Prediction of the histopathological grade of hepatocellular carcinoma using qualitative diffusion-weighted, dynamic, and hepatobiliary phase MRI

To investigate the effectiveness of qualitative diffusion-weighted imaging (DWI), subtraction of unenhanced from arterial phase images, and hepatobiliary phase (HBP) images in estimating the histopathological grade of hepatocellular carcinoma (HCC). We retrospectively reviewed gadoxetic acid-enhanced magnetic resonance images of 175 patients with 201 surgically resected HCCs. The signal intensity and its relationship with histopathological grade were assessed for each sequence and a combination of sequences. There was a tendency towards higher grades in tumours showing restricted diffusion on DWI (P < 0.001) or arterial enhancement on subtraction imaging (P < 0.001), but not hepatocyte-defect on HBP images (P = 0.33). When lesions were divided into three groups based on combined findings on DWI and subtraction imaging, a linear trend was observed between group and grade (P < 0.001). The positive predictive value (PPV) of the combination of no restricted diffusion and no arterial enhancement in predicting well-differentiated HCC was 100%, higher than the PPV of individual findings on DWI (74%) or subtraction imaging (81%). DWI and subtraction imaging are helpful for predicting the histopathological grade of HCC, especially when the two sequences are considered together. aEuro cent Predicting the histopathological grade of hepatocellular carcinoma (HCC) preoperatively is important. aEuro cent Diffusion-weighted imaging (DWI) and subtraction imaging are recently developed MR techniques. aEuro cent Retrospective study showed DWI and subtraction imaging helps predict HCC grades. aEuro cent Management of patients with HCC becomes more appropriate.