At Mount Sinai, we use nuclear medicine imaging called positron emission testing (PET) scans for diagnosis. This noninvasive and painless scan helps us develop a treatment plan. PET scans use a small amount of radioactive tracer into your vein. Depending on the exam, you get the tracer through injection, inhaling, or ingesting. Tracers give off radiation in the form of gamma rays, which a special camera (called a gamma camera) uses to create images of your internal organs. The gamma camera does not give off radiation. The test is especially helpful in evaluating:
- Cardiovascular system
- Central nervous system
- Endocrine system
- Gastrointestinal system
- Genitourinary system
- Musculoskeletal system
- Respiratory system
Sometimes we combine PET scans with other types of scans, such as PET/CT and PET/FDG scans.
- A PET/CT combines two types of scans into one. The CT (computed tomography) scan shows the anatomical structures of organs, bones, and tissues in greater detail than regular X-rays. It produces images and shows any abnormal cell activity.
- PET FDG scans can show the abnormal cell activity even when an abnormal growth is not yet visible on a CT scan. They combine fluorodeoxyglucose (FDG), a type of radiotracer, with PET scans.
To prepare for a PET/CT scan, do not exercise, chew gum, or perform any strenuous physical activity the day before. Wear comfortable clothing and leave your jewelry at home. Depending on the type of test, we may ask you to follow a special diet or to avoid eating for four to six hours before the scan. You can generally drink water and take medications up until the time for the exam. We will contact you a day or two before the exam to go over the procedure details.
Bring this information to the PET scan:
- Any medications you are taking
- Bone marrow stimulant medications taken, including date last received
- Chemotherapy treatments, including date of the last therapy
- History of contrast reaction
- Recent imaging studies (CT, PET/CT, MRI, etc.), including where and when performed
- Other types of cancer treatments received
- Previous surgeries or other major medical procedures performed, including dates
- Radiation therapy treatments, including dates, and area of body treated
Please let your technologist know beforehand whether you:
- Are afraid of small spaces (claustrophobic)
- Have had any problems with a prior nuclear medicine procedure
- Are pregnant or breastfeeding
- Have diabetes
If you are claustrophobic, your doctor may give you a mild sedative to take right before the scan. The technologist can keep in constant contact with you during the examination. Different procedures take different amounts of time. If you have any questions, ask the scheduler when you make your appointment.
During the Scan. PET scans use a machine that resembles a large donut. You lie on a table that slides in and out of the center of the machine. Your technologist will be in an adjoining room the entire time. You can communicate by intercom. Your technologist may ask you to hold your breath for a minute or two so the images do not come back blurry. PET scans typically take about a half hour. You shouldn’t feel any pain during this process.
We may need you to wait after the procedure while the doctor reviews the scans. This does not mean there is a problem, just that we need a clearer or additional picture. Your doctor will get the results of the scans and discuss them with you. To request a copy of your images or your report, call the Radiology Medical Records at 212-241-3146.
After the Scan. There may still be a bit of radioactive material in your body after the exam. Try not to spend a lot of time near pregnant women or small children for 20 hours. After the exam, drink plenty of fluids to flush the tracer out of your body. You may resume your normal diet. If you need to travel, let us know. Depending on the scan, there may be very small amounts of radiation in your body that a very sensitive detector at an airport, ferry port, and train station can detect. We can give you a card identifying the procedure done and the length of time that sensitive detectors can detect any radiation.