CT cholangiography (protocol)
Updates to Article Attributes
CT cholangiography is a technique of imaging the biliary tree with the usage of hepatobiliary excreted contrast. It is useful in delineating biliary anatomy, identifying a bile leak or looking for retained gallstones within the biliary system.
Indications
Second-line test (after ultrasound) when investigating for right upper quadrant pain, obstructive LFTs, etc. It can also be used in the postoperative setting (e.g. post-cholecystectomy) where there is a concern for common bile duct injury or retained gallstones, or where intraoperative cholangiography (IOC) is unable to be performed due to extensive inflammation or a narrow cystic duct, proving direct cannulation difficult.
Purpose
The purpose of CT cholangiography is to identify a filling defect in the biliary tree that represents choledocholithiasis or a contrast leak from the biliary tree in case of injury.
Contraindications
- bilirubin should be <30
mmolµmol/L nor should it be rising rapidly (as the impaired excretory ability of hepatocytes can affect contrast excretion in bile) - severe hepatic or renal dysfunction
- thyroid dysfunction
- iodinated-contrast adverse reactions
Technique
CT cholangiography may be performed with either intravenous or oral cholangiographic contrast agents both of which outline the biliary tree with positive contrast.
Agents
- meglumine iotroxate (BiliscopinTM): intravenous CT cholangiography agent
Findings
- choledocholithiasis
- biliary stricture
- bile leak / biloma
- aberrant biliary tree anatomy
- other causes of biliary tree obstruction, e.g. pancreatic head tumours
Alternative examinations
- magnetic resonance cholangiopancreatography (MRCP)
- contrast-enhanced MR cholangiography: with gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid
- endoscopic retrograde cholangiopancreatography (ERCP): carries a 5% risk of post-procedure pancreatitis
- intraoperative cholangiography (IOC): performed during cholecystectomy to allow intraoperative detection of retained gallstones or common bile duct injury
Mimics
- occasionally vicarious contrast material excretion can give opacification of the gallbladder and biliary system
-<li>bilirubin should be <30 mmol/L nor should it be rising rapidly (as the impaired excretory ability of hepatocytes can affect contrast excretion in bile) </li>- +<li>bilirubin should be <30 µmol/L nor should it be rising rapidly (as the impaired excretory ability of hepatocytes can affect contrast excretion in bile) </li>
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