Direct comparison of PI-RADS version 2 and version 1 regarding interreader agreement and diagnostic accuracy for the detection of clinically significant prostate cancer.

PURPOSE: to simultaneously evaluate interreader agreement and diagnostic accuracy in the of PI-RADS v2 and compare it to v1.

METHODS: A total of 67 patients (median age 65.3 y, range 51.2-78.2 y; PSA 6.8μg/L, 0.2-33μg/L) undergoing MRI of the prostate and subsequent transperineal template biopsy within ≤6 months from MRI were included. Four readers from two institutions evaluated the likelihood of prostate cancer using PI-RADS v1 and v2 in two separate reading sessions ≥3 months apart. Interreader agreement was assessed for each pulse-sequence and for total PI-RADS scores using the intraclass correlation coefficient (ICC). Differences were considered significant for non-overlapping 95%-confidence intervals. Diagnostic accuracy was assessed with the area under the receiver operating characteristic curve (AZ ). A p-value <0.05 was considered statistically significant.

RESULTS: Interreader agreement for DCE-scores was good in v2 (ICC2 =0.70; 95% CI: 0.66-0.74) and slightly lower in v1 (ICC1 =0.64, 0.59-0.69). Agreement for DWI scores (ICC1 =0.77, ICC2 =0.76) as well as final PI-RADS scores per quadrant were nearly identical (ICC1 =ICC2 =0.71). Diagnostic accuracy showed no significant differences (p=0.09-0.93) between v1 and v2 in any of the readers (range: AZ =0.78-0.88).

CONCLUSION: PI-RADS scores show similar interreader agreement in v2 and v1 at comparable diagnostic performance. The simplification of the DCE interpretation in v2 might slightly improve agreement while not negatively affecting diagnostic performance.