Prediction of histological grade of hepatocellular carcinoma using quantitative diffusion-weighted MRI: a retrospective multivendor study

Objective: To evaluate the usefulness of quantitative diffusion-weighted (DW) imaging acquired by multivendor magnetic resonance units for predicting grade of hepatocellular carcinoma (HCC). Methods: 83 patients with 100 histologically diagnosed HCCs who underwent pre-operative liver DW imaging with b = 0 and 1000 s mm(-2) or b =0 and 800 s mm(-2) at any of six institutions were included. Two radiologists independently measured the apparent diffusion coefficient (ADC) of the lesion as well as non-ADC parameters, such as the relative contrast ratio and the contrast-to-noise ratio (CNR) between the lesion and the liver parenchyma on high b-value DW images. The diagnostic performance of the DW parameters in discriminating poorly-differentiated HCCs was compared using receiver operating characteristic (ROC) analysis. Results: The areas under the receiver operating characteristic curves for the CNR (86.4% [95% confidence interval (CI) (77.2-95.6] and 83.9% [95% CI 71.2-96.6] for b = 1000 and 800s mm(-2), respectively] and the relative contrast ratio (85.3% [95% CI 75,5-94.8] and 83.5% [95% CI 70.5-96.4]) tended to be superior to the ADC [71.1% [95% CI (56.9-85.2)] and 75.7% [95% CI (55.1-96.2)]: p < 0.05 for CNR vs ADC for b = 1000 s mm(-2), but not significant for other parameters) for discrimination of poorly-differentiated HCCs. Conclusion: All DW parameters could discriminate HCC grade. Non-ADC parameters might be more useful than the ADC for predicting poorly-differentiated HCCs. Advances in knowledge: The utility of quantitative DW parameters for predicting HCC grade was demonstrated by using multivendor MR units.