TY - JOUR T1 - Matched-pair comparison of <sup>68</sup>Ga-PSMA-11 and <sup>18</sup>F-rhPSMA-7 PET/CT in patients with primary and biochemical recurrence of prostate cancer: frequency of non-tumor related uptake and tumor positivity JF - Journal of Nuclear Medicine JO - J Nucl Med DO - 10.2967/jnumed.120.251447 SP - jnumed.120.251447 AU - Markus Kroenke AU - Lilit Mirzoyan AU - Thomas Horn AU - Jan C Peeken AU - Alexander Wurzer AU - Hans-Juergen Wester AU - Marcus Makowski AU - Wolfgang Andreas Weber AU - Matthias Eiber AU - Isabel Rauscher Y1 - 2020/12/01 UR - http://jnm.snmjournals.org/content/early/2020/12/04/jnumed.120.251447.abstract N2 - Purpose: Radiohybrid prostate-specific membrane antigen (rhPSMA) ligands are a new class of prostate cancer theranostic agents. 18F-rhPSMA-7, offers the advantages of 18F-labelling and low urinary excretion compared with 68Ga-PSMA-11. Here, we compare frequency of non-tumor related uptake and tumor positivity with 68Ga-PSMA-11 and 18F-rhPSMA-7 in patients with primary or recurrent prostate cancer. Methods: This retrospective matched-pair comparison matched 160 18F-rhPSMA-7 with 160 68Ga-PSMA-11 PET/CT studies for primary staging (n = 33) and biochemical recurrence (n = 127) according to clinical characteristics. Two nuclear medicine physicians reviewed all scans, first, identifying all PET-positive lesions, then differentiating lesions suspicious for prostate cancer from those that were benign, based on known pitfalls and ancillary information from CT. For each region, SUVmax of the lesion with the highest PSMA-ligand uptake was noted. Tumor positivity rates were determined and SUVmax were compared separately for each tracer. Results: 18F-rhPSMA-7 and 68Ga-PSMA-11 PET revealed 566 and 289 PSMA-ligand positive lesions, respectively. Of these, 379 and 100 lesions, equaling 67.0 % and 34.6 % of all PSMA-positive lesions were considered benign, respectively. The distribution of their etiology was similar (42%, 24%, 25% in 18F-rhPSMA-7 vs. 32%, 24%, 38% in 68Ga-PSMA-11 for ganglia, bone and unspecific lymph nodes, respectively). All primary tumors were positive with both agents (n = 33 each) while slightly more metastatic lesions were observed with 68Ga-PSMA-11 in both disease stages (113 for 18F-rhPSMA-7 and 124 for 68Ga-PSMA-11). SUVmax of 18F-rhPSMA-7 and 68Ga-PSMA-11 did not differ (P &gt; 0.05) in local recurrence or primary prostate cancer, however, the tumor-to-bladder ratio was significantly higher with 18F-rhPSMA-7 (4.9±5.3 vs 2.2±3.7, P = 0.02 for local recurrence and 9.8±9.7 vs 2.3±2.6, P &lt; 0.001 for primary prostate cancer). Conclusion: The tumor positivity rate was consistently high for 68Ga-PSMA-11 and 18F-rhPSMA-7. Both tracers revealed a considerable number of areas of uptake that were reliably identified as benign by trained physicians making use of corresponding morphological imaging and known PSMA pitfalls. These were more frequent with 18F-rhPSMA-7. However, the matched-pair comparison could have introduced a source of bias. Adequate reader training can allow physicians to differentiate benign uptake from disease and be able to benefit from the logistical and clinical advantages of 18F-rhPSMA-7. ER -