Dilated Intrahepatic Biliary Ducts: US Guide

Dilated intrahepatic biliary ducts, a significant finding in abdominal ultrasound, often indicate an obstruction within the biliary system. The American College of Radiology (ACR) provides guidelines for the appropriate use of ultrasound in evaluating suspected biliary obstruction, emphasizing the importance of identifying dilated intrahepatic biliary ducts. Ultrasound, a non-invasive imaging modality, serves as the primary tool for initial assessment due to its accessibility and cost-effectiveness in visualizing the liver and biliary tree. Understanding the sonographic features of dilated intrahepatic biliary ducts is crucial for radiologists and sonographers at institutions specializing in hepatobiliary diseases, aiding in the differential diagnosis of various conditions such as choledocholithiasis or strictures.

Ultrasound plays a pivotal role in the assessment of the intrahepatic biliary system. Its non-invasive nature, portability, and real-time imaging capabilities make it an indispensable tool. It’s used for the diagnosis and management of a wide range of biliary disorders.

The Biliary System: An Overview

The biliary system is a complex network of ducts and organs responsible for the production, storage, and transportation of bile. Bile, produced by the liver, aids in the digestion and absorption of fats.

The intrahepatic biliary ducts, a critical component of this system, are a network of channels within the liver. These ducts collect bile from the liver cells. They progressively merge, eventually forming the right and left hepatic ducts.

Understanding the anatomy and function of these ducts is crucial. It’s important for accurately interpreting ultrasound images and identifying abnormalities.

Ultrasound's Role in Diagnosing Cholestasis

Cholestasis, a condition characterized by the impaired flow of bile, can have various underlying causes. Ultrasound is a primary imaging modality. It’s used for evaluating patients presenting with jaundice, elevated liver enzymes, or other signs of biliary obstruction.

Ultrasound can effectively visualize the intrahepatic and extrahepatic biliary ducts. It helps determine whether the obstruction is intrahepatic or extrahepatic. It can also identify the level and cause of obstruction.

Furthermore, ultrasound can detect gallstones, masses, or strictures within the biliary tree. All of these contribute to cholestasis.

The Collaborative Expertise: Radiologists and Sonographers

The successful performance and interpretation of intrahepatic biliary ultrasound examinations rely on the expertise of both radiologists and sonographers.

Sonographers, skilled in ultrasound techniques, perform the examination. They obtain high-quality images of the biliary system.

Radiologists, with their comprehensive knowledge of anatomy and pathology, interpret these images. They provide accurate diagnoses.

The collaboration between sonographers and radiologists is essential. It ensures optimal patient care and effective management of biliary disorders. This collaboration leverages the strengths of each professional.

Anatomy and Physiology: Understanding the Intrahepatic Biliary System

A thorough comprehension of the anatomy and physiology of the liver and intrahepatic biliary system forms the bedrock for accurate interpretation of ultrasound images. This section elucidates the intricate network of ducts within the liver, the flow of bile and its key components, and the roles of the gallbladder and cystic duct. This foundational knowledge is indispensable for recognizing and characterizing biliary abnormalities during ultrasound examinations.

The Liver: A Brief Overview

The liver, the largest internal organ, resides in the upper right quadrant of the abdomen. It performs a multitude of vital functions. These include metabolism, detoxification, and the production of essential substances like bile.

Understanding the liver's overall structure is crucial before delving into the biliary system. It’s key to correctly identifying related structures on ultrasound.

Intrahepatic Biliary Ducts: The Network Within

The intrahepatic biliary ducts constitute a complex network of channels. They are located within the liver parenchyma. These ducts are responsible for collecting bile produced by the hepatocytes (liver cells).

These ducts gradually converge, forming larger ducts that ultimately drain into the right and left hepatic ducts. Ultrasound's ability to visualize these ducts allows for the detection of any obstruction or dilation.

Right and Left Hepatic Ducts

The right and left hepatic ducts emerge from the respective lobes of the liver. They represent the primary drainage pathways for bile.

On ultrasound, these ducts can be visualized as tubular structures. They are located near the porta hepatis. The porta hepatis is where the major vessels and ducts enter and exit the liver.

Confluence to Form the Common Hepatic Duct

The right and left hepatic ducts join outside the liver. They merge to form the common hepatic duct.

