FluoroDeoxyGlucose

Fluorodeoxyglucose (FDG) is a radiopharmaceutical used in positron emission tomography (PET) imaging. It is the fluorine-18 labeled analogue of glucose and is commonly referred to as 18F-FDG.

FDG is taken up by glucose transporters into cells and phosphorylated by hexokinase to FDG-6-phosphate. Unlike glucose, FDG-6-phosphate cannot undergo further glycolysis, so it becomes trapped inside the cell, allowing imaging of glucose metabolism. Tissues with high metabolic activity, such as the brain or cancerous tissues, typically show prominent FDG uptake.

FDG-PET is widely used in oncology to detect tumors, stage disease, and monitor response to therapy. It is also used in neurology to study metabolic patterns in epilepsy and neurodegenerative diseases, and in cardiology to assess myocardial viability. Inflammation and infection can also produce increased FDG uptake, which can aid or confound interpretation depending on the clinical context.

Preparation and administration involve producing FDG in a cyclotron by radiochemical synthesis using [18F]fluoride. It is prepared in a radiopharmacy and administered by injection after patient fasting. The uptake period is typically about 60 minutes, and doses commonly range around 370–555 MBq. Elevated blood glucose levels can reduce tumor FDG uptake and affect image quality.

Limitations include variable uptake among tumors and potential false positives from infection or inflammatory processes. High physiologic uptake in the brain, heart, and urinary tract can complicate interpretation. Radiation exposure is a consideration, and the use of FDG-PET is guided by regulatory approvals and institutional safety protocols.

FDG-PET is often combined with CT (PET/CT) or MRI for anatomical reference and accurate localization. It has broad clinical utility and is supported by guidelines in oncology, neurology, and cardiology.