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Limited reproducibility of PI-RADS v2.1 upgrading rule subcategorization in MRI-visible peripheral zone lesions: A
Fernando Morbeck Almeida Coelho1, Thais Caldara Mussi1, Larissa Fernandes Moreira1
1Department of Radiology, Hospital Israelita Albert Einstein, Sao Paulo, SP, Brazil, Albert Einstein Avenue, 627/701 - Morumbi Zip code: 05652-900, Sao Paulo, SP, Brazil.
Purpose:
To evaluate inter-reader reproducibility of PI-RADS v2.1 upgrading rule subcategorization in prelocalized MRI-visible peripheral zone (PZ) lesions and assess its association with lesion-level clinically significant prostate cancer (csPCa) yield at MRI-targeted biopsy.
Methods:
This retrospective single-center lesion-level study included 310 men with 375 MRI-visible PZ lesions who underwent 3-T multiparametric MRI followed by MRI-TRUS fusion-targeted biopsy. Three radiologists independently rescored prelocalized lesions using PI-RADS v2.1. PI-RADS 4 lesions were classified as upgraded when assigned DWI score 3 with positive dynamic contrast-enhanced (DCE) imaging, or non-upgraded when assigned DWI score 4 regardless of DCE status. csPCa was defined as ISUP grade group ≥ 2. Inter-reader agreement was assessed, and generalized estimating equations were used to account for within-patient clustering.
Results:
csPCa was present in 176/375 lesions (47 %). Inter-reader agreement was moderate-to-substantial for overall PI-RADS categorization, but only fair-to-moderate for PI-RADS 4 subcategorization (Gwet's AC1 range, 0.29-0.57). Across readers, csPCa yield ranged from 39 % to 68 % for upgraded PI-RADS 4 lesions and from 63 % to 81 % for non-upgraded lesions. The magnitude and significance of this subgroup contrast varied by reader.
Conclusion:
In this multireader, lesion-level, targeted-biopsy cohort, subcategorization of the PI-RADS 4 upgrading rule showed limited reproducibility. Although nonupgraded lesions generally showed higher csPCa yield, subgroup-specific estimates were reader-dependent, supporting cautious interpretation of this split.
Insights
The subcategorization of Prostate Imaging Reporting and Data System (PI-RADS) v2.1 upgrading rule for MRI-visible prostate lesions showed limited reader reproducibility. This impacts the reliability of differentiating clinically significant prostate cancer (csPCa) yield from these lesions.
Area of Science:
- Radiology
- Urology
- Oncology
Background:
- Prostate cancer detection relies on multiparametric MRI (mpMRI) and the Prostate Imaging Reporting and Data System (PI-RADS).
- PI-RADS v2.1 introduced an upgrading rule for peripheral zone (PZ) lesions, aiming to refine risk stratification.
- Reproducibility of this rule is crucial for consistent clinical decision-making.
Purpose of the Study:
- To assess the inter-reader reproducibility of PI-RADS v2.1 upgrading rule subcategorization.
- To evaluate the association between subcategorized PI-RADS 4 lesions and clinically significant prostate cancer (csPCa) yield.
- To analyze the impact of this subcategorization on MRI-targeted biopsy outcomes.
Main Methods:
- Retrospective analysis of 375 MRI-visible PZ lesions from 310 men who underwent mpMRI and MRI-TRUS fusion-targeted biopsy.
- Three radiologists independently rescored prelocalized lesions using PI-RADS v2.1 criteria.
- PI-RADS 4 lesions were classified as 'upgraded' (DWI score 3 + positive DCE) or 'non-upgraded' (DWI score 4).
- Clinically significant prostate cancer (csPCa) defined as ISUP grade group ≥ 2.
Main Results:
- csPCa was detected in 47% of lesions.
- Inter-reader agreement was moderate-to-substantial for overall PI-RADS but only fair-to-moderate for PI-RADS 4 subcategorization (Gwet's AC1: 0.29-0.57).
- csPCa yield varied significantly across readers for both upgraded (39%-68%) and non-upgraded (63%-81%) PI-RADS 4 lesions.
Conclusions:
- Subcategorization of the PI-RADS 4 upgrading rule demonstrated limited inter-reader reproducibility.
- While non-upgraded lesions generally had higher csPCa yield, these estimates were reader-dependent.
- Cautious interpretation of PI-RADS 4 subcategories is recommended due to variability in reproducibility and csPCa yield.
