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Fluorothymidine F-18
Definition 1
A radioconjugate consisting of a thymidine analogue radiolabeled with fluorine F 18, a positron emitting isotope. Phosphorylated by S-phase-specific thymidine kinase 1, 3'-deoxy-3'-[18F]fluorothymidine (18F-FLT) is trapped intracellularly by entering the salvage pathway of DNA synthesis without incorporation into DNA. 18F-FLT serves a marker of tumor cell proliferation for imaging with positron emission tomography (PET); as a marker of proliferation rather than metabolism, it is more specific to tumor tissue than 2-deoxy-2-[18F] fluoro-D-glucose (18F-FDG). This agent is metabolically stable, accumulates in the normal bone marrow and the liver, and does not cross the blood-brain barrier. (NCI Thesaurus)
Definition 2
A radioactive substance being studied in the diagnosis of cancer. 18F-FLT is injected into the blood and builds up in cells that are dividing, including cancer cells. The radiation that it gives off as it decays (breaks down) helps make clear pictures of tumors during positron emission tomography (PET) scans. It is a type of radiopharmaceutical. (NCI Dictionary)