A PET radiotracer (also known as PET tracer) is a positron-emitting radiopharmaceutical used in positron emission tomography (PET). 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. The ideal PET radiopharmaceutical should only interact with the protein target and not give accumulation phenomena.
For example, the pre-eminent PET radiotracer fluorodeoxyglucose (FDG) is comprised of a fluorine-18 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 the early carbohydrate metabolism; thus, FDG is chemically linked to cellular metabolic activity. 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-”).
- FDG PET
- fluorodeoxyglucose
- Chemically linked to cellular metabolic activity
- fluorodeoxyglucose
- Gallium-68 DOTATATE
- Three parts
- Gallium (Ga) radiotracer
- linked, via a chemical macrocyclic chelator, known as DOTA
- to the short-chain peptide Tyr3-octreotate (TATE)
- Somatostatin-receptor (SSTR) functional imaging
- Three parts