Fluorodeoxyglucose (18F)

Fluorodeoxyglucose (18F) (FDG) is a radiopharmaceutical used in the medical imaging modality positron emission tomography (PET). Chemically, it is 2-deoxy-2-18Ffluoro-D-glucose, a glucose analog, with the positron-emitting radioactive isotope fluorine-18 substituted for the normal hydroxyl group at the 2' position in the glucose molecule.

Chemistry

The uptake of FDG by cells is regulated by the enzyme hexokinase, which phosphorylates glucose to form glucose-6-phosphate. The phosphorylated FDG, being nearly structurally identical to glucose, is similarly transported into cells by the glucose transporter (GLUT). Once inside, FDG is phosphorylated to FDG-6-phosphate, which cannot be further metabolized by most tissues. As a result, FDG-6-phosphate accumulates in the cell.

Medical Use

In oncology, FDG is used in PET scanning to assess abnormal glucose metabolism and to differentiate benign from malignant lesions. It is also used in cardiology for myocardial viability studies, and in neurology to diagnose Alzheimer's disease, epilepsy, and other conditions.

Production

FDG is produced by nuclear transmutation of oxygen-18 to fluorine-18 in a cyclotron, followed by chemical synthesis of the radiotracer.

Safety

The radiation dose received from an FDG PET scan is comparable to that received from conventional radiology procedures. However, as with any radiopharmaceutical, there is a risk of radiation exposure, which should be minimized by following appropriate safety procedures.

See Also

• Radiopharmaceutical
• Positron emission tomography
• Glucose transporter
• Hexokinase