Gastrointestinal ImagingFree Access

MR Cholangiopancreatography: What Every Radiology Resident Must Know

Published Online:https://doi.org/10.1148/rg.2020200030

Abstract

The full digital presentation is available online.

MR cholangiopancreatography (MRCP) is a noninvasive method that is widely used in the evaluation of pancreatobiliary disorders. Combining the advantages of projectional imaging with those of cross-sectional imaging, it is an established diagnostic technique that in most clinical settings can be a substitute for endoscopic retrograde cholangiopancreatography (ERCP) or even percutaneous transhepatic cholangiography. MRCP depicts biliary ducts upstream and downstream from an eventual lesion, as well as extraductal diseases when combined with additional T1- and T2-weighted imaging or even the use of contrast media. These capabilities are some of the most useful characteristics of MRCP (Figure).

Comparison of ERCP and MRCP in evaluation of the biliary tree. (a) Drawing of                 an ERCP procedure where the endoscope reaches the duodenal papilla. Contrast agent                 is injected into the common bile duct, opacifying it partially. An extrinsic                 obstruction (question mark) blocks the contrast agent, preventing delineation of the                 upstream biliary tract. (b) Drawing of an MRCP examination with additional MR                 sequences demonstrates a tumoral lesion in the pancreatic head with dilatation of                 upstream bile ducts, including the pancreatic duct. (c) Coronal MRCP maximum                 intensity projection (MIP) reformation shows dilated intra- and extrahepatic bile                 ducts as well as the main pancreatic duct with abrupt distal obstruction                 (arrowheads). (d) Axial T2-weighted image shows a tumoral mass (arrowheads) in the                 pancreatic head that is compatible with adenocarcinoma.

Figure Comparison of ERCP and MRCP in evaluation of the biliary tree. (a) Drawing of an ERCP procedure where the endoscope reaches the duodenal papilla. Contrast agent is injected into the common bile duct, opacifying it partially. An extrinsic obstruction (question mark) blocks the contrast agent, preventing delineation of the upstream biliary tract. (b) Drawing of an MRCP examination with additional MR sequences demonstrates a tumoral lesion in the pancreatic head with dilatation of upstream bile ducts, including the pancreatic duct. (c) Coronal MRCP maximum intensity projection (MIP) reformation shows dilated intra- and extrahepatic bile ducts as well as the main pancreatic duct with abrupt distal obstruction (arrowheads). (d) Axial T2-weighted image shows a tumoral mass (arrowheads) in the pancreatic head that is compatible with adenocarcinoma.

Comparison of ERCP and MRCP in evaluation of the biliary tree. (a) Drawing of                 an ERCP procedure where the endoscope reaches the duodenal papilla. Contrast agent                 is injected into the common bile duct, opacifying it partially. An extrinsic                 obstruction (question mark) blocks the contrast agent, preventing delineation of the                 upstream biliary tract. (b) Drawing of an MRCP examination with additional MR                 sequences demonstrates a tumoral lesion in the pancreatic head with dilatation of                 upstream bile ducts, including the pancreatic duct. (c) Coronal MRCP maximum                 intensity projection (MIP) reformation shows dilated intra- and extrahepatic bile                 ducts as well as the main pancreatic duct with abrupt distal obstruction                 (arrowheads). (d) Axial T2-weighted image shows a tumoral mass (arrowheads) in the                 pancreatic head that is compatible with adenocarcinoma.

Figure Comparison of ERCP and MRCP in evaluation of the biliary tree. (a) Drawing of an ERCP procedure where the endoscope reaches the duodenal papilla. Contrast agent is injected into the common bile duct, opacifying it partially. An extrinsic obstruction (question mark) blocks the contrast agent, preventing delineation of the upstream biliary tract. (b) Drawing of an MRCP examination with additional MR sequences demonstrates a tumoral lesion in the pancreatic head with dilatation of upstream bile ducts, including the pancreatic duct. (c) Coronal MRCP maximum intensity projection (MIP) reformation shows dilated intra- and extrahepatic bile ducts as well as the main pancreatic duct with abrupt distal obstruction (arrowheads). (d) Axial T2-weighted image shows a tumoral mass (arrowheads) in the pancreatic head that is compatible with adenocarcinoma.

Comparison of ERCP and MRCP in evaluation of the biliary tree. (a) Drawing of                 an ERCP procedure where the endoscope reaches the duodenal papilla. Contrast agent                 is injected into the common bile duct, opacifying it partially. An extrinsic                 obstruction (question mark) blocks the contrast agent, preventing delineation of the                 upstream biliary tract. (b) Drawing of an MRCP examination with additional MR                 sequences demonstrates a tumoral lesion in the pancreatic head with dilatation of                 upstream bile ducts, including the pancreatic duct. (c) Coronal MRCP maximum                 intensity projection (MIP) reformation shows dilated intra- and extrahepatic bile                 ducts as well as the main pancreatic duct with abrupt distal obstruction                 (arrowheads). (d) Axial T2-weighted image shows a tumoral mass (arrowheads) in the                 pancreatic head that is compatible with adenocarcinoma.

