PET radiotracer is a type of

radioligand A radioligand is a microscopic particle which consists of a Radiopharmaceutical, therapeutic radioactive isotope and the cell-targeting compound - the ligand. The ligand is the target binding site, it may be on the surface of the targeted cancer c ...

that is used for the diagnostic purposes via

positron emission tomography Positron emission tomography (PET) is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in metabolic processes, and in other physiological activities including blood flow, r ...

imaging technique.

Mechanism

PET is a

functional imaging Functional imaging (or physiological imaging) is a medical imaging technique of detecting or measuring changes in metabolism, blood flow, regional chemical composition, and absorption. As opposed to structural imaging, functional imaging center ...

technique that produces a three-dimensional image of functional processes in the body. The system detects pairs of

gamma ray A gamma ray, also known as gamma radiation (symbol ), is a penetrating form of electromagnetic radiation arising from high energy interactions like the radioactive decay of atomic nuclei or astronomical events like solar flares. It consists o ...

s emitted indirectly by a

positron The positron or antielectron is the particle with an electric charge of +1''elementary charge, e'', a Spin (physics), spin of 1/2 (the same as the electron), and the same Electron rest mass, mass as an electron. It is the antiparticle (antimatt ...

-emitting

radionuclide A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess numbers of either neutrons or protons, giving it excess nuclear energy, and making it unstable. This excess energy can be used in one of three ...

(

tracer Tracer may refer to: Science * Flow tracer, any fluid property used to track fluid motion * Fluorescent tracer, a substance such as 2-NBDG containing a fluorophore that is used for tracking purposes * Histochemical tracer, a substance used for ...

), which is introduced into the body on a biologically active molecule.

Pharmacology

In ''in vivo'' systems it is often used to quantify the binding of a test molecule to the binding site of radioligand. The higher the affinity of the molecule the more radioligand is displaced from the binding site and the increasing radioactive decay can be measured by scintillography. This assay is commonly used to calculate

binding constant The binding constant, or affinity constant/association constant, is a special case of the equilibrium constant ''K'', and is the inverse of the dissociation constant. It is associated with the binding and unbinding reaction of receptor (R) and li ...

of molecules to receptors. Due to the probable injuries of PET-radiotracers, they could not be administered in the normal doses of the medications. Therefore, the binding affinity (P_KD) of the PET-tracers must be high. In addition, since via the PET imaging technique is desired to investigate a function accurately, the selectivity of bindings to the specific targets is very important.

References

{{Diagnostic radiopharmaceuticals Positron emission tomography Neuroimaging Nuclear medicine Radiopharmaceuticals Medicinal radiochemistry Chemicals in medicine

Mechanism

Pharmacology

See also

References