Magnetic Resonance Cholangiopancreatography Ahmet Mesrur Halefoglu, MD M agnetic resonance cholangiopancreatography (MRCP) is a noninvasive imaging technique for the evaluation of pancreatico-biliary disorders It uses magnetic resonance imaging to visualize fluid in the biliary and pancreatic ducts as high signal intensity on T2-weighted sequences and provides improved spatial resolution and permits imaging of the entire pancreatico-biliary tract during a single breath-hold It is being used with increasing frequency as a noninvasive alternative to diagnostic endoscopic retrograde cholangiopancreatography (ERCP) and, in most institutions, has become the initial imaging tool for the pancreatico-biliary system, with ERCP reserved for only therapeutic indications The literature indicates that MRCP is equivalent in diagnostic accuracy to ERCP across numerous pancreatico-biliary pathologies and therefore can reliably be used as the first-line investigation MRCP is noninvasive, less operator dependent, does not require anesthesia or contrast material, and uses no radiation It is only a diagnostic procedure and therapeutic intervention cannot be performed as part of this procedure, whereas ERCP is a diagnostic as well as a therapeutic procedure However, ERCP is highly operator dependent, has significant morbidity and mortality, and operators cannot cannulate the common bile duct (CBD) and pancreatic duct in up to 9% of examinations.1 MRCP avoids the potential morbidity and mortality associated with ERCP MRCP is an appropriate noninvasive tool in suspected pancreato-biliary pathology especially when no or low likelihood of therapeutic intervention is anticipated MRCP is particularly useful where ERCP is difficult, dangerous, or impossible (eg, previous gastroenteric anastomosis or gastrojejunostomy) It is also an important option for patients with failed ERCPs MRCP and ERCP have different contraindications allowing them to be used as complementary techniques.2 In this article, we provide an overview of the MRCP technique and clinical applications in a variety of diseases Sisli Etfal Training and Research Hospital, Department of Radiology, Istanbul, Turkey Address reprint requests to Ahmet Mesrur Halefoglu, MD, Sisli Etfal Training and Research Hospital, Department of Radiology, 34360, Sisli, Istanbul, Turkey E-mail: halefoglu@hotmail.com 282 0037-198X/08/$-see front matter © 2008 Elsevier Inc All rights reserved doi:10.1053/j.ro.2008.06.004 Technical Aspects The MRCP technique relies on the use of heavily T2-weighted imaging sequences, which display stationary fluid (ie, bile and pancreatic secretions) as areas of high signal intensity MRCP was initially performed with gradient-echo sequences These were generally slow and gave poor quality images When the fast spin-echo pulse sequence became available, it replaced the gradient-echo MRCP technique The advent of fast sequences has led to dramatically shortening the imaging time and has provided breath-hold techniques viable Single shot fast spin-echo (SSFSE) (or half-Fourier turbo spin-echo) technique is a variant of fast spin-echo technique and is currently the sequence of choice for MRCP.3 These techniques allow cholangiographic images to be obtained in a very short breath-hold Rapid imaging avoids motion artifacts (eg, related to bowel peristalsis, respiration, and voluntary motion) and allows noncooperative patients to be evaluated Optimal MRCPs are required with a high-field scanner, a torso phased-array coil, and fast (breath-hold) sequences MRCP is usually performed initially with a single-shot projection technique in which thick-slab (40-70 mm) axial and coronal images of the upper abdomen are obtained to localize the extrahepatic bile duct Next, a multisection technique involving the acquisition of multiple thin-slab source images (3 to mm) in the coronal oblique plane along the longitudinal axis of the bile duct is performed Three-dimensional (3D) images can be generated from these source images with a maximum-intensity projection (MIP) algorithm Although the thick collimation and 3D MIP images more closely resemble conventional cholangiograms and are familiar to many clinicians, spatial resolution is degraded because of volumeaveraging effects Diagnostic decisions should be made on the basis of the source images, although these