MRI for evaluating congenital bile duct abnormalities.

Congenital bile duct diseases consist of ductal plate development abnormalities and are genetically determined. These biliary abnormalities are encountered mainly in congenital fibrocystic diseases, represented by congenital hepatic fibrosis and different forms of Caroli disease. On the other hand, polycystic hepatic diseases also present cystic abnormalities, which could be confused with biliary dilatations, especially in the perihilar area. Further, intricate forms between Caroli and polycystic hepatic diseases are possible. In congenital bile duct paucity, which is extremely rare, the biliary tree, located on the opposite, is not visible. MRI modalities for the analysis of the biliary tree are mainly represented by T -weighted sequence, also known as MR cholangiography (MRCP), and T gadolinium-enhanced sequences. Familiarity with the most common appearances of congenital bile duct dilations, its variants, and related complex diseases facilitates accurate diagnosis and allows and helps avoid misinterpretation.