Investigation of the Non-Gaussian Water Diffusion Properties in Bladder Cancer Using Diffusion Kurtosis Imaging: A Preliminary Study

Objective: The objective of this study was to investigate the non-Gaussian water diffusion properties in bladder cancer and assess the efficacy of diffusion kurtosis imaging for estimating the histological grade of bladder cancer. Methods: Twenty-one patients with bladder cancer (high-grade, 12; low-grade, 9) and 17 negative controls who underwent preoperative 3.0-T magnetic resonance imaging including multi-b value diffusion-weighted imaging (b values, 0, 500, 800, 1200, 1500, and 2000 s/mm(2)) were included. Besides apparent diffusion coefficient (ADC) maps, diffusion kurtosis imaging maps for diffusion coefficient (D-app) and kurtosis (K-app) were also obtained. Data were analyzed using the Mann-Whitney U test, Spearman correlation test, and receiver operating characteristic curves. Results: Bladder cancer showed significantly lower ADC values, lower D-app values, and higher K-app values compared with normal bladder wall (all P < 0.001). The K-app values were significantly higher in high-grade than in low-grade tumors (P = 0.007). Significant correlations were found between D-app and ADC (r = 0.901, P < 0001) as well as between K-app and ADC (r = -0.910, P < 0.001). The areas under the receiver operating characteristic curve were 0.843 and 0.796 for estimation of high-grade bladder cancer by using the K-app values and ADC values, respectively. Conclusions: Diffusion in bladder cancer follows a non-Gaussian behavior. The new metric K-app may potentially serve as a biomarker of grade of bladder cancer.