Abstract
Ultrasonography, including color Doppler US is useful in assessing right hepatic artery invasion and portal vein invasion of the superior bile duct carcinoma. On the other hand, endoscopic ultrasonography via the transduolenal scanning has some limitations in staging superior bile duct carcinoma compared to it of inferior bile duct carcinoma. Intraductal ultrasonography produces high-quality cross-sectional images of the bile duct without blind area, and is useful in assessing tumor depth infiltration, hepatic parenchymal invasion, portal vein invasion, and right hepatic artery invasion of superior bile duct carcinoma. However, it has limitations in assessing lymph nodes metastases. The assessment of longitudinal cancer extension along the bile duct is a promising aspect of this area. Transpapillary IDUS prior to biliary drainage is essential to prevent inflammatory changes that may result from mechanical irritation by a biliary drainage catheter.
