HEPATOCELLULAR ADENOMA - MR-IMAGING FEATURES WITH PATHOLOGICAL CORRELATION

OBJECTIVE. The purpose of this study was to describe the MR imaging ch aracteristics of hepatic adenomas and to correlate these features with pathologic findings. MATERIALS AND METHODS. Sixteen patients from fou r institutions who had 31 hepatocellular adenomas underwent MR imaging with T1- and T2-weighted pulse sequences at 1.5 T. Dynamic gadolinium -chelate-enhanced gradient-recalled-echo (GRE) MR imaging was done in eight patients with 15 lesions. Twenty-three lesions in 15 patients we re confirmed by surgical excision. MR images were retrospectively revi ewed by three experienced radiologists for signal intensity of lesions relative to liver, heterogeneity, contrast enhancement, and presence of signs of histopathologic correlates. These imaging findings were th en compared with histopathologic findings. RESULTS. Nearly all (29 of 31 lesions) hepatocellular adenomas showed heterogeneous signal intens ity on MR images. Most (19/31) were predominantly hyperintense on prot on density- or T2-weighted images; the predominant signal intensity on T1-weighted images varied. Thirteen of 15 lesions showed early arteri al enhancement relative to liver on dynamic GRE MR images. MR imaging was most successful in showing intratumoral hemorrhage (10 of 12 histo pathologically proven lesions), large intratumoral vessels (five of fi ve), fatty change (three of six), and peliosis (three of three cases). In two lesions, capsules (one of five) and central scars (one of thre e) were detected. CONCLUSION. Hepatocellular adenomas have a highly va riable appearance on MR images because of their varied histologic appe arances. Although no definitive MR imaging signal or structural charac teristics can be identified, tumor heterogeneity, particularly when re lated to hemorrhage, and early arterial enhancement can suggest a diag nosis of hepatocellular adenoma in the proper patient population.