Progress of endoscopic ultrasonography and intraductal ultrasonography in the diagnosis of malignant biliary diseases

In recent years, ultrasound technology has made remarkable strides, and the application of these latest advances to endoscopic ultrasonography (EUS) and intraductal ultrasonography (IDUS) is crucially important. EUS equipped with electronic scanners (both radial and convex types) has been developed, and now EUS with the function of tissue harmonic imaging (THI) and color/power Doppler is applicable clinically. THI facilitates the acquisition of ultrasound images clearer than those of fundamental imaging, and color/power Doppler sonography demonstrates the precise hemodynamics with the use of a contrast agent. In addition, the progress of image processing technology has realized three-dimensional (3D) images in EUS and IDUS. Reconstruction of 3D images enables us to diagnose more objectively. Here we describe the roles of these new ultrasound technologies in the diagnosis of biliary malignancies.