Accuracy of MRCP is comparable with that of ERCP. Regardless of modality, a lengthy segment of extrahepatic bile duct stricture with irregular margin and asymmetric narrowing suggests cholangiocarcinoma, and a short segment with regular margin and symmetric narrowing suggests benign cause.

Microvessel invasion is a major prognostic factor in hepatocellular carcinoma (HCC) that influences the suitability of surgery, but rarely can be evaluated preoperatively. This study was performed to identify preoperative MRI findings that reflect histopathological microvessel invasion in hepatocellular carcinoma. Gadobenate dimeglumine-enhanced four-arterial phase dynamic study and hepatobiliary phase images of preoperative MRI of 70 HCC lesions were retrospectively reviewed. Tumor size (cm), peritumoral enhancement, tumor margins, and radiological capsule were analyzed as radiological parameters reflecting microvessel invasion and were compared with histopathological references. The chi-square test and the independent t-test were used for univariate analysis, and a logistic regression analysis was performed for multivariate analysis. In univariate analysis, tumor size (p = 0.030), peritumoral enhancement (p < 0.001), and tumor margins (p = 0.007) were associated with microvessel tumor invasion. However, in multivariate analysis irregular circumferential peritumoral enhancement only showed statistical significance (odds ratio 13.0), suggesting a high probability of microvessel invasion of HCC. Irregular circumferential peritumoral enhancement on contrast-enhanced multi-arterial phase dynamic MRI could be a preoperative surrogate marker for microvessel tumor invasion.

Stomach cancer is one of the leading causes of cancer mortality worldwide. Complete resection of a gastric tumor and adjacent lymph nodes represents the only potentially curative intervention. Computed tomography (CT) has remained the modality of choice for the preoperative staging of gastric cancer and for follow-up. A recently developed advanced CT technique that makes use of thin sections, optimal contrast material enhancement, and multiplanar reformation allows more accurate staging. However, CT may be limited in the identification of nonenlarged lymph node metastasis, peritoneal dissemination, and small hematogenous metastasis. Positron emission tomography (PET) with 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) has been recognized as a useful diagnostic technique in clinical oncology. FDG PET allows scanning of a larger volume than is possible with CT. Although FDG PET is not an appropriate first-line diagnostic procedure in the detection of stomach cancer and is not helpful in tumor staging, it may play a valuable role in the detection of distant metastases, such as those of the liver, lungs, adrenal glands, ovaries, and skeleton. FDG PET may also be helpful in the follow-up of patients undergoing chemotherapy, as it allows the identification of early response to treatment. Further studies are needed to determine the efficacy of FDG PET in the detection of local nodal metastases and peritoneal dissemination. Nevertheless, the combined use of CT and PET can be helpful in the preoperative staging of stomach cancer and in the therapeutic monitoring of affected patients.

Gadoxetic acid enhanced magnetic resonance imaging (EOB-MRI) can identify the sinusoidal obstruction syndrome (SOS). The diagnosis can be achieved with high specificity and good interobserver agreement. SOS typically demonstrates diffuse hypointensity on hepatobiliary phase images on EOB-MRI. EOB-MRI may be falsely negative in patients with minimal degree of SOS.