Apparent diffusion coefficient ratio correlates significantly with prostate cancer gleason score at final pathology

PURPOSE: To evaluate the correlation between apparent diffusion coefficient measurements (ADCtumor and ADCratio ) and the Gleason score from radical prostatectomy specimens. MATERIALS AND METHODS: Seventy-one patients with clinically localized prostate cancer scheduled for radical prostatectomy were prospectively enrolled. Multiparametric magnetic resonance imaging (MRI) was performed prior to prostatectomy and mean ADC values from both cancerous (ADCtumor ) and benign (ADCbenign ) tissue were measured to calculate the ADCratio (ADCtumor divided by ADCbenign ). The ADC measurements were correlated with the Gleason score from the prostatectomy specimens. RESULTS: The association between ADC measurements and Gleason score showed a significant negative correlation (P < 0.001) with Spearman's rho for ADCtumor (-0.421) and ADCratio (-0.649). There was a statistically significant difference between ADC measurements and the Gleason score for all tumors (P = 0.001). Receiver operating characteristic curve analysis showed an overall area under the curve (AUC) of 0.73 (ADCtumor ) to 0.80 (ADCratio ) in discriminating Gleason score 6 from Gleason score ≥7 tumors. The AUC changed to 0.72 (ADCtumor ) and 0.90 (ADCratio ) when discriminating Gleason score ≤7(3+4) from Gleason score ≥7(4+3). CONCLUSION: ADC measurements showed a significant correlation with tumor Gleason score at final pathology. The ADCratio demonstrated the best correlation compared to the ADCtumor value and radically improved accuracy in discriminating Gleason score ≤7(3+4) from Gleason score ≥7(4+3) tumors.