PET/CT

What is a PET/CT?

PET/CT combines two imaging tools in one exam. PET (positron emission tomography) shows how cells in your body are working on a metabolic level. CT shows detailed anatomy. Combining the two on the same scanner lets your radiologist see exactly where unusual activity is happening.

PET works because cancer cells, infections, and certain tissues use sugar differently than normal cells. We give you a tiny amount of a sugar-based radiotracer that lights up areas of unusual activity on the images.

What it's used for

• Cancer detection, staging, and monitoring response to treatment
• Finding hidden tumors or recurrence after treatment
• Distinguishing scar tissue from active cancer
• Evaluating heart muscle viability before bypass surgery
• Assessing certain neurologic conditions and infections

How to prepare

Most PET/CT exams use FDG, a sugar-based radiotracer:

• Don't eat for 4 to 6 hours beforehand — only water and your prescribed medications
• Avoid sugary drinks, gum, and mints
• If you have diabetes, we'll give you specific instructions about insulin and food timing
• Avoid heavy exercise for 24 hours beforehand — muscles use sugar and can interfere with the images
• Keep warm before and during the exam (cold activates brown fat that lights up on PET)
• Wear comfortable clothes without metal

What to expect during your exam

After your blood sugar is checked, the radiotracer is injected through a small IV. You'll then rest quietly for about 60 minutes while the tracer travels through your body and settles into the right places. Reading or screen time is discouraged during this rest period — we want your brain and muscles to stay quiet.

Then you'll lie still on a padded table that moves slowly through a ring-shaped scanner for 20 to 40 minutes. The exam is painless. Plan on being at the imaging center for about 2 to 3 hours total.

Is it safe?

PET/CT uses small amounts of radiation from both the radiotracer and the CT portion of the exam. The radiotracer breaks down naturally and clears from your body within a day. The information PET/CT provides is often impossible to get any other way, and we use the lowest dose that yields a diagnostic study.

If you are pregnant, breastfeeding, or might be pregnant, tell us before the exam.

After your exam

Drink plenty of water for the rest of the day to help flush the tracer from your body. As a precaution, avoid close, prolonged contact with infants and pregnant women for the rest of the day. You can resume normal activities and a normal diet. Your report typically reaches your physician within 24 hours.