Positron Emission Tomography (PET) is a non-invasive nuclear imaging technique. It enables the three-dimensional, quantitative determination of the distribution of radioactivity within the human body.
PET is becoming an increasingly important tool for the measurement of physiological, biochemical, and pharmacological functions at a molecular level, both in healthy and pathological states. During the last decade, some three hundred PET centers have been established worldwide. This reflects the great interest of scientists and clinicians in PET-related fields.
Positron Emission Tomography (PET) provides physicians with information about the body's chemistry not available through any other procedure. Unlike CT or MRI, which look at anatomy or body form, PET studies metabolic activity or body function. PET has been used primarily in cardiology, neurology, and oncology. In a PET procedure, the patient receives a short half-lived radiopharmaceutical (produced by a cyclotron or a generator).
Since the radioisotope used in a PET scan is short-lived, the amount of radiation exposure the patient receives is about the same as from a few chest X-rays.
The radiopharmaceuticals emit positrons from wherever they accumulate in the body. As the positrons encounter electrons within the body, a reaction producing gamma rays occurs. The patient lies on a table that slides into the middle of the scanner. Within the scanner are rings of detectors containing special crystals that produce light when struck by a gamma ray. The scanner's electronics record these detected gamma rays and map an image of the area where the radiopharmaceutical is located.
Since the radiopharmaceutical contains a molecule commonly used by the body, PET enables the physician to see the location of the metabolic process. For example, glucose (which the body uses to produce energy) combined with a radioisotope will show where and how much glucose is being used in the brain, the heart muscle, or a growing tumor. PET is extremely helpful in the diagnosis and follow-up of several diseases such as : different kind of cancers, Epilepsy, Parkinson, Alzheimer, viability in ischemic heart diseases.