Diffusion- weighted and diffusion kurtosis imaging analysis of microstructural differences in clear cell renal cell carcinoma: a comparative study

Objective: To quantitatively compare the diagnostic values of conventional diffusion-weighted imaging (DWI) and diffusion kurtosis imaging (DKI) analysis of microstructural differences for clear cell renal cell carci-noma (CRCC).Methods: A total of 108 patients with pathologically confirmed CRCC, including 38 Grade I, 37 Grade II, 18 Grade III and 15 Grade IV, were enrolled and divided into groups according to tumor grade [low grade (I+II, n = 75) and high grade (III+IV, n = 33)]. Apparent diffusion coefficient (ADC), mean diffusivity (MD), mean kurtosis (MK), kurtosis anisotropy (KA) and radial kurtosis (RK) were performed.Results: Both the ADC (r =-0.803) and MD (-0.867) values showed a negative correlation with tumor grading (p < 0.05) and MK (r = 0.812), KA (0.816) and RK (0.853) values a positive correlation with tumor grading (p <0.05). Mean FA values showed no significant differences among CRCC grades (p > 0.05). ROC curve analyses showed that MD values had the highest diagnostic efficacy in differentiating low/high and II/III tumor grading. MD values gave AUC: 0.937 (0.896); sensitivity: 92.0% (86.5%); specificity: 78.8% (77.8%) and accuracy: 90.7% (87.3%). ADC performed worse than MD, MK, KA or RK (all p < 0.05) during pair -wise comparisons of ROC curves to show diagnostic efficacy. Conclusion: DKI analysis performs better than ADC in differentiating CRCC grading.Advances in knowledge: Both the ADC and MD values correlated negatively with CRCC grading.The MK, KA and RK values correlated positively with CRCC grading.MD values had the highest diagnostic efficacy in differentiating low/high and II/III CRCC grading.