Imaging of Biliary Tree

Biliary imaging includes different techniques, starting with ultrasound as the first-line imaging modality of choice, then the cross-sectional or tomography imaging—computed tomography and magnetic resonance imaging, ending with invasive procedures as endoscopic retrograde cholangiography and percutaneous transhepatic cholangiography. Positron-emission tomography scan and endosonography are additional imaging studies to be mentioned. In this chapter, the imaging approach is discussed according to different clinical scenarios. Jaundice is the most common biliary/liver disease, and the most important question imaging has to answer is whether the icterus is obstructive or non-obstructive. Which imaging methods would define the biliary tree pathology as indicated for surgical treatment is another important question. Diagnostic pathways in biliary colic and acute cholecystitis are discussed. Sonographic Murphy’s sign, gallstones, and pericholecystic fluid are important imaging findings. Choledocholithiasis and cholangitis are key findings on ultrasound, computed tomography, and magnetic resonance cholangiopancreatography. Cholangiocarcinoma is the cancer deriving from the biliary structures. It has different types, and in many cases, it is radiographically indistinguishable from hepatocellular carcinoma and even from benign tumors of liver and biliary tree. Imaging hallmarks on computed tomography and magnetic resonance imaging, especially on contrast-enhanced techniques, should be taken into consideration. Lastly are included post-surgical and iatrogenic biliary injuries such as bile leak and bilomas. Not on focus in this chapter are some special considerations—pediatric and congenital biliary disorders, biliary atresia, choledochal cysts, liver transplantation, and biliary imaging, pre- and post-transplant complications. Emerging technologies and future directions, especially artificial intelligence in biliary imaging, are also excluded.