use this information to help diagnose, monitor or treat your condition.
Cancer
Cancer cells show up as bright spots on PET scans because they have a higher metabolic rate than do normal cells. PET scans may be useful in:
PET scans must be interpreted carefully because noncancerous conditions can look like cancer, and some cancers do not appear on PET scans. Many types of solid tumors can be detected by PET-CT including:
Heart disease
PET scans can reveal areas of decreased blood flow in the heart. This information can help you and your doctor decide, for example, whether you might benefit from a procedure to open clogged heart arteries (angioplasty) or coronary artery bypass surgery.
Brain disorders
PET scans of the brain for Alzheimer's
PET scans can be used to evaluate certain brain disorders, such as tumors, Alzheimer's disease and seizures.
Risks
For your PET scan, a radioactive drug (tracer) will be injected into a vein. Because the amount of radiation you're exposed to in the tracer is small, the risk of negative effects from the radiation is low. But the tracer might:
Talk with your doctor about the benefits and risks of a PET scan.
Tell your doctor:
Your doctor will give you detailed instructions on how to prepare for your scan. A general rule is to avoid strenuous exercise for a couple of days before the study and to stop eating four hours before the scan.
During the exam
The PET-CT is a large machine that looks a little like a giant doughnut standing upright, similar to CT or MRI scanners.
From start to finish, the procedure takes about two hours to complete. When you arrive for your scan, you may be asked to:
A member of your health care team injects the radioactive drug (tracer) into a vein in your arm or hand. You may briefly feel a cold sensation moving up your arm. You rest and remain silent in a reclining chair for 30 to 60 minutes while the tracer is absorbed by your body.
When you are ready, you lie on a narrow, padded table that slides into the part of the scanner that looks like a doughnut hole. During the scan you must be very still so that the images aren't blurred. It takes about 30 minutes to complete a PET-CT scan.
The test is painless. If you're afraid of enclosed spaces, you may feel some anxiety while in the scanner. Be sure to tell your doctor about any anxiety causing you discomfort. He or she may give you a drug to help you relax.
After the exam
After the test you can carry on with your day as usual, unless your doctor tells you otherwise. You'll need to drink plenty of fluids to help flush the tracer from your body.
Results
Brighton’s board-certified radiologist studies your PETCT and provides the results to your doctor.