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AbdomenDemonstration data

MRCP (MR Cholangiopancreatography)

MR cholangiopancreatography is a non-invasive, contrast-free technique that exploits the long T2 of static bile and pancreatic secretions to render the biliary tree and pancreatic duct as bright structures against a dark background. It has largely replaced diagnostic ERCP, reserving the endoscopic procedure for therapeutic intervention, and provides a road map of ductal anatomy prior to intervention or surgery.

Indications

  • Suspected choledocholithiasis and evaluation before or after cholecystectomy
  • Characterisation of benign versus malignant biliary strictures (e.g. cholangiocarcinoma, PSC)
  • Assessment of pancreatic duct in chronic and recurrent acute pancreatitis
  • Congenital anomalies: choledochal cysts, pancreas divisum, anomalous pancreaticobiliary junction
  • Delineation of ductal anatomy prior to hepatobiliary or pancreatic surgery and living-donor transplant
  • Evaluation of biliary-enteric anastomoses and post-operative bile leaks or strictures

Contraindications & Cautions

  • Non-MRI-conditional cardiac pacemakers, ICDs and neurostimulators unless formally cleared
  • Ferromagnetic intracranial aneurysm clips and certain cochlear implants
  • Intra-ocular or unstable metallic foreign bodies
  • Severe claustrophobia unable to tolerate the bore (consider open or wide-bore MRI, sedation)
  • First-trimester pregnancy is a relative caution; MRCP itself uses no gadolinium and no ionising radiation

Patient Preparation

  • Fast 4-6 hours to reduce bowel motion, promote gallbladder distension and empty the stomach
  • Administer oral negative (superparamagnetic) contrast such as pineapple or blueberry juice to suppress overlapping gastroduodenal fluid
  • MRI safety screening questionnaire and removal of all ferromagnetic objects
  • Coach breath-holding and quiet respiration for triggered acquisitions
  • Optional secretin stimulation to improve pancreatic duct distension and assess exocrine flow

Technique & Parameters

  • Heavily T2-weighted acquisitions where only near-stationary fluid remains bright
  • Thick-slab (20-70 mm) single-shot fast/turbo spin-echo projection images acquired in a single breath-hold at multiple radial obliquities
  • Thin-section 3D respiratory-triggered T2 fast spin-echo for source data and multiplanar/MIP reconstruction
  • Coronal oblique planning along the long axis of the common bile duct
  • Axial and coronal T2 and T1 in/out-of-phase of the upper abdomen for parenchymal and wall assessment
  • Fat suppression on 3D sequences to increase duct-to-background contrast; add secretin-enhanced dynamic imaging when pancreatic duct assessment is required

Systematic Review

  • Assess intrahepatic ducts for dilatation, beading, pruning and strictures
  • Measure the common bile duct calibre and trace it to the ampulla for filling defects
  • Evaluate the cystic duct insertion, gallbladder and any aberrant/accessory ducts
  • Follow the main pancreatic duct from tail to ampulla and note side branches
  • Correlate ductal findings with parenchymal signal on the axial T1/T2 source images
  • Review for complications: abscess, pseudocyst, portal or vascular involvement

Key Findings & Significance

  • Choledocholithiasis: rounded low-signal filling defect within bright bile, often meniscus at the calculus
  • Malignant stricture: abrupt, irregular, shouldered narrowing with proximal dilatation (double-duct sign in pancreatic head cancer)
  • Primary sclerosing cholangitis: multifocal beaded intra- and extrahepatic strictures with a pruned-tree appearance
  • Pancreas divisum: dorsal duct draining through the minor papilla, crossing the common bile duct
  • Chronic pancreatitis: dilated, irregular main duct with dilated side branches (chain-of-lakes) and calcifications
  • Choledochal cyst: fusiform or saccular dilatation of the extrahepatic duct (Todani classification)

Differential Considerations

  • Filling defect: calculus, sludge, blood clot, pneumobilia (air rises, non-dependent), tumour or parasite
  • Biliary stricture: cholangiocarcinoma, pancreatic head carcinoma, PSC, IgG4 cholangiopathy, post-operative or ischaemic stricture
  • Cystic lesion communicating with the duct: choledochal cyst, IPMN, duplication cyst
  • Dilated pancreatic duct: obstructing tumour, chronic pancreatitis, main-duct IPMN, stricture
  • Pseudo-obstruction artefact from flow void, susceptibility or pulsation mimicking a stone

Pearls & Pitfalls

  • Pneumobilia is non-dependent and rises anteriorly, distinguishing it from dependent stones on axial images
  • Always correlate the thick-slab projection with thin-section source images to avoid missing small stones summed out on MIP
  • Secretin-MRCP improves detection of subtle pancreatic duct anomalies and grades exocrine function by duodenal filling
  • The double-duct sign (dilated CBD and pancreatic duct) should prompt a search for a periampullary or pancreatic head tumour
  • A negative MRCP does not exclude microlithiasis; correlate with clinical and biochemical findings

Structured Report

  • State field strength, sequences and whether secretin or negative oral contrast were used
  • Report intrahepatic and extrahepatic duct calibre with measurements and the level of any obstruction
  • Characterise filling defects and strictures (benign versus malignant features)
  • Describe the pancreatic duct, congenital variants and parenchymal changes
  • Give an impression with recommendation regarding ERCP, EUS or surgical correlation

References

  • Griffin N, et al. Magnetic resonance cholangiopancreatography: the ABC of MRCP. Insights Imaging 2012
  • Sahani DV, et al. Radiographics: MRCP technique and clinical applications
  • ACR-SAR-SPR Practice Parameter for the Performance of MRI of the Abdomen
  • Vullierme MP, et al. Secretin-enhanced MRCP. Radiographics
  • Todani T, et al. Classification of congenital biliary cystic disease

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.