This confluence is a critical landmark. It’s important for distinguishing between intrahepatic and extrahepatic biliary anatomy on ultrasound. The location of this confluence must be accurately identified. This is essential for the proper interpretation of ultrasound images.

Bile Flow and Components

Bile, a fluid produced by the liver, plays a vital role in the digestion and absorption of fats in the small intestine. It contains bile salts, cholesterol, phospholipids, bilirubin, electrolytes, and water.

Bilirubin, a breakdown product of heme, is a key component of bile. Elevated levels of bilirubin can lead to jaundice, a common clinical sign of biliary obstruction. Ultrasound is often used to investigate the cause of jaundice.

The Gallbladder and Cystic Duct

The gallbladder is a small, pear-shaped organ located beneath the liver. It serves as a reservoir for bile. It concentrates bile produced by the liver.

The cystic duct connects the gallbladder to the common hepatic duct. It allows bile to flow into and out of the gallbladder.

During digestion, the gallbladder contracts, releasing bile through the cystic duct into the common bile duct. From there, it empties into the small intestine.

Ultrasound is highly effective in visualizing the gallbladder. It is also used for detecting gallstones and other abnormalities. Understanding the interplay between the gallbladder, cystic duct, and biliary tree is essential for a complete assessment of the biliary system.

Ultrasound Techniques: Mastering Intrahepatic Biliary Imaging

This section explores the fundamental ultrasound techniques employed to visualize and assess the intrahepatic biliary system. A thorough understanding of these techniques, including their advantages and limitations, is critical for accurate diagnosis and effective patient management. We will discuss transabdominal ultrasound, endoscopic ultrasound (EUS), and the application of Doppler ultrasound in evaluating hepatic vascularity.

Transabdominal Ultrasound: The First-Line Imaging Modality

Transabdominal ultrasound is often the initial imaging modality used to evaluate the intrahepatic biliary system.

Patient Preparation and Technique

Optimal visualization requires careful patient preparation. This typically involves fasting for at least 6-8 hours prior to the examination. Fasting reduces bowel gas, improving image quality.

The patient is usually examined in the supine position. Oblique or lateral decubitus positions may be necessary. These positions can improve access to the liver and biliary tree by displacing bowel gas.

The examination begins with a systematic survey of the liver. Attention should be paid to the size, echotexture, and any focal lesions. The biliary ducts are then carefully assessed.

The Crucial Role of Acoustic Coupling

The ultrasound transducer requires direct contact with the skin to transmit and receive sound waves effectively.

Ultrasound gel is applied to the skin surface to eliminate air between the transducer and the patient. Air is a significant impediment to ultrasound transmission. This is because of the large acoustic impedance mismatch between air and soft tissues.

The gel acts as an acoustic coupling agent. It allows for optimal sound wave penetration and image quality.

Endoscopic Ultrasound (EUS): A Complementary Imaging Tool

Endoscopic ultrasound (EUS) offers a unique perspective for evaluating the biliary system. It involves inserting an endoscope with an attached ultrasound transducer into the gastrointestinal tract.

The probe’s close proximity to the biliary tree provides high-resolution images. It is particularly useful for evaluating the distal common bile duct and pancreatic lesions.

Advantages and Limitations Compared to Transabdominal Ultrasound

EUS offers several advantages over transabdominal ultrasound. These are mainly in its ability to overcome limitations related to body habitus and bowel gas.

EUS provides superior image resolution. This is due to the closer proximity of the transducer to the biliary structures. It is especially helpful in visualizing small lesions and subtle ductal abnormalities.

EUS can also be used to obtain tissue biopsies. This makes it valuable for diagnosing biliary malignancies.

However, EUS also has limitations. It is an invasive procedure with associated risks, such as perforation and bleeding.

The procedure also requires sedation. This adds to the complexity and cost of the examination. Transabdominal ultrasound is non-invasive and readily available.

Doppler Ultrasound and Color Doppler: Assessing Hepatic Vasculature

Doppler ultrasound, including color Doppler imaging, plays a crucial role in evaluating blood flow within the hepatic vessels.

Assessment of Blood Flow in Hepatic Vessels

Doppler techniques allow for the assessment of blood flow direction and velocity.

This helps in identifying vascular abnormalities. Examples include portal vein thrombosis or hepatic artery stenosis.

