PET Scan

Posted September 30, 2022 by Anusha ‐ 3 min read

Positron emission tomography (PET) scans detect early signs of cancer, heart disease and brain disorders. An injectable radioactive tracer detects diseased cells.

What is a PET scan?

  • A positron emission tomography (PET) scan produces images of your organs and tissues at work.

  • The test uses a safe injectable radioactive chemical called a radiotracer and a device called a PET scanner.

  • The scanner detects diseased cells that absorb large amounts of the radiotracer, which indicates a potential health problem.

Why do healthcare providers use PET scans?

Your healthcare provider may order a PET scan to check for signs of:

  • Cancer, including breast cancer, lung cancer and thyroid cancer.

  • Coronary artery disease, heart attack or other heart problems.

  • Brain disorders, such as brain tumors, epilepsy, dementia and Alzheimer’s disease.

What does a PET scan show?

A PET scan can:

  • Measure vital functions, such as blood flow, oxygen use and blood sugar (glucose) metabolism.

  • Identify organs and tissues that aren’t working as they should.

  • Detect cancerous tumor cells to help gauge cancer spread (metastasis).

  • Evaluate how well a treatment plan is working and help your healthcare provider adjust treatment, if needed.

Process of PET scan

The following steps occur during a PET scan:

  • You receive an IV injection of a radiotracer that contains a safe amount of a radioactive drug. The most commonly used radiotracer is fluorodeoxyglucose (FDG).

  • You sit in a chair for about an hour while the radiotracer moves through your bloodstream.

  • Too much activity can send the radiotracer to areas of your body that your healthcare provider isn’t testing.

  • You won’t be able to feel the radiotracer.

  • In approximately one hour, your organs and tissues absorb the radiotracer.

  • If you are getting a PET/CT scan, you may also get an IV injection of a contrast dye.

  • This dye helps produce sharper CT images.

  • You lie on an exam table that slides in and out of the PET/CT scanner.

  • This scanner is shaped like a doughnut. The doughnut or tunnel opening is about 30 inches in diameter.

  • During the scan, you must remain still. Movement can blur the images.

  • You’ll hear buzzing and clicking sounds as the scanner takes images.

  • Tell your healthcare provider if being in an enclosed space makes you anxious.

  • You may be able to take a mild sedative to help you relax during the procedure.

  • A technologist will review the scans before you leave to ensure the images are in focus.

Risks of PET scan

The amount of radiation in the radioactive tracer is very low. It doesn’t stay in your body for long. You should drink lots of water after a PET scan to help flush the radioactive drug from your body.

In general, PET scans are safe and rarely cause problems. Exceptions include:

  • Women who are pregnant or breastfeeding should not get PET scans. The radiation may be harmful to an unborn baby and can pass to an infant in breast milk.

  • Some people have an allergic reaction to PET scan radioactive tracers or CT scan contrast dyes. Your medical team can give you medication to quickly slow and stop this response.

  • People with diabetes may not absorb the sugar in the radiotracer, which can affect scan results. Your healthcare provider will offer suggestions to modify your diet and medications before the test.

pet-scan lab-tests lab-investigations investigations positron-emission-tomography

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