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Diagnostic ultrasound ( PDFDrive )

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170 PART II Abdominal and Pelvic Sonography

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FIG. 6.7 Choledochal Cysts. (A)-(C) Type I. Fusiform dilation of the common bile duct (CBD) is seen, but no obstructive lesion is noted. This

is the most common type of choledochal cyst. (B) Careful examination of the distal CBD using high-frequency linear transducer reveals a long

common channel (arrow) between the CBD and pancreatic duct. (C) Coronal computed tomography image conirms the presence of long common

channel (arrow). (D) and (E) Type II. A large diverticulum (arrow) is shown in (D) arising from the common hepatic duct at the portal hepatis and

containing mobile debris. (E) Thick-slab magnetic resonance cholangiopanreatography (MRCP) conirms the same. (F) Type III. Fusiform dilation

of the distal CBD (arrow) is demonstrated protruding into the duodenum. (G)-(I). Type IV. (G) Sagittal view of the liver shows a markedly dilated

bile duct (BD) and left hepatic duct (LD). (H) Transverse view of the left lobe of the liver depicts marked enlargement of the left hepatic duct with

dilated branches. (I) Thick-slab MRCP shows both intrahepatic and extrahepatic involvement.

has a diferent embryonic origin and is not a true choledochal

cyst. 10

On sonography, a cystic structure is identiied that may contain

internal sludge, stones, or even solid neoplasm. In some cases

the cyst is large enough that its connection to the bile duct is

not immediately recognized. Use of various scanning windows

and angles allows for demonstration of the relationship of the

lesion to the biliary tract, diferentiating it from pancreatic

pseudocysts or enteric duplication cysts. Biliary scintigraphy,

MRCP, and endoscopic retrograde cholangiopancreatography

(ERCP) have been used to delineate further the structure of

choledochal cysts. ERCP is necessary to ensure that the dilation

is not a result of distal neoplasm, especially in the case of type

I choledochal cysts (see Fig. 6.7). Because there is a risk of

cholangiocarcinoma with all choledochal cysts, surgical resection

is advocated.

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