*2.5. Subpopulation*

Based on EAU guidelines, which suggest the examination of PSMA PET/CT in patients with PSA serum values of ≥1 ng/mL and based on the definition of BC (PSA is >0.2 ng/mL in prostatectomized patients), we highlighted and examined the patient collective of restaging patients (P-P) in the range from 0.2 to <1 ng/mL as particularly assessable [3,15]. In baseline PET/CT, 33% (58/178) of patients (P-P) showed PSA values in the range of 0.2 to <1 ng/mL, of which 29% were PSMA-positive and 14% showed local metastases (*p* < 0.001) (Table 5). There was no difference in the results determined by delayed PET/CT images.

In one of our previous studies, we determined an optimal PSA cutoff level of 1.24 ng/mL for distinguishing between positive and negative PSMA PET/CT results for BC patients after primary prostatectomy (P-P) [13]. In this study, P-P patients in baseline shots, with PSA < 1.24 ng/mL, showed an overall positivity in 34% (24/71), PSMA-avid local metastases in 13% (9/71), and distant metastases in 10% (7/71), compared to 84% (90/107), 29% (31/107), and 22% (24/107) in patients with PSA ≥ 1.24 ng/mL (*p* < 0.001) (Table 5). The results were comparable in delayed images.


**Table 5.** Baseline PET/CT: LPR P-P of different subgroups related to PSA subgroups.

Abbreviations: PSA, prostate-specific-antigen; *p* < 0.05 is considered significant; *r*, Pearson correlation coefficient.
