Basic imaging modalities
When biliary obstruction is suspected, ultrasonography (US) is the first-line investigation. Tumors are most frequently visualized as hyperechoic masses or focal thickening of the duct wall. Contrast-enhanced ultrasound (CEUS) demonstrates hyper- or isoenhancing uptake with characteristic rapid washout in the portal venous phase.
Computed tomography (CT) requires dual-phase contrast administration:
- Infiltrative-stenosing type shows avid contrast enhancement in the arterial phase.
- Exophytic type is best visualized in the portal phase, remaining hypodense relative to the normal liver parenchyma. On unenhanced scans, masses are typically isodense or slightly hypodense.
On magnetic resonance imaging (MRI), tumor tissue is hypointense on T1-weighted images and hyperintense on T2-weighted images. Dynamic contrast-enhanced imaging reveals progressive contrast accumulation. Diffusion-weighted imaging (DWI) is indispensable for detecting small lesions and the intraductal component.
Assessment of tumor resectability
The primary role of the radiologist is to provide surgeons with comprehensive information for treatment planning. Evaluation includes identifying lobar atrophy of the liver, assessing intra- and extrahepatic extension, and analyzing the involvement of the portal vein, hepatic artery, and ducts of the caudate lobe.
Dual-phase high-resolution CT (CT angiography) and magnetic resonance cholangiopancreatography (MRCP) are the best non-invasive modalities for this purpose. MRCP is critical for classifying hilar strictures (e.g., using the Bismuth classification) and outperforms standard ultrasound and CT. The role of positron emission tomography (PET) is limited to detecting lymph node and distant metastases, as well as evaluating treatment response.
Intraductal papillary mucinous neoplasm (IPMN-B)
This is the biliary counterpart of the well-known pancreatic neoplasm. IPMN-B is characterized by the growth of intraductal papillary projections and excessive mucin production. Approximately 70% of cases are located in the intrahepatic ducts.
A key clinical feature is the intermittent nature of symptoms (pain, fever, jaundice) caused by mucus impaction. On cholangiograms, the tumor and mucin accumulations create a lobulated filling defect. Duct dilatation is present in 100% of cases, whereas intraductal masses are visualized in only half of patients.
Interventional procedures and palliative treatment
The majority of patients with cholangiocarcinoma are unresectable; therefore, palliative drainage to relieve jaundice becomes paramount.
- Endoscopic stenting is preferred for distal obstructions.
- Percutaneous transhepatic drainage is used for proximal strictures (hilar strictures). Access is most commonly established via the right hepatic lobe (right lateral approach) as it provides a less acute angle and reduces the risk of hemobilia.
For hilar strictures (Bismuth types II–IV) separating the ducts, authors recommend placing a single, carefully positioned self-expandable metallic stent. Unilateral stenting to drain the maximal volume of healthy parenchyma is as effective as complex bilateral drainage. Bilateral drainage is mandatory only in the presence of infected bile in the contralateral lobe.
Biopsy guidelines
Biliary tract biopsy carries inherent risks (bleeding, bile leakage, tract seeding). Several strict rules apply:
- The procedure should be deferred until complete biliary decompression has been achieved.
- Biopsy is contraindicated if the patient is considered a candidate for radical surgical resection.
- Endoscopic ultrasound-guided (EUS) biopsy is generally preferred over percutaneous needle biopsy as it carries a lower risk of tumor seeding and offers high diagnostic sensitivity.
Briefly: answers to topical questions
What are the types of hilar strictures according to the Bismuth-Corlette classification?
The Bismuth classification categorizes proximal bile duct strictures into four types based on the anatomical location of involvement.
| Type | Location of involvement |
|---|---|
| Type I | Involvement of the common hepatic duct |
| Type II | Involvement of the confluence of the hepatic ducts |
| Type IIIA | Involvement of the right hepatic duct |
| Type IIIB | Involvement of the left hepatic duct |
What complications may arise from percutaneous transhepatic drainage and biliary biopsy?
Complications of percutaneous transhepatic catheterization of the biliary tree include hemorrhage, biliary peritonitis, and complications similar to those of percutaneous transhepatic cholangiography; these occur twice as frequently as with PTC. Liver biopsy complications may include hemorrhage, pneumothorax, biliary peritonitis, bowel or gallbladder perforation, hemobilia, and arterioportal shunt formation.
What are the macroscopic types of cholangiocarcinoma?
The source text describes two types of cholangiocarcinoma based on growth pattern and contrast enhancement:
- Infiltrative-stenosing type — tends to accumulate contrast during the arterial phase.
- Exophytic type — is best visualized in the portal phase, remaining hypodense relative to the liver parenchyma.
Intraductal papillary mucinous neoplasm of the bile ducts (IPMN-B) is recognized as a separate entity, characterized by the intraductal growth of branching papillary projections and hypersecretion of mucin.
For the differential diagnosis between pancreatic carcinoma and cholangiocarcinoma, look for the "double-duct sign" — adjacent strictures of the common bile duct and the main pancreatic duct. This is a highly specific sign of pancreatic pathology.
Class and exam questions
Why is PET performed in cholangiocarcinoma if it evaluates the primary tumor poorly?
PET is used to detect regional lymph node involvement, search for distant metastases, and monitor tumor response to ongoing therapy.
Which stents are preferred for palliative drainage?
Self-expandable metallic stents are preferred over plastic stents because they have a larger lumen, last longer, and are associated with a lower rate of early complications.
What else to study on this topic
- Bismuth-Corlette classification criteria for hilar strictures.
- Differential diagnosis with gallbladder carcinoma and Mirizzi syndrome.
- Radiological appearance of metastatic involvement of the biliary tract (scalloped contour).
- Management of patients with hemobilia and the role of selective angiography.
- Indications for and technique of percutaneous cholecystostomy.
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