F-18 fluorodeoxyglucose

F-18 fluorodeoxyglucose (FDG) is the most common PET radiotracer.

Structure

The radiopharmaceutical consists of the fluorine-18 radionuclide substituting the hydroxyl group at the C-2 position of glucose. The IUPAC chemical name is 2-deoxy-2-[F-18]fluoroglucose.

Production

F-18 fluoride ion is created in a cyclotron and then converted via an automated chemistry module into F-18 FDG. Specifically, F-18 FDG is produced through a nucleophilic substitution reaction, using the F-18 fluoride by nuclear reaction ¹⁸O (p,n) ¹⁸F starting from water (H₂O) enriched with oxygen-18.

Pharmacokinetics

• physical half-life: 110 minutes
• excretion: renal

Biodistribution

Physiologic activity is commonly seen in the following organs:

• brain
• heart (especially left ventricular myocardium)
• kidneys and bladder (due to urinary excretion)
• liver (often used as an internal reference standard on whole body scans)

Other sites of physiologic uptake are variable or less intense:

• skeletal muscle (in extremities after strenuous activity, in mouth and larynx after speech or chewing)
• brown fat (especially in the neck and mediastinum)
• gastrointestinal mucosa
• hematopoietic/lymphoid tissue: Waldeyer ring, thymus, spleen, and bone marrow
• salivary glands
• lactating breasts
• conus medullaris

Clinical uses

• brain
  • identification of foci associated with epileptic seizures
  • evaluation of suspected Alzheimer dementia
• whole body
  • cancer staging and surveillance
  • evaluation of patients with fever of unknown origin
• cardiac
  • identification of viable and ischemic myocardium

See also

• F-18 fluorodeoxyglucose (FDG) embolism