EUS anatomy of the liver segments

Clinical applications of EUS for the liver have been recently increasing. They include the screening and diagnosis of liver parenchymal disease and malignant tumors as well as EUS-guided interventions such as hepaticogastrostomy, tumor ablation therapy, and portal pressure gradient measurement. Although the segmental localization of the targeted tumor, bile duct, and vessel in the liver is important to complete these procedures, little information is available regarding hepatic segmental anatomy on EUS. The liver can be visualized with EUS by transgastric and transduodenal scanning, and the EUS determination of segmental location can be achieved using various anatomical landmarks. Identification of the right posterior segments is, however, technically difficult because they are located far from the stomach and duodenum. In the present review, we describe the normal anatomy of liver segments using linear EUS.