Prostate imaging after focal ablation scoring after irreversible electroporation treatment in localized prostate...

Detecting recurrence after focal therapy for prostate cancer is challenging due to treatment-induced MRI changes and unreliable PSA kinetics. The Prostate Imaging after Focal Ablation (PI-FAB) scoring system was developed to standardize post-treatment MRI interpretation, yet validation in irreversible electroporation (IRE) populations is lacking. We evaluated PI-FAB diagnostic accuracy for detecting clinically significant prostate cancer (csPCa) recurrence after IRE and assessed inter-reader agreement.

This single-institution retrospective study included consecutive patients undergoing primary IRE for localized prostate cancer with post-IRE multiparametric MRI and confirmatory biopsy at minimum one-year follow-up. Two radiologists independently assigned PI-FAB scores (1-3) while blinded to pathology. The reference standard was confirmatory biopsy (csPCa defined as ISUP Grade Group ≥ 2). Inter-reader agreement was assessed using percent agreement, unweighted and weighted Cohen's kappa, Gwet's AC1, and Gwet's AC2.

Of 71 screened patients, 44 met inclusion criteria. Seven (15.9%) had in-field csPCa recurrence. Both readers achieved sensitivity of 71.4% (95% CI: 29.0-96.3%), with specificity of 89.2% and 81.1%, respectively. Negative predictive value exceeded 93% for both readers. Inter-reader agreement was substantial (percent agreement: 81.8%; weighted kappa: 0.680; Gwet's AC1: 0.770; Gwet's AC2: 0.805). Limitations include small sample size, wide confidence intervals, and single-institution design.

PI-FAB demonstrated good specificity, high negative predictive value, and substantial inter-reader agreement for post-IRE surveillance. Patients with low PI-FAB scores may be managed with continued monitoring rather than immediate biopsy. Larger multicenter studies are needed before routine clinical implementation.