Brain Scanning Test (PET) 
What is a brain scan? This test gives information about the brain through a special camera. Scanning can detect collections of blood in the brain, locate areas of reduced blood supply to the brain, and brain hemorrhaging. Why would I need a brain scan? Brain scans using positron emission tomography (known as PET) are useful in the early diagnosis of cerebrovascular disease and in the detection of stroke and/or transient ischemic episodes before abnormalities develop on computed tomography (CT) or magnetic resonance imaging (MRI) scans. Brain scans can be used to detect tumors and evaluate the course of a tumor post-operatively and during chemotherapy. Other uses include the assessment of attention deficit hyperactivity disorder and neuropsychiatric disorders such as schizophrenia, depression, and Alzheimer's disease. Is a brain scan safe? Yes. The amount of radiation you receive is minute, similar to an x-ray examination. If you are pregnant or if you think you may be pregnant, please inform the staff before the scan. Also, inform them if you are breastfeeding. While pregnant women should avoid exposure to x-rays if at all possible, the risk to the baby with a brain scan is practically nil because the scan exposes only the head of the patient and not other parts of the body. How should I prepare for the test? No special preparations are necessary. What happens during the test? A radioactive chemical will be injected into a vein in your arm. A short time later, you will be scanned with a special camera, which rotates around your head. The camera detects rays being emitted from the radioactive chemical. These rays will be converted into an image that can be displayed and interpreted by the radiologist. The scan time is about 30 to 45 minutes. There may be a sharp prick when the radioactive chemical is injected. Otherwise no discomfort should be felt during the scanning procedure. What happens after the test? A nuclear radiologist (physician) will evaluate your pictures and send a report to your physician. Sources: National Institute of Mental Health Nuclear Medicine Service, Walter Reed Army Medical Center
This article was reviewed and updated June 2007.
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