Diffusion-weighted MRI in intrahepatic bile duct adenoma arising from the cirrhotic liver

Benign focal liver lesions masquerading as primary liver cancers on MRI

Hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC) are the most common primary liver malignancies. HCC and ICC have characteristic imaging findings, but a number of benign entities can appear similar and can cause diagnostic dilemma. Ideally, accurate and timely diagnosis of these conditions can help the patient to avoid a needle biopsy or even unnecessary treatment. In this article, we present various benign liver lesions that display imaging characteristics that are similar to HCC and ICC on magnetic resonance imaging (MRI) and discuss salient features that may assist in accurate diagnosis.

Hepatic nodules with arterial phase hyperenhancement and washout on enhanced computed tomography/magnetic resonance imaging: how to avoid pitfalls

This essay aimed to illustrate the various hepatic nodules that may exhibit arterial phase hyperenhancement and washout on computed tomography/magnetic resonance imaging (CT/MRI). Hepatic nodules with arterial phase hyperenhancement and washout on CT/MRI include hepatocellular carcinoma, focal nodular hyperplasia-like nodules, serum amyloid A-positive hepatocellular neoplasms, intrahepatic cholangiocarcinoma, intrahepatic bile duct adenoma, hepatoblastoma, hepatocellular adenoma, hepatic epithelioid angiomyolipoma, and metastasis including neuroendocrine and gastrointestinal stromal tumors. Understanding the imaging findings is important to ensure correct diagnosis.

Bile duct adenoma: imaging features and radiologic-pathologic correlation

PURPOSE

This study aimed to reveal characteristic imaging features of bile duct adenoma (BDA) by radiologic-pathologic correlation.

MATERIALS AND METHODS

We retrospectively analyzed pathological and imaging findings of seven patients with BDA.

RESULTS

The median maximum diameter of BDA was 5.5 mm. Six lesions had hemispheric morphology. Seven lesions were located in the liver subcapsular region, and proliferation of bile ductules without atypia and fibrous stroma was observed. Two lesions had different microscopic findings. In both lesions, proliferation of bile ductules without atypia was observed in the margin. In one lesion, the percentage of fibrosis and hyalinization was higher at the center than at the margin. In the other lesion, inflammatory cell infiltration was observed in the center. On contrast-enhanced imaging, BDAs showed hypervascularity in the early phase and prolonged enhancement in the delayed phase. On contrast-enhanced multidetector computed tomography during hepatic arteriography, two lesions showed ring-like enhancement in the first phase and prolonged enhancement in the second phase. These were the different histopathologic features of BDAs between the margin and center.

CONCLUSION

Bile duct adenoma can be characterized as a small semicircular lesion located in the liver subcapsular region, which show hypervascularity in the early phase with prolonged enhancement.

Imaging features of bile duct adenoma: case series and review of literature

PURPOSE

We aimed to evaluate the imaging features of bile duct adenoma (BDA) on ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI).

METHODS

Retrospective search in our institution database was performed for histologically confirmed BDA. Their imaging studies before histologic confirmation were reviewed. The search identified seven adults (mean age, 52.9 years) with histologically proven single BDA each. US (n=3), CT (n=5), and MRI (n=3) were performed before histologic confirmation. Additionally, a systematic English literature review for BDA and reported imaging findings since 2000 was also conducted using the following search criteria "bile duct adenoma, peribiliary hamartoma, biliary adenoma, CT, ultrasound, MRI" (date range: 01/01/2000 through 08/31/2016). The imaging findings of those cases reported were summarized and compared with our series.

RESULTS

All seven individual nodules were well circumscribed. Five lesions were located in the right hepatic lobe and two in the left hepatic lobe. On US, lesions appeared hypoechoic (n=2) and hyperechoic (n=1). BDA was hypodense on unenhanced CT images (n=1). On MRI, BDA were hypointense on T1 (n=3), hyperintense on T2 (n=3), and hyperintense on diffusion-weighted images (n=2). On contrast-enhanced CT and MRI, BDAs showed arterial phase hyperenhancement that persisted on portal venous/delayed phase images.

CONCLUSION

BDA demonstrates characteristic arterial phase hyperenhancement that persisted into the portal venous and delayed phases on CT and MRI, which may be useful in differentiating from other hepatic lesions.

Technical advancements and protocol optimization of diffusion-weighted imaging (DWI) in liver

An area of rapid advancement in abdominal MRI is diffusion-weighted imaging (DWI). By measuring diffusion properties of water molecules, DWI is capable of non-invasively probing tissue properties and physiology at cellular and macromolecular level. The integration of DWI as part of abdominal MRI exam allows better lesion characterization and therefore more accurate initial diagnosis and treatment monitoring. One of the most technical challenging, but also most useful abdominal DWI applications is in liver and therefore requires special attention and careful optimization. In this article, the latest technical developments of DWI and its liver applications are reviewed with the explanations of the technical principles, recommendations of the imaging parameters, and examples of clinical applications. More advanced DWI techniques, including Intra-Voxel Incoherent Motion (IVIM) diffusion imaging, anomalous diffusion imaging, and Diffusion Kurtosis Imaging (DKI) are discussed.

