Intrahepatic arterioportal shunt

Zufallsbefund

eines arterio-portalvenösen Shunts in der Leber bei einer 63-jährigen in der Computertomographie, links in der arteriellen Phase, rechts portalvenös. Ein Tumor, ein Trauma oder eine vorangegangene Intervention ließ nicht eruieren. In der portalvenösen Phase gleicht sich das Parenchym an.

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MR imaging in

liver cirrhosis: classical and new approaches. Vascular changes: arterioportal shunts. Transverse fat suppression T1W spoiled GRE image after administration of contrast media shows small and non-encapsulated areas with enhancement in the arterial phase (a), but without wash-out on the portal phase image (b)

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Intrahepatic arterioportal shunts represent abnormal flow between the portal venous system and a hepatic arterial system within the liver. They can be a reversible cause of portal hypertension.

Clinical presentation

Clinical features will depend on the size and other underlying pathology. Small shunts can be asymptomatic.

Pathology

Intrahepatic vascular shunts can be divided according to the cause into:

tumorous shunt
- occurs with hepatocellular carcinoma and to a lesser extent hepatic hemangioma
- trans-tumoral shunt is due to abnormal communication between the feeding artery and draining vein of the tumor which results in increased vascularity around the tumor manifested as peritumoral transient hepatic attenuation differences (THAD)
- portal vein may show early enhancement in the dynamic arterial scan without enhancement of its main tributaries the splenic and superior mesenteric veins
non tumorous shunt
- mainly due to liver biopsy and other hepatic intervention
- may be due to liver cirrhosis itself owing to deformation of hepatic sinusoids which increases arterial pressure or portal vein extrinsic compression that also leads to increased arterial pressure
- congenital intrahepatic arterioportal fistula (rare)

Differential diagnosis

Sometimes arterioportal shunt appears in dynamic CT as enhancing nodule, which can mimic hepatocellular carcinoma. The best way to differentiate is by using MRI with SPIO (superparamagnetic iron oxide) which is deposited in hepatocellular carcinoma and washed out in vascular shunt.