Choledochal cysts

Choledochal cysts: While ultrasound is often the initial diagnostic tool, MRI, particularly with MR cholangiopancreatography (MRCP), plays a crucial role in further characterizing these cysts in children. MRI provides detailed anatomical information of the biliary system, aiding in the precise classification of cyst type (according to the Todani classification) and identifying associated anomalies or complications like biliary obstruction, stones, or even potential malignant transformation. MRI/MRCP is invaluable for pre-operative planning, clearly delineating the extent of the cyst, its relationship with adjacent structures including the pancreatic ductal union, and guiding the surgical approach, which typically involves complete cyst excision and biliary reconstruction to mitigate the risks of long-term complications, including cholangitis, cirrhosis, and bile duct cancer.

Example: ​Choledochal Cyst.  T2-weighted MRI images reveal marked dilation of the common bile duct and the common hepatic duct.  Intrahepatic ducts are also dilated, though determining whether that reflects direct involvement (type 4 choledochal cyst) or dilated secondary to obstruction often requires imaging after relief of the obstruction.

Post contrast imaging: ​Axial post-contrast imaging.