What is PET?
 Positron Emission Tomography (PET) is an imaging technology that can be used to assess tissue biochemistry. Diagnosticians have traditionally been trained to interpret information provided by anatomically based imaging techniques. With the advent of molecular biology-based medicine, a transition must be made to incorporate information based on biochemical perturbations that exist in disease, frequently in the absence of change in anatomy, into diagnostic interpretation. PET is the only clinical technique currently available that provides such information.
The fundamental significance of PET is that it can be used to quantify metabolic changes. Biochemical processes are altered in virtually all disease states. Radioactive tracers can be used to detect changes in these processes in advance of, or in the absence of, gross structural changes. PET is a very useful adjunct to anatomic imaging techniques, providing unique information and an additional dimension to the characterization of disease.
PET utilizes biologically active compounds, or drugs, labeled with positron emitters. These radiolabeled agents are primarily administered intravenously, and are processed internally in a manner virtually identical to their nonradioactive counterparts, providing the mechanism to record metabolic activity in vivo. The biodistribution of these compounds can be assessed with a PET scanner, which produces both images and quantitative indexes of tissues and organs in the whole body. Biochemical rates of glucose metabolism, amino acid transport, protein synthesis, cell division, oxygen consumption, blood flow, and neuroreceptor status can be determined. Since only tracer level amounts of material are administered, no pharmacological effect occurs, and hence, there is no perturbation of the targeted biochemical process.
PET is already making critical contributions to more cost-effective patient management in three primary medical disciplines: oncology, cardiology and neurology.
As researchers use PET to explore the basic physiology underlying disease processes, additional clinical applications are likely to evolve.
PET has the unique ability to cross the boundaries of specialties, adding new dimensions to a physician's ability to:
- Diagnose disease before structural changes become detectable with anatomical imaging techniques, potentially improving the prognosis.
- Manage patient therapy by monitoring response to a given regimen and providing early feedback on its efficacy. This can help reduce or avoid the cost of ineffective treatments or unnecessary hospitalization. In some cases, replace multiple diagnostic procedures with a single exam.
- Help predict the prognosis for surgical procedures, to eliminate those that won't benefit the patient, thus significantly reducing the cost of healthcare delivery.
- Identify distant, occult metastases that may affect the course of treatment and therefore change patient management.
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