Fludeoxyglucose (18F) - Applications

Applications

In PET imaging, 18F-FDG can be used for the assessment of glucose metabolism in the heart, lungs, and the brain. It is also used for imaging tumors in oncology, where a static 18F-FDG PET scan is performed and the tumor 18F-FDG uptake is analyzed in terms of Standardized Uptake Value (SUV). 18F-FDG is taken up by cells, phosphorylated by hexokinase (whose mitochondrial form is greatly elevated in rapidly growing malignant tumours), and retained by tissues with high metabolic activity, such as most types of malignant tumours. As a result FDG-PET can be used for diagnosis, staging, and monitoring treatment of cancers, particularly in Hodgkin's disease, non-Hodgkin's lymphoma, colorectal cancer, breast cancer, melanoma, and lung cancer. It has also been approved for use in diagnosing Alzheimer's disease.

In body-scanning applications in searching for tumor or metastatic disease, a dose of 18F-FDG in solution (typically 5 to 10 millicurie, 200 to 400 MBq) is typically injected rapidly into a saline drip running into a vein, in a patient who has been fasting for at least 6 hours, and who has a suitably low blood sugar. (This is a problem for some diabetics; usually PET scanning centers will not administer the isotope to patients with blood glucose levels over about 180 mg/dL = 10 mmol/L, and such patients must be re-scheduled). The patient must then wait about an hour for the sugar to distribute and be taken up into organs which use glucose – a time during which physical activity must be kept to a minimum, in order to minimize uptake of the radioactive sugar in muscles (this causes unwanted artifacts when the organs of interest are inside the body). Then, the patient is placed in the PET scanner for a series of one or more scans which may take from 20 minutes to as long as an hour (often, only about one quarter of the body length may be imaged at a time).