Caroli disease (Todani type V choledochal cyst) is an autosomal-recessive disorder resulting cystic dilation of the intrahepatic bile ducts. Imaging methods show intrahepatic saccular or fusiform dilated cystic structures of varying sizes that communicate with the biliary tree. The presence of tiny dots with contrast enhancement within the dilated intrahepatic bile duct ("central dot sign") is considered very suggestive of Caroli disease. The "central dot sign" represents the enhancing poal branches surrounded by cystic alterations of the intrahepatic biliary ducts. Also know: Caroli syndrome: If all levels of the intrahepatic biliary tree are involved, features of both congenital hepatic fibrosis and Caroli disease are present; this condition has been termed Caroli syndrome. Ref: Moele K.J. (2012). Chapter 9. State-of-the-A Imaging of the Gastrointestinal System. In N.J. Greenberger, R.S. Blumberg, R. Burakoff (Eds), CURRENT Diagnosis & Treatment: Gastroenterology, Hepatology, & Endoscopy, 2e.