First, even in the setting of BCR with low PSA levels, and across the three major types of putative prostate cancer recurrence, i.e., prostate bed, lymph node, and bone lesions, previously-indeterminate foci appeared to be readily amenable to such dichotomization on 24-hr and 48-hr [89Zr]Zr-PSMA-617 PET/CT images. This evidence concerns the gene KLK3 and prostate carcinoma.