Comparative analysis of TARGET and PI-FAB scores in mpMRI surveillance after HIFU therapy for localized prostate cancer.

Purpose: To validate the TARGET score for multiparametric MRI (mpMRI) following high-intensity focused ultrasound (HIFU) therapy and to compare its diagnostic performance to the PI-FAB score.

Methods: This IRB-approved retrospective, single-center study included 83 patients who underwent follow-up mpMRIs and subsequent prostate biopsies at 6, 12, and 36 months after HIFU therapy for localized prostate cancer (05/2014-10/2021). Two radiologists independently assessed TARGET and PI-FAB scores. Inter-reader agreement was assessed using Gwet's AC1. Diagnostic performance was analyzed for both scores using histopathologic biopsy results as the reference standard.

Results: Follow-up mpMRIs of 83 patients were evaluated. Inter-reader agreement was substantial to almost perfect for both scores (AC1 = 0.78-0.83/ 0.70-0.96; TARGET/PI-FAB, ranges across the different follow-up intervals). Both the TARGET and PI-FAB score demonstrated high overall specificities (TARGET: 92 %/89 %; PI-FAB: 90 %/90 % for Reader 1/Reader 2) and NPVs (87 %/81 %; 84 %/80 %). Overall sensitivities (55 %/35 %; 45 %/30 %) and PPVs (69 %/50 %; 60 %/50 %) for both scores were comparatively lower. No statistically significant differences in diagnostic performance were identified between the two scores and readers (p > 0.05).

Conclusion: Both scores demonstrated comparable diagnostic performance particularly in excluding in-field clinically significant prostate cancer recurrence post-HIFU and thus may be valuable, non-invasive tools as part of comprehensive monitoring strategies after HIFU treatment. However, challenges in detecting local tumor recurrence after HIFU therapy persist and require further refinement and optimization of the scores.