1981. Added Value of PIRADSv2.1 Guidelines for Characterization of Category 3 Transition Zone Lesions
Authors * Denotes Presenting Author
  1. Melina Hosseiny *; UCLA
  2. Voraparee Suvannarerg; UCLA
  3. Teeravut Tubtawee; UCLA
  4. Ely Felker; UCLA
  5. David Lu; UCLA
  6. Preeti Ahuja; UCLA
  7. Steven Raman; UCLA
To assess the detection rate of clinically significant prostate cancer (csPCa) in Prostate Imaging-Reporting and Data System version 2.1 (PIRADSv2.1) category 3 transition zone (TZ) lesions in comparison with PIRADSv2 on 3 Tesla muliparametric MR Imaging (3TmpMRI).

Materials and Methods:
This IRB-approved, HIPAA-compliant, single-center observational study cohort was derived from database of 846 consecutive men who underwent 3TmpMRI prior to radical prostatectomy (n=467) or in bore MR-guided biopsy (n=379) between 2013-2019. Each 3TmpMRI was scored prospectively based upon PIRADSv2 and re-scored later by two GU radiologists using PIRADSv2.1 criteria in consensus, blinded to the clinical information. Patients who had a TZ lesion ranked as category 3 on either PIRADS v2 or v2.1 were included. The outcomes of lesions downgraded from v2 category 3 or upgraded from v2 category 2 were assessed including the proportion of csPCa defined as Gleason Grade (GG) group > 2. Significance in differences in detection rate was assessed using Chi-square test.

Of 106 men with TZ lesions scored as PIRADSv2 category 3, detection rate of PCa and csPCa was 45.3% (48/106) and 24.5% (26/106), respectively. On review, 22.6% (24/106) of PIRADSv2 category 3 lesions were downgraded to category 2 on PIRADS v2.1, of which, 22/24 were benign and 2/24 were small volume GG 1 PCa, without csPCa. Of the 86 men with TZ lesions scored as PIRADSv2.1 category 3, seven were upgraded from PIRADS v2 score 2, including 1 csPCa, one GG 1 PCa and five benign lesions. On PIRADSv2.1 reinterpretation, the number of category 3 TZ lesions decreased by 16% (P<.001), while the detection rate of PCa and csPCa (53.9%, (48/89) and 30.3%, (27/89) respectively) increased (P<.001) compared to PIRADSv2.

Compared to PIRADSv2, PIRADSv2.1 reinterpretation resulted in a 16% decrease in scoring TZ lesions as category 3 and 6% increase in the detection of csPCa in this subcohort. No csPCa was observed in TZ lesions which were downgraded in PIRADSv2.1 reinterpretation. Downgrading non-significant TZ lesion in PIRADSv2.1 could potentially decrease the number of un-necessary prostate biopsies.