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Magnetic Resonance Cholangiopancreatography (MRCP)
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When
patients have suspected biliary or pancreatic disease, ultrasound
imaging is the traditional screening technique. However, ultrasound is
limited in its ability to image abnormalities in the biliary and
pancreatic ductal systems and further evaluation may be necessary with
either endoscopic retrograde cholangiopancreatography (ERCP) or MRCP.
ERCP is a minimally invasive procedure that combines endoscopy with the
injection of iodinated contrast agent into the biliary and pancreatic
ducts. ERCP has the advantage of combining diagnosis with intervention.
In addition, manometry can be performed and the ampulla can be directly
visualized. However, ERCP carries a small but significant risk of
complications, including pancreatitis, hemorrhage, and perforation. At
MGH, the complication rate is 1-2%, significantly lower than the
national average. In addition, ERCP may be difficult in patients with
post-surgical anastomotic complications.
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.
General Guidelines for the Selection of MRCP or ERCP
| MRCP should be considered as alternative to ERCP or prior to ERCP for: |
- Pediatric patients, elderly patients, and those with many comorbidities
- Acute pancreatitis
- Cholangitis
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Normal MRCP image showing the common bile duct (curved arrow) and the pancreatic duct (arrow). Note the fluid filled duodenum.
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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.
Biliary Disease
- Cystic disease of bile duct (choledochal cyst, choledochocele, Caroli’s disease)
- Congenital variants (low or medial duct insertion, aberrant right hepatic duct)
- Choledocholilithiasis
- Primary sclerosing cholangitis
- Post-surgical biliary complications
- Cholangiocarcinoma
Pancreatic Disease
- Pancreas divisum
- Chronic pancreatitis
- Pancreatic cancer
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Limitations
Low
grade strictures may be missed and may be seen better with ERCP because
distension and higher resolution of this examination. Occasionally,
false positive diagnoses of bile duct stones or obstruction result from
air bubbles, blood clots, metallic clips, or extra-ductal compression.
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.
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Common Bile Duct Stone. MRCP image shows a dilated bile duct with a dark stone (arrow) in its distal end.
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Klatskin
Tumor of the Bile Duct. MRCP image shows dilatation of intrahepatic
ducts along with stricture from the tumor seen at the confluence of
right and left intrahepatic ducts (arrow). Note the normal caliber of
distal common bile duct and pancreatic duct.
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Scheduling
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Further Information
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MRCP
can be performed at Mass General West Imaging in Waltham, Mass General
Imaging in Chelsea, MassGeneral MRI in Charlestown, or the main MGH
campus (including the Emergency Department) and can be ordered online
via ROE (http://mghroe
) or by calling 4-XRAY (617-724-9729).
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For further questions on MRCP, please contact Mukesh Harisinghani, MD, 617-726-8396, Division of Abdominal and Interventional Radiology or Peter Kelsey, MD, 617-724-6044, Gastrointestinal Unit.
This article provided useful information about the appropriate use of imaging studies:
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References
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Fayad, LM, Kowalski, T and Mitchell, DG. (2003) MR cholangiopancreatography: evaluation of common pancreatic diseases. Radiol Clin North Am 41: 97-114
Kalra, M, Sahani, D, Ahmad, A and Saini, S. (2002) The role of magnetic resonance cholangiopancreatography in patients with suspected biliary obstruction. Curr Gastroenterol Rep 4: 160-6
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Lopez Hanninen, E, Amthauer, H, Hosten, N, Ricke, J, et al. (2002) Prospective evaluation of pancreatic tumors: accuracy of MR imaging with MR cholangiopancreatography and MR angiography. Radiology 224: 34-41
Romagnuolo, J, Bardou, M, Rahme, E, Joseph, L, et al. (2003) Magnetic resonance cholangiopancreatography: a meta-analysis of test performance in suspected biliary disease. Ann Intern Med 139: 547-57
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