MR cholangiopancreatography (MRCP)
MR Cholangiopancreatography (MRCP) = a specialised MRI technique focusing on the liver, bile ducts, gallbladder, pancreas, and pancreatic ducts. Non-invasive alternative to ERCP → no endoscope, no iodinated contrast needed. Based on heavily T2-weighted MRI sequences → fluid (bile, pancreatic juice) appears bright → ducts are well visualised.
🎯 Indications
- 🪨 Choledocholithiasis: Detect + localise CBD stones.
- ➖ Biliary strictures: Assess benign vs malignant narrowing.
- 💥 Trauma: Evaluate biliary/pancreatic duct injury.
- 🔥 Chronic pancreatitis: Show ductal changes, strictures, stones.
- 🧬 Congenital anomalies: e.g. choledochal cysts, Caroli’s disease.
- 🩺 Post-surgical anatomy: After cholecystectomy, transplant, biliary diversion.
- 🔀 Pancreas divisum: Failure of duct fusion (important cause of recurrent pancreatitis).
- 💧 Pancreatic cystic lesions: Assess communication with ducts.
- ⚠️ Anomalous pancreaticobiliary junction: Pre-cancerous risk factor.
🖼️ Imaging Details
- Uses heavily T2-weighted sequences → static/dilated fluid = bright.
- Stones = signal voids (dark spots) within bright bile.
- Thin-slice 3D reconstructions give detailed “cholangiogram-like” images of biliary tree + pancreatic duct.
- No ionising radiation → suitable for younger patients and follow-up.
🛠️ Preparation
- ⏱️ Fast ≥4 hours → reduces bowel peristalsis and fluid artefact.
- 🍐 Promotes gallbladder distension → better ductal visualisation.
- Some centres use negative oral contrast (e.g. pineapple juice 🥤, iron oxide solutions) to suppress duodenal fluid signal.
📌 Key Teaching Points
- ✅ MRCP = first-line for ductal imaging when ERCP is not immediately indicated.
- ✅ ERCP is now mainly therapeutic (stone removal, stenting), not diagnostic.
- 🚩 MRCP cannot biopsy → tissue diagnosis still requires ERCP/EUS.
