18Fcholine

18F-choline is a fluorine-18 labeled choline radiotracer used in positron emission tomography (PET) imaging. It encompasses choline analogs in which a radioactive fluorine-18 atom is incorporated into the molecule, most commonly as [18F]fluorocholine. The tracer is produced in radiopharmacies by chemical synthesis from a choline precursor and [18F]fluoride, and is suitable for regional or on-site PET imaging due to the radionuclide’s ~110-minute half-life.

Biological basis and mechanism of uptake

18F-choline uptake reflects cellular membrane synthesis. It is transported into cells via choline transporters and phosphorylated by choline kinase to form phosphocholine, effectively trapping the radiotracer inside cells. Malignant tissues often exhibit increased choline uptake and phosphorylation compared to normal tissue, enabling visualization of tumor involvement. However, uptake can also occur in inflammatory or regenerative processes, reducing specificity in some settings.

Clinical applications

The principal clinical use of 18F-choline PET is in the management of prostate cancer, particularly for detecting biochemical recurrence and identifying metastatic sites. It is also used, with varying availability, for imaging other cancers such as brain tumors, hepatocellular carcinoma, and certain lymphomas, and can aid in staging or treatment planning. Its utility is influenced by factors such as background liver activity and inflammation, and it is often considered alongside other tracers like 18F-FDG or PSMA-targeted imaging.

Comparisons and considerations

Compared with carbon-11 choline, 18F-choline benefits from a longer half-life that allows wider distribution and longer imaging windows. Limitations include moderate specificity for malignancy and physiologic uptake in organs such as the liver and pancreas. Regulatory approval for specific indications varies by country, and adoption is influenced by local guidelines and available alternatives.

Safety and availability

As with other PET tracers, use requires appropriate radiopharmacy facilities and radiation safety. Typical considerations include radiation exposure and contraindications for pregnancy.