Apparent Diffusion Coefficient Value of Diffusion-Weighted Imaging for Hepatocellular Carcinoma: Correlation with the Histologic Differentiation and the Expression of Vascular Endothelial Growth Factor

Objective: To evaluate whether the histopathological differentiation and the expression of vascular endothelial growth factor (VEGF) of hepatocellular carcinoma (HCC) do show correlation with the apparent diffusion coefficient (ADC) value on diffusion-weighted imaging (DWI). Materials and Methods: Twenty-seven HCCs from 27 patients who had undergone preoperative liver MRI (1.5T) and surgical resection were retrospectively reviewed. DWI was obtained with a single-shot, echo-planar imaging sequence in the axial plane (b values: 0 and 1,000 sec/$mm^2$). On DWIs, the ADC value of the HCCs was measured by one radiologist, who was kept 'blinded' to the histological findings. Histopathologically, the differentiation was classified into well (n = 9), moderate (n = 9) and poor (n = 9). The expression of VEGF was semiquantitatively graded as grade 0 (n = 8), grade 1 (n = 9) and grade 2 (n = 10). We analyzed whether the histopathological differentiation and the expression of VEGF of the HCC showed correlation with the ADC value on DWI. Results: The mean ADC value of the poorly-differentiated HCCs ($0.9{\pm}0.13{\times}10^{-3}\;mm^2/s$) was lower than those of the well-differentiated HCCs ($1.2{\pm}0.22{\times}10^{-3}\;mm^2/s$) (p = 0.031) and moderately-differentiated HCCs ($1.1{\pm}0.01{\times}10^{-3}\;mm^2/s$) (p = 0.013). There was a significant correlation between the differentiation and the ADC value of the HCCs (r = -0.51, p = 0.012). The mean ADC of the HCCs with a VEGF expression grade of 0, 1 and 2 was $1.1{\pm}0.17$, $1.1{\pm}0.21$ and $1.1{\pm}0.18{\times}10^{-3}\;mm^2/s$, respectively. The VEGF expression did not show correlation with the ADC value of the HCCs (r = 0.07, p = 0.74). Conclusion: The histopathological differentiation of HCC shows inverse correlation with the ADC value. Therefore, DWI with ADC measurement may be a valuable tool for noninvasively predicting the differentiation of HCC.