[7 alpha-F-18]fluoro-17 alpha-methyl-5 alpha-dihydrotestosterone: a ligandfor androgen receptor-mediated imaging of prostate cancer

We have synthesized a F-18-labeled androgen, [7 alpha-F-18]fluoro-17 alpha -methyl-5 alpha -dihydrotestosterone, in a no-carrier-added radiosynthesis by exchange of F-18- (tetrabutylammonium fluoride) with the 7 beta -tosylox y of 17 alpha -methyl-5 alpha -dihydrotestosterone. The nonradioactive ster oid binds with high affinity and specificity to the androgen receptor and b inds poorly, if at all, to other steroid receptors and plasma sex hormone b inding globulin, The 7 alpha-F-18-androgen concentrates markedly in the pro state of rats by an androgen receptor-dependent mechanism. It is likely tha t [7 alpha-F-18]fluoro-17 alpha -methyl-5 alpha -dihydrotestosterone will b e an excellent positron emission tomography imaging agent for prostate canc er. (C) 2001 Elsevier Science Inc. All rights reserved.