What is the normal appearance of the biliary tree and gallbladder on cross sectional imaging?
The intrahepatic bile ducts are normally ≤ 2 mm in caliber, and they coalesce to form segmental bile ducts. The segmental bile ducts then join to form the right and left hepatic ducts, which subsequently coalesce to form the extrahepatic bile duct.
The extrahepatic bile duct extends from the liver to the second portion of the duodenum within the hepatoduodenal ligament, anterior to the main portal vein and lateral to the hepatic artery. It is comprised of the more superiorly located common hepatic duct (CHD), which is normally ≤ 6 mm in caliber, and the more inferiorly located common bile duct (CBD), which is normally ≤ 8 mm in caliber (see Figure 28-1, B ). The cystic duct, which communicates with the gallbladder, joins to the CHD to form the CBD. The CBD then joins inferiorly with the main pancreatic duct to form the ampulla of Vater, which then drains into the second portion of the duodenum via the major duodenal papilla.
Bile duct walls are normally thin and smooth, and no filling defects are normally seen in the biliary tree or gallbladder.
The gallbladder is ≈10 cm long and 3 to 5 cm in diameter and is located inferiorly to the liver along the interlobar fissure in the gallbladder fossa. The normal gallbladder wall thickness is ≤ 3 mm, and the surrounding visceral fat is normally homogeneous and similar in attenuation and signal intensity to fat elsewhere in the body