Purification of [18F]-fluoro-l-thymidine ([18F]-FLT) for positron emission tomography imaging

3′-Deoxy-3′-[18F]fluorothymidine ([18F]-FLT) has recently been described as a positron emission tomography (PET) radiopharmaceutical for visualizing cellular proliferation in vivo. All published radiosyntheses of [18F]-FLT provide crude products that must be purified before injection to human. This study describes a reliable purification procedure for [18F]-FLT. It is based on HPLC. In 17.9 ± 0.5 min, pure [18F]-FLT is obtained that could be injected to human after a passage through a sterile 0.22 μm filter.