Figure Comparison of ERCP and MRCP in evaluation of the biliary tree. (a) Drawing of an ERCP procedure where the endoscope reaches the duodenal papilla. Contrast agent is injected into the common bile duct, opacifying it partially. An extrinsic obstruction (question mark) blocks the contrast agent, preventing delineation of the upstream biliary tract. (b) Drawing of an MRCP examination with additional MR sequences demonstrates a tumoral lesion in the pancreatic head with dilatation of upstream bile ducts, including the pancreatic duct. (c) Coronal MRCP maximum intensity projection (MIP) reformation shows dilated intra- and extrahepatic bile ducts as well as the main pancreatic duct with abrupt distal obstruction (arrowheads). (d) Axial T2-weighted image shows a tumoral mass (arrowheads) in the pancreatic head that is compatible with adenocarcinoma.

Comparison of ERCP and MRCP in evaluation of the biliary tree. (a) Drawing of                 an ERCP procedure where the endoscope reaches the duodenal papilla. Contrast agent                 is injected into the common bile duct, opacifying it partially. An extrinsic                 obstruction (question mark) blocks the contrast agent, preventing delineation of the                 upstream biliary tract. (b) Drawing of an MRCP examination with additional MR                 sequences demonstrates a tumoral lesion in the pancreatic head with dilatation of                 upstream bile ducts, including the pancreatic duct. (c) Coronal MRCP maximum                 intensity projection (MIP) reformation shows dilated intra- and extrahepatic bile                 ducts as well as the main pancreatic duct with abrupt distal obstruction                 (arrowheads). (d) Axial T2-weighted image shows a tumoral mass (arrowheads) in the                 pancreatic head that is compatible with adenocarcinoma.

Figure Comparison of ERCP and MRCP in evaluation of the biliary tree. (a) Drawing of an ERCP procedure where the endoscope reaches the duodenal papilla. Contrast agent is injected into the common bile duct, opacifying it partially. An extrinsic obstruction (question mark) blocks the contrast agent, preventing delineation of the upstream biliary tract. (b) Drawing of an MRCP examination with additional MR sequences demonstrates a tumoral lesion in the pancreatic head with dilatation of upstream bile ducts, including the pancreatic duct. (c) Coronal MRCP maximum intensity projection (MIP) reformation shows dilated intra- and extrahepatic bile ducts as well as the main pancreatic duct with abrupt distal obstruction (arrowheads). (d) Axial T2-weighted image shows a tumoral mass (arrowheads) in the pancreatic head that is compatible with adenocarcinoma.

The high water content in bile composition and its relative stasis in the bile ducts are unique properties that are exploited to aid visualization with nearly all MRCP sequences. Although technique and protocols may vary, including two-dimensional radial and three-dimensional acquisitions as well as contrast material–enhanced MR cholangiography or even postsecretin administration acquisition (S-MRCP), there are some key points that every radiologist must know to perform MRCP and obtain the best images with this modality.

MRCP is indicated in the diagnosis of many benign and malignant pathologic conditions that affect the biliary tree and pancreas. These conditions are listed in the online presentation, with emphasis on their characteristic biliary obstruction patterns. MRCP is also useful in pre- and postoperative evaluation of biliary drainage, since it allows excellent visualization of the biliary ducts and possible anatomic variations.

MRCP also has its disadvantages. Although it is less operator dependent than US, it is more expensive and requires a longer period of time to perform imaging. In comparison with ERCP, MRCP cannot be used during interventions such as biopsy since it is a noninvasive method. It also has poorer spatial resolution when compared with endoscopic or even percutaneous cholangiography. Patients play an important role in the MRCP examination since they are responsible for cooperation by holding their breath or staying still during the study.

MRCP evaluation can also be challenging because the radiologist must be aware of possible anatomic variations of the bile tree and related structures as well as imaging artifacts or pitfalls that can often be present and may lead to misinterpretation.

After reviewing the online presentation, which is meant for residents, trainees, and their educators, the reader should be able to understand how MRCP is performed, focusing on current techniques, advantages, disadvantages, and possible artifacts and pitfalls and how to avoid them. The reader should also be able to discuss when MRCP, ERCP, or other biliary tree evaluation methods are indicated, how to access normal or variant biliary anatomy, and identify common biliary disease such as stones, benign or malignant stricture patterns, bile leaks, and iatrogenic lesions.

Presented as an education exhibit at the 2019 RSNA Annual Meeting.

All authors have disclosed no relevant relationships.

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Article History

Received: Mar 23 2020
Revision requested: Apr 23 2020
Revision received: May 26 2020
Accepted: May 29 2020
Published online: Sept 01 2020
Published in print: Sept 2020