Luminal water imaging (LWI) is an MRI technique that detects regions of decreased lumen volume in prostate. Recent studies on LWI have shown promising results regarding the accuracy of this technique in diagnosis of prostate cancer. However, to the best of our knowledge no study has yet compared the performance of LWI against the current clinical assessment. In this study, we perform a comparison between the diagnostic accuracy of LWI with the PI-RADSv2.1 assessment. Our results show that LWI performs similar to the PI-RADSv2.1 in the entire prostate and peripheral zone, and outperforms significantly in transition zone.