Positron emission tomography (PET) is a non-invasive imaging method that provides quantitative biochemical and molecular information on the physiological processes of the body. This concept was first introduced by Roy Edwards, Luke Chapman and David E. Kuhl in the later 1950’s.
This technique provides all possible metabolic information that is difficult to produce using other imaging techniques. Positron emitting radionuclides used in this technique are elements with low atomic mass, and most of them are naturally found in the human body such as nitrogen, carbon and oxygen.
Radioisotopes of these elements are capable of imaging a large number of metabolic and physiological processes by labeling metabolically active compounds. Helmholtz-Zentrum Dresden-Rossendorf, a member of the Helmholtz Association of German Research facilities dedicated to improving human lives provide a great overview of how PET worsk in the following video:
Positron Emission Tomography (PET) at the Helmholtz-Zentrum Dresden-Rossendorf
PET works based on the detection of small quantities of biological substances that are labeled with radionuclides using a positron emitter.
Fluorodeoxyglucose is the widely used radionuclide in PET scanning. Other substances can also be used for PET scanning based on the application. Radioactive gallium, nitrogen, carbon or oxygen are commonly used as radionulceotides for detecting the blood flow and perfusion of an organ or tissue.
The process of PET first begins with introducing the radionuclide into the body via an intravenous injection followed by the PET scanner being slowly moved over the part of the body to be examined. Positrons are emitted through the breakdown of the radionuclide.
During the emission of positrons, gamma rays are produced which are detected by the scanner. These gamma rays are analyzed by a computer, and the information thus obtained is used to produce an image of the tissue or organ being examined.
The function of the tissue and the clarity of the image depend on the quantity of the radionuclide collected in the tissue.
PET is most often used in oncology, neurology, and cardiology. It is also used in conjunction with other diagnostic procedures such as computed tomography to provide specific information about lesions and malignant tumors.
Other uses of PET include the following:
- Detecting and diagnosing brain disorders
- Quantifying the extent of heart disease
- Help predicting the need for a surgical procedure.