cholangiogram-like MIP images are very helpful in providing an overview of ductal anatomy Thin source images are shown to be more sensitive than the MIPs in detecting small calculi.4 The breath-hold technique is superior to non-breath-hold techniques in that it eliminates artifacts arising from respiratory motion In addition, the use of phased-array surface coils has resulted in improved image quality by increasing signalto-noise ratios Because of improvements in image quality, MRCP is capable of showing ducts as small as mm.3,5 An MR cholangiopancreatography 283 Table MRCP Protocol (optimized for 1.5-Tesla scanner) Localizer: Coronal oblique SSFSE T2-weighted 2D sequence (TR: 1200 msec; TE: 140 msec; Bandwidth: 31.25; Section thickness: 70 mm; Intersection gap: 1.5 cm; FOV: 44 mm; Matrix: 320 ؋ 192; Slice number: 20; Scanning time: 24 seconds) Axial images: Axial fast spin-echo, respiratory triggered T2-weighted 2D thin-slabe fat-suppressed sequence (TR: 6600 msec; TE: 90 msec; Echo train length: 13; Bandwidth: 41.67; Section thickness: mm; Intersection gap: 1-1.5 mm; NEX: 3; FOV: 44 mm; Matrix: 256 ؋ 224; Slice number: 24; Scanning time: minutes) Coronal oblique images along the expected angle of the common and pancreatic ducts: Coronal SSFSE T2-weighted 2D thick-slab fat-suppressed breath-hold sequence (TR: 2715 msec; TE: 1360 msec; Bandwidth: 31.25; Section thickness: 50 mm; Intersection gap: 0; FOV: 34 mm; Matrix: 388 ؋ 288; Slice number: 6; scanning time: 16 seconds) additional advantage of the SSFSE or half-Fourier turbo spinecho technique is the ability to reduce suspectibility effects from surgical clips, metallic biliary and vascular stents, biliary drainage catheters, and spinal fixation rods The reduction of suspectibility effects is important because MRCP is often performed in patients who have multiple clips secondary to cholecystectomy, biliary-enteric anastomosis, or liver transplantation A routine MRCP protocol for a 1.5-Tesla scanner in our institution is shown in Table Gadolinium-enhanced images of the liver and pancreas may also be added to the protocol in the case of suspected tumor This uses a 3D spoiled gradient echo T1 sequence before and after gadolinium administration, with images acquired 20 and 70 seconds after the start of the bolus gadolinium injection Patient Preparation Clinical Applications Choledocholithiasis MRCP is very helpful in the diagnosis of choledocholithiasis because CBD stones appear as low-signal-intensity foci within the high-signal-intensity bile (Fig 2) Calculi as small as mm in diameter can be visualized.8,9 Small calculi may not cause secondary dilation of the ducts9 and are best seen on the axial images.9 It is crucial to scrutinize the thin, source images because the sensitivity for detection of small stones decreases with an increase in section thickness owing to volume averaging of high-signal-intensity bile surrounding the stone Shanmugam and coworkers10 assessed the predictive value of MRCP in the diagnosis of choledocholithiasis MRCP findings were compared with ERCP or operative findings Of the 221 patients, the MRCP showed a sensitivity of 97.98% and specificity of 84.4% The authors stated that MRCP is highly sensitive and specific for choledocholithiasis and avoids the MRCP can be performed in all patients apart from those with specific internal ferro-magnetic foreign bodies or claustrophobia Patients should be fasted approximately to hours before examination to provide gallbladder filling and gastric emptying IV contrasts or antispasmodics are not used No exogenous contrast material is needed to demonstrate the pancreatico-biliary system Similarly, glucagon use is not recommended to obviate peristalsis due to rapid enough pulse sequences Administration of a negative contrast agent can be helpful by providing reduction of the signal intensity from overlapping fluid-filled structures such as the stomach and duodenum Normal Anatomy The gallbladder and CBD are visualized in up to 98% of patients6 (Fig 1) Visualization of the biliary tree is variable distal to the right and left hepatic ducts.6 In addition, MRCP is 95% accurate in differentiation of normal from dilated ducts.7 MRCP using SSFSE technique allows visualization of the entire normal-caliber pancreatic duct in the head and body in 97% of cases and in the tail in 83% of