Basic techniques of Radial/Convex arrayed echoendoscope for biliary system

Abstract

There are two types of EUS: Radial and Convex scan type, and either one can be used to perform the screening of the biliary system. However, the method of drawing the biliary tract differs in each echoendoscope, and there are also differences in the structure of the obtained images. In Radial scanning, it is possible to observe the bile duct in the long axis direction from the vicinity of the ampulla to so-called the superior bile duct, but in many cases, the hilar region cannot be observed sufficiently. On the other hand, in Convex scan type, the long axis observation of the bile duct is inferior to Radial scan type, but detailed observation of the hilar region can be performed. In addition, EUS-guide fine-needle aspiration biopsy for biliary disease is also performed with high diagnostic ability. By firmly understanding the advantages/weaknesses of each EUS model and performing biliary observation in accordance with the basic scanning method, accuracy of EUS diagnosis will certainly improve.