Characterization of hepatic adenoma and focal nodular hyperplasia with gadoxetic acid

Abstract

Purpose-To characterize imaging features of histologically proven hepatic adenoma (HA) as well as histologically and/or radiologically proven focal nodular hyperplasia (FNH) using delayed hepatobiliary MR imaging with 0.05mmol/kg gadoxetic acid. Materials and Methods-Five patients with sixHAs with histological correlation were retrospectively identified on liver MRI studies performed with gadoxetic acid, and T1-weighted imaging acquired during the delayed hepatobiliary phase. Additionally, 23 patients with 34 radiologically diagnosed FNH lesions (interpreted without consideration of delayed imaging) were identified, two of which also had histological confirmation. Signal intensity ratios relative to adjacent liver were measured on selected imaging sequences.Results-All six hepatic adenomas (100%), which had histological confirmation, demonstrated hypointensity relative to adjacent liver on delayed imaging. Further, all of the FNH (including 34 radiologically proven, 2 of which were also histologically proven) were either hyperintense (23/34, 68%) or isointense (11/34, 32%) relative to the adjacent liver on delayed imaging. None of the FNHs were hypointense relative to liver.Conclusion-Distinct imaging characteristics of HA versus FNH on delayed gadoxetic acidenhanced MRI, with adenomas being hypointense and FNH being iso-or hyperintense on delayed imaging may improve specificity for characterization, and aid in the differentiation of these two lesions.

Rules, Roles, and Room for Discussion in Gadoxetic Acid-enhanced Magnetic Resonance Liver Imaging: Current Knowledge and Future Challenges

“…59,61 The central hypointense core of FNHs is generally larger in extent than the central scar observed in dynamic phases. 60,62 Even in such cases, however, the peripheral hyperintense rim on hepatocyte phase might imply an uptake ability of the lesion, i.e., FNH rather than HA (Fig. 4b).…”

“…4a, b). 59,60 On the other hand, hepatocyte phase images of HAs generally show hypointensity. A central scar, an anomalous portal area with abundant loose connective tissue, is a well known and speciˆc imagingˆnding of FNH but not observed in all cases.…”

“…However, we should be aware that such scars appear on hepatocyte phase images with much lower intensity than the remainder of the tumor. 60 Although hepatocyte phaseˆndings can aid diŠerential diagnosis, it is also important to note that 10z of FNHs show hypointensity on hepatocyte phase images despite the fact they are non-neoplastic and benign. 59,61 The central hypointense core of FNHs is generally larger in extent than the central scar observed in dynamic phases.…”

“…4b). 60 HAs have recently been subclassiˆed into 4 categories on the basis of genetic and pathologic features, 63 but only a little has been studied on the role of gadoxetic acid for this subclassiˆcation. 61 …”

Focal liver lesions detection and characterization: The advantages of gadoxetic acid-enhanced liver MRI

“…Zech et al [25] reported enhancement in the hepatobiliary phase in the 90% of FNH examined in their series where only a minority of lesions showed no enhancement or peripheral enhancement. The presence of biliary canaliculi, even if not functioning, leads to a "slower excretion in comparison to the surrounding parenchyma", and this gadoxetic acid retention explains the hyperintense appearance of FNH [26] (Figures 1 and 2). Nevertheless, atypical lesions are very difficult to diagnose, even using Gd-EOB-DTPA.…”