Added value of hepatobiliary phase gadoxetic acid-enhanced MRI for diagnosing hepatocellular carcinoma in high-risk patients

AIM: To determine the added value of hepatobiliary phase (HBP) gadoxetic acid-enhanced magnetic resonance imaging (MRI) in evaluating hepatic nodules in high-risk patients. METHODS: The institutional review board approved this retrospective study and waived the requirement for informed consent. This study included 100 patients at high risk for hepatocellular carcinoma (HCC) and 105 hepatic nodules that were larger than 1 cm. A blind review of two MR image sets was performed in a random order: set 1, unenhanced (T1- and T2-weighted) and dynamic images; and set 2, unenhanced, dynamic 20-min and HBP images. The diagnostic accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were compared for the two image sets. Univariate and multivariate analyses were performed on the MR characteristics utilized to diagnose HCC. RESULTS: A total of 105 hepatic nodules were identified in 100 patients. Fifty-nine nodules were confirmed to be HCC. The diameter of the 59 HCCs ranged from 1 to 12 cm (mean: 1.9 cm). The remaining 46 nodules were benign (28 were of hepatocyte origin, nine were hepatic cysts, seven were hemangiomas, one was chronic inflammation, and one was focal fat infiltration). The diagnostic accuracy significantly increased with the addition of HBP images, from 88.7% in set 1 to 95.5% in set 2 (P = 0.002). In set 1 vs set 2, the sensitivity and NPV increased from 79.7% to 93.2% and from 78.9% to 91.8%, respectively, whereas the specificity and PPV were not significantly different. The hypointensity on the HBP images was the most sensitive (93.2%), and typical arterial enhancement followed by washout was the most specific (97.8%). The multivariate analysis revealed that typical arterial enhancement followed by washout, hyperintensity on T2-weighted images, and hypointensity on HBP images were statistically significant MRI findings that could diagnose HCC (P < 0.05). CONCLUSION: The addition of HBP gadoxetic acid-enhanced MRI statistically improved the diagnostic accuracy in HCCs larger than 1 cm. Typical arterial enhancement followed by washout and hypointensity on HBP images are useful for diagnosing HCC. (C) 2013 Baishideng Publishing Group Co., Limited. All rights reserved.