Abstract

Aim: We aimed to compare the inter- and intra-observer variability and diagnostic performance of PI-RADS v2 and Likert scoring in the evaluation of prostate cancer on multiparametric prostate MR imaging.
Material and Methods: MRI findings of 53 patients who had histopathologic diagnosis of prostate cancer and 51 patients who had one or more negative transrectal ultrasound guided prostate biopsy were evaluated retrospectively. The images were assessed by three independent observers blinded to histopathologic results of the patients. Intra-observer and inter-observer variability were evaluated by Cohen’s Kappa coefficient for all possible pairs of observers. ROC curve analysis was used to determine AUC to evaluate diagnostic performance of Likert and PI-RADS v2 scoring with a 1.5T MR in the diagnosis of prostate cancer.
Results: Kappa values for 4 or higher PI-RADS v2 scores were calculated and κ=0.59-0.71 for intra-observer and κ=0.48-0.67 for inter-observer variability were obtained. κ=0.54-0.69 for intra-observer and κ=0.42-0.75 for inter-observer reliability were obtained for 4 or higher Likert scoring. AUC was 72% for PI-RADS v2 scores and was 75.9% for Likert scores for determining Gleason 6 or higher prostate cancers. There was not a statistically significant difference in the comparison of Likert and PI-RADS v2 ROC curves.
Conclusion: PI-RADS v2 has no significant superiority compared to Likert scoring in intra-observer and inter-observer reliability. Likert and PI-RADS v2 scoring has no difference in the terms of diagnostic capability of prostate cancers.

Key words: Prostate Cancer; Magnetic Resonance Imaging; PI-RADS v2; Likert.