Evaluation of qualitative and quantitative imaging features of hepatic hemangiomas with and without pseudo-washout sign on gadoxetic acid-enhanced MRI: a descriptive and comparative study

BACKGROUND

Hepatic hemangiomas are the most common benign liver tumors. It is important to know the imaging features of hemangiomas on gadoxetic acid (GA)-enhanced magnetic resonance imaging (MRI).

PURPOSE

To evaluate the qualitative and quantitative imaging features of hemangiomas on GA-enhanced MRI, and to compare imaging features of hemangiomas with and without pseudo-washout sign (PWS).

MATERIAL AND METHODS

We retrospectively included 93 cases of hemangioma that underwent GA-enhanced MRI. The presence of an enhancement pattern in the arterial phase (AP) and PWSs in the transitional phase (TP) were evaluated. Signal-to-norm ratios (SINorm) of hemangiomas, liver parenchyma, and portal vein (PV) as well as contrast-to-norm ratio (CNorm) were assessed. Additionally, hemangiomas with and without PWSs were defined as two separate subgroups, and imaging features were compared.

RESULTS

Of the 93 cases of hemangiomas, 49 (52.6%) had PWSs in the TP. The mean SINorms of hemangiomas showed the highest value in the AP (P < 0.05). The mean CNorms showed positive values in the AP, and gradually decreased (P < 0.05). Hemangiomas with PWSs were significantly rapidly enhanced and smaller in size (P < 0.05), and the mean SINorms was lower in the TP (P = 0.023). While the mean CNorms showed a significant difference in the AP between subgroups (P < 0.001), the enhancement pattern was equal to that of the PV.

CONCLUSION

When evaluating GA-enhanced MRI, radiologists should utilize quantitative measures in addition to qualitative assessment and should be aware that SI matching with PV in all phases can be a distinguishing finding in the diagnosis of hemangioma.

Evaluation of Primary Liver Cancers Using Hepatocyte-Specific Contrast-Enhanced MRI: Pitfalls and Potential Tips

When radiologists interpret hepatic focal lesions seen on dynamic magnetic resonance imaging (MRI) scans, it is important not only to distinguish malignant lesions from benign ones but also to distinguish nonhepatocellular carcinoma (HCC) malignancies from HCCs. In addition, most major guidelines, including those of the American Association for the Study of Liver Disease, European Association for the Study of the Liver, and Korean Liver Cancer Association and National Cancer Center, allow for the noninvasive imaging diagnosis of HCC in at-risk patients. However, ~40% of HCC cases show atypical imaging features mimicking non-HCC malignancies. Furthermore, several benign and malignant lesions, such as flash-filling hemangioma and intrahepatic mass-forming cholangiocarcinoma, frequently look like HCC. In contrast, although multiparametric MRI options, including hepatobiliary phase and diffusion-weighted imaging, provide useful information that could help address these challenges, there remain several unresolved issues with regard to the noninvasive diagnostic criteria characterizing HCC. In this article, we discuss the typical imaging features and challenging situations related to primary liver cancers in MRI, while considering how to make a correct diagnosis. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY STAGE: 3.

Gadoxetic acid-enhanced MR imaging for hepatocellular carcinoma: molecular and genetic background

Gadoxetic acid-enhanced magnetic resonance imaging (MRI) plays important roles in diagnosis of hepatic lesions because of its superiority in the detectability of small lesions, its differentiation ability, and its utility for the early diagnosis of hepatocellular carcinoma (HCC). In HCC, expression of organic anion transporting polypeptide (OATP) 1B3 correlates with the enhancement ratio in the hepatobiliary phase. Gadoxetic acid-enhanced MRI, an indirect molecular imaging method, reflects OATP1B3 expression in HCC. OATP1B3 expression gradually decreases from the dysplastic nodule stage to advanced HCC. Decreased expression is a sensitive marker of multistep hepatocarcinogenesis, especially in the early stages. Hypervascular HCCs commonly show hypointensity in the hepatobiliary phase corresponding to a decrease in OATP1B3; however, approximately 10% of HCCs show hyperintensity due to OATP1B3 overexpression. This hyperintense HCC shows less aggressive biological features and has a better prognosis than hypointense HCC. Hyperintense HCC can be classified into a genetic subtype of HCC with a mature hepatocyte-like molecular expression. OATP1B3 expression and the less aggressive nature of hyperintense HCC are regulated by the molecular interaction of β-catenin signaling and hepatocyte nuclear factor 4α, a tumor suppressor factor. Gadoxetic acid-enhanced MR imaging has the potential to be an imaging biomarker for HCC. KEY POINTS: • The hepatobiliary phase is a sensitive indirect indicator of organic anion transporting polypeptide1B3 (OATP1B3) expression in hepatocellular carcinoma (HCC). • The OATP1B3 expression, namely, enhancement in the hepatobiliary phase, decreases from the very early stage of hepatocarcinogenesis, contributing to early diagnosis of HCC. • HCC showing hyperintensity on the hepatobiliary phase is a peculiar genetic subtype of HCC with OATP1B3 overexpression, a less aggressive nature, and mature hepatocyte-like molecular/genetic features.

