Performance of PI-FAB and TARGET scoring systems in post focal therapy mpMRI surveillance

BACKGROUND: Prostate Imaging after Focal Ablation (PI-FAB) and Transatlantic Recommendations for Prostate Gland Evaluation with Magnetic Resonance Imaging After Focal Therapy (TARGET) scoring systems have been recently developed to improve detection of post-ablation recurrence of clinically significant prostate cancer (csPCa). However, it is unknown how these two scoring systems compare in clinical practice. METHODS: Patients who underwent focal therapy (FT) for prostate cancer (PCa) and had post-FT MRI and biopsy were identified from a prospective registry. Post-FT MRIs were reviewed by two radiologists blinded to biopsy results using the PI-FAB and TARGET systems with scores of 3 and ≥ 4, respectively considered positive for csPCa. csPCa recurrence was defined as ≥ Gleason 3+4 (Grade Group [GG] 2) on biopsy. Diagnostic performance metrics, including sensitivity/specificity/positive predictive value (PPV)/negative predictive value (NPV)/accuracy, were calculated. Area under the receiver operating characteristic curve (AUC) was generated using logistic regression and compared using DeLong's tests. Inter-reader agreement was assessed with Cohen's Kappa (κ). RESULTS: 90 patients were eligible. Radiologist #1 showed PI-FAB sensitivity/specificity/PPV/NPV/accuracy/AUC of 67%/82%/54%/89%/78%/0.74, respectively; TARGET had values of 67%/79%/50%/88%/76%/0.73, respectively. Radiologist #2 showed PI-FAB sensitivity/specificity/PPV/NPV/accuracy/AUC of 62%/68%/42%/83%/66%/0.65, respectively; TARGET 62%/68%/42%/83%/66%/0.66. Logistic regression showed no difference in AUC for PI-FAB and TARGET (0.69; 95%CI 0.59-0.79 vs. 0.71; 95%CI 0.62-0.80, p = 0.696). Inter-reader agreement was fair for PI-FAB (k = 0.35, p = 0.02) and moderate for TARGET (k = 0.45, p < 0.01). CONCLUSION: PI-FAB and TARGET scoring systems perform similarly in diagnostic performance, though inter-reader agreement is limited. Clinical parameters may be needed to fully assess csPCa recurrence after focal therapy.