Fluorothymidine F-18

**Semantic type:** Pharmacologic Substance

**Definition:** 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.

**Synonyms:** - 18F-FLT - 18F-FLT - 3'-Deoxy-3'-(18F) Fluorothymidine - 3'-deoxy-3'-(18F) fluorothymidine - 3'-deoxy-3'-[18F]fluorothymidine - ALOVUDINE F-18 - Fluorothymidine F 18 - Thymidine, 3'-deoxy-3'-(18F)fluoro- - fluorothymidine F 18