Positron emission tomography, also called PET imaging or a PET scan, is a diagnostic examination that involves the acquisition of physiologic images based on the detection of radiation from the emission of positrons. Positrons are tiny particles emitted from a radioactive substance administered to the patient. The subsequent images of the human body developed with PET technique are used to evaluate a variety of diseases.
Because PET allows study of body function, it can help physicians detect alterations in biochemical processes that suggest disease before changes in anatomy are apparent with other imaging tests, such as CT or MRI. It is both a medical and research tool and is used heavily in clinical oncology (medical imaging of tumors and the search for metastases) and for clinical diagnosis of brain diseases such as dementias. PET is also an important research tool to map human brain and heart function.
The PET scanner has a hole in the middle and looks like a large doughnut. Within this machine are multiple rings of detectors that record the emission of energy from the radioactive substance in your body and permit an image of your body to be obtained. While lying on a cushioned examination table, you will be moved into the hole of the machine. The images are displayed on the monitor of a nearby computer, which is similar in appearance to the personal computer you may have in your home.
Before the PET scan examination begins, a radioactive substance is produced in a machine called a cyclotron and attached, or tagged, to a natural body compound, most commonly glucose, but sometimes water or ammonia. Once this substance is administered to the patient, the radioactivity localises in the appropriate areas of the body and is detected by the PET scanner. Different colors or degrees of brightness on a PET image represent different levels of tissue or organ function. For example, because healthy tissue uses glucose for energy, it accumulates some of the tagged glucose, which will show up on the PET images. However, cancerous tissue, which uses more glucose than normal tissue, will accumulate more of the substance and appear brighter than normal tissue on the PET images.
The value of a PET scan is enhanced when it is part of a larger diagnostic work-up which often entails comparison of the PET scan with other imaging studies, such as CT or MRI.
For indicative costs of a private PET scan, view our PET prices list.
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