*Article* **Primary Staging of Prostate Cancer Patients with [ 18F]PSMA-1007 PET/CT Compared with [68Ga]Ga-PSMA-11 PET/CT**

**Manuela A. Hoffmann 1,2,\*, Jonas Müller-Hübenthal 3, Florian Rosar 4, Nicolas Fischer 5, Finn Edler von Eyben 6, Hans-Georg Buchholz 2, Helmut J. Wieler <sup>7</sup> and Mathias Schreckenberger <sup>2</sup>**


**Abstract:** Background: Hybrid imaging with prostate-specific membrane antigen (PSMA) is gaining importance as an increasingly meaningful tool for prostate cancer (PC) diagnostics and as a guide for therapy decisions. This study aims to investigate and compare the performance of [18F]PSMA-1007 (18F-PSMA) and [68Ga]Ga-PSMA-11 positron emission tomography/computed tomography ( 68Ga-PSMA) in the initial staging of PC patients. Methods: The data of 88 biopsy-proven patients were retrospectively evaluated. PSMA-avid lesions were compared with the histopathologic Gleason Score (GS) for prostate biopsies, and the results were plotted by receiver operating characteristic (ROC)-curve. Optimal maximum standardized uptake value (SUVmax) cut-off values were rated using the Youden index. Results: 18F-PSMA was able to distinguish GS <sup>≤</sup> 7a from <sup>≥</sup>7b with a sensitivity of 62%, specificity of 85%, positive predictive value (PPV) of 92%, and accuracy of 67% for a SUVmax of 8.95, whereas sensitivity was 54%, specificity 91%, PPV 93%, and accuracy 66% for 68Ga-PSMA (SUVmax 8.7). Conclusions: Both methods demonstrated a high concordance of detected PSMA-avid lesions with histopathologically proven PC. 18F-PSMA and 68Ga-PSMA are both suitable for the characterization of primary PC with a comparable correlation of PSMA-avid lesions with GS. Neither method showed a superior advantage. Our calculated SUVmax thresholds may represent valuable parameters in clinical use to distinguish clinically significant PC (csPC) from non-csPC.

**Keywords:** PSMA hybrid imaging; staging of primary prostate cancer; [18F]PSMA-1007; [68Ga]Ga-PSMA-11; SUVmax cut-off level; prostate carcinoma