Magnetic Resonance Imaging Findings of Intrahepatic Bile Duct Adenoma: A Report of 4 Cases

Intrahepatic bile duct adenoma (BDA) is a rare type of benign hepatic lesions. In this study, 4 cases of BDA diagnosed from surgical resection pathology were examined. Their clinical and magnetic resonance imaging (MRI) data were retrospectively analyzed. The 4 cases (1 men and 3 women) were aged 21 to 55 years without obvious clinical symptoms. Three were identified through routine examination. Three had a history of chronic hepatitis B virus infection. Two cases were accompanied by hepatocellular carcinoma, and one had a higher level of α-fetoprotein. The MRI images of BDA all manifested as peripheral hepatic nodules with abnormal signals. The diameters of the lesions in the 4 cases were 7.7 to 17.0 mm. The MRI images showed slight hypointensity on T1WI and slight hyperintensity on T2WI in all cases, and they showed slight hyperintensity in 2 cases and hyperintensity in 2 cases on diffusion-weighted imaging. Dynamic contrast-enhanced MRI scans show hyperintensity in the arterial phase and slight hyperintensity in the late stage in 3 cases. The other case shows hyperintensity in the arterial and portal phases and isointensity at the delayed phase. During follow-up, 3 cases were recurrence-free. The other case was complicated by the reoccurrence of HCC. In general, BDA shows specific MRI characteristics, and peripheral hepatic nodules show slight hypointensity on T1WI and slight hyperintensity on T2WI. Dynamic contrast-enhanced MRI scans showed obvious enhancement in the arterial phase and continuous enhancement at the late stage.

Intrahepatic bile duct adenoma in a patient with chronic hepatitis B accompanied by elevation of alpha-fetoprotein

A 51-year-old male patient with chronic hepatitis B was referred to our hospital due to a 1-cm liver nodule on ultrasonography. Alpha-fetoprotein (AFP) was slightly elevated. The nodule showed prolonged enhancement on dynamic liver magnetic resonance imaging and appeared as a hyperintensity on both diffusion-weighted and T2-weighted imaging. The nodule was followed up because it was small and typical findings of hepatocellular carcinoma (HCC) were not observed in the dynamic imaging investigations. However, liver contrast-enhanced ultrasonography performed 1 month later showed enhancement during the arterial phase and definite washout during the delayed phase. Also, AFP had increased to over 200 ng/mL even though AST and ALT were decreased after administering an antiviral agent. He was presumptively diagnosed as HCC and underwent liver segmentectomy. Microscopy findings of the specimen indicated bile duct adenoma. After resection, the follow-up AFP had decreased to within the normal range. This patient represents a case of bile duct adenoma with AFP elevation mimicking HCC on contrast-enhanced ultrasonography.

Imaging findings of bile duct hamartomas: a case report and literature review

Bile duct hamartomas (BHs), also called von Meyenburg complex (VMC), are benign biliary malformations that originate from disorganization of the small intrahepatic bile ducts. This disorganization is often associated with the abnormal involution of embryonic ductal end plates in the liver. This is clinically significant, as the development of BHs can cause diagnostic confusion with liver metastases and small hepatocellular carcinoma (SHCC). Currently, we report a specific case of BHs and review the literature to better define and diagnose BHs. In the following case, a 37 year-old male bearing a lesion in his liver is presented and undergoes both radiological and pathological diagnosis. The lesion is preliminarily suspected to be a hepatic hemangioma by examination of conventional ultrasound (US), contrast enhanced ultrasound (CEUS), computerized tomographic scanning (CT) and magnetic resonance imaging (MRI). However, SHCC is suspected by follow-up analysis of US and CEUS, due to the patient's background history of hepatitis B and growth of the lesion and a tumor-feeding vessel in BHs via CEUS. However, BHs are finally diagnosed by biopsy pathology under the guidance of ultrasound. Therefore, we believe pathology is imperative for correct diagnosis of BHs over other similar diseases when the imaging findings are atypical. Here we report the novel and unique detection of a tumor-feeding vessel, which mimicked SHCC strongly, during the course of CEUS. We also present a comprehensive review of the previous reported radiological examination related to BHs.

Intrahepatic bile duct adenoma (peribiliary gland hamartoma): a case report and review of literature

Bile duct adenoma (BDA) is a comparatively rare disease and there are relatively few reported cases in the English-language literature. Herein, we present a 63-year-old woman, who was incidentally found to have a liver-occupying lesion during a routine medical examination. Ultrasonography suggested "quick wash-in and wash-out" sign with an obvious nodular enhancement in the peripheral of the right intrahepatic nodular. Computed tomography revealed a 33 mm×25 mm×28 mm mass in the right hepatic segment. The patient underwent a liver tumor resection. Histological examination showed that the tumor was consisted of small heterogeneous tubular ducts with fibrous tissues and several inflammatory cells, without cell atypia and mitotic activity. Immunohistochemically, the tumor cells were positive for CK19, CK7, CD56 and CD10. The final histopathological diagnosis was intrahepatic BDA.