Luminal water imaging (LWI) is an emerging technique for noninvasive characterization of prostate cancer (PCa) aggressiveness. The goal of our ongoing study is to compare the diagnostic performance of LWI to DWI for assessment of PCa aggressiveness. We observed that the luminal water fraction (LWF) from LWI showed high diagnostic performance for differentiation between Grade Group (GG) 2 (i.e. Gleason 3+4) and GG 3 and higher (i.e. Gleason 4+3 and higher) cancers (AUC=0.86), while ADC showed an AUC of 0.62. These initial results suggest additional value of LWI for PCa characterization, which will be verified in a larger cohort.