What is a PET-CT?

A PET-CT combines 2 types of imaging exams to find changes in your body at different stages of a disease such as cancer:
  • PET (positron emission tomography) looks at how the cells in your body process a radioactive tracer that you drink, inhale, or have injected.
  • CT (computed tomography) uses X-ray technology to produce detailed images. Learn More

A Note About Tracers

We use the lowest dose of radioactive tracer to get the highest quality images. The radiation risk is very low compared to potential benefits.

How to Prepare for a PET-CT

A PET-CT appointment lasts about two to three hours. The actual scan lasts about 30 to 45 minutes. Adequate preparation is important so we don't have to reschedule your appointment. 
  • When to Arrive - We want to help you prepare for your exam with plenty of time. Please arrive 30 minutes before your appointment. You may need to fill out some paperwork.
  • Eating and Drinking - Do not eat or drink anything for at least six hours before the exam, except for plain water (no additives or flavors). Avoid candies, gum, cough drops, cough syrups or drinks other than plain water.
  • Medicines - If your doctor has told you to take your regular medicine, take it with plenty of water. You can drink only plain water prior to the scan.
  • Diabetes - Patients with diabetes have special instructions to help control blood sugar. Your blood sugar should not be more than 250 mg/dl on the day of your exam. 

    Do not eat or drink anything for at least four hours before your appointment time, except for plain water, unless otherwise instructed.

    Take your oral diabetic medication as usual but stop any injectable insulin at least four hours before your appointment time.

    If you use an insulin pump, talk to your doctor before your appointment to find out when to stop using it. Our recommendation is for patients to turn the pump off four hours before to the scheduled appointment time. If your blood glucose level is greater than 250 mg/dl, you can keep the pump on the night/basal setting until after the scan. Once the scan is completed, you can adjust the pump as needed.
  • Contrast - Patients may receive IV contrast during a PET-CT exam. The need for contrast is typically indicated by your doctor. We carefully assess your risk before giving you contrast. We will give you more details at your appointment.
  • Claustrophobia - Ask your doctor about medicine to help you relax during your exam if you have a fear of small spaces. We don't have any in our department that we can give you.
  • Clothing - If possible, please wear loose, comfortable clothing without metal (zippers, underwire bras, etc). Metal can blur the images. We may ask you to change into hospital attire.
  • Pregnant or Breastfeeding - Please tell your doctor and your technologist if you might be pregnant or if you are breastfeeding. 
  • Children - Please don’t bring kids or pregnant people with you to your appointment.
  • Valuables - Please leave your valuables at home. You can keep your things with you during the exam.