Magnetic Resonance Cholangiopancreatography (MRCP)

MRCP is a less costly, non-invasive, and sensitive technique for evaluating the biliary and pancreatic ductal systems. In MRCP, multiplanar images are obtained parallel to the orientation of the biliary tree, using an MR sequence that is sensitive to static fluid without the need for exogenous contrast agents. Fluid in the ducts appears bright against the darker tissue. Image post-processing (maximal intensity projection) is used to make multi-dimensional images of the entire biliary tree and the pancreatic ducts. Although MRCP images have somewhat lower resolution than ERCP, MRCP shows the ducts in their natural, non-distended state and can easily be combined with MRI of the surrounding viscera.

Diseases Diagnosed by MRCP:

MRCP can diagnose the presence of bile duct obstruction and the level of obstruction in most cases. Biliary calculi smaller than 6 mm can be missed although 2 mm calculi can be seen in some cases. Primary sclerosing cholangitis can be diagnosed from the multiple irregular strictures seen in the biliary ducts. Benign and malignant causes of biliary dilatation can be differentiated and, as MRCP can be coupled with imaging of the adjacent viscera, malignant neoplasms and metastases can be detected and evaluated. MRCP has an advantage over ERCP for the detection of cholangiocarcinoma, since there is a risk sepsis following ERCP. Post-operative bile-duct injuries and anastomotic leaks can be readily detected with MRCP and it is suitable for assessment of the biliary tree after orthotopic liver transplantation.

In patients with recurrent pancreatitis, MRCP can be performed to look for stones, divisum, or strictures. MRCP in conjunction with MRI can be used to evaluate parenchymal changes due to pancreatitis or to detect pancreatic cancer.

Patient Preparation and MRCP Procedure:

No patient preparation is required for MRCP but fasting 2-4 hours prior to the examination can be beneficial because it reduces the fluid in the gastric antrum and the duodenum, which may overlie the ducts. The MRCP examination takes 30-40 minutes. If a complete MRI of the liver and pancreas is necessary, the entire procedure takes about one hour and may include the administration of a contrast agent.