Enhancing Risk Stratification in Equivocal Prostate Magnetic Resonance Imaging Lesions: Clinical Utility of Prostate Health Index and Prostate Health Index Density in Prostate Imaging-Reporting and Data System 3.

[PURPOSE] Managing Prostate Imaging-Reporting and Data System (PI-RADS) 3 lesions on prostate magnetic resonance imaging (MRI) remains challenging due to their intermediate and equivocal nature. The Prostate Health Index (PHI) and its derivative, PHI density (PHID), have shown promise in improving risk stratification beyond prostate-specific antigen (PSA); however, their utility in PI-RADS 3 lesions is not well established. This study aimed to assess the diagnostic performance of PHI and PHID in detecting clinically significant prostate cancer (csPCa), focusing on PI-RADS 3 lesions.

[MATERIALS AND METHODS] This study analyzed 1,001 male who underwent multiparametric MRI and prostate biopsy. PHI and PHID were calculated prior to biopsy. Logistic regression, receiver operating characteristic (ROC) analysis, decision curve analysis (DCA), and reclassification metrics (integrated discrimination improvement/net reclassification improvement) were used to evaluate diagnostic performance across PI-RADS categories.

[RESULTS] csPCa was diagnosed in 485 patients (48.5%). PHID demonstrated superior risk stratification compared to PHI, particularly in PI-RADS 3 lesions. A PHID≥0.49 identified all csPCa cases (100% sensitivity), allowing 15.8% of PI-RADS 3 patients to avoid biopsy. Models combining PHID+PI-RADS yielded the highest area under the ROC curve and the greatest net benefit in DCA, outperforming models based on PSA or PHI alone.

[CONCLUSIONS] PHID significantly enhances risk stratification for csPCa, especially in PI-RADS 3 lesions. A PHID threshold of 0.49 may serve as a safe criterion to reduce unnecessary biopsies. Integrating PHID with PI-RADS improves diagnostic accuracy and facilitates more personalized biopsy decisions.