Jørgen Frøkiær

The aim of this work was to evaluate Rb-82 PET/CT as a diagnostic tool for quantitative tumor blood flow (TBF) imaging in prostate cancer (PCa). Study 1 was performed to evaluate Rb-82 as a marker of TBF, using O-15-H2O PET as a reference method. Study 2 investigated the ability of Rb-82 uptake measurements to differentiate between PCa and normal prostate. Methods: Study 1:9 PCa patients scheduled for radical prostatectomy were included. Prostate multiparametric MRI and both cardiac and pelvic O-15-H2O PET and Rb-82 PET were performed. PET findings were compared with postprostatectomy Gleason grade group (GGG). Study 2:15 primary high-risk PCa patients and 12 controls without known prostate disease were included in a clinical drug trial (EudraCT 2016-003185-26). Ga-68-prostate-specific membrane antigen PET/CT scans of PCa patients were available. Pelvic Rb-82 PET was performed. Results: Study 1: both Rb-82 K-1 and Rb-82 SUVs correlated strongly with O-15-H2O TBF (rho = 0.95, P <0.001, and rho = 0.77, P = 0.015, respectively). Rb-82 SUV and K-1 were linearly correlated (r = 0.92, P = 0.001). Rb-82 SUV correlated with postprostatectomy GGG (rho = 0.70, P = 0.03). Study 2: Rb-82 SUV in PCa (3.19 +/- 0.48) was significantly higher than prostate Rb-82 SUV in healthy controls (1.68 +/- 0.37) (P <0.001), with no overlap between groups. Conclusion: Study 1 shows that Rb-82 Rb-82 PET/CT can be used for TBF quantification and that TBF can be estimated by simple SUV and suggests that Rb-82 SUV is associated with postprostatectomy GGG and, hence, cancer aggressiveness. Study 2 shows that Rb-82 uptake is significantly higher in PCa than in normal prostate tissue with no overlap between cohorts, confirming the primary hypothesis of the clinical trial. Consequently, Rb-82 PET/CT may have potential as a noninvasive tool for evaluation of tumor aggressiveness and monitoring in nonmetastatic PCa.