Hepatocellular Adenoma Subtypes Based on 2017 Classification System: Exploratory Study of Gadoxetate Disodium–Enhanced MRI Features With Proposal of a Diagnostic Algorithm

Abstract

<b>BACKGROUND.</b> The classification of hepatocellular adenomas (HCAs) was updated in 2017 on the basis of genetic and molecular analysis. <b>OBJECTIVE.</b> The purpose of this article was to evaluate features on gadoxetate disodium-enhanced MRI of HCA subtypes on the basis of the 2017 classification and to propose a diagnostic algorithm for determining subtype using these features. <b>METHODS.</b> This retrospective study included 56 patients (49 women, seven men; mean age, 37 ± 13 [SD] years) with histologically confirmed HCA evaluated by gadoxetate disodium-enhanced MRI from January 2010 to January 2021. Subtypes were reclassified using 2017 criteria: hepatocyte nuclear factor-1α mutated HCA (HHCA), inflammatory HCA (IHCA), β-catenin exon 3 activated HCA (β-HCA), mixed inflammatory and β-HCA (β-IHCA), sonic hedgehog HCA (shHCA), and unclassified HCA (UHCA). Qualitative MRI features were assessed. Liver-to-lesion contrast enhancement ratios (LLCERs) were measured. Subtypes were compared, and a diagnostic algorithm was proposed. <b>RESULTS.</b> The analysis included 65 HCAs: 16 HHCAs, 31 IHCAs, six β-HCA, four β-IHCA, five shHCA, and three UHCAs. HHCAs showed homogeneous diffuse intralesional steatosis in 94%, whereas all other HCAs showed this finding in 0% (<i>p</i> < .001). IHCAs showed the "atoll" sign in 58%, whereas all other HCAs showed this finding in 12% (<i>p</i> < .001). IHCAs showed moderate T2 hyperintensity in 52%, whereas all other HCAs showed this finding in 12% (<i>p</i> < .001). The β-HCAs and β-IHCAs occurred in men in 63%, whereas all other HCAs occurred in men in 4% (<i>p</i> < .001). The β-HCAs and β-IHCAs had a mean size of 10.1 ± 6.8 cm, whereas all other HCAs had a mean size of 5.1 ± 2.9 cm (<i>p</i> = .03). The β-HCAs and β-IHCAs showed fluid components in 60%, whereas all other HCAs showed this finding in 5% (<i>p</i> < .001). Hepatobiliary phase iso- or hyperintensity was observed in 80% of β-HCAs and β-IHCAs versus 5% of all other HCAs (<i>p</i> < .001). Hepatobiliary phase LLCER was positive in nine HCAs (eight β-HCAs and β-IHCAs; one IHCA). The shHCA and UHCA did not show distinguishing features. The proposed diagnostic algorithm had accuracy of 98% for HHCAs, 83% for IHCAs, and 95% for β-HCAs or β-IHCAs. <b>CONCLUSION.</b> Findings on gadoxetate disodium-enhanced MRI, including hepatobiliary phase characteristics, were associated with HCA subtypes using the 2017 classification. <b>CLINICAL IMPACT.</b> The algorithm identified common HCA subtypes with high accuracy, including those with β-catenin exon 3 mutations.