cases5 (Fig 1) Complete visualization of a dilated pancreatic duct is possible in 100% of cases Demonstration of pancreatic side branches varies from 19% in the head to 5% in the tail.1 Figure Coronal MIP image Gallbladder (GB), cystic duct (CD), common bile duct (CBD), and pancreatic wirsung duct (PD) are clearly seen in this normal patient A Mesrur Halefoglu 284 Figure (A) Axial thin slab source image shows multiple hypointense calculi in the gallbladder and CBD (B) Coronal MIP image clearly demonstrates CBD stone as a hypointense round lesion located in the distal region need for invasive imaging in most patients with suspected choledocholithiasis Griffin and coworkers11 prospectively assessed the accuracy of MRCP in diagnosing bile duct stones as an alternative to ERCP in 115 patients with suspected CBD stones awaiting laparoscopic cholecystectomy MRCP showed a sensitivity of 84%, specificity of 96%, positive-predictive value of 91%, negative-predictive value of 93%, and diagnostic accuracy of 92% when compared with ERCP as the gold standard The authors concluded that MRCP can be reliably used as the first-line investigation for choledocholithiasis Barish and colleagues12 state that MRCP can visualize the normal or dilated CBD in 96 to 100% of patients Stones appear as areas of signal void within the high-signal-intensity bile on MRCP The authors note the sensitivity of MRCP for detecting choledocholithiasis has been reported to be between 71 and 100% longer with more gentle sloping shoulders than malignant strictures and not have associated masses (Fig 3) Intrahepatic Duct Disease The role of MRCP in the evaluation of intrahepatic duct disease (eg, primary sclerosing cholangitis (PSC), acquired im- Benign Biliary Strictures More than 80% of bile duct strictures occur after an injury to the extrahepatic bile ducts during a cholecystectomy, with a minority attributable to other benign causes such as infection, pancreatitis, stone passage, trauma, primary sclerosing cholangitis, ischemia, chemotherapy, and acquired immunodeficiency syndrome MRCP and ERCP have complementary roles in the diagnosis of biliary strictures Although normal and dilated CBDs are consistently demonstrated on MRCP, early strictures that have not yet caused biliary dilation are relatively difficult to demonstrate on MRCP Once the biliary tree is dilated, MRCP performs well.13 In many cases, it is very difficult to distinguish between benign and malignant etiologies Benign strictures tend to be Figure Coronal MIP image CBD distal segment stenosis (arrow) is seen secondary to infection in a patient MR cholangiopancreatography 285 olinium-enhanced images, and bile duct information obtained from the MRCP images, can be used to accurately stage cholangiocarcinoma MRCP images alone are not adequate to identify the cause of biliary obstruction due to the fact that they solely provide luminal information, and gadoliniumenhanced images are necessary for complete evaluation of the biliary obstructions Inflammatory Changes Pancreatitis is the most common benign disease involving the pancreas and is classified as acute or chronic on the basis of clinical, morphological, and histologic criteria Figure Axial thin slab source image, multiple strictures, and dilatations of the intrahepatic biliary ducts leading to a beaded appearance typical of primary sclerosing cholangitis in a patient munodeficiency syndrome cholangiopathy) is increasing Preliminary data suggest that MRCP may be used to establish the diagnosis of PSC14 and obviate diagnostic ERCP The performance of MRCP in PSC depends on the severity of disease When there are focal strictures with intervening dilated segments, the diagnosis is readily made on MRCP (Fig 4), but in earlier phases of the disease, early stenoses may be missed and short strictures may be overestimated because the downstream duct is collapsed Nevertheless, good correlation between ERCP and MRCP images in the diagnosis of PSC has been shown in a published study.15 In another recently published case-control study, Moff and coworkers16 reviewed 36 patients with PSC to determine the diagnostic accuracy of both MRCP and ERCP The authors, based on their study, stated that MRCP could be a useful screening test for PSC, but ERCP should remain as the confirmatory test, given its higher specificity