KLK3 and posterior cortical atrophy: According to MRI imaging of prostate zonal anatomy, the prostate comprises a peripheral zone (PZ), a transition zone (TZ), a central zone, and an anterior fibromuscular stroma.[9] The PZ is the source of 75% to 85% of PCa.[10] Compared with PSA levels alone, the accuracy of diagnosing PCa will be improved using PZ- adjusted PSA levels (PSA density of peripheral zone [PSADPZ]), derived from the ratio of PSA and peripheral zone volume, or TZ-adjusted PSA levels (PSA density of transition zone [PSADTZ]), derived from the ratio of PSA and transition zone volume (TZV).[11–14]