Intrahepatic arterioportal shunts：an annotation of the functional shunts / 介入放射学杂志

ABSTRACT

In this paper, all the intrahepatic arterioportal shunts (IHAPSs) that result from the functional redistribution of hepatic arterial and portal venous blood flow are defined as functional IHAPSs (F-IHAPSs) so as to make the differentiation from organic IHAPSs (O-IHAPSs) that result from the intrahepatic arterioportal fistula or direct communication, such as those IHAPSs that are associated with advanced hepatocellular carcinoma (HCC) and other malignant hepatic tumors as well as those IHAPSs that are accompanied by congenital hepatic vascular malformations, hereditary hemorrhagic telangioectasia (HHT) and liver trauma (including iatrogenic injury), etc. In F-IHAPSs, the most common one is formed by the compensatory (or secondary) increase of arterial blood flow that is caused by the decrease of hepatopetal portal blood flow due to a variety of reasons; its formation mechanisms can be divided into three categories:(1) trans-sinusoidal type, such as the F-IHAPSs that is associated with cirrhosis;(2) post-sinusoidal type, such as the F-IHAPSs that is accompanied with the acute stage of Budd-Chiari syndrome; and (3) pre-sinusoidal type, such as the F-IHAPSs that occurs along with the gastrointestinal hemorrhagic shock. Another kind of F-IHAPSs has been commonly seen in some hepatic diseases that have primary increase of hepatic arterial blood flow, including hypervascular hepatic cavernous hemangioma, small hepatocellular carcinoma that has rich blood supply, hepatobiliary inflammatory diseases, etc.;and in this paper they are all classified as F-IHAPSs category, however, the formation mechanisms of such F-IHAPSs vary with their basic diseases. Clinically, imaging diagnosis of F-IHAPSs can be made based on the following three signs:(1) all kinds of hepatic diseases that have concomitant intrahepatic arterioportal fistula or direct communication, as mentioned above, have been definitely excluded:(2) hepatic artery DSA reveals early visualization of portal vein in arterial phase, known as the characteristic sign of F-IHAPSs;and/or: (3) hepatic dynamic enhanced CT/MR scanning demonstrates transient enhancement of liver parenchyma in arterial phase, especially early visualization of portal vein is also present; in this case the diagnosis of F-IHAPSs can be undoubtedly confirmed. However, in making differential diagnosis, F-IHAPSs must be carefully differentiated from O-IHAPSs, local hepatic parenchymal perfusion caused by hepatic aberrant vein or by abnormal hepatopetal draining vein from systemic circulation, etc. In addition, when cirrhosis-related transient hepatic parenchymal enhancement presents as a solitary small nodule, differentiation with small HCC should be taken into consideration. In order to provide the readers with a complete and up-to-date understanding of F-IHAPSs, the relevant example illustrations, figures and graphics are accompanied with the text.