When symptoms lack a definite cause or when physicians require a deeper understanding of an organ's function, they may turn to a positron emission tomography (PET) scan. This test can detect functional changes at a cellular level, providing insights that may not show on other types of scans. It can assist in early disease detection and help your doctor monitor treatment effectiveness. In this post, we'll answer common questions about the procedure so you know what to expect at every step.
What is a PET scan?
A PET scan is a nuclear medicine imaging technique that examines organs in the body using a special doughnut-shaped camera and a radioactive substance called a tracer. A computed tomography (CT) scan is often done at the same time as a PET scan.
Your doctor may order a PET scan for a variety of reasons. Here are some ways providers use the test to understand what's going on in your body:
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Assess the brain's blood flow and metabolic activity. A PET scan can help a doctor find nervous system problems, such as:
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Huntington's disease
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Find changes in the brain that may cause epilepsy.
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Evaluate the extent of some cancers. In its early stages, cancer may appear more clearly on a PET scan than on a CT scan or MRI, particularly in cases of lymphoma or cancers of the head and neck, brain, lung, colon or prostate.
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Determine whether a growth in an organ or tissue, such as lung tissue, is likely to be cancer.
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See how advanced a cancer is and whether it has spread to another area of the body (metastasized). Both CT and PET scans are often needed to evaluate cancer.
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Help a doctor choose the best treatment for cancer or to see how well treatment is working. PET scans may also help determine whether tumor removal surgery is an option.
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Support Alzheimer's disease diagnosis when the symptoms are not apparent or when a person has dementia symptoms at a young age (usually younger than 65). This is called amyloid imaging.
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Find poor blood flow to the heart, which may indicate coronary artery disease.
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Locate damaged heart tissue, especially after a heart attack.
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Assist in selecting the most appropriate treatment, such as coronary artery bypass surgery, for an individual with heart disease.
What are the risks of a PET scan?
PET scans are typically safe, but they carry some risks. Anytime you're exposed to radiation, there's a slight chance it can damage cells or tissue. That can occur with the low-level radioactive tracer used for this test. However, the possibility of damage is very low compared with the benefits of the test.
Allergic reactions to the tracer are very rare. In some cases, mild soreness or swelling may develop at the tracer injection site. Applying a moist, warm compress to your arm can help relieve this discomfort.
How do you prepare for a PET scan?
Your care team will provide specific instructions before your scan. Here are some general guidelines to help make the process smoother:
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Tell your doctor about any medications, vitamins, supplements and herbal remedies you take. Some may increase the risk of problems during your test. Your doctor will tell you if you should stop taking any of them before the test and how soon to do it.
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Do not smoke or drink caffeine or alcohol for at least 24 hours before a PET scan.
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Refrain from engaging in any exercise or other strenuous activity for at least 48 hours before this test.
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Don't eat or drink (except water) for at least 6 hours before this test.
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If you are breastfeeding, consider pumping and storing enough milk for 1 to 2 days of feeding before the test. The radioactive tracer can transfer to your breast milk, which is harmful to the baby.
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If you get nervous in tight spaces, let your doctor know. They may prescribe medication to help you relax. If you think you'll get this medicine, be sure you have someone to take you home.
How is a PET scan done?
Before the test, a member of the care team will inject the tracer liquid into a vein in your arm. As the tracer moves through your body, it collects in specific organs or tissues. This process may take 30 to 60 minutes. During this time, you will need to avoid moving and talking as much as possible.
Next, you will lie on a table that is attached to a PET scanner. The table will slowly pass through the doughnut-shaped scanner, which detects tiny positively charged particles from the tracer. A camera inside the machine records the positrons and converts the recording into digital images. It is very important to lie still while each scan is being done.
What happens after a PET scan?
After the scan you will likely be able to go home right away and resume your usual activities. The radiologist may discuss the preliminary results of your PET scan right after the test. Complete results are typically available within 1 to 2 days.
If you are breastfeeding, avoid nursing for 1 or 2 days after this test. During this time, you can give your baby the breast milk you stored before the test or formula and discard any breast milk you pump afterward.
After the test, drink lots of fluids for the next 24 hours to help flush the tracer out of your body. Most of the tracer will exit your body through urine or stool within one day. Be sure to flush the toilet immediately after use and wash your hands thoroughly with soap and water. The amount of radiation in the tracer is minimal and does not pose a risk to those around you.
To learn more about the full range of services offered at Parkview's imaging centers, visit our website here.
Copyrighted material adapted with permission from Healthwise, Incorporated. This information does not replace the advice of a doctor.
