APT-MRI is a contrast-agent-free MRI technique that exploits signal from the amide protons (NH groups) contained in proteins and peptides. No studies have reported the use of 3DAPT. Quantitative analysis (ADC and APT SI (%)) were calculated for PC lesions and for benign regions that included normal PZ and benign prostatic lesions. APT SI was comparable among normal regions, benign lesions, and PC. However, APT SI was significantly higher in large PC than in small PC. In addition, the APT SIs of PC lesions correlated well with PSA. APT SI may represent tumor volume, PC staging, and prognosis.