The Usefulness of Magnetic Resonance Cholangio-Pancreatography in the Diagnosis of Choledochal Cyst

ABSTRACT

PURPOSE: Choledochal cysts are cystic or diffuse dilatation of any portion of the biliary tree. An anomalous pancreaticobiliary ductal union (APBDU) is one of the commonly accepted causes of a cholodochal cyst. The ability of MRCP to demonstrate an APBDU has not been established in children and appears to have limited value in demonstrating an associated APBDU. We investigate the usefulness, and application, of MRCP in delineating the cyst type and an APBDU in patients with choledochal cysts, and compared it with operative cholangiography. METHODS: Ten children with choledochal cyst, who had both MRCP and cholangiography, as preoperative diagnostic modalities, at the Division of Pediatric Surgery, Keimyung University, Dongsan Medical Center, between March 1999 and August 2002, were selected for this study. We analyzed and compared their MRCP images with those of the intraoperative cholangiographies, with regard to the type of cyst, size and association of an APBDU. RESULTS: The types of the choledochal cyst, based on the MRCP, were two Ia, three Ic, and five IVa, whereas those based on the operative cholangiographies were one Ic and nine IVa. A common channel was demonstrated by MRCP and operative cholangiography in four (40%) and six (60%) of the ten patients, respectively. Each diagnostic modality correlated with the size (Pearson correlation, P<0.01) and the length of the cyst, but an APBDU on both modalities did not reach statistical significance, even though the common channel was not identified in a large cyst on MRCP. CONCLUSION: MRCP is a noninvasive and safe diagnostic modality for the delineation an APBDU in children with choledochal cysts. However, it has limited value for demonstrating an APBDU in children with a large cyst due to overlapping with the pancreaticobiliary ductal system. Operative cholangiography seems to be more valuable than MRCP in patients with large choledochal cysts.