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Positron emission tomography (PET) scans

A positron emission tomography (PET) scan is used to look at organs inside of your body, such as your heart and brain. It can also look at body tissues, including lymph nodes.

PET scans show how your organs or tissues are functioning chemically. This helps your doctor diagnose problems and develop a treatment plan that’s customized specifically for you.

  • Preparing for Your PET Scan

    You’ll be given instructions detailing how to prepare for your PET scan. It’s important to follow them exactly. If you don’t, your scan might not be accurate. In that case, your scan might need to be repeated or even rescheduled. 

    You should not: 

    • eat, drink anything other than plain water, chew gum or use mints at least six (6) hours before your scan.
    • do any intense physical activities 24 hours before your scan.

    You should:

    • wear comfortable clothes to your PET scan appointment. 

    If you’re having a cardiac PET scan and/or if you’re diabetic, you might be given additional instructions to follow. Speak with your healthcare provider before your scan to confirm how you need to prepare.

  • Arriving for Your Appointment

    You’ll need to arrive at least 30 minutes before your appointment so that you can check in and complete paperwork. If you’ve had previous PET scans done at facilities outside of the Vanderbilt Health system, bring copies of them with you. 

  • What Happens During Your PET Scan

    The first thing that will happen during your PET scan is the insertion of an IV (intravenous line) into your arm. It will deliver a safe, radioactive substance — called a tracer — into your vein.

    While your body absorbs the tracer, you’ll rest in a reclining chair for about an hour.

    Once the tracer is absorbed, your PET scan can begin. You’ll need to lie completely still on the cushioned table of the scanning machine for 30 to 45 minutes. This table will slide into a large tunnel-shaped scanner. Only move when you’re asked to do so.

    If you’re claustrophobic (afraid of enclosed spaces), tell your doctor or nurse. If possible, make them aware of this before you arrive for your PET scan. In such cases, you might be given a sedative to help you relax. 

    Most PET scans take 1½ to 2 hours. You should plan for your entire visit — from check in to check out — to be at least 2½ hours. In some cases, it might take longer. 

  • What Happens After Your PET Scan

    If you were given a sedative during your PET scan, you must have a friend or family member available to drive you home and care for you for the 24 hours following your exam.

    During the 24 hours after your PET scan, drink plenty of clear fluids to help flush the radioactive material out of your body.