Iso- or hyperintensity of hepatocellular adenomas on hepatobiliary phase does not always correspond to hepatospecific contrast-agent uptake: importance for tumor subtyping

This study was conducted in order to evaluate if iso- or hyperintensity of HCAs on HBP is systematically related to a high uptake of hepatospecific contrast agent, using a quantitative approach. This bicentric retrospective study included all patients with histologically confirmed and subtyped HCA from 2009 to 2017 who underwent MRI with HBP after Gd-BOPTA injection and who showed iso- or hyperintensity on HBP. The signal intensity of tumors on pre- and postcontrast images and the presence of hepatic steatosis were noted. Contrast uptake on HBP was quantified using the liver-to-lesion contrast enhancement ratio (LLCER) and compared between HCA subtypes (Wilcoxon signed-rank test). Categorical variables were compared using chi-square tests. Twenty-four HCAs showed iso- or hyperintensity on HBP, specifically 17 inflammatory (IHCAs) and 7 β-catenin HCAs (BHCAs). Eighteen HCAs (75%) (17 IHCAs and 1 BHCAs) had a LLCER < 0% (median − 13.6%, group 1), of which 94% were hyperintense on precontrast T1-W images, with background hepatic steatosis. Six HCAs (25%) had LLCER ≥ 0% (median 2.9%, group 2), and all were BHCAs. A LLCER ≥ 1.6% was associated with the diagnosis of BHCA with a sensitivity of 86% and a specificity of 100%. In conclusion, iso- or hyperintensity of hepatocellular adenomas on HBP does not necessarily correspond to an increased hepatospecific contrast-agent uptake. In IHCA, tumor hyperintensity on precontrast images and the underlying steatosis likely explain such iso- or hyperintensity, which do show reduced HBP contrast-agent uptake. On the other hand, marked contrast uptake can be observed, especially in BHCA.