In the context of biliary obstruction, Doppler ultrasound can help differentiate between benign and malignant causes. For example, tumor invasion into the portal vein may be seen in cholangiocarcinoma.

Color Doppler can also highlight increased vascularity in inflammatory conditions. This can be helpful in distinguishing inflammatory strictures from malignant lesions.

The use of spectral Doppler can further characterize the flow patterns. This can aid in identifying specific vascular abnormalities. Combining B-mode imaging with Doppler techniques provides a comprehensive assessment of the intrahepatic biliary system and surrounding vasculature.

Ultrasound Findings: Normal vs. Pathological Conditions

This section pivots to the practical application of ultrasound in identifying biliary pathology. A keen understanding of the normal sonographic appearance of the intrahepatic biliary system is paramount for detecting and differentiating various pathological conditions. We will delineate the key ultrasound features of both normal and diseased biliary ducts, focusing on specific conditions commonly encountered in clinical practice.

The Normal Biliary Tree on Ultrasound

The normal intrahepatic biliary ducts are typically visualized as thin, anechoic (black) tubular structures coursing alongside the portal veins within the liver parenchyma. Their walls are usually imperceptible, and their diameter should remain relatively uniform throughout their course.

In a healthy individual, the intrahepatic ducts are usually less than 2mm in diameter. However, this can slightly vary depending on age and hydration status.

Normal intrahepatic ducts should not be mistaken for dilated vessels. Color Doppler imaging is helpful here. Doppler can confirm the presence of blood flow within the vessels and distinguishing them from bile ducts.

Ultrasound Characteristics of Pathological Conditions

When the biliary system is compromised, ultrasound can reveal characteristic findings that aid in diagnosis. We will explore the typical ultrasound features of several key biliary disorders.

Choledocholithiasis: Gallstones in the Common Bile Duct

Choledocholithiasis refers to the presence of gallstones within the common bile duct. On ultrasound, these stones typically appear as hyperechoic (bright) foci within the bile duct lumen, often accompanied by posterior acoustic shadowing.

The shadowing obscures the structures deep to the stone. The bile duct proximal to the stone may be dilated, depending on the degree and duration of obstruction.

Careful attention should be paid to the distal common bile duct. It is sometimes obscured by bowel gas, requiring specific maneuvers or alternative imaging techniques like EUS.

Biliary Strictures: Narrowing of the Bile Ducts

Biliary strictures represent a narrowing of the bile ducts, which can be caused by benign or malignant processes. Ultrasound findings may include:

• Focal narrowing of the duct.
• Proximal ductal dilatation.
• Possible identification of the underlying cause, such as a mass.

Differentiation between benign and malignant strictures can be challenging on ultrasound alone. However, certain features may suggest malignancy, such as irregular ductal walls or the presence of a mass.

Cholangiocarcinoma: Cancer of the Bile Ducts

Cholangiocarcinoma is a malignancy arising from the bile ducts. Its ultrasound appearance can vary depending on the location and extent of the tumor. Potential findings include:

• A mass within the bile duct.
• Focal or diffuse ductal thickening.
• Proximal biliary dilatation.
• Invasion into adjacent structures, such as the portal vein or hepatic artery.
• Color Doppler may reveal increased vascularity within the tumor.

Mirizzi Syndrome: Extrinsic Compression of the Common Hepatic Duct

Mirizzi syndrome occurs when a gallstone impacts in the cystic duct or neck of the gallbladder. This causes extrinsic compression of the common hepatic duct.

Ultrasound findings classically include:

• A gallstone impacted in the gallbladder neck or cystic duct.
• Dilatation of the intrahepatic ducts.
• Normal caliber of the common bile duct distal to the point of compression.

Differentiating Mirizzi syndrome from other causes of biliary obstruction is crucial because it has specific surgical implications.

Primary Sclerosing Cholangitis (PSC): Chronic Inflammatory Disease

Primary Sclerosing Cholangitis (PSC) is a chronic inflammatory disease characterized by fibrosis and stricturing of the bile ducts. Ultrasound findings in PSC may include:

• Thickening of the bile duct walls.
• Irregularity of the ductal lumen, creating a beaded appearance.
• Alternating areas of stricture and dilatation.
• These findings are subtle. Often, diagnosis requires MRCP.

