Pitfalls in the imaging diagnosis of hepatocellular nodules in the cirrhotic and noncirrhotic liver

Contrast-enhanced CT and MR are the most commonly used modalities for objective evaluation of hepatocellular nodules. Various types of pseudolesions as seen on CT or MR have been reported, which are attributable to either focal alteration in hemodynamics or parenchymal metabolism, or to both. Pseudolesions specifically seen in cirrhotic liver include arterio-portal shunt, regenerating or hyperplastic nodules, and confluent fibrosis. In noncirrhotic liver, transient focal compression to the liver, third inflow other than normal hepatic arterial and portal venous flow, and vessel compromise are the causes of pseudolesions. To understand the characteristic features of these pseudolesions, and their underlying mechanism as well, is important for proper diagnosis of true hepatocellular lesions.