Quantitative analysis for detection and grading of hepatocellular carcinoma: Comparison of diffusion kurtosis imaging, intravoxel incoherent motion and conventional diffusion-weighted imaging

The aim of the present study was to compare the diagnostic performance of the main parameters derived from diffusion kurtosis imaging (DKI), intravoxel incoherent motion (IVIM) and diffusion-weighted imaging (DWI) regarding the detection and grading of hepatocellular carcinoma (HCC). A total of 78 patients diagnosed with HCC by biopsy were prospectively enrolled in the present study, and underwent routine magnetic resonance imaging (MRI), DWI, IVIM, DKI and contrast-enhanced MRI prior to surgery. Measurements, including mean diffusivity (MD), mean diffusional kurtosis (MK), true diffusion coefficient (D), pseudo-diffusion coefficient (D*), perfusion fraction (f) and apparent diffusion coefficient (ADC), were compared with grading HCC using one-way ANOVA followed by the Student-Neuman-Keuls-q post-hoc test. Spearman's correlation coefficient was used to analyze the correlation between each parameter and pathological grade, while the diagnostic efficiency was evaluated using a receiver operating characteristic (ROC) curve. The 78 patients enrolled in the present study were grouped into highly (n=22), moderately (n=41) or poorly (n=15) differentiated HCC groups according to the criteria of Pathology and Genetics Tumors of the Digestive System. MK values differed significantly between different grades and decreased gradually with the degree of tumor differentiation. The MD, D and ADC values in the highly differentiated HCC group were significantly higher than those in the moderately or poorly differentiated HCC groups (all P<0.001), whereas no significant differences were observed in D* or f (P=0.502 and P=0.853, respectively). A significant correlation was observed between MK, MD, D and ADC, and HCC grades (r=0.705, r=0.570, r=0.423 and r=0.687, respectively). The comparison of the ROC curves of MK, MD, D, ADC, D* and f values for predicting highly differentiated HCC suggested that MK and D were the best indicators for predicting highly differentiated HCC, as the area under the ROC curve (AUC) of MK and D was significantly higher than that of ADC (Z=2.247 and 2.428, P=0.025 and 0.016, respectively), whereas non-statistically significant differences were observed in the AUC values between MK and D (Z=0.072; P=0.942). The DKI-derived MK and IVIM-derived D values had a similar diagnostic performance and were superior to ADC in discriminating the histological grade of HCC. In addition, the combination of MK and D values exhibited an improved diagnostic performance.