Post-Surgical Strictures: Narrowing of the Bile Ducts After Surgery

Post-surgical strictures can occur following biliary surgery, such as cholecystectomy or liver transplantation. Ultrasound may reveal:

• Focal narrowing at the site of the anastomosis (surgical connection).
• Proximal biliary dilatation.
• The location of the stricture can provide clues to the etiology.

The Importance of Comprehensive Assessment

It is imperative to emphasize that ultrasound findings should always be interpreted in conjunction with clinical history, laboratory data, and other imaging modalities when necessary. Correlation with other imaging methods such as MRCP or CT can greatly improve diagnostic accuracy.

Ultrasound Terminology and Interpretation: A Practical Guide

Understanding the language of ultrasound is crucial for accurately interpreting reports and effectively communicating findings. This section provides a practical guide to the key terms used in ultrasound reporting, focusing on the specific signs that indicate biliary obstruction and highlighting the importance of differentiating intrahepatic from extrahepatic abnormalities.

Essential Ultrasound Terminology

The echogenicity of a structure refers to its ability to reflect ultrasound waves. This is the basis for differentiating structures and identifying abnormalities. Mastering the terminology associated with echogenicity is fundamental to understanding ultrasound reports.

Hypoechoic, Hyperechoic, and Anechoic: Describing Echogenicity

Hypoechoic structures appear darker than surrounding tissues because they reflect fewer ultrasound waves. Examples include fluid-filled structures like cysts or certain types of tumors.

Conversely, hyperechoic structures appear brighter due to increased reflection of ultrasound waves. Gallstones, bone, and air are examples of hyperechoic structures.

Anechoic structures appear completely black, indicating no reflection of ultrasound waves. Simple fluid collections, such as bile within the gallbladder, are typically anechoic.

Posterior Acoustic Enhancement: A Clue to Fluid-Filled Structures

Posterior acoustic enhancement (PAE) is a phenomenon observed distal to anechoic or hypoechoic structures. It appears as an area of increased brightness behind the structure.

This occurs because the sound beam is not attenuated as much as it passes through the fluid. PAE is a useful indicator of fluid-filled structures, such as cysts or dilated bile ducts.

Specific Ultrasound Signs of Biliary Obstruction

Certain characteristic signs on ultrasound strongly suggest biliary obstruction. Recognizing these signs is crucial for prompt diagnosis and appropriate management.

Parallel Channel Sign and Shotgun Sign: Visual Cues of Dilatation

The parallel channel sign refers to the visualization of the dilated bile duct alongside the portal vein. This is seen as two parallel, anechoic structures running together, resembling parallel channels.

The shotgun sign is another term used to describe this appearance, emphasizing the side-by-side arrangement, similar to the barrels of a shotgun. The parallel channel sign strongly suggests biliary obstruction, prompting further investigation.

Differentiating Intrahepatic from Extrahepatic Abnormalities

Determining whether an abnormality is within the liver (intrahepatic) or outside the liver (extrahepatic) is a critical step in diagnosis. This guides further imaging and management strategies.

Intrahepatic biliary dilatation typically involves smaller, more peripheral ducts within the liver parenchyma. Extrahepatic dilatation usually involves the larger, more proximal ducts, such as the common hepatic duct and common bile duct.

Careful tracing of the biliary tree and identifying the point of obstruction can help differentiate between intrahepatic and extrahepatic causes. Evaluating surrounding structures for masses or other abnormalities is also crucial.

Differential Diagnosis: Narrowing Down the Possibilities

The ultrasound, while a powerful initial imaging tool, often serves as a stepping stone in the diagnostic journey. The process of differential diagnosis is crucial for accurately identifying the underlying cause of intrahepatic biliary duct dilatation and guiding appropriate management. This involves systematically considering various potential etiologies and utilizing all available information to arrive at the most likely diagnosis.

Differentiating Causes of Biliary Obstruction

Ultrasound findings of dilated intrahepatic biliary ducts warrant a thorough differential diagnosis. Several conditions can manifest similarly on ultrasound, making it essential to consider each possibility carefully.

Choledocholithiasis, or gallstones in the common bile duct, is a common cause of biliary obstruction, presenting with echogenic foci and potential shadowing within the duct. Biliary strictures, whether benign or malignant, also lead to dilatation proximal to the narrowing. Cholangiocarcinoma, a malignancy of the bile ducts, can present as a mass obstructing the biliary tree. Mirizzi syndrome, involving extrinsic compression of the common hepatic duct by a gallstone, requires careful evaluation of the gallbladder and surrounding structures.

