Understanding a PET Scan

If you or a loved one has been referred for a comprehensive PET scan, we encourage you to read the frequently asked questions below. They can help you understand the purpose of the test and make informed decisions about your healthcare.

What Is a PET Scan?

A nuclear PET scan is a medical imaging technique that uses a small amount of radioactive material to show how tissues and organs function in the body.

You might need a positron emission tomography (PET) scan for many reasons. Your primary care doctor may want to evaluate abnormalities, injuries, or illnesses in your

  • Brain
  • Breasts
  • Cervix
  • Esophagus
  • Heart
  • Lungs
  • Prostate
  • Rectum
  • And more

What Does a PET Scan Show?

A PET scan shows the metabolic activity of tissues and organs in the body. It provides essential information about how cells function and use energy.

PET imaging results show areas of increased, decreased, or abnormal metabolic activity, which help your doctor diagnose several conditions.

Are PET Scans Dangerous?

Any medical procedure does come with some risks. However, the benefits of having a PET scan far outweigh its risks. Here are some risks to consider

  • Radiation exposure
    Those undergoing a PET scan will be exposed to a small amount of ionizing radiation from the radioactive tracer. This dose is generally considered safe for adults and is carefully controlled and monitored throughout the test to minimize potential risks.
  • Allergic reaction
    Though rare, some may have an allergic reaction to the radioactive tracer. To avoid this complication, please inform your healthcare provider about any known allergies or adverse reactions to medications.
  • Pregnant and breastfeeding women
    PET scans are generally not recommended for pregnant women (especially during the first trimester) and women who are breastfeeding due to radiation exposure.

How Long Does a PET Scan Take?

The duration of a PET scan appointment can vary (due to preparations), but the actual scanning process typically lasts 30-45 minutes.

How Does a PET Scan Work?

A PET scan procedure involves several steps, including

  • Preparation—to ensure your body is ready for the radioactive tracer
  • Radioactive tracer injection—to help the PET scan identify areas of high or low metabolic activity
  • Uptake phase or waiting period—to allow the tracer to circulate throughout your body and be absorbed by tissues (typically 60-90 minutes)
  • Scanning—to identify areas highlighted by the tracer
  • Image reconstruction or PET scan results—to help identify areas of abnormal function

What Are the Types of PET Scans?

There are several positron emission tomography scans, depending on the area of the body being examined. Here are some standard PET scans 

  • Whole body
  • Brain
  • Cardiac
  • PET/CT
  • PET/MRI
  • Breast
  • Prostate
  • Gastrointestinal

What Is a PET Scan Used to Diagnose?

A PET scan is used to diagnose and monitor several medical conditions, illnesses, and chronic diseases, especially those related to metabolic activity. They are commonly used to diagnose

  • Cancer
  • Alzheimer’s disease
  • Parkinson’s disease
  • Epilepsy
  • Brain tumors
  • Heart conditions
  • Bone disorders
  • Lung diseases

A PET scan for cancer is useful where the primary location is unknown. It helps pinpoint the primary site, aiding healthcare providers in diagnosis and treatment planning.

Does a PET Scan Show Cancer?

Yes, a PET scan can show the presence of cancer tumors as well as their location, size, and metabolic activity.

This means that PET scans can diagnose, stage, monitor, and treat several types of cancer. They can also be combined with MRIs (Magnetic Resonance Imaging) and CTs (Computed Tomography) to deliver an even more comprehensive assessment.

What Is the Difference Between a Normal vs. Abnormal PET Scan?

A normal PET scan means no abnormal activity was detected within the imaged cells and tissues. Abnormal results, however, show areas of increased or decreased uptake of the radioactive tracer material, indicating the presence of abnormal growths (benign or malignant tumors).

PET Scan Preparation Tips

Proper PET scan prep is crucial for ensuring accurate results. Here are general guidelines, but check with your healthcare provider for specific instructions.

  • A typical PET scan prep diet
    Typically, patients are required to avoid eating or drinking anything (including mints and gum) for a set time before the scan. Water is often allowed, but check with your healthcare provider to be certain.
    • What to eat before a PET scan
      While many healthcare providers recommend fasting before a PET scan, especially for abdominal scans, there may be some exceptions. Please confirm what you can eat before your PET scan.
    • Are there certain medications to avoid before a PET scan?
      Certain medications can interfere with a PET scan. Be sure to inform your healthcare provider of all medication you take, including prescription and over-the-counter drugs and supplements, to ensure they will not interfere with PET imaging. This may include medicines that include caffeine or medications for
      • Diabetes
      • Heart
      • Blood sugar
      • Muscular pain
  • Can you shower before a PET scan?
    Yes, you can shower before a PET scan. It is important, however, to avoid wearing lotions, creams, perfume, deodorant, or anything that could leave a residue behind. We also recommend wearing loose, comfortable clothing on the day of the scan to ensure an easy process.
  • Why rest before a PET scan?
    Resting before a PET scan can help improve its overall quality because it helps reduce motion artifacts (e.g., voluntary or involuntary patient movements), contributing to clearer and more reliable images. Here are three things that resting before a PET scan can do
    • Stabilize metabolic activity
    • Reduce the risk of false positives
    • Enhance tracer absorption and distribution

Precautions After PET Scan

A PET scan is a non-invasive imaging procedure. However, it does involve exposure to ionizing radiation. For this reason, it is important to follow instructions from your healthcare provider. Here are some general precautions following a PET scan

  • Hydrate and void to help eliminate the radioactive tracer from your body
  • Rest for a short period following the procedure
  • Limit close contact with pregnant women and children to minimize their radiation exposure

After PET Scan, How Long Are You Radioactive?

You are radioactive from a PET scan for a very short period. In most cases, most of the radioactive material is eliminated from the body within a few hours.

Can You Drive After a PET Scan?

In most cases, yes. However, if your PET scan requires sedation or medication, your healthcare provider will give you specific instructions regarding driving.

If unsure, we recommend having a friend, family member, taxi, or public transportation drive you.

How Long Does It Take to Get PET Scan Results?

Once your scan is complete, it will be reviewed by a board-certified imaging specialist for evaluation and interpretation. Once complete, your primary care doctor will receive a complete detailed report of their findings.

However, it’s important to ask your healthcare provider to find out when you can expect your results.

How Many PET Scans Can You Have in a Year?

The number of PET scans you can safely have in a year depends on several factors. If you are concerned about the number of PET scans recommended for your unique medical situation, discussing them with your healthcare provider is essential.

They can provide information specific to your medical history and help you make informed decisions about your care.