Currently the role of MRCP is confined to the follow-up of advanced cases and/or the development of complications Acute Pancreatitis In patients presenting with acute pancreatitis, the detection of gallstones and the state of the pancreatico-biliary tree are of major importance MRCP provides the opportunity to acquire similar diagnostic information to ERCP in this regard without risk The pancreatic duct may be normal in mild cases of acute pancreatitis Occasionally, the enlarged and edematous pancreas can cause compression of the pancreatic duct In these cases, the pancreatic duct is either not visualized or presents a smooth and symmetric narrowing MRCP provides information relating to ductal dilation, ductal disruption, leakage, peripancreatic fluid collections, and intraductal lesions predisposing to pseudocyst formation.20 MRCP can easily detect pancreatic pseudocysts, their shape, number, and size, providing valuable information for the surgeon (Fig 6) Cholangiocarcinoma Cholangiocarcinoma arises from the bile duct epithelium and may occur anywhere along the intrahepatic or extrahepatic bile ducts, from the liver to the ampulla of vater MRCP plays an important role in the assessment of perihilar cholangiocarcinoma and in many institutions it has replaced ERCP and percutaneous transhepatic cholangiography for the preoperative staging of the tumor.17 In cholangiocarcinoma cases, MRCP can accurately depict the presence and level of obstruction17 and has been shown to be more effective than ERCP in delineating the anatomic extent of the cancerous infiltration18 (Fig 5) Romagnuolo and coworkers19 performed a literature search to estimate the overall sensitivity and specificity of MRCP in suspected biliary obstruction They concluded that MRCP seems to be highly accurate for diagnosing the presence of obstruction, but it is less accurate at differentiating malignant from benign causes of obstruction The combination of parenchymal and vascular information obtained from the T1-weighted, T2-weighted, and gad- Figure Coronal MIP image Klatskin tumor is visible, causing extensive dilation of the main and intrahepatic biliary ducts A Mesrur Halefoglu 286 Congenital Abnormalities Figure Coronal thin slab source image A large pseudocyst formation located at the head of the pancreas (arrow) seen in an acute pancreatitis patient Chronic Pancreatitis Chronic pancreatitis represents irreversible exocrine damage to the pancreas and irreversible morphologic changes in the pancreas and pancreatic duct These changes include dilation of the main pancreatic duct and its side branches and contour irregularities In severe pancreatitis, side branches have a “chain of lake” appearance Additional pancreatic ductal changes include stricture formation and intraductal calculi These calculi are seen as low-signal-intensity filling defects surrounded by high-signal-intensity pancreatic fluid (meniscus sign) Stones as small as mm can be detected by MRCP.5 In advanced chronic pancreatitis cases, the pancreatic duct dilation is more pronounced and can be accompanied by CBD dilation producing “double duct sign” as in the case of pancreatic head carcinoma (Fig 7) Sica and coworkers21 compared MRCP with ERCP in 30 patients with chronic pancreatitis and in with acute pancreatitis MRCP sensitivity was found to be 91% They concluded that in patients with pancreatitis, MRCP provides diagnostic information similar to that with ERCP and thus could be used similarly to guide patient treatment MRCP is also helpful in all patients with technically failed ERCP examinations In another study performed by Soto and coworkers,22 they found the sensitivity of MRCP for ductal dilation as 87-100%, for ductal narrowing as 75%, and for ductal calculi as 100% They concluded that MRCP can accurately demonstrate pancreatic duct abnormalities in chronic pancreatitis MRCP can be used to demonstrate a variety of congenital anomalies of the pancreatico-biliary tract MRCP has been shown to be 98% accurate in diagnosis of aberrant hepatic ducts and 95% accurate in diagnosis of cystic duct variants.23 A potential use of MRCP is in the evaluation of bile duct anatomy before cholecystectomy By demonstrating aberrant anatomy before surgery, the risk of bile duct injury can be reduced Anatomic variants with a high potential for injury include an aberrant