Imaging of choledochal cysts

Abstract

Choledochal cysts are rare cystic dilatations of the intrahepatic and/or extrahepatic biliary tree, which may be mistaken for other cystic lesions if their characteristic features are not recognized. The etiology is unknown, and likely multifactorial, and it is uncertain whether they are congenital or acquired. Multiple imaging modalities can be used to diagnose choledochal cysts, including ultrasound, computed tomography, magnetic resonance (MR) cholangiopancreatography (MRCP), endoscopic retrograde cholangiopancreatography, and percutaneous transhepatic cholangiography. MRCP has replaced the more invasive techniques as the gold standard of diagnosis. In addition, MRCP is helpful in detecting an abnormal pancreaticobiliary junction, which is seen in the majority of choledochal cysts. Reaching a correct diagnosis is essential, given the associated risk of complications, including cholangitis, biliary strictures, stones, and malignancy, and accurately assessing the location and length of involvement is important for surgical planning. This review aims to familiarize radiologists with the different types of choledochal cysts and their imaging features according to the Todani classification.

Ultrasonographic and clinicopathologic features of segmental dilatations of the common bile duct in four cats

“…Congenital and acquired etiologies have been described in the human literature. 16,17,25 Congenital CCs may be related to malformations of the intrahepatic bile ducts resulting from anomalous remodeling of the biliary primordium called the ‘ductal plate’; these conditions can be collectively referred to as ductal plate malformations and have been reported in cats. 18,25,26 Although the choledochus is not derived from the ductal plate the presence of concurrent intrahepatic anomalies falls within the accepted six-type classification scheme of CCs, as type IV.…”

“…17,25 In humans, APBJ is described as confluence of the pancreatic duct and CBD into a common channel prior to insertion into the duodenal wall; this configuration permits distal mixing of bile and pancreatic enzymes and is thought to lead to mechanical weakening of the CBD wall with secondary pathologic dilatation. 17 Overall, the presence of CCs, with or without concurrent APBJ, often leads to biliary stasis, predisposing the patient to chronic inflammation (choledochitis, cholangitis, pancreatitis), cholelith formation, infection and possibly increased risk for biliary malignancy. 8,16–18,21,25,27 …”

“…17 Overall, the presence of CCs, with or without concurrent APBJ, often leads to biliary stasis, predisposing the patient to chronic inflammation (choledochitis, cholangitis, pancreatitis), cholelith formation, infection and possibly increased risk for biliary malignancy. 8,16–18,21,25,27 …”

“…The latter is considered the gold standard for anatomic evaluation in humans. 17,27 Abdominal MRI studies are currently not commonplace in veterinary medicine; however, a recent article reported the use of MRCP for evaluating cats with pancreatitis and cholangitis – the CBD was identified in all 10 cats. 32 …”

“…16–20 In this context (and throughout this report) the term ‘cyst’ denotes a morphological appearance of a rounded, fluid-filled structure with a thin wall as opposed to a true histological cyst (eg, non-communicating, epithelium-lined, fluid-filled sac). Only two case reports of cats with segmental CBD dilatation consistent with CCs have been previously published.…”