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MRCP (MAGNETIC RESONANCE CHOLANGIO PANCREATICOGRAPHY)

MRCP (MAGNETIC RESONANCE CHOLANGIO PANCREATICOGRAPHY). Dr.Vasudha Agarwal. MRCP is a non invasive imaging technique which has a fundamental role in investigation of many pancreatico-biliary disorders. CONCEPT. makes use of heavily T2-weighted pulse sequences.

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MRCP (MAGNETIC RESONANCE CHOLANGIO PANCREATICOGRAPHY)

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  1. MRCP(MAGNETIC RESONANCE CHOLANGIO PANCREATICOGRAPHY) Dr.Vasudha Agarwal

  2. MRCP is a non invasive imaging technique which has a fundamental role in investigation of many pancreatico-biliary disorders.

  3. CONCEPT • makes use of heavily T2-weighted pulse sequences. •  originally achieved using a gradient-echo (GRE) balanced steady-state free precession technique . • A fast spin-echo (FSE) pulse sequence with a long echo time (TE) was then introduced shortly after. 

  4. PRE SCAN PREPARATION • Patients are fasted for 8-12 h prior to the study (in order to reduce fluid secretions within the stomach and duodenum, reduce bowel peristalsis and promote gallbladder distension. ) • Some centres use a negative oral contrast agent (e.g. iron oxide or blueberry juice) to reduce the signal intensity of overlapping fluid within the stomach and duodenum.

  5. SCAN PROCEDURE Patient is positioned supine, in a feet first position in a body coil . The respiratory bellows are placed on the patient. Check for respiratory wave form on the computer console. If its clear and visible, alignment and land marking of the patient is done. Landmark is marked below the xiphoid at the rib cage margin. After which the MRCP protocol is selected.

  6. Sequences used in GE system in our hospital Axial T2 RtrFatSat Axial T2 SSFSE Rtr Cor SSFE Rtr 3D MRCP Rtr ASSET Thick slab MRCP-BH Axial 2D FIESTA FATSAT-BH Cor 2D FIESTA –BH

  7. 8.Ax T1 FSPGR FATSAT –BH 9.COR T1 FSPGR FATSAT-BH 10.POST CONTRAST Ax T1 FSPGR 11.POST CONTRAST COR T1 FSPGR 12.POST CONTRAST SAG T1 FSPGR

  8. MIP (Maximum Intensity Projection) •  A MIP reformat can be generated. This displays only the pixel with the highest signal intensity along a ray perpendicular to the plane of projection. • It thus highlights bile-filled and fluid-filled structures very well. MIP reformats can be generated in various coronal and sagittal oblique planes.

  9. 3D FSE SEQUENCE • High TE • Respiratory gating technique • MIP formatting • Long time ( 4-5 mins) • Requires regular breathing

  10. SSFSE SEQUENCE • Single-shot FSE • Radial coronal slabs • Slabs of 2-5 cm thickness • Respiratory triggering • Regular breathing required • MIP formatting not needed

  11. FIESTA SEQUENCE • Balanced SSFP sequence • Breath holding • Motion insensitive sequence • Highest possible SNR • Advantage: Good visualization of ducts without motion artifacts

  12. INDICATIONS FOR MRCP • CYSTIC DISEASES OF BILE DUCT • Choledochal cyst • Choledochocele • Caroli’s disease It is as effective as ERCP in evaluating the above.

  13. CHRONIC PANCREATITIS • Detection of chronic pancreatitis- dilated pancreatic duct, narrowing/stricture and irregularity. • Identification of a surgically or endoscopically correctable lesion.

  14. CONGENITAL ANOMALIES • Low Cystic duct insertion • Medial cystic duct insertion • Aberrant right hepatic duct • Parallel course of cystic and hepatic duct MRCP is superior to ERCP in the above.

  15. CHOLEDOCHOLITHIASIS • Before cholecystectomy • Superior to USG and CT • Comparable to ERCP • PRIMARY SCLEROSING CHOLANGITIS • Beaded appearance • MRCP for diagnosis and follow up • ERCP may cause cholestasis and may not show ducts proximal to severe stenosis.

  16. POST SURGICAL COMPLICATION • Benign strictures, retained stones, biliary leak, biliary fistula • Patency of biliary-enteric anastomosis • NEOPLASTIC LESIONS • Shows duct proximal to obstruction caused by neoplasms like cholangiocarcinoma and pancreatic head carcinoma • Fat sat images for extent and spread of lesion

  17. MEDIAL INSERTION OF CYSTIC DUCT WITH SMALL PSEUDOCYST

  18. PANCREATIC DIVISUM

  19. PRIMARY SCLEROSING CHOLANGITIS

  20. SECRETIN INDUCED MRCP • Secretin: an endogenous hormone • When given as a synthetic agent intravenously (1 ml/10 kg body weight), it improves the visualisation of the pancreatic duct by increasing its calibre.

