Diagnostic performance of low b-value versus high b-value diffusion kurtosis imaging in the detection of renal cell carcinoma: a comparative study

Abstract

Background Although diffusion kurtosis imaging (DKI) values of renal tumors have been well analyzed by previous studies, no study has yet examined the b-values of DKI with respect to renal cell carcinoma (RCC). The aim of the current study was to produce a quantitative comparison of the potential of low b-value (0, 500, 1000 s/mm² ) versus high b-value (0, 1000, 2000 s/mm² ) obtained from DKI in the differentiation of RCC. Methods A total of 146 patients with pathologically confirmed RCC, including 103 patients with clear cell RCC (ccRCC) and 43 patients with non-ccRCC were examined.The DKI derived parametric results, i.e., Mean Diffusivity (MD), Fractional anisotropy(FA), Mean kurtosis (MK), Kurtosis anisotropy (KA) and Radial kurtosis (RK), as well as signal-to-noise ratio (SNR) and scanning time were compared. Receiver operating characteristic (ROC) curve analysis was used for obtaining the optimum diagnostic thresholds, the area under the ROC curve (AUC), sensitivity, specificity and accuracy of these parameters. Results The mean SNRs of DKI at low b values were higher than that of high b values (14.2 ± 2.1 vs. 9.1 ± 1, p < 0.05). The scanning time of low b-values DKI was shorter than that of high b-values DKI (8.6 ± 1.6 mins vs. 17.6 ± 2.3 mins, p < 0.05). The MD values of ccRCCs were higher than those of non-ccRCCs (p < 0.05), however, MK, KA and RK values of ccRCCs were lower than those of non-ccRCCs (p < 0.05). ROC curve analyses showed that MD values at high b values had the highest diagnostic efficacy in differentiating ccRCC from non-ccRCC. For pairwise comparisons of ROC curves and diagnostic efficacy, DKI at low b-values was worse than high b-values analysis (p < 0.05). Conclusion High b-values DKI analysis showed a superior diagnostic efficacy to low b-values DKI analysis in differentiating ccRCC from non-ccRC.