Hepatobiliary contrast agents are desirable for several reasons: to detect mass lesions such as metastases within the liver; to evaluate functional status of the liver in diffuse hepatocellular diseases such as cirrhosis; and to obtain high resolution images of the gallbladder and biliary tree.
Three advantages of a hepatobiliary contrast agent over a particulate agent targeted for Kupffer cells exist. First of all, there are many more hepatocytes than Kupffer cells (78% vs. 2% by volume) in the liver, improving uptake efficiency of contrast material. Second, the biliary ducts are opacified by excreted contrast material, eliminating confusion of normal bile ducts from focal abnormalities as may occur with particulate agent contrast materials. Third, the contrast agent is rapidly excreted from the body reducing potential toxicity. In contrast, materials phagocytized by the reticuloendothelial system (including Kupffer cells) remain in the body for a long period of time.
The uptake and excretion of contrast material allows visual assessment of basic hepatocyte function. The biliary opacification will allow functional information to be obtained as with radionuclide hepatobiliary studies but with significantly higher spatial resolution.