Intrahepatic Cholangiocarcinoma in Patients with Cirrhosis: Differentiation from Hepatocellular Carcinoma by Using Gadoxetic Acid-enhanced MR Imaging and Dynamic CT.

Purpose To determine the imaging features at gadoxetic acid-enhanced magnetic resonance (MR) imaging of intrahepatic cholangiocarcinoma (IHCC) in a cirrhotic liver, with an emphasis on the distinction between IHCC and hepatocellular carcinoma (HCC) and on the comparison of nodule enhancement patterns between MR imaging and computed tomography (CT). Materials and Methods The institutional review board approved this study and waived the requirement for informed consent. Gadoxetic acid-enhanced MR and CT images in 72 consecutive patients (61 men; mean age, 56.6 years) with 78 IHCCs and one-to-one matched control patients (56 men; mean age, 56.6 years) with 77 HCCs were evaluated retrospectively by two independent readers. Findings that could differentiate IHCC from HCC were evaluated with univariate and multivariate analyses. Using the enhancement criteria and the Liver Imaging Reporting and Data System with modifications (mLI-RADS), the sensitivity and specificity for diagnosing HCC were calculated with conventional washout and portal venous phase (PVP) washout. Results At MR imaging with conventional washout, the specificities for diagnosing HCC were 94.9% (74 of 78) with the enhancement criteria and 96.2% (75 of 78) with mLI-RADS, while the use of PVP washout achieved 100% (78 of 78) specificity for diagnosing HCC with both diagnostic criteria at the expense of decreased sensitivity (from 76.6% [59 of 77] to 63.6% [49 of 77] with the enhancement criteria and from 64.9% [50 of 77] to 55.8% [43 of 77] with mLI-RADS, P ≤ .016). At CT, the sensitivities and specificities with conventional washout were 72.7% (56 of 77) and 97.4% (76 of 78), respectively, with the enhancement criteria and 67.5% (52 of 77) and 97.4% (76 of 78), respectively, with mLI-RADS. Conclusion The use of PVP washout instead of conventional washout at gadoxetic acid-enhanced MR imaging prevents the misclassification of IHCC as HCC in a cirrhotic liver but leads to a decreased sensitivity for HCC. RSNA, 2016 Online supplemental material is available for this article.