Magnetic Resonance Cholangiopancreatography- MRCP

Magnetic Resonance Cholangiopancreatography- MRCP

1. Magnetic Resonance C holang i opancreatogra p hy (MRCP)

2. Introduction Introduced in 1991. Magnetic resonance cholangiopancreatography (MRCP) is performed with heavily T2-weighted fast spin-echo sequences. Noninvasive, less costly, and sensitive alternative to diagnostic ERCP

3.  It is a MRI technique used to investigate Biliary and Pancreatic pathologies.  It makes use of heavily T2-weighted pulse sequences, thus exploiting the inherent differences in the T2-weighted contrast between stationary fluid-filled structures in the abdomen (which have a long T2 relaxation time) and adjacent soft tissue (which has a much shorter T2 relaxation time).  Static or slow moving fluids within the biliary tree and pancreatic duct appear of high signal intensity on MRCP, whilst surrounding tissue is of reduced signal intensity. Introduction

4. PATIENT PREPARATION It is very crucial to optimize imaging of the biliary system with MRCP. The patient fasts for 4 hours to help reduce peristalsis and gastroduodenal fluid before imaging. Oral contrast material that lowers the signal intensity of intraluminal fluid in the bowel on T2-weighted images. Superparamagnetic iron oxide particles, gadolinium- meglumine compounds or pineapple juice administered to suppress the signal from fluid in the gastrointestinal tract. Patient removes all external metal items prior to entering the magnet, and is given ear plugs.

5. TECHNIQUE  Patients are fasted for 4 – 6 hrs prior to the study in order to reduce fluid secretions within the stomach and duodenum, reduce bowel peristalsis and promote gallbladder distension.  A negative oral contrast agent (e.g. iron oxide or Blueberry or Pineapple juice) to reduce the signal intensity of overlapping fluid within the stomach and duodenum.  A phased array body coil is used.  Modified Fast Spin Echo (FSE) sequences like Rapid Acquisition with Rapid Enhancement sequence (RARE) and Half Fourier acquisition single shot turbo spin echo (HASTE) are ideally used in combination for MRCP which takes only 10 minutes of imaging time while providing improved quality of image

6.  First an axial 2D breath-hold HASTE sequence is taken. Two breath-hold acquisitions are obtained, so that the whole of the liver down to the duodenal ampulla is visualized.  Following this, two 3D respiratory-triggered heavily T2-weighted FSE sequences in the coronal oblique plane are taken.  Around 40-45 slices are obtained, which are contiguous and each of 1.5 mm in thickness. As the images are heavily T2-weighted, the pancreatico-biliary tree is displayed as high signal intensity, whilst adjacent structures are of reduced signal intensity.  A thick collimation slab can be obtained in the coronal plane involving a fat saturated HASTE sequence where a single slab of data 4 cm in thickness is acquired in a 1- to 2-s breath-hold. It is useful in depicting the entire pancreatico-biliary tree and no post- processing is required.  In order to evaluate the duct walls, and any focal parenchymal pathology, 3D fat suppressed T1-weighted GRE sequences are taken.

7. IMAGING PARAMETERS

8. APPLIC A TIONS BILIARY DISEASE Cystic disease of bile ducts (choledochal cyst, choledochocele, caroli’s disease) Congenital variants (aberrant right hepatic artery, low or medial duct insertion). Choledocholithiasis Primary sclerosing cholangitis Post surgical biliary complications Cholangiocarcinoma

9. APPLIC A TIONS PANCREATIC DISEASE Pancreatic divisum Chronic pancreatitis Ca pancreas

10. APPLIC A TIONS In choledochal cysts : MRCP is equivalent to ERCP. detects the presence of anomalous union of pancreatic & bile ducts. the length of extrahepatic bile duct involved by the cyst is known – an important consideration in planning surgery. well suited for pediatric patients.

11. Secretin-stimulated MRCP  Secretin is an endogenous hormone normally produced by the duodenum, which stimulates exocrine secretion of the pancreas.  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.  Its effect starts almost immediately and peaks between 2 to 5 mins. By 10 min, the calibre of the main pancreatic duct should return to baseline with persistent dilatation of >3 mm considered abnormal.  The indications for this technique include the detection and characterisation of pancreatic ductal anomalies and strictures, evaluation of the integrity of the pancreatic duct, characterisation of any communication between the pancreatic duct and pseudocysts/pancreatic fistulas, and the assessment of pancreatic function and sphincter of Oddi dysfunction.

12. Functional MR cholangiography  This involves the use of MR lipophilic paramagnetic contrast agents, which when given intravenously, show hepato-biliary excretion. Contrast agents include gadobenate dimeglumine , gadolinium ethoxybenzyldiethylenetriamine penta-acetic acid and mangafodopir trisodium.  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.  Advantages : (1) it better demonstrates communications between cystic lesions and draining bile ducts in the diagnosis of congenital biliary disorders (e.g. Caroli’s disease) (2) it helps to distinguish true obstruction in a dilated biliary system (where delayed or no biliary excretion is demonstrated) from pseudo-obstruction and (3) it can demonstrate active extravasation of contrast in suspected bile leaks.

13. Pitfalls on MRCP  Artefacts related to technique and reconstruction.  Normal variants mimicking pathology.  Intra-ductal factors.  Extra-ductal factors.

14. INDICATIONS Biliary Disease Cystic disease of bile duct (choledochal cystcholedochocele, Caroli’s disease) Congenital variants (low or medial duct insertion, aberrant right hepatic duct) Choledocholilithiasis Primary sclerosing cholangitis Post-surgical biliary complications Cholangiocarcinoma Pancreatic Disease Pancreas divisum Chronic pancreatitis Pancreatic cancer

15. CHOLEDOCHAL CYST

16. Caroli’s disease

17. Choledocholilithiasis

18. Primary Sclerosing Cholangitis

19. Post-surgical biliary complications

20. Cholangiocarcinoma

21. Pancreas divisum

22. MRCP vs ERCP  Magnetic Resonance Choloangiopancreatography (MRCP) is a relatively newer, non- invasive, radiation free modality for visualization of biliary system. It is mainly useful in patients with contraindication to invasive modality like Endoscopic Retrograde Choloangiopancreatography (ERCP) .

23. SUMMA R Y Over the past decade, MRCP has evolved not only as a feasible means of non-invasively evaluating the pancreatobiliary tract but also as a technique with documented clinical utility. In fact, at some institutions MRCP has replaced diagnostic ERCP such that ERCP is preserved for only therapeutic interventions. MRCP + abd MR + MRA – evaluates solid organs & vessels of abd & ductal systems

24. REFERENC E S Hemant T. Patel, Ankur J. Shah, Shikha R. Khandelwal, Hiren F. Patel, Megha D. Patel: MR Cholangiopancreatography at 3.0 T. RadioGraphics 2009; 29:1689–1706 . Computed body tomography with MRI correlation-Lee & Sagel.

25. Thank You Nitish Virmani Lecturer Department of Radio-Imaging Technology Faculty of Allied Health Sciences SGT University Email- [email protected]