Imaging Modalities for Calculi
The differential diagnosis when searching for calculi using cholangiography is based on the same principles as ultrasound examination. Diagnostic imaging allows for the precise determination of the number, size, and localization of stones.
- CT intravenous cholangiography: an examination performed in the coronal projection, enabling clear visualization of multiple small calculi located within the common bile duct.
- MRCP (magnetic resonance cholangiopancreatography): optimally suited for detecting both single and multiple calculi. In practice, thick oblique coronal slices providing high contrast of the biliary tract are frequently analyzed for this purpose.
Hepatolithiasis and Associated Conditions
Although calculi are more frequently localized extrahepatically in Western populations, intrahepatic stone formation—hepatolithiasis—also occurs. The imaging features of intrahepatic calculi are entirely analogous to those of stones in the extrahepatic bile ducts.
Hepatolithiasis may present in combination with classic choledocholithiasis, but it is much more frequently associated with specific pathological conditions:
- Formation of benign strictures.
- Primary sclerosing cholangitis (PSC).
- Postoperative biliary strictures.
- Recurrent pyogenic cholangitis (RPC).
- Caroli disease (Caroli disease).
Benign Biliary Strictures
Bile duct strictures frequently cause impaired bile outflow, with new calculi potentially forming proximal to any narrowing. Detailed evaluation of strictures, especially in the complex anatomy of the hepatic hilum, requires high-quality cholangiography.
Post-cholecystectomy strictures These represent the most frequent etiology of postoperative narrowings. They are characterized by a short length—typically less than 10 mm (very short 1–2 mm strictures are frequently encountered). They are predominantly localized in the common bile duct, but the pathological process may involve the right and left hepatic ducts, as well as aberrant biliary pathways (especially the lower right segmental or sectoral branches).
Post-liver transplantation strictures Two types of narrowings are distinguished in donor liver recipients:
- Anastomotic strictures — develop in approximately 8.9% of patients.
- Non-anastomotic strictures — occur more frequently, in approximately 16% of cases.
Primary Sclerosing Cholangitis (PSC)
Primary sclerosing cholangitis (PSC) stands out as the most frequent form of cholangitis that consistently leads to the formation of multiple biliary tree strictures. An important clinical feature is that this disease develops against the background of concomitant inflammatory bowel disease (IBD) in 70% of patients.
Differential Diagnosis: Pseudostrictures on MRCP
When interpreting MRCP data, it is important not to confuse a true narrowing with an artifact—a pseudostricture. This frequent artifact is typically projected onto the region of the common hepatic duct.
The cause of this visual defect is the anatomical intersection of the duct with the hepatic artery (or its right branch). On T2-weighted magnetic resonance images, this intersection appears as a hypointense area of signal loss due to active blood flow (flow void).
How to distinguish a pseudostricture from a true one:
- The vascular signal void effect is not always visible, but the key sign is that the caliber of the bile duct proximal and distal to the pseudostricture remains identical.
- On 3D reconstructions, the pseudostricture has an eccentric character (located strictly along the anterior or posterior surface of the duct wall).
Briefly: answers to topical questions
What diagnostic imaging modalities are used to detect choledocholithiasis?
A wide range of diagnostic imaging modalities is used to detect choledocholithiasis.
- Ultrasound examination (US) is the preferred primary imaging modality.
- Computed tomography (CT) is used in the form of CT intravenous cholangiography to visualize calculi.
- Magnetic resonance cholangiopancreatography (MRCP) is highly informative for detecting stones approximately 5 mm in size.
- Endoscopic ultrasonography (EUS) is the method of choice for evaluating distal obstruction and detecting stones smaller than 5 mm.
- Direct cholangiography includes endoscopic retrograde cholangiopancreatography (ERCP) and percutaneous transhepatic cholangiography (PTC).
What direct and indirect CT signs are characteristic of choledocholithiasis?
Computed tomography allows for the visualization of calculi in choledocholithiasis. CT intravenous cholangiography may demonstrate multiple small calculi within the common bile duct. Indirect CT signs are not described in the cited sources.
What is the normal width of the common bile duct in a healthy individual and after cholecystectomy?
The normal width of the common bile duct is not represented by a single fixed value in the sources: the size varies significantly and depends on age and the measurement site.
| Patient category | Duct Width Characteristics |
|---|---|
| Young patients | Diameter is typically smaller than in elderly patients. |
| Elderly patients | A diameter greater than 8 mm is a frequent finding. |
| Jaundiced patients | A diameter greater than 7 mm is frequently used as a predictor of obstruction, but has limited specificity. |
| Post-cholecystectomy | Size is variable, frequently greater than 10 mm. |
Class and exam questions
What is the main difference between a pseudostricture and a true stricture on MRCP?
In pseudostricture, the caliber of the bile duct before and after the "narrowing" remains completely identical. Additionally, on 3D reconstruction, the defect appears eccentric, and on T2-weighted images, a signal void effect (flow void) from the crossing artery can be observed.
What are the typical sizes and locations of strictures following gallbladder removal?
Postoperative strictures are typically short—less than 10 mm (often only 1–2 mm). Most frequently they are located in the common bile duct, but may involve the hepatic and aberrant ducts.
Which gastrointestinal pathology most frequently accompanies primary sclerosing cholangitis?
In 70% of patients, primary sclerosing cholangitis (PSC) occurs concomitantly with inflammatory bowel disease (IBD).
What else to study on this topic
- Anatomy and Imaging of Aberrant Bile Ducts
- Recurrent Pyogenic Cholangitis (RPC): Mechanisms of Development
- Caroli Disease: Differential Diagnosis of Cystic Dilations
- Liver Transplantation Complications: Anastomotic Strictures
Master the entire topic in the "Diagnostic Radiology" course
This is a summary. The course covers everything tested in classes and exams.
- Complete Study Guide on "Choledocholithiasis" and 2,199 More Subject Pages
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 10 video lessons on the subject
Other topics in the section "Diagnostic Radiology of the Abdominal Organs"
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.