Utility of computed diffusion-weighted MRI for predicting aggressiveness of prostate cancer

PurposeTo investigate the value of computed (c) diffusion-weighted imaging (DWI) in assessing prostate cancer aggressiveness. Materials and MethodsFifty-five patients with peripheral zone prostate cancer who underwent prebiopsy 1.5T magnetic resonance imaging (including native DWI at b-values of 0 and 1000 s/mm(2)) were included. cDWI signal intensities of peripheral zone prostate cancer and nonmalignant prostate tissue were measured. Association between changes in monoexponentially calculated cDWI signals according to different b-values and primary Gleason grades were assessed. ResultsThe cDWI signal intensity of prostate cancer was lower at b=0 s/mm(2) and higher at b=1000 s/mm(2) compared to nonmalignant prostate tissue. The b-value at which the signal intensities of prostate cancer and nonmalignant prostate tissue were equal was defined as the iso-b-value. On multivariate analysis, only the iso-b-value was a significant predictor of primary Gleason grade 4/5 cancer (P=0.001). The area under the curve (AUC) of the iso-b-value for diagnosing primary Gleason grade 4/5 cancer was 0.94, and significantly higher than that of the tumor apparent diffusion coefficient (ADC) value with an AUC of 0.68 (P<0.001). ConclusioncDWI with iso-b-value-based semiquantitative analysis was found to be useful for predicting the aggressiveness of prostate cancer and may potentially outperform tumor ADC measurements in this setting. Level of Evidence: 3 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;46:490-496