The use of a micro-bubble contrast agent to allow visualization of the biliary tree

Micro-bubble contrast agents have been used as contrast agents in the vascular system to allow visualization of blood flow by ultrasound. We examined the use of this type of contrast agent for visualization of bile duct by ultrasound. A laparotomy was performed on a domestic farm pig and the common bile duct was cannulated with a 20 gauge catheter. The contrast agent, perflutren lipid microspheres (Definity), was injected in different dilutions. Sonographic images were obtained by scanning directly on the pig liver. The use of the micro-bubble contrast in the biliary system provided excellent visualization of the bile duct down to ducts as small as fifth-order branches and demonstrated bile ducts < 2 mm. The use of micro-bubble contrast agents in the biliary tree may allow for real-time imaging of the bile duct and could be helpful in living donor liver transplantation.