What To Expect During a Positron Emission Tomography (PET) Scan for Lung Cancer

A positron emission tomography (PET) scan is an imaging test that uses a small amount of radioactive tracer to measure the rate of glucose (sugar) that the cells in your lung use. Cancer cells use sugar differently than healthy cells, so this test can help detect the presence of cancer cells in your lungs.

A radiologist (a doctor specializing in imaging scans) performs the test with a special machine. Your results serve as an important diagnostic for lung cancer testing.

Purpose of PET Scan for Lung Cancer

Your healthcare provider can recommend a lung cancer PET scan for several reasons. The most common include the following:

• See if cancer cells are present in your lungs
• Detect how far your cancer has spread after you receive a diagnosis
• Understand how effectively cancer treatment is working
• Learn exactly where cancer cells are present, which can help determine what type of lung cancer you have

In some cases, your healthcare team can also recommend other imaging tests, such as a magnetic resonance imaging (MRI) or computed tomography (CT) scan, to get a more holistic picture of your condition.

How To Prepare for a PET Scan

Getting tested for cancer can be a worrisome experience. However, knowing how to prepare may help ease any anxiety you might be experiencing. Your healthcare provider will likely give you a specific list of instructions to follow, but these are some things to keep in mind before heading into your appointment:

• Avoid eating or drinking for at least eight hours before the exam
• Let your healthcare provider know about any medications or supplements you're taking
• Tell your radiologist if you are pregnant, breastfeeding, or have any allergies or illnesses
• Do not wear metal items (such as jewelry or sunglasses) to your test
• Remove metal objects from your body, such as your keys or phone before starting the exam
• Bring your insurance card and photo ID to your appointment

Tell the provider if you are diabetic. Because the scan evaluates glucose (sugar) uptake, uncontrolled diabetes with high blood sugar levels will lead to an ineffective scan. Ask what your goal blood sugar should be on the test day and if there are any special diet instructions if you are diabetic.

When you arrive at your appointment, you'll also need to change out of your clothing into a hospital gown. It may help to wear easy-to-remove items to ensure this process goes smoothly. Before the exam is also a good time to ask your healthcare team any questions you have about the PET scan so you know what to expect during the test.

How Does It Work?

Once you've changed into your hospital gown and have signed any paperwork your provider needs, you're ready to begin the test. Here's what you can expect during and after the test.

During the Test

A healthcare provider will take you to the PET scan room, where you will lie on the exam table and connect to the PET scan machine. Your radiologist will then inject a radioactive tracer into your bloodstream through an intravenous (IV) line into a vein in your arm. This helps your body use the tracer as sugar in your cells, which emits a form of energy called gamma rays. You'll need to stay on the table for 30-60 minutes as your body absorbs the tracer.

After your body absorbs the tracer, the exam table will slowly move into the large central hole of the doughnut-shaped PET machine. A healthcare provider controls the exam table and overall scanning process from a room just outside the room you're in. They will also have the capability to hear you and talk to you during the test should you have questions or concerns.

The scan will take about 20-30 minutes to complete, and it's important to lay still as the testing continues. As the PET machine moves slowly over your body, it detects the gamma rays from your cells and sends that information to a computer in the control room for your healthcare provider to examine. The computer connected to the PET scan machine also creates an image to view signs of radioactivity in your lungs.

After the Test

After the scan is complete, your healthcare provider may ask you to remain on the table for a few minutes longer to determine if you need any additional scans.

After they examine the images the computer created and notify you your test is complete, the exam table will slowly back out of the machine. Your provider will then remove the IV from your arm and ask you to change back into your regular clothing.

This exam is an outpatient procedure, which means that you can go home on the same day. Unless you are given special instructions after the test, you can typically resume your everyday activities as is.

Your exam results will be available relatively quickly, taking anywhere from 1-3 days. Your healthcare provider will either call you or send you a message via an online portal to discuss your results or schedule a follow-up appointment.

Risks and Precautions

PET scans are generally safe. While the exam uses some radiation, it's typically in small and undetectable amounts and doesn't pose any health risks. The radiation will leave your body between two and 10 hours. Drinking plenty of water also helps remove the radiation from your body through your urine.

However, there are some side effects to be aware of, such as:

• Slight pain near the vein the IV was inserted into
• Discomfort while lying down on the exam table
• Minor risk of an allergic reaction to the radioactive tracer

If you develop a fever or a severe reaction to the radioactive tracer, it's essential to tell your healthcare provider about your symptoms immediately. You should also tell your healthcare team if you're trying to conceive, pregnant, or recently gave birth, as the radiation can be harmful to your baby and affect your breastmilk.

Results

Your results will be available within a few days after completing your exam. The PET scanner detects the gamma radiation from the tracer. Any areas of your lungs showing clusters of radiation show up as bright areas on your scan.

A radiologist (a doctor who specializes in medical imaging) analyzes the image created by the computer from your scan and sends a report to your healthcare provider who ordered your PET scan. Your healthcare provider will then contact you about your results.

Interpreting Your Results

You can receive three possible results: positive, negative, or inconclusive. If there are no bright areas on your PET scan image, your test is negative. This means that your radiologist did not detect any concerning areas or cancer cells.

Your PET scan can return a positive result if there are any clusters of bright spots on your image. The increased activity of cancer cells increases the uptake of the radioactive sugar compared with normal cells, making them brighter on your scan than normal cells. Receiving a positive test result can either determine that you have lung cancer or prompt your provider to order additional diagnostics to confirm the initial findings from your PET scan.

Some people receive an inconclusive test result, which means that your radiologist did not find any cancer cells present in your lungs but also cannot rule out lung cancer completely. When this happens, your provider will order additional tests. Imaging tests do not always pick up small tumors, so a second imaging test is done to prevent false negatives or positives. This can help you and your provider understand the overall status of your condition and determine next steps.

A Quick Review

A PET scan is an imaging technique often used in lung cancer testing to help detect the presence of cancer cells in your lungs.

The test involves injecting a radioactive tracer into your body which helps identify whether cancer cells show up on the PET scan technology. The test then generates images of your lungs, which helps your radiologist diagnose you for lung cancer or recommend additional testing.