Clinical Utility of Apparent Diffusion Coefficient (ADC) Values in Patients With Prostate Cancer: Can ADC Values Contribute to Assess the Aggressiveness of Prostate Cancer?

Purpose: To retrospectively evaluate the relationship between apparent diffusion coefficient (ADC) values and Gleason score (GS) in prostate cancer. Methods: A total of 60 patients who underwent radical prostatectomy for clinically localized prostate cancer were selected for this study. Diffusion-weighted magnetic resonance (MR) images were obtained using a 1.5 T system. ADC values were analyzed between three groups: GS of 6 or less (n = 7); GS of 7 (n = 37); and GS of 8 or higher (n = 16). ADC values of the three GS groups were statistically analyzed in order to determine the relationship with GS. In the 37 patients with GS = 7 the difference in ADC values between GS 3+4 and GS 4+3 was analyzed. Results: Median ADC values (10(-3) mm(2)/s) of the three GS groups were 1.04 (GS = 6 or less), 0.867 (GS = 7), and 0.729 (GS = 8 or higher). Although there was considerable overlap among the groups, the differences in ADC were statistically significant (P < 0.0001). There was a significant inverse correlation between GS and ADC values (z = -0.437, P < 0.0005). Median ADC values (10(-3) mm(2)/s) of GS 3+4 and GS 4+3 patients were 0.88 and 0.814, respectively (P< 0.05). Conclusion: ADC values showed a negative correlation with GS. Pathologically, however, there was considerable intrasubject heterogeneity.