Comparison of diffusion-weighted imaging mono-exponential mode with diffusion kurtosis imaging for predicting pathological grades of clear cell renal cell carcinoma

Abstract

PurposeTo evaluate the role of diffusion kurtosis imaging (DKI11DKI: diffusion kurtosis imaging.) in the characterization of clear cell renal cell carcinoma (ccRCC22ccRCC: clear cell renal cell carcinoma.) compared with standard diffusion-weighted imaging (DWI33DWI: diffusion-weighted imaging.). Methods89 patients with histologically proven ccRCC were evaluated by DKI and DWI on a 3-T scanner. All ccRCCs were classified as grade 1–4 according to the Fuhrman classification system. The apparent diffusion coefficient (ADC44ADC : apparent diffusion coefficient.), fractional anisotropy (FA55FA: fractional anisotropy.), mean diffusivity (MD66MD: mean diffusivity.), mean kurtosis (MK77MK: mean kurtosis.), axial kurtosis (Ka88Ka: axial kurtosis.) and radial kurtosis (Kr99Kr: radial kurtosis.) values were recorded. The differences in DWI and DKI parameters were evaluated by independent-sample t test and a receiver operating characteristic (ROC1010ROC: receiver operating characteristic.) analysis was performed. The DeLong test was performed to compare the ROCs. ResultsCompared to normal renal parenchyma, ADC and MD values of ccRCC decreased and MK, Ka, and Kr values increased (p < 0.05). ADC and MD values of ccRCC decreased with the increase in pathological grade, while MK, Ka, and Kr values were increased (p < 0.05). ADC could discriminate G1 vs G3, G1 vs G4, G2 vs G3, G2 vs G4, and G3 vs G4 (p < 0.05) except for G1 vs G2 (p > 0.05). Ka and Kr could discriminate G1 vs G2, G1 vs G3, G1 vs G4, G2 vs G4, and G3 vs G4 (p < 0.05) except for G2 vs G3 (p > 0.05). MD and MK could discriminate G1 vs G2, G1 vs G3, G1 vs G4, G2 vs G3, G2 vs G4, and G3 vs G4 (p < 0.05). The AUC of MK was the highest. The DeLong test showed that there were significant differences regarding ROCs between ADC/MK, ADC/Ka, ADC/Kr in grading G1/G2, and ADC/MK, MK/Ka in grading G3/G4 (p < 0.05). ConclusionDKI was superior compared to the mono-exponential mode of DWI in grading ccRCC.