Biodistribution and breast tumor uptake of 16 alpha-[F-18]-fluoro-17 beta-estradiol in rat

To evaluate the usefulness of 16 alpha-[F-18]-fluoro-17 beta-estradiol (FES ) for the assessment of estrogen receptor (ER), we examined the tissue dist ribution and kinetics of FES in immature female Sprague-Dawley rats and the n examined FES uptake in rat breast tumors induced by 7,12-dimethylbenz(a) anthracene (DMBA). The FES uptake by the uterus, an ER-rich tissue, was hig hly selective and it was 3.34 +/- 0.79%ID/g at 60 minutes and 1.57 +/- 0.57 %ID/g at 120 minutes after injection. The FES uptakes in ER-negative tissue s were 0.12 +/- 0.05%ID/g or less and 0.05 +/- 0.03%ID/g or less, respectiv ely. Coadministration of unlabeled beta-estradiol showed marked depression of uterine FES uptake. The FES uptake by rat breast tumors was 0.14 +/- 0.0 6%ID/g at 60 min and 0.12 +/- 0.09%ID/g at 120 min. The FES uptake by rat b reast tumors correlated with the ER concentration (r = 0.45, p < 0.05). In conclusion, these results suggest that the FES uptake by tissue is mainly E R mediated and FES is thus useful for detecting ER positive breast tumors.