Common pitfalls when using the Liver Imaging Reporting and Data System (LI-RADS): lessons learned from a multi-year experience

The goal of the Liver Imaging Reporting and Data System (LI-RADS) is to standardize the interpretation and reporting of liver observations on contrast-enhanced CT and MR imaging of patients at risk for hepatocellular carcinoma. Although LI-RADS represents a significant achievement in standardization of the diagnosis and management of cirrhotic patients, complexity and caveats to the algorithm may challenge correct application in clinical practice. The purpose of this paper is to discuss common pitfalls and potential solutions when applying LI-RADS in practice. Knowledge of the most common pitfalls may improve the diagnostic confidence and performance when using the LI-RADS system for the interpretation of CT and MR imaging of the liver.

Performance of Gd-EOB-DTPA-enhanced MRI for the diagnosis of LI-RADS 4 category hepatocellular carcinoma nodules with different diameters

In 2011, the American College of Radiology released a standardized reporting and data collection system, named Liver Imaging Reporting and Data System (LI-RADS), to improve the consistency of diagnostic imaging examinations of hepatocellular carcinoma (HCC). When the LI-RADS guideline was updated in 2014, hepatobiliary contrast agents, including gadoxetate acid (Gd-EOB-DTPA), were incorporated into the system. However, the diagnostic performance of Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) for nodules of different diameters has not been addressed. In the present study, a total of 263 LI-RADS 4 category hepatic nodules were examined blindly and independently by two radiologists. All nodules were divided into two datasets: Set 1 (n=86) that included nodules with iso/hypo-intensity in the arterial phase (HCC, n=42; non-HCC, n=44) and set 2 (n=177) that included nodules with hyper-intensity in the arterial phase (HCC, n=131; non-HCC, n=46). The diagnostic performance of Gd-EOB-DTPA-enhanced MRI for evaluation of nodules with different diameters was evaluated. The present study revealed that the diagnostic performance of Gd-EOB-enhanced MRI of larger nodules (>2 cm) was higher compared with (<2 cm) smaller nodules. The FPR of large nodules (>2 cm) with a hypervascular pattern was lower compared with smaller nodules (<2 cm) with hypovascular pattern. In conclusion, Gd-EOB-enhanced MRI is useful for the diagnosis of HCC where hypervascular LI-RADS 4 nodules are >2 cm in diameter. However, Gd-EOB-enhanced MRI may be of limited use for the assessment of nodules that <20 mm due to low diagnostic performance and high FPR.

[Differential diagnosis of hepatocellular carcinoma and hepatic hemangiomas based on radiomic features of gadoxetate disodium-enhanced magnetic resonance imaging]

OBJECTIVE

To evaluate the feasibility of using radiomic features for differential diagnosis of hepatocellular carcinoma (HCC) and hepatic cavernous hemangioma (HHE).

METHODS

Gadoxetate disodium-enhanced magnetic resonance imaging data were collected from a total of 135 HCC and HHE lesions. The radiomic texture features of each lesion were extracted on the hepatobiliary phase images, and the performance of each feature was assessed in differentiation and classification of HCC and HHE. In multivariate analysis, the performance of 3 feature selection algorithms (namely minimum redundancy-maximum relevance, mRmR; neighborhood component analysis, NCA; and sequence forward selection, SFS) was compared. The optimal feature subset was determined according to the optimal feature selection algorithm and used for testing the 3 classifier algorithms (namely the support vector machine, RBF-SVM; linear discriminant analysis, LDA; and logistic regression). All the tests were repeated 5 times with 10-fold cross validation experiments.

RESULTS

More than 50% of the radiomic features exhibited strong distinguishing ability, among which gray level co-occurrence matrix feature S (3, -3) SumEntrp showed a good classification performance with an AUC of 0.72 (P<0.01), a sensitivity of 0.83 and a specificity of 0.57. For the multivariate analysis, 15 features were selected based on the SFS algorithm, which produced better results than the other two algorithms. Testing of these 15 selected features for their average cross-validation performance with RBF-SVM classifier yielded a test accuracy of 0.82∓0.09, an AUC of 0.86∓0.12, a sensitivity of 0.88∓0.11, and a specificity of 0.76∓0.18.

CONCLUSION

The radiomic features based on gadoxetate disodium-enhanced magnetic resonance images allow efficient differential diagnosis of HCC and HHE, and can potentially provide important assistance in clinical diagnosis of the two diseases.