Can DW-MRI, with its ADC values, be a reliable predictor of biopsy outcome in patients with suspected prostate cancer?

Purpose To relate the multiparametric magnetic resonance imaging (mp-MRI) of patients with suspect peripheral prostate cancer (PCa) to the results of the subsequent biopsy: in particular to explore whether DWI and ADC can predict the biopsy outcome and to investigate the relation between ADC and Gleason score (GS). Materials and methods 175 consecutive patients who underwent 1.5 T mp-MRI followed by prostate biopsy were retrospectively analyzed by two independent radiologists. ADC values were measured in the peripheral suspect lesion areas (ADC SL ) and in the contralateral zones (ADC NSL ) obtaining ADC norm = ADC SL /ADC NSL . Results on T2W images, DWI, ADC values, and perfusion studies were matched to their corresponding biopsy. Results Negative DWI and T2W had 100% negative predictive value (NPV). When DWI was positive, ADC SL > 0.90 × 10 > 0.90 × 10 −3 mm 2 /s (ADC norm > 0.60) identified by the ROC curve (AUC = 0.80) corresponded to NPV = 85%. In positive biopsies, ADC SL and ADC norm decreased significantly from GS = 6 to GS ≥ 8 with Spearman coefficient ρ = −0.40 and ROC curve AUC = 0.72. Conclusion mp-MRI allows a reliable prediction of a negative biopsy through the values of DWI, T2W, and ADC. In positive biopsies, there is a moderate correlation between ADC and the various GS levels.