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Mrcp Radiology
- 4. 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.
- 6. 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
- 7. 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.
- 9. 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.
- 10. 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.
- 11. Pitfalls on MRCP Artefacts related to technique and reconstruction. Normal variants mimicking pathology. Intra-ductal factors. Extra-ductal factors.
- 12. 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
- 13. CHOLEDOCHAL CYST
- 14. Caroli’s disease
- 19. Pancreas divisum
- 20. 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) .
- 21. THANK YOU
Editor's Notes
- #14: Type I is a true choledichal cyst with focal dilatation of the extrahepatic duct. This is the most frequent type (90-95% of the cases). Type II and III are extremely rare and it is debatable whether or not these are true choledochal cysts. Type II is a diverticulum of the extrahepatic duct. Type III is a choledochocele, where there is dilatation of the distal part of the bile duct. Type IV is also a true choledichal cyst with dilatation of the entire extrahepatic duct with involvement of portions of the intrahepatic ducts.
- #15: Caroli disease is a congenital disorder comprising of multifocal cystic dilatation of segmental intrahepatic bile ducts. However, some series show that extrahepatic duct involvement may exist 2. It is also classified as a type V choledochal cyst, according to the Todani classification. 1- T1 contrast fat sat 2- T2 fat sat 3- MRCP MRI T1: hypointense dilatation of IHBD T2: hyperintense T1 C+ (Gd): enhancement of the central portal radicles within the dilated IHBD 1 MRCP: demonstrates continuity with the biliary tree
- #16: 33 year old female with right upper quadrant pain. MRCP demonstrated multiple calculi in both dilated extrahepatic bile duct( arrow) and gallbladder.( arrowheads) Stones appear as low signal intensity foci within high- signal intensity bile.
- #17: When we see intrahepatic bile duct dilatation with strictures and only mild dilatation, the first diagnosis we think of is primary sclerosing cholangitis (PSC). Multiple intrahepatic strictures and strictures seen in the common hepatic duct and distal CBD (arrows). There is dilatation of the proximal CBD
- #18: Post-operative cholangiography showing a cysto-biliary fistula
- #19: Cholangiocarcinoma (i.e., adenocarcinoma of the bile duct) arises from the columnar epithelium of the bile duct. It is characterized by malignant glands within a desmoplastic stroma. These tumors have an infiltrative growth pattern and do not have a capsule. Coronal MIP reformat shows dilatation of the intrahepatic bile ducts with disconnection between the left and right sided ducts and the common duct, due to a hilar cholangiocarcinoma (arrow) The distal CBD and pancreatic duct appear normal (arrowheads).
- #20: MRCP/MRI pancreas This is the standard method of evaluation in modern times. The key imaging features are: the dorsal pancreatic duct being in direct continuity with the duct of Santorini, which drains into the minor ampulla ventral duct, which does not communicate with the dorsal duct but joins with the distal bile duct to enter the major ampulla Shows distal bile duct( arrowheads) which joins with ventral pancreatic duct( arows) to enter major ampulla. shows dorsal pancreatic duct ( arrows) enteriing minor ampulla( arrow heads) cephalad to the major ampulla.