Primary Sclerosing Cholangitis (PSC), a chronic inflammatory condition, often demonstrates characteristic beading and irregularity of the bile ducts. Post-surgical strictures are also a consideration, particularly in patients with a history of biliary surgery.

Correlation with Advanced Imaging Modalities

While ultrasound offers valuable initial information, correlation with other imaging modalities is often necessary to refine the differential diagnosis and confirm the underlying pathology. Computed Tomography (CT) scans provide excellent anatomical detail and can help identify masses, strictures, or other abnormalities not clearly visualized on ultrasound.

Magnetic Resonance Cholangiopancreatography (MRCP) is particularly useful for visualizing the biliary tree in detail, allowing for accurate assessment of strictures, dilatations, and other abnormalities. MRCP is often considered the gold standard for evaluating biliary anatomy and pathology. The selection of the appropriate advanced imaging modality depends on the clinical context and the specific questions that need to be addressed.

Integrating Clinical Information and Expert Opinions

Accurate diagnosis demands integration of clinical information with imaging findings. Input from specialists such as gastroenterologists, hepatologists, and general/hepato-biliary surgeons is crucial.

These specialists bring their expertise to bear, providing insights from patient history, physical examination, and laboratory results. Their clinical perspectives, combined with the ultrasound findings and advanced imaging results, helps formulate a comprehensive understanding of the patient's condition and guide the optimal management strategy.

Interventional Ultrasound: Guiding Therapeutic Procedures

Beyond its diagnostic capabilities, ultrasound plays a pivotal role in guiding therapeutic interventions within the biliary system. Interventional ultrasound provides real-time visualization, enabling precise and minimally invasive procedures that can alleviate biliary obstruction and improve patient outcomes. This section delves into the crucial contributions of interventional radiologists and explores the array of ultrasound-guided procedures employed in biliary interventions.

The Role of Interventional Radiologists

Interventional radiologists are at the forefront of ultrasound-guided biliary procedures. These specialists possess extensive training in both diagnostic imaging and minimally invasive techniques. Their expertise is indispensable in navigating the complexities of the biliary anatomy and performing intricate interventions with precision. They are the drivers of care in minimally invasive image-guided interventions.

Interventional radiologists collaborate closely with gastroenterologists, hepatologists, and surgeons to determine the most appropriate treatment strategies for patients with biliary disorders. Their involvement ensures a comprehensive and multidisciplinary approach to patient care.

Percutaneous Biliary Drainage (PBD): Relieving Obstruction

Percutaneous biliary drainage (PBD) is a cornerstone of interventional ultrasound in the biliary system. This procedure involves the insertion of a drainage catheter into the obstructed biliary ducts under real-time ultrasound guidance. PBD serves to decompress the biliary system, relieve jaundice, and provide access for further interventions.

Ultrasound guidance is crucial for accurate needle placement and minimizing the risk of complications, such as bile leakage or vascular injury. PBD can be performed either internally, with the catheter draining into the duodenum, or externally, with the catheter draining into a collection bag.

Indications for Percutaneous Biliary Drainage

PBD is indicated in a variety of clinical scenarios, including:

• Malignant biliary obstruction: PBD can palliate jaundice and improve quality of life in patients with unresectable cholangiocarcinoma or metastatic disease.

• Benign biliary strictures: PBD can be used to decompress the biliary system and facilitate balloon dilation or stent placement.

• Choledocholithiasis: When endoscopic removal of gallstones is not feasible, PBD can provide temporary drainage until definitive treatment can be pursued.

• Post-surgical biliary leaks: PBD can divert bile flow away from the leak, promoting healing and preventing complications.

Other Ultrasound-Guided Biliary Interventions

Beyond PBD, interventional ultrasound facilitates several other important biliary procedures:

• Biliary Stent Placement: Ultrasound guidance can assist in the placement of stents across biliary strictures, maintaining patency and ensuring adequate bile flow. Both metallic and plastic stents can be deployed under ultrasound visualization.

• Biliary Biopsy: Ultrasound-guided needle biopsy allows for accurate tissue sampling of biliary lesions, aiding in the diagnosis of cholangiocarcinoma and other biliary malignancies. The use of fine-needle aspiration (FNA) or core biopsy techniques is determined by the clinical context and the characteristics of the lesion.

