RT Journal Article SR Electronic T1 Tumor Localization of 16β-18F-Fluoro-5α-Dihydrotestosterone Versus 18F-FDG in Patients with Progressive, Metastatic Prostate Cancer JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 366 OP 373 VO 45 IS 3 A1 Larson, Steven M. A1 Morris, Michael A1 Gunther, Ilonka A1 Beattie, Brad A1 Humm, John L. A1 Akhurst, Timothy A. A1 Finn, Ronald D. A1 Erdi, Yusuf A1 Pentlow, Keith A1 Dyke, Jon A1 Squire, Olivia A1 Bornmann, William A1 McCarthy, Timothy A1 Welch, Michael A1 Scher, Howard YR 2004 UL http://jnm.snmjournals.org/content/45/3/366.abstract AB This trial was an initial assessment of the feasibility, in vivo targeting, and biokinetics of 16β-18F-fluoro-5α-dihydrotestosterone (18F-FDHT) PET in patients with metastatic prostate cancer to assess androgen receptor expression. Methods: Seven patients with progressive clinically metastatic prostate cancer underwent 18F-FDG and 18F-FDHT PET scans in addition to conventional imaging methods. Three patients had their studies repeated 1 mo later, 2 while on testosterone therapy, and the third after treatment with 17-allylamino-17-demethoxygeldanamycin (17-AAG). High-pressure liquid radiochromatography was used to separate 18F-FDHT from radiolabeled metabolites. Lesion-by-lesion comparisons between the 18F-FDHT, 18F-FDG, and conventional imaging methods were performed. Results: Metabolism of 18F-FDHT was rapid, with 80% conversion within 10 min to radiolabeled metabolites that circulated bound to plasma proteins. Tumor uptake was rapid and tumor retention was prolonged. Fifty-nine lesions were identified by conventional imaging methods. 18F-FDG PET was positive in 57 of 59 lesions (97%), with an average lesion maximum standardized uptake value (SUVmax) = 5.22. 18F-FDHT PET was positive in 46 of 59 lesions (78%), with the average positive lesion SUVmax = 5.28. Treatment with testosterone resulted in diminished 18F-FDHT uptake at the tumor site. Conclusion: 18F-FDHT localizes to tumor sites in patients with progressive clinically metastatic prostate cancer and may be a promising agent to analyze antigen receptors and their impact on the clinical management of prostate cancer.