  21.  A thick slab MRCP is performed at baseline and then at 1, 3, 5, 7 and 9 min following injection. • Its effect starts almost immediately and peaks between 2 to 5 mins. • By 10 min, the caliber of the main pancreatic duct should return to baseline with persistent dilatation of >3 mm considered abnormal.

  22. The indications for this technique include detection and characterization of pancreatic ductal anomalies and strictures, evaluation of the integrity of the pancreatic duct, characterization of any communication between the pancreatic duct and pseudocysts/pancreatic fistulas, and the assessment of pancreatic function and sphincter of Oddi dysfunction.

  23. SECRETIN INDUCED MRCP Pancreatic duct appears prominent in Image b. It returns to normal caliber in Image c.

  24. FUNCTIONAL MR CHOLANGIOGRAPHY • MR lipophilic paramagnetic contrast agents used, given intravenously, show hepato-biliary excretion. • These contrast agents include: • gadobenate dimeglumine (Gd-BOPTA) • gadolinium ethoxybenzyldiethylenetriamine genta-acetic acid (Gd-EOB-DTPA)

  25. Delayed imaging in the axial and coronal plane, performed between 10-120 min following intravenous administration, normally results in hyper-intense bile on 3D T1-weighted fat-saturated GRE images. • The signal-to-noise ratio is higher than conventional T2-weighted MRCP, allowing better delineation of the bile ducts.

  26. DISADVANTAGE: • It is more expensive than conventional T2-weighted MRCP

  27. INDICATIONS • It better demonstrates communications between cystic lesions and draining bile ducts in the diagnosis of congenital biliary disorders (e.g. Caroli’s disease) • It helps to distinguish true obstruction in a dilated biliary system (where delayed or no biliary excretion is demonstrated) from pseudo-obstruction.

  28. It can demonstrate active extravasation of contrast in suspected bile leaks . • Another advantage is that these gadolinium-based hepatobiliary-specific contrast agents initially distribute in the extracellular fluid compartment, thus allowing for early dynamic pre-contrast and post-contrast images in the arterial, portal venous and equilibrium phase prior to the functional cholangiogram.

  29. PITFALLS ON MRCP 1.Technique & reconstruction artefacts • A thick slab MRCP may obscure small filling defects or strictures as the spatial resolution is degraded because of volume averaging effects. • Partial volume effects also degrade spatial resolution in MIP reformats, leading to the missed filling defects and over- or under-estimation of strictures.

  30. Due to respiratory motion artefact, the biliary tree may appear stenotic, dilated, disconnected or duplicated on MIP reformats. • Hence it is important to always review the original thin-section data set also.

  31. Intra-ductal factors • Filling defects in the bile may arise, not only from bile duct calculi but also from the presence of gas, debris, hemorrhage and tumor. • Aerobilia is seen as a non-dependent filling defect on the axial images .

  32. A signal void in the central part of the bile duct is due to flow phenomenon and may occur in dilated ducts and at the point of insertion of a large cystic duct. • The presence of iodinated contrast material will reduce the signal intensity of bile.

  33. a Axial T2-weighted MRI shows an air-fluid level in a dilated proximal CBD (arrow) adjacent to the duodenum (D), which also shows an air-fluid level.  b More distally in the same patient, the cause of the obstruction is seen with a dependent filling defect (arrowhead) in the distal CBD in keeping with a stone. This should not be confused with the non-dependent aerobilia also shown at this level (arrow)  c Axial T2-weighted MRI in a different patient shows a central filling defect in a dilated CBD which is due to flow artefact (arrow). The patient also has chronic cholecystitis with a contracted gallbladder (arrowheads)

  34. Extra- ductal factors • Pulsatile vascular compression from adjacent vessels may mimic a stricture. • The commonest site of extrinsic vascular compression is the common hepatic duct, followed by the left hepatic duct, both due to the right hepatic artery crossing its posterior aspect. • The mid portion of the CBD may also be narrowed due to the gastro-duodenal artery.

  35. Pseudo-obstruction is typically seen as a bandlike compression with minimal proximal dilatation. • Susceptibility artefacts from metallic clips and gas may give rise to difficulties in interpretation, although titanium clips used nowadays for cholecystectomy are not magnetic. • Overlapping of the biliary tree with other stationary fluids (i.e. from adjacent bowel, cystic collections or ascites) may also cause interpretation problems.

  36. THANK YOU !!

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