A PET radiotracer (also known as PET tracer) is a positron-emitting radiopharmaceutical used in positron emission tomography. Each tracer consists of a positron-emitting isotope (radioactive tag) bound to an organic ligand (targeting agent). The ligand component of each tracer interacts with a protein target, resulting in a characteristic distribution of the tracer throughout the tissues.
For example, the preeminent PET radiotracer fluorodeoxyglucose (FDG) is comprised of 18F isotope bound to 2-deoxy-2-glucose, an analogue to glucose. The 2-deoxy-2-glucose ligand is a substrate for the hexokinase/glucokinase enzymes involved in early carbohydrate metabolism; thus, FDG is chemically linked to cellular metabolic activity 1. It serves as a particularly good tracer agent because it tends to stay "trapped" within metabolically active cells due to the absence of the hydroxide group ("deoxy-").
There is an increasing list of chemical compounds which are being used for PET imaging. A list of commonly used compounds includes:
- 1. Smith TA. The rate-limiting step for tumor [18F]fluoro-2-deoxy-D-glucose (FDG) incorporation. (2001) Nuclear medicine and biology. 28 (1): 1-4. Pubmed