Kiyarash Mohajer MD, Presenter: Nothing to Disclose

Alex Frydrychowicz MD, Abstract Co-Author: Support, Bracco Group

Jessica B. Robbins MD, Abstract Co-Author: Nothing to Disclose

Agnes Loeffler, Abstract Co-Author: Nothing to Disclose

Thomas David Reed MD, Abstract Co-Author: Nothing to Disclose

Scott Brian Reeder MD, PhD, Abstract Co-Author: Spouse, Employee, General Electric Company Medical Advisory Board, General Electric Company

Hepatic adenoma (HA) and focal nodular hyperplasia (FNH) are common benign hepatic lesions found predominantly in women of child-bearing age. Characterization of HA vs. FNH with extracellular gadolinium-based contrast-agents can be challenging because imaging characteristics during dynamic contrast imaging may be similar. The advent of the hepatobiliary agent gadoxetic acid has offered new opportunities to characterize HA and FNH. However, there are very few related reports in the literature, especially in the case of HA. We therefore describe imaging features of histologically proven hepatic adenoma (HA) as well as focal nodular hyperplasia (FNH) using delayed hepatobiliary MR imaging with gadoxetic acid.

Five patients with six HA’s with histological correlation were retrospectively identified on liver MRI studies performed with gadoxetic acid and T1-weighted imaging was 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 diagnosis of FNH. Signal intensity ratios (SIR) were measured on selected imaging sequences by measuring the ratio of the signal within the lesion compared to the adjacent liver. Lesions were characterized as hypointense if the SIR was <0.95, isointense if the lesion had a SIR from 0.95 – 1.05, and hyperintense if the SIR was >1.05.

All six histologically confirmed HA (100%) demonstrated hypointensity relative to adjacent liver on delayed imaging. All FNH (100%) were either hyperintense (23/34, 68%) or isointense (11/34, 32%) relative to the adjacent liver on delayed imaging. No FNH was hypointense relative to liver.

We have reported imaging features of 6 HA's on delayed gadoxetic acid-enhanced MRI which doubles the number of histologically proven HA described in the literature to date. HA and FNH have distinct appearances on the delayed phase of gadoxetic acid-enhanced MRI, with adenomas being hypointense and FNH being iso- or hyperintense. This can aid in the differentiation of these two lesions with more confidence.

Distinct imaging appearance of hepatic adenoma vs. FNH on delayed phase gadoxetic acid-enhanced MRI may improve specificity for characterization, and aid in the differentiation of these two lesions.

Mohajer, K, Frydrychowicz, A, Robbins, J, Loeffler, A, Reed, T, Reeder, S, Differentiation of Hepatic Adenoma vs Focal Nodular Hyperplasia on Delayed Hepatobiliary Imaging with Gadoxetic Acid.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11034307.html