Abstract: Objective The purpose of this study was to investigate the diagnostic performance of magnetic resonance cholangiopancreatography (MRCP) and diffusion-weighted imaging (DWI) in infants with biliary atresia (BA). Methods 40 children with congenital BA were admitted to our hospital between October 2019 and October 2022, and all underwent MRI, MRCP and DWI scan before operation. The imaging manifestations were recorded, and the diagnostic performances of MRI, 3D-MRCP and DWI were compared. Results Out of the 40 children with BA, the 3D-MRCP showed the extrahepatic bile duct undeveloped in 7 cases (17.5%), tiny bile ducts in 24 cases (60.0%), slightly dilated in 8 cases (20.0%) and choledochal cyst in 1 case (2.5%), the sparse intrahepatic bile ducts or not developed bile ducts in 34 cases (85.0%) and developed bile ducts in 6 cases (15.0%), the small gallbladder in 31 cases (77.5%) and normal gallbladder in 9 cases (22.5%); the DWI showed the undeveloped extrahepatic bile duct in 15 cases (37.5%), tiny ducts in 19 cases (47.5%), slightly dilated ducts in 5 cases (12.5%), the choledochal cyst in 1 case (2.5%), the sparse or not developed intrahepatic bile ducts in 31 cases (77.5%), the developed ducts in 9 cases (22.5%), the tiny gallbladders in 29 cases (72.5%) and normal gallbladders in 11 cases (28.5%); the T2-weighted imaging showed intrahepatic triangular shadows in 31 cases (77.5%), and the DWI showed high intrahepatic signals in 33 cases (82.5%), with the high signal intensity of (0.8±0.2) cm in hilar region; the MRI found the enlarged right lobes of liver in 12 cases (30.0%); the intraoperative cholangiography revealed the undeveloped common bile duct, common hepatic duct and intrahepatic bile duct in 29 cases (72.5%), and the cystic dilatation of common bile ducts in 11 cases (28.5%); during the operation, the fibrous mass in the hilar region was found in 36 cases (90.0%), with the average diameters of (1.2±0.5)cm, and we also found gallbladder atrophy in 33 cases (82.5%), the hepatomegaly in 22 cases (55.0%) and liver cirrhosis in 6 cases (15.0%); the diagnosis based on intraoperative examination included BA type ⅰ in 1 case (2.5%) and BA type ⅲ in 39 cases (97.5%); the diagnostic accuracy by MRI, MRCP and DWI combination was 90.5%, much higher than 77.5% by MRI and 3D-MRCP(P＜0.05). Conclusion The MRCP and DWI scan for infantile biliary atresia could display objectively the whole imaging of biliary system, and have a high diagnostic performance.

Key words: Biliary atresia, Magnetic resonance cholangiopancreatography, Diffusion-weighted imaging, Cholangiography, Diagnosis, Infants and young children