KLK3 and posterior cortical atrophy: After multivariate logistic analysis of tPSA, NLR, PLR, ALP, PSAD, and prostate MRI predictors, the difference in the predictive index of PSAD and prostate MRI abnormalities was significant (p<0.001), and PSAD and prostate MRI abnormalities were the independent risk factors for PCa with PSA in the gray zone.