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PET/CT Imaging (Molecular Imaging): The Added Advantage
What is PET/CT?
Positron emission tomography (PET)/Computed Tomography (CT) is an extremely accurate imaging scan that helps physicians determine the exact size, shape, location and type of tumors or lesions in the body. Using a small amount of radioactive material, called a “tracer,” PET imaging, also called a PET scan, creates images of the body that shows how the tracer has collected in different parts of the body.
Why is it used?
A PET scan provides accurate information that can be used to decide if a tumor is cancerous, which a CT scan cannot do. A CT scan provides detailed information about the location, size, and shape of various lesions. The combined PET/CT scanner merges these images together so your doctor can more effectively diagnose and treat your illness.
PET/CT scans can also be used to tell if a patient has Alzheimer’s, versus other memory-related conditions, as well as to help manage the treatment of stroke, brain tumors and epileptic seizures.
How does it work?
You will be given an IV that contains the tracer. For best results we ask that you sit quietly for 45 to 60 minutes until you are taken in to be scanned. Once scanning begins, exams usually takes 35 to45 minutes. Exams for melanoma patients may last up to an hour and ten minutes.
Different colors or degrees of brightness on a PET image represent how different parts of the body are working. For example, healthy tissue accumulates some of the tracer, which will show up on the PET images. But cancerous tissue accumulates more of the tracer and appears brighter than normal tissue.
Each tracer that is used for a PET scan is ordered specifically for you the day before your scheduled test. It is important for you to receive the tracer at the scheduled time because the tracer is only effective for a very short period of time.
How does it feel?
The radioactive tracer will produce no side effects and you will not be able to feel it in your body. You will be asked to remain still for the entire examination, with your arms above your head while laying down, which may be uncomfortable. Patients who are claustrophobic may feel some anxiety while positioned in the scanner.
How to prepare
- Prepare a list of any prescription or nonprescription medicines you are currently taking; a brief medical history; and any recent treatments you have had, such as chemotherapy, radiation therapy or surgery.
- Do not eat or drink fluids - except water - starting at midnight on the evening prior to your test. If you are diabetic, please call MultiCare's Nuclear Medicine staff at 253-403-1642 (Tacoma General and Mary Bridge Children's Hospital) or 253-697-4880 (Good Samaritan Hospital) to discuss dietary restrictions.
- Do not exercise or do heavy physical activity for at least 24 hours before the scan.
- The day of the scan, patients should wear warm comfortable clothing that does not have metal buttons or zippers and they should leave their jewelry at home.
- Do not take your diabetic medication the morning of the test. You may take all other medications as usual. All diabetic medication should be brought with you to your test and you should also bring your home glucometer (diabetic patients should ask for any specific diet guidelines to control glucose levels during the day of the test).
- Confirm your appointment 24 hours prior to your test. If a MultiCare Nuclear Medicine staff member does not call you prior to the test, please contact Tacoma General Hospital at 253-403-1642, or for appointments at Good Samaritan Hospital, call 253-697-4880, to confirm.
- Your testing will take between one and a half and two hours total, so please plan accordingly. If you are unable to keep your appointment for any reason, please notify us 24 to 48 hours in advance by calling 253-403-1642 (Tacoma General and Mary Bridge Children's Hospital) or 253-697-4880 (Good Samaritan Hospital).
After the scan
You may go home when the study is finished and resume your regular diet and medication. Test results will be forwarded to your physician within 24 to 48 hours.
Drink lots of water and urinate frequently after your scan to make sure that the tracer flushes completely out of your body.
There is always a slight risk of damage to cells or tissue from being exposed to any radiation, including the low level of radiation released by the radioactive tracer used for this test.
Some soreness or swelling may develop at the injection site, but this is rare. This can usually be treated by applying moist, warm compresses to your arm.