RESUMO
PURPOSE: To elucidate a role of apparent diffusion coefficient (ADC) value as a biomarker of bladder cancer, we investigated its associations with Ki-67 labeling index (LI) along with classical clinicopathological prognosticators. MATERIALS AND METHODS: Diffusion-weighted MRI (DW-MRI) at 1.5 Tesla using b-values of 0, 500, 1000, and 2000 s/mm(2) was prospectively taken before transurethral resection by 132 bladder cancer patients. ADC value of index tumors was measured and compared with clinicopathological prognosticators including Ki-67 LI. RESULTS: ADC value was significantly lower in tumors with higher Ki-67 LIs, sessile tumors (versus papillary), larger tumors, higher grade disease, and higher T stage disease. ADC value inversely correlated with Ki-67 LI (ρ = -0.57; P < 0.0001). On multiple regression analysis, T stage and Ki-67 LI significantly correlated with ADC value. The Akaike information criterion confirms these two parameters constitute the best model for determining ADC value. Similarly, T stage and ADC value significantly correlated with Ki-67 LI and these two parameters composed the best model for predicting Ki-67 LI. CONCLUSION: ADC value would reflect T stage and Ki-67 LI, representing invasive and proliferative potential, respectively. ADC value is likely to serve as a biomarker reflecting aggressiveness of bladder cancer.