Biliary Tree and Gallbladder Flashcards
Normal common duct size
<6 mm, increasing 1 mm per decade (Ex. 7 mm is normal for patients in their 70s)
CT of the bile ducts technique
- Water as oral contrast agent: (300 ml of water 15-20 min before exam)
- Multiphase CT (4 phases)
Biliary obstruction causes (in general) (6)
- Impacted Gallstones
- Bile duct stricture
- Malignancy
- Parasites
- AIDS related cholangiopathy
- Choledocal cysts
Biliary duct’s stricture causes (6)
- Trauma/surgery/instrumentation
- Chronic pancreatitis
- PSC
- Recurrent pyogenic cholangitis
- AIDS-associated cholangitis
- Benign tumors of the biliarty tract
Biliary obstruction main malignancies (5)
- Pancreas head carcinoma
- Duodenal/ampullary carcinoma
- Cholangiocarcinoma
- Gallbladder carcinoma
- Metastases
Mirizzi Syndrome
A gallbladder stone impected in the cystic duct induces cholangitis or erodes into the common duct to cause obstructive jaundice.
Clues to the cause of biliary obstruction
- Abrupt termination of a dilated CBD: Malignancy.
- Gradual tapering of a dilated duct: Benign.
- Choledocholithiasis: Might be difficult to recognize due to the wide variation in CT appearance of gallstones.
How many percent of gallstones are not visualized by CT?
15-25% of gallstones
Types of Gallstones to CT
- Calcific: Calcium billirubinate stones
- Soft-tissue: Mixed stones
- Fat: Cholesterol stones
Target or crescent sign
Stone as central density surrounded by a rim or crescent of lower-density bile
Rim sign
Low-attenuation stone may be defined by a higher attenuation outer rim
Cholangiocarcinoma growth patterns (4)
- Mass forming intrahepatic
- Periductal infiltrating
- Intraductal growing
- Extrahepatic
Cholangiocarcinoma localization %
- Extrahepatic bile ducts (65%)
- Hilum (25%)
- Periphery of the liver (10%)
Intrahepatic mass forming CCA - CT findings
- Homogeneous tumor, irregular borders, low attenuation
- Arterial phase: Weak peripheral enhancement
- Delayed phase: Central or diffuse enhancement
- Bile ducts peripheral to the tumor obstructed and dilated
Periductal infiltrating CCA - CT findings
- Bile ducts are invaded by lesions in an elongated and branching pattern
- Tumor’s Bile ducts are narrowed with thick walls
- Peripheral bile ducts are dilated with thin walls
Klatskin tumor
Periductal-infiltrating CCA at the confluence of the right and left hepatic bile ducts
Intraductal CCA - CT findings
- Polypoid or sessile papilary lesions that extend superficially along the bile duct mucosa
- May produce mucin, which disproportionately dilates the biliary system
Extrahepatic CCA - CT findings
May appear as:
-Duct obstructing polypoid tumor nodule 1-2 cm in diameter.
- Abrupt stricture with wall thickening up to 1 cm
- Single or multiple intraductal frond-like masses
Cholangitis main causes (5)
- Primary schlerosing cholangitis
- Acute pyogenic cholangitis
- Recurrent pyogenic cholangitis (Oriental cholangitis)
- AIDS - Cholangiopathy
- Autoimmune pancreatitis-associated cholangitis
Primary schlerosing cholangitis
Idiopathic inflammatory condition, causes progessive fibrosis of bile ducts leading to: obstruction, cholestasis and biliary cirrhosis
- 70% associated with ulcerative colitis and other inflammatory bowel diseases
- CT findings: Multiple segmental strictures thickening (2-5 mm) of bile ducts alternating with normal ones (Beaded appearance)
Acute pyogenic cholangitis
- Acute abdominal pain, feber, jaundice (Charcot Triad)
- CT: Periductal edema, bile duct dilatation and inhomogeneous enhancement of the liver parenchyma
- Complications: Liver abcess, sepsis
- May produce pneumobilia
Recurrent pyogenic cholangitis (Oriental cholangitis)
- Recurrent episodes of cholangitis, associated with pigmented stones, multifocal biliary strictures and dilations
- Causes: Clonorchis sinensis, ascaris lumbricoides, malnutrition and portal vein bacteremia
- Endemic to southeast asia and china
- CT: Marked dilation of CBD
- Complications: Liver abscess, portal vein thrombosis, pneumobilia and CCA
AIDS-Cholangiopathy
- Opportunistic infection with criptosporidium or CMV
- Intrahepatic bile ducts narrowing similar to PSC
- KEYPOINT: Might generate obstruction of the distal part of CBD (near the ampula)
Autoimmune pancreatitis-associated cholangitis
- Autoimmune pancreatitis + involment of bile tree
- Ig4-positive lymphocytes infiltrate the wall of intrahepatic and extrahepatic bile ducts
- Thickening and enhancement of the wall of the bile ducts occurs in association with multiple strictures
- The distal part of the CBD is most commonly affected
