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

Background The 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 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%/74%, respectively; TARGET had values of 67%/79%/50%/88%/76%/73%, respectively. Radiologist #2 showed PI-FAB sensitivity/specificity/PPV/NPV/accuracy/AUC of 62%/68%/42%/83%/66%/65%, respectively; TARGET 62%/68%/42%/83%/66%/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 = 0.352, p = 0.02) and moderate for TARGET (k = 0.445, 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.