Diagnostic Ultrasound - Abdomen and Pelvis

Caroli Disease
TERMINOLOGY
Synonyms
• Communicating cavernous biliary ectasia
Definitions
• Caroli disease: Congenital, multifocal, segmental, cystic
dilatations of intrahepatic bile ducts (IHBD)
• Caroli syndrome: Caroli disease + congenital hepatic fibrosis
IMAGING
General Features
• Best diagnostic clue
○ "Central dot" sign: Portal radicles within dilated
intrahepatic bile ducts on ultrasound, CECT/MR
○ Multiple intrahepatic cysts of varying size that
communicate with biliary tree
• Location
○ Liver; diffuse, lobar, or segmental distribution
– Caroli disease: Mostly diffuse, occasionally lobar
– Caroli syndrome: Almost always diffuse
• Size
○ Varies from few millimeters to few centimeters
• Morphology
○ Segmental saccular dilatation of large intrahepatic bile
ducts separated by normal or dilated bile ducts
○ Contiguous with biliary tree
○ Common bile duct is usually normal in caliber
– If dilated, consider coexisting obstructing stone,
cholangitis, concurrent choledochal cyst, or prior
intervention
○ Todani classification of congenital bile duct cysts
– Caroli disease is classified as type V:Cystic dilatation of
intrahepatic bile ducts
Ultrasonographic Findings
• Grayscale ultrasound
○ Dilated intrahepatic bile ducts
– Focal or diffuse involvement in liver
– Saccular or fusiform configuration
– Contains sludge due to biliary stasis
– May contain calculi, which do not form casts of ducts
○ "Intraductal bridging" sign
– Echogenic septa partially or completely traversing
dilated lumen of bile ducts
○ "Central dot" sign
– Small portal venous branches partially or completely
surrounded by dilated IHBDs
○ Abscess formation if complicated by cholangitis
• Color Doppler
○ Color flow in portal radicles surrounded by dilated IHBDs:
"Central dot" sign
Radiographic Findings
• Endoscopic retrograde cholangiopancreatogram (ERCP)
findings
○ Saccular dilatations communicating with IHBDs
○ Sludge and hepatolithiasis, biliary stricture
○ May show communicating hepatic abscesses
CT Findings
• NECT
○ Multiple, rounded, hypodense areas inseparable from
dilated IHBD
○ May see hyperdense biliary stones
○ Findings related to concurrent hepatic fibrosis
– Hypertrophic left lobe, atrophic right lobe of liver
• CECT
○ Nonenhancing cysts of varying size communicating
biliary tree
○ "Central dot" sign
– Enhancing tiny dots (portal radicles) surrounded by
dilated IHBD
MR Findings
• T1WI
○ Multiple hypointense, saccular dilatations of IHBDs
○ Hypointense in area of hepatic fibrosis
• T2WI
○ Hyperintense cystic spaces
• T1WI C+
○ "Central dot" sign: Enhancement of portal radicles within
dilated IHBD
○ Cystic structures fill with contrast agent (gadoxetic acid)
in hepatobiliary phase, contiguous with biliary tree
• MRCP
○ Multiple hyperintense, oval-shaped, cystic dilatations
○ Continuity with biliary tree
○ Luminal contents of bile ducts appear hyperintense in
contrast to portal vein, which appears as signal void
Nuclear Medicine Findings
• Hepatobiliary scan:Unusual pattern of retained activity
throughout liver
• Technetium sulfur colloid:Multiple cold defects
DIFFERENTIAL DIAGNOSIS
AD Polycystic Liver Disease
• Hepatic cysts
○ Numerous: > 10, usually hundreds
○ Do not communicate with each other or biliary tract
○ Not associated with biliary ductal dilatation
○ Do not demonstrate saccular configuration
• Often harbor renal cysts; not confined to medulla
Recurrent Pyogenic Cholangitis
• Intra- and extrahepatic biliary stones: Cast-like
• Dilatation of both intra- & extrahepatic bile ducts, usually of
cylindrical and not saccular type
• Associated with parasitic and bacterial biliary infection (liver
flukes)
Primary Sclerosing Cholangitis
• Strictures of both intra- and extrahepatic bile ducts
• Ductal dilatation not as great as Caroli disease; not saccular
• Often shows isolated obstructions of IHBDs
• Often progresses to cirrhosis and liver failure
Ascending Cholangitis
• Intrahepatic abscesses communicate with bile ducts:
Irregular margin
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Diagnoses: Liver
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