Prostate cancer: Value of the PI-FAB score and volume-adjusted PSA density in recurrence assessment after HIFU

Purpose To evaluate the diagnostic performance of the Prostate Imaging after Focal Ablation (PI-FAB) score on multiparametric MRI in combination with volume-adjusted PSA density (vaPSA-D, derived from volumetrically assessed residual vital prostate tissue) for detecting in-field recurrence after HIFU ablation of localized prostate cancer. Methods In this retrospective single-center study, 117 men treated with HIFU underwent follow-up mpMRI and prostate biopsies at 6 (n = 99), 12 (n = 74), and 36 (n = 52) months. PI-FAB scores and vaPSA-D were assessed independently. Diagnostic performance was evaluated using biopsy-based histopathology as the reference standard. Results PI-FAB demonstrated good diagnostic performance, particularly at 36 months (AUC 0.92). vaPSA-D showed increasing accuracy over time (AUC 0.64, 0.82, 0.84 at 6, 12, and 36 months; overall 0.78), outperforming PI-FAB at 12 months. Integrating vaPSA-D into PI-FAB subgroups significantly enhanced recurrence assessment: PI-FAB 1: sensitivity/specificity 75%/79% (threshold 0.14 ng/ml); PI-FAB ≥ 2: sensitivity/specificity 65%/85% (0.18 ng/ml); PI-FAB 3: sensitivity/specificity 67%/90% (0.18 ng/ml). Conclusion Both PI-FAB and vaPSA-D provide reliable recurrence assessment after HIFU, with complementary strengths: PI-FAB performs best at later follow-up stages, whereas vaPSA-D maintains high sensitivity throughout. Their combined application offers the most accurate evaluation of post-HIFU recurrence and may help reduce unnecessary biopsies.