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.

MRCP (MR Cholangiopancreatography)

📋 Indications

⛔ Contraindications & Cautions

🧑‍⚕️ Patient Preparation

⚙️ Technique & Parameters

🔎 Systematic Review

🩻 Key Findings & Significance

🧠 Differential Considerations

💡 Pearls & Pitfalls

📝 Structured Report

📚 References