• Abscess Drainage: Ultrasound can guide the drainage of biliary abscesses, providing source control and facilitating antibiotic therapy. Precise needle placement is essential to avoid injury to adjacent structures.

Advantages of Ultrasound Guidance

Utilizing ultrasound to guide biliary interventions offers distinct advantages:

• Real-time visualization: Ultrasound provides continuous imaging, allowing the interventional radiologist to monitor needle placement and catheter advancement in real-time.

• Portability and accessibility: Ultrasound machines are readily available in most hospitals and can be easily transported to the patient's bedside.

• Lack of ionizing radiation: Unlike fluoroscopy, ultrasound does not expose patients or healthcare providers to ionizing radiation.

• Cost-effectiveness: Ultrasound is generally less expensive than other imaging modalities, such as CT or MRI.

The use of ultrasound contrast agents can further enhance visualization of biliary structures during interventions.

Equipment and Technology: A Look at Ultrasound Machines and Transducers

The effectiveness of intrahepatic biliary ultrasound hinges not only on the skills of the operator but also on the capabilities of the ultrasound equipment used. Modern ultrasound machines offer a range of features designed to optimize image quality and facilitate accurate diagnosis. Understanding the nuances of these machines and the different transducer types is crucial for achieving optimal results in biliary imaging.

Overview of Ultrasound Machines and Their Features

Several manufacturers dominate the ultrasound market, each offering machines with unique strengths and features. Prominent players include General Electric (GE) Healthcare, Philips Healthcare, Siemens Healthineers, and Canon Medical Systems. These companies continuously innovate, integrating advanced technologies into their platforms.

Key features to consider in ultrasound machines for biliary imaging include:

• Image Resolution: High-resolution imaging is essential for visualizing the fine details of the intrahepatic biliary ducts and detecting subtle abnormalities.

• Frequency Range: Machines should support a range of frequencies to allow for optimal penetration and resolution depending on the patient's body habitus. Higher frequencies provide better resolution but have limited penetration, while lower frequencies offer deeper penetration but at the expense of resolution.

• Doppler Capabilities: Color Doppler and Power Doppler are valuable for assessing blood flow in hepatic vessels and differentiating vascular structures from biliary ducts.

• Contrast-Enhanced Ultrasound (CEUS): Some machines support CEUS, which involves the intravenous administration of microbubble contrast agents to enhance the visualization of biliary structures and improve the detection of subtle lesions. CEUS significantly improves diagnostic confidence in challenging cases.

• Ergonomics and User Interface: An intuitive user interface and ergonomic design can improve workflow and reduce operator fatigue, particularly during lengthy examinations.

• Image Storage and Reporting: Efficient image storage and reporting capabilities are essential for documentation and communication of findings.

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• Advanced Imaging Modes: Features such as speckle reduction imaging, harmonic imaging, and compound imaging can enhance image quality and reduce artifacts.

Types of Transducers/Probes Used for Biliary Imaging

The choice of transducer is critical for successful biliary imaging. Different transducer types offer varying performance characteristics in terms of frequency, footprint, and field of view.

Linear Array Transducer

Linear array transducers typically operate at higher frequencies (e.g., 5-12 MHz) and provide excellent superficial resolution. They are well-suited for imaging the gallbladder and superficial portions of the liver in patients with a thin body habitus. The rectangular field of view of linear transducers can be advantageous for measuring the dimensions of biliary ducts.

Curvilinear Array Transducer

Curvilinear array transducers operate at lower frequencies (e.g., 2-5 MHz) and offer deeper penetration, making them ideal for imaging the deeper portions of the liver and biliary system, especially in patients with a larger body habitus. The curved footprint allows for a wider field of view, facilitating comprehensive evaluation of the biliary tree.

In practice, sonographers often use a combination of both linear and curvilinear transducers to optimize image quality and obtain a complete assessment of the intrahepatic biliary system. The selection of the appropriate transducer depends on patient-specific factors and the clinical question being addressed.

So, next time you're scanning and suspecting biliary issues, remember these US tips and tricks. Finding those dilated intrahepatic biliary ducts early can make a real difference for your patients, and hopefully this guide helps you do just that! Happy scanning!