Histological grade of hepatocellular carcinoma correlates with arterial enhancement on gadoxetic acid-enhanced and diffusion-weighted MR images

To retrospectively determine the correlation between heptic tumor signal intensity on gadoxetic acid-enhanced and diffusion-weighted MR images and histopathological grading of hepatocellular carcinoma (HCC). We retrospectively reviewed the MR images of 79 patients with 141 surgically resected HCCs. The signal intensity and its relationship with histopathological grade were assessed. We measured the apparent diffusion correlation (ADC) values and calculated arterial enhancement ratios, washout ratios, and relative intensity ratios of HCCs relative to the surrounding liver parenchyma in gadoxetic-enhanced MR images in order to determine their relationship to the histological grade. Morphological evaluation showed that larger tumor size and extrahepatic extension were associated with higher histologic grade (p < 0.01). Multivariate logistic regression showed that low ADC value and low relative intensity ratio in the arterial phase (RIRa) predict high histological grade. ADC value (cut-off 1.7 x 10(-3) mm(2)/s, sensitivity 82.4%, specificity 83.2%) was the best predictor of well-differentiated HCC, and RIRa (cut-off 0.93, sensitivity 81.4%, specificity 93.9%) was superior to ADC for predicting poorly differentiated HCC. Relative low arterial enhancement on gadoxetic acid-enhanced MR images and low ADC are predictive of worse histological grades of HCC.