Contrast-enhanced dynamic and diffusion-weighted MR imaging at 3.0T to assess aggressiveness of bladder cancer

Abstract

Background: Diffusion weighted magnetic resonance imaging (DWI) and dynamic contrast-enhanced (DCE) MRI have been considered useful for pathological staging and histological grading in bladder cancer. To our knowledge, no study has combined the two imaging modalities together to assess aggressiveness of bladder cancer.

Objective: To assess the clinical aggressiveness of bladder cancer with DCE MRI and DWI at 3.0T.

Materials and methods: A total of 59 patients with 69 pathologically confirmed tumor lesions were included in this study. All patients underwent MR examination at 3.0T basing on DWI and DCE imaging. Tumor staging and histological grade were evaluated. The aggressiveness of bladder cancer was classified as low-, intermediate-, or high-aggressiveness according to its pathological phenotype. Apparent diffusion coefficient (ADC) value and semi-quantitative parameters (wash-in rate and wash-out rate) were determined. The correlation between clinical aggressiveness and ADC value, wash-in rate and wash-out rate were analyzed. In addition, the diagnostic accuracy of the diffusion and semi-quantitative parameters were estimated using receiver operating characteristic curve (ROC).

Results: Aggressiveness of bladder cancer is negatively correlated with ADC value (r=-0.705, p<0.0001) and wash-out rate (r=-0.719, p<0.0001). The tumor ADC value is positively correlated with wash-out rate (r=0.555, p<0.0001). The diagnostic specificity and accuracy using tumor ADC value and wash-out for the tumor with size <24mm were better than that tumors with size ≥24mm. The sensitivity, specificity and accuracy of ADC and wash-out rate in combination in diagnosis of bladder cancer aggressiveness were 96.7%, 94.9% and 95.7%, respectively. ROC curve revealed the diagnostic performance of aggressiveness of bladder cancer using ADC value and wash-out rate were 0.928 (cut-off value: 0.905×10(-3)mm(2)/s) and 0.891 (cut-off value: 0.685min(-1)), respectively.

Conclusion: ADC and wash-out rate derived from DWI and DCE-MRI at 3.0T have good potential to assess the aggressiveness of bladder cancer and the accuracy was greater for ADC than for semi-quantitative parameters.

Keywords: Apparent diffusion coefficient; Bladder cancer; Dynamic contrast enhancement; Magnetic resonance imaging.