Imaging Spectrum of Intrahepatic Mass-Forming Cholangiocarcinoma and Its Mimickers: How to Differentiate Them Using MRI.

Intrahepatic cholangiocarcinoma (ICC) is the second most common primary hepatic malignancy, with mass-forming growth pattern being the most common. The typical imaging appearance of mass-forming ICC (mICC) consists of irregular ring enhancement in the arterial phase followed by the progressive central enhancement on portal venous and delayed phases. However, atypical imaging presentation in the form of hypervascular mICC might also be seen, which can be attributed to distinct pathological characteristics. Ancillary imaging features such as lobular shape, capsular retraction, segmental biliary dilatation, and vascular encasement favor the diagnosis of mICC. Nevertheless, these radiological findings may also be present in certain benign conditions such as focal confluent fibrosis, sclerosing hemangioma, organizing hepatic abscess, or the pseudosolid form of hydatid disease. In addition, a few malignant lesions including primary liver lymphoma, hemangioendothelioma, solitary hypovascular liver metastases, and atypical forms of hepatocellular carcinoma (HCC), such as scirrhous HCC, infiltrative HCC, and poorly differentiated HCC, may also pose a diagnostic dilemma by simulating mICC in imaging studies. Diffusion-weighted imaging and the use of hepatobiliary contrast agents might be helpful for differential diagnosis in certain cases. The aim of this manuscript is to provide a comprehensive overview of mICC imaging features and to describe useful tips for differential diagnosis with its potential mimickers.

Endometrioid adenocarcinoma of the ovary: MRI findings with emphasis on diffusion-weighted imaging for the differentiation of ovarian tumors.

BACKGROUND: Preoperative differentiation of ovarian malignant tumors still remains a challenge. Diffusion-weighted imaging (DWI) provides information about cellularity of the lesion and might facilitate discrimination between different malignant ovarian lesions. PURPOSE: To evaluate magnetic resonance imaging (MRI) findings of endometrioid adenocarcinoma of the ovary and to determine the value of DWI in the differential diagnosis of malignant and benign adnexal tumors. MATERIAL AND METHODS: The following MRI findings were reviewed in 162 patients (21 endometrioid adenocarcinoma, 103 other malignant tumors, 38 benign tumors): lesion size, morphological appearance, T2-weighted (T2W) signal intensity, T1-weighted (T1W) signal intensity, contrast-enhancement pattern, DWI signals with apparent diffusion coefficient (ADC) calculated for b = 800 s/mm(2) in solid tumor components. RESULTS: The most common morphological appearance was predominantly cystic lesion, found in 90.3% of patients with endometriod adenocarcinoma. The solid parts were slightly hyperintense on T2W images in 19 patients with marked enhancement after contrast administration. No significant difference (P = 0.13) in conventional MRI features was found between endometrioid adenocarcinoma and other malignant ovarian tumors. Hyperintensity on DWI was more frequently observed in malignant tumors than in benign lesions (P < 0.001). ADC values were significantly lower in endometrioid adenocarcinoma than other malignant tumors (0.79 ± 0.21 vs. 0.90 ± 0.19; P = 0.04) and in all malignant lesions compared with benign tumors (0.88 ± 0.31 vs. 1.33 ± 0.17; P < 0.001). CONCLUSION: DWI with ADC measurement could indicate the presence of endometrioid adenocarcinomas due to a slightly but significantly lower ADC values compared to other malignant ovarian lesions. Thus, DWI is beneficial and should be part of a standard protocol for the evaluation of indeterminate adnexal lesions.