Steroids labeled with F-18 for imaging tumors by positron emission tomography

The chemistry to label radiopharmaceuticals for imaging with positron emiss ion tomography (PET) with the 2 h half Life positron-emitting radionuclide fluorine-18 (F-18) requires ease, efficiency, and speed. Furthermore, when high specific activities are needed, as in imaging high affinity, low capac ity receptors, reactions need to work well at the tracer level scale. This review covers F-18 synthetic methods and their application to the preparati on of [F-18]-labeled steroids for imaging hormone-responsive cancers. The m ethods exemplified are fluoride ion displacement of sulfonates and opening of cyclic sulfates, nucleophilic aromatic substitution, and halogen fluorid e addition to alkenes. (C) 2001 Elsevier Science B.V. All rights reserved.