ABSTRACT
Background and purpose:In preparation for using this tracer in humans, this study estimated thedosimetry of18F-FES with the method established by MIRD based on whole-body PET imaging of mice.Methods:Three female mice receivedⅣ tail injections of18F-FES and were scanned for 160 min in an Inveon dedicated PET/CT scanner. This study selected some important organs (brain, lung, liver, heart wall, small intestine, large intestine, kidney and urinary bladder), computed their residence times. Then, the residence times in mice organs were converted to human values using scale factors based on differences between organ and body weights. OLINDA/EXM 1.1 software was used to compute the absorbed human doses in multiple organs for both adult female and adult male body phantoms. Results:The highest absorbed doses in gallbladder wall, urinary bladder wall, small intestine, upper large intestine and liver are 0.072 5, 0.044 5, 0.043 0, 0.031 5 and 0.028 2 mGy/MBq, respectively. The organs which have the lowest ab-sorbed doses were brain (0.005 2 mGy/MBq), followed by skin (0.001 1 mGy/MBq), breast (0.001 1 mGy/MBq), heart wall (0.001 2 mGy/MBq) and thyroid (0.001 2 mGy/MBq). The mean absorbed doses for the other major organs ranged from 0.009 5 to 0.023 5 mGy/MBq. The total mean effective dose is 0.019 0 mSv/MBq and the mean effective doses equivalent is 0.025 0 mGy/MBq. A 370-MBq injection of18F-FES leads to an estimated effective dose of 7.03 mSv for the female. There was no statistical difference in the doses results obtained from direct measurement of18F-FES ab-sorption in normal people between previous publications by others and our work.Conclusion:The whole-body mouse imaging can be used as a preclinical tool for initial estimation of the absorbed doses of18F-FES in humans. Furthermore, the potential radiation risk associated with18F-FES imaging is well within the accepted limits.
ABSTRACT
Background and purpose:16α-[18F]lfuoroestradiol (18F-FES) is an in vivo speciifc imaging agent for estrogen receptor (ER). We investigated the concordance between tumor ER status as determined by FES-PET and in vitro immunohistochemical assays. Methods: 18F-FES was prepared by ourselves. Twenty-six patients were enrolled (17 primary and 9 metastatic/recurrent). Patients underwent both 18F-FES and 18F-FDG PET/CT. Results:We found good overall agreement (96.15%) between in vitro ER assays and FES-PET. The ER status diagnosis sensitivity of 18F-FES was 93.33%and the speciifcity was 100%when using cut-off value of SUVmax≥1.5. There was a positive correlation between in vitro ER, PR assays and the SUVmax of 18F-FES while in vitro HER-2/neu assays correlatived negatively with 18F-FES SUVmax. Conclusion:These results suggested 18F-FES may be useful for studying the ER expression of all malignant lesions in patients with breast cancer and guiding individual therapy.