Hepatocellular adenomas: is there additional value in using Gd-EOB-enhanced MRI for subtype differentiation?

Abstract

Purpose: To differentiate subtypes of hepatocellular adenoma (HCA) based on enhancement characteristics in gadoxetic acid (Gd-EOB) magnetic resonance imaging (MRI).

Materials and methods: Forty-eight patients with 79 histopathologically proven HCAs who underwent Gd-EOB-enhanced MRI were enrolled (standard of reference: surgical resection). Two blinded radiologists performed quantitative measurements (lesion-to-liver enhancement) and evaluated qualitative imaging features. Inter-reader variability was tested. Advanced texture analysis was used to evaluate lesion heterogeneity three-dimensionally.

Results: Overall, there were 19 (24%) hepatocyte nuclear factor (HNF)-1a-mutated (HHCAs), 37 (47%) inflammatory (IHCAs), 5 (6.5%) b-catenin-activated (bHCA), and 18 (22.5%) unclassified (UHCAs) adenomas. In the hepatobiliary phase (HBP), 49.5% (39/79) of all adenomas were rated as hypointense and 50.5% (40/79) as significantly enhancing (defined as > 25% intralesional GD-EOB uptake). 82.5% (33/40) of significantly enhancing adenomas were IHCAs, while only 4% (1/40) were in the HHCA subgroup (p < 0.001). When Gd-EOB uptake behavior was considered in conjunction with established MRI features (binary regression model), the area under the curve (AUC) increased from 0.785 to 0.953 for differentiation of IHCA (atoll sign + hyperintensity), from 0.859 to 0.903 for bHCA (scar + hyperintensity), and from 0.899 to 0.957 for HHCA (steatosis + hypointensity). Three-dimensional region of interest (3D ROI) analysis showed significantly increased voxel heterogeneity for IHCAs (p = 0.038).

Conclusion: Gd-EOB MRI is of added value for subtype differentiation of HCAs and reliably identifies the typical heterogeneous HBP uptake of IHCAs. Diagnostic accuracy can be improved significantly by the combined analysis of established morphologic MR appearances and intralesional Gd-EOB uptake.

Key points: •Gd-EOB-enhanced MRI is of added value for subtype differentiation of HCA. •IHCA and HHCA can be identified reliably based on their typical Gd-EOB uptake patterns, and accuracy increases significantly when additionally taking established MR appearances into account. •The small numbers of bHCAs and UHCAs remain the source of diagnostic uncertainty.

Keywords: Gd-DTPA; Hepatic neoplasms; Hepatocellular adenoma; Liver; Magnetic resonance imaging.

Fig. 1

IHCA (a, b—white stars) showing a classical atoll sign with a typical hyperintense rim in the T2w HASTE and T2 FS sequences (a, b white arrows). (c, d) Another patient with IHCA (c, d—white stars) showing the typical appearance of intralesional bleeding (c—white arrow; c, non-CE T1w GRE sequence; d, T2w HASTE sequence)

Fig. 2

Flowchart of HCA subgroup diagnostic algorithm including combined evaluation of Gd-EOB uptake behavior and established MRI features. Intralesional Gd-EOB uptake in the HBP was rated subjectively as iso- to hyperintensity percentage on a 5-point scale (score 0, 0%; score 1, 10–25%; score 2, 25–50%; score 3, 50–75%; score 4, > 75%)

Fig. 3

ROC curve analyses. (a–c) Calculated for IHCA, bHCA, and HHCA and their known established MRI feature. (d–f) ROC analyses of a binary logistic regression model containing the established MRI feature + the Gd-EOB uptake behavior

Fig. 4

Relative lesion-to-liver (%) enhancement in the arterial (art), portal venous (pv) and transitional (trans) phases for the four subgroups of HHCA, IHCA, bHCA, and UHCA. Kruskal-Wallis test showed significant differences for the arterial (p = 0.024) and portal venous (p = 0.018) phases and nonsignificant differences for the transitional phase (p > 0.05)

Fig. 5

HHCA (white stars) shows isointense signal in the IN-phase image (a) with a strong drop in signal in the OPP-phase image indicating presence of lipids (b). c–f Contrast enhancement behavior in the T1w arterial phase with a mild hyperintense signal to the surrounding liver (c), an isointense signal in the portal venous phase (d) and mildly hypointense in the transitional phase (e). In the HBP (f), the lesion appears homogeneously hypointense without a significant uptake (0%)

Fig. 6

IHCA (white stars) showing isointense signal in the T1w image (a) and hyperintensity on standard HASTE image (b). c–f Contrast enhancement behavior in the T1w arterial (hyperintense washin) (c), portal venous (heterogeneous washout) (d), and transitional (washout) (e) phases. In both the portal venous (d) and venous phases, the adenoma appears mildly hypointense to the surrounding liver. In the HBP, the lesion shows heterogeneous patchy uptake behavior > 50% and is iso- to hyperintense to surrounding liver (white arrow—(f))

Fig. 7

bHCA (white stars) shows isointense signal in the unenhanced T1w VIBE image (a) and a central scar/central hypointensity (white arrows) in the T2w FS image (b). c–f Contrast enhancement behavior in the T1w arterial phase with heterogeneous hyperintense washin (c), isointensity in the portal venous phase (d), and transitional signal intensity to the surrounding liver (e). In the HBP, the lesion shows heterogeneous uptake rated as low (0–25%) and is hypointense to the liver