Pharmacokinetic Assessment of the Uptake of 16b-18F-Fluoro-5a-Dihydrotestosterone (FDHT) in Prostate Tumors as Measured

The aim of this study was to develop a clinically applicable non-invasive method to quantify changes in androgen receptor (AR) levels based on 18F-16b-fluoro-5a-dihydrotestosterone (18F-FDHT) PET in prostate cancer patients undergoing therapy. Methods: Thirteen patients underwent dynamic 18F-FDHT PET over a selected tumor. Concurrent venous blood samples were acquired for blood metabolite analysis. A second cohort of 25 patients injected with 18F-FDHT underwent dynamic PET of the heart. These data were used to generate a population-based in-put function, essential for pharmacokinetic modeling. Linear compartmental pharmacokinetic models of increasing complex-ity were tested on the tumor tissue data. Four suitable models were applied and compared using the Bayesian information cri-terion (BIC). Model 1 consisted of an instantaneously equilibrat-ing space, followed by a unidirectional trap. Models 2a and 2