The caudate lobe, or segment I of the liver in the Couinaud classification, is the portion of the liver situated between portal vein bifurcation and inferior vena cava. It has specific arterial and portal venous supply, as well as independent venous drainage, making it anatomically and functionally independent. Due to its unique particularities, it is often affected differently by various chronic liver diseases. [1]
The most obvious example is the particular venous drainage of the caudate lobe, being the only segment which drains directly to the inferior vena cava through multiple short hepatic veins (Spieghel veins). The particular venous outflow spares the caudate lobe from the increased venous pressure in various liver diseases.[2]
The arterial and portal venous blood supply is provided through multiple caudate arteries and short portal veins arising from both the right and left branches of the hepatic artery and portal veins. Thus, both the arteries and the portal vein branches have a shorter intraparenchymal course (compared to the vessels of the other lobes). [1,3]
Atrophy-hypertrophy complex (AHC) represents the liver’s ability to regenerate after hepatocyte loss and is the main mechanism through which the caudate lobe undergoes compensatory hypertrophy. As the initial injury can be different (toxins, biliary obstruction, ischemia), the AHC may have different morphologic features for particular etiologies and can be an important clue in diagnostic imaging. Sometimes, caudate lobe hypertrophy may be the most striking imaging feature, even associating different density or signal intensity, thus simulating a mass - “pseudotumor”. [4,5]
