What is a PET Scan?
PET stands for Positron Emission Tomography. A PET scan is a diagnostic test that allows physicians to determine the body's cellular metabolic activity, which is useful in detecting:
- Cancer - breast, lung, colorectal, lymphoma, melanoma, head and neck cancers
- Brain disorders - Alzheimer's disease, Parkinson's disease and epilepsy
- Heart disease - such as coronary artery disease
What PET Sees
PET is a procedure that is able to detect small cancerous tumors and also subtle changes in the brain and heart. Prior to changes in structure that normally would show up on a CT or MRI scan, a PET scan can reveal metabolic changes in the body. This enables physicians to treat diseases earlier and more accurately than by waiting for the results from other imaging techniques.
PET shows the staging of many types of cancers. For patients whose disease is already diagnosed, it is important to determine if the cancer has spread to other parts of the body, so treatment can be started. PET can search the entire body for cancer in a single exam, revealing the primary site as well as any new areas of cancer growth.
PET also shows whether a tumor is benign or malignant. Reports in scientific literature find that PET correctly identifies detected lesions 95 percent of the time. Once a diagnosis has been made, PET can show the effectiveness of therapy. It is an excellent way to monitor progress and test for recurrent disease.
What to Expect
A PET scan is relatively painless and has no side effects. After fasting four to six hours, you will receive an injection of a trace amount of radioactive sugar, which distributes throughout the body.
About 60 to 90 minutes after the injection, you will empty your bladder, lie down on the scanning bed, which will move incrementally through the donut-shaped hole of the PET scanner.
The scan will take approximately 20 to 60 minutes, depending on the type of scan you are having and the type of scanner being used. A nuclear medicine technologist will perform the test. The results are then interpreted by a trained nuclear medicine physician or radiologist and sent to your referring physician.
If you are diabetic, you should take your insulin or oral medication and eat as directed by your physician. There will still be a fasting requirement of four to six hours. In general, your blood sugar level at the time of the test should be 70-180 mg/dL. The technologist will test your level prior to the injection.
To prepare for the scan
- Dress comfortably and avoid wearing clothing with metal such as zippers or bra hooks (changing into a hospital gown and pants can be done prior to the scan).
- Avoid eating anything including sugar-free gum and beverages other than water, for at least four to six hours before your scan.
- No strenuous exercise the day of the exam.
- Please bring a copy of your most recent CT or MRI films with you on the day of your PET scan.
- Be prepared to lie still for 15-60 minutes while the scan is being performed.