Hepatocellular carcinoma: clinical significance of signal heterogeneity in the hepatobiliary phase of gadoxetic acid-enhanced MR imaging

Objectives To clarify the relationship between the biological behaviour of hepatocellular carcinomas (HCCs) and their signal intensity in the hepatobiliary phase of gadoxetic acid-enhanced MR imaging with a special focus on the signal heterogeneity. Methods A total of 68 patients with 70 pathologically proven HCCs were enrolled. On the basis of the signal intensity in the hepatobiliary phase, the lesions were classified into three groups: group 1, homogeneous hypointensity (n=44); group 2, heterogeneous hyperintensity (n=20); and group 3, homogeneous hyperintensity (n=6). The clinicopathological findings were compared among the three groups. Results The tumour size and the serum level of protein induced by vitamin K absence or antagonist-II (PIVKA-II) were significantly higher in group 2 compared to group 1 (p=0.0155, p=0.0215, respectively) and compared to group 3 (p=0.0330, p=0.0220, respectively). The organic anion transporting polypeptide 8 (OATP8) expression in group 2 and group 3 was significantly higher than in group 1 (p<0.0001, p<0.0001, respectively). Group 2 showed a significantly lower disease-free survival rate compared to group 1 (p=0.0125), and group 2 was an independent prognostic factor for disease-free survival (p=0.0308). Conclusions HCCs in the hepatobiliary phase that are heterogeneously hyperintense on gadoxetic acid-enhanced MR imaging have more malignant potential than other types of HCCs.