1702. Second-Opinion Reads in Prostate MRI: Added Value of Subspecialty Interpretation and Review at Multidisciplinary Rounds
Authors * Denotes Presenting Author
  1. Jessica Li *; University of British Columbia
  2. Drew Phillips; University of British Columbia
  3. Amanda Wong; University of British Columbia
  4. Rehab Mohammedeid; University of British Columbia
  5. Peter Black; University of British Columbia
  6. Alison Harris; University of British Columbia
  7. Silvia Chang; University of British Columbia
Interobserver variability in multiparametric prostate MRI interpretation for cancer detection has been investigated since the introduction of PI-RADS, however no study has compared reporting between community and tertiary care centres. This study aims to evaluate how often second-opinion review of prostate MRIs by multidisciplinary review board at a tertiary care centre is discordant with the initial community radiologist interpretation.

Materials and Methods:
Cases were collected retrospectively from multidisciplinary prostate MRI rounds from 2017-2019 at a single tertiary care centre. Patients with suspected prostate cancer or on active surveillance were referred for consideration of TRUS/MRI fusion biopsy based on community-read prostate MRIs. All MRIs were re-read by subspecialized abdominal radiologists and a PI-RADS score assigned. Targeted fusion and 8-12 core systematic biopsy was performed in patients with PIRADS=3 lesions. Cohen kappa values were used to quantify interobserver agreement. Positive predictive value (PPV) was used to determine accuracy of PIRADS score for detection of clinically significant prostate cancer (csPCa) (Grade Group =2).

266 lesions in 215 patients were reviewed and 186 lesions in 161 patients biopsied. The PI-RADS score was concordant in 56.9% of lesions, downgraded in 29.2%, and upgraded in 5.0%. 23 lesions were missed, 6 of which contained csPCa. Agreement between community and tertiary centre interpretation was fair (kappa=0.403), with greater agreement for PI-RADS= 4 (kappa=0.597) than PI-RADS= 3 (kappa=0.493), and peripheral zone (kappa=0.496) than transition zone lesions (kappa=0.294). Prevalence of csPCa in biopsied lesions was 37.6%. In PI-RADS = 4 lesions, the PPV for csPCa was higher in tertiary centre than community interpretations (54.0% vs 43.5%). Re-interpretation altered clinical management in 56 patients.

There is variability in community and tertiary care centre interpretation of prostate MRI in cancer detection. Most discrepancies are in overcalling benign lesions rather than missing clinically significant cancers. Overall concordance rates were improved for higher grade and peripheral zone lesions. These discrepancies in the interpretation of prostate MRI for cancer detection between community and tertiary care centres highlight the need for ongoing education and feedback.