right hepatic duct with insertion into the common hepatic duct, or a cystic duct inserting medially on the CBD.24 Pancreas divisium is the most common pancreatic congenital anomaly and results from failure of fusion of the dorsal and ventral pancreatic ducts Its prevalence is around 10% The larger dorsal duct drains the tail, body, and superior part of the head of the pancreas and passes anterior to the distal CBD to end at the minor papilla The smaller ventral duct drains the inferior head and uncinate process and joins with the CBD to exit via the major papilla (Fig 8) Although this variant may be detected incidentally in asymptomatic patients, pancreas divisium occurs more frequently in patients who present with acute idiopathic pancreatitis than in the general population.25 MRCP has a sensitivity of up to 100% in its detection.26 Annular pancreas is seen in of every 20,000 autopsies and is characterized by pancreatic tissue completely or incompletely surrounding the duodenum, most commonly the descending duodenum Definitive diagnosis relies on ERCP demonstration of the annular pancreatic duct MRCP now allows the diagnosis of this anomaly noninvasively.27 Figure Coronal MIP image Both CBD and pancreatic duct dilation leading to double duct sign are demonstrated in this chronic pancreatitis patient MR cholangiopancreatography Figure Coronal thick slab image A dorsal pancreatic duct (PD) passing anterior to the common bile duct (CBD) and draining into the minor papilla through the small duct of Santorini (SD) is demonstrated A smaller ventral pancreatic duct (VD) and CBD draining into the major papilla can also be seen Malignant Neoplasms The majority of pancreatic malignant tumors are ductal adenocarcinoma and between 60 and 70% of these adenocarcinomas are located in the head of the pancreas MRCP is useful in the evaluation of pancreatic adenocarcinoma and intra- 287 ductal papillary mucinous tumors The typical MRCP appearance of pancreatic head carcinoma is represented by sudden obstruction at the level of the head of the pancreas with a double duct sign, due to biliary and pancreatic duct dilation, and evidence of mass effect (Fig 9).This sign is highly suggestive but not specific to malignancy and occurs in 77% of cases.28 The morphology of the obstruction can be helpful in the differential diagnosis between pancreatitis and neoplastic lesion, although not pathognomonic In general, the obstruction secondary to pancreatic cancer presents with a “mouse tail” pattern or with sudden reduction of the caliber of the bile duct In the case of pancreatitis the biliary duct stenosis has a tapered aspect Regarding pancreatic duct, in neoplastic lesions it is usually homogenously dilated, whereas in chronic pancreatitis an irregular dilation with a beaded appearance can be seen Intraductal papillary mucinous tumors are slow-growing tumors and produce large amounts of mucin They originate from the main pancreatic duct or side branches epithelium These tumors are seen as cystic side branches dilation or grape-like lesions with a communicating channel with the main pancreatic duct (Fig 10) MRCP can be regarded superior to ERCP in the diagnosis, because mucin often impedes contrast filling of these ducts In ampullary carcinoma cases, together with the CBD obstruction, high-grade obstruction with abrupt termination accompanying dilation of the pancreatic duct is usually prominent29 (Fig 11) Postsurgical Biliary Tract Alterations MRCP plays a critical role in evaluating the surgically altered biliary tract ERCP is often difficult or impossible to perform Figure (A) Axial thin slab source image, dilation of the CBD, and pancreatic duct leading to a double duct sign due to pancreatic head carcinoma is seen (B) Coronal thick slab image A huge pancreatic head mass causing marked dilation of the CBD and pancreatic duct is demonstrated on the same patient A Mesrur Halefoglu 288 Figure 10 Coronal MIP image A cystic dilation communicating with a channel to main pancreatic duct representative of intraductal papillary mucinous tumor is seen in patients with biliary-enteric anastomoses, including choledochojejunostomy, hepaticojejunostomy, and Billroth type gastrectomy MRCP is now the technique of choice in this situation, with a sensitivity of 100% in demonstrating the biliary-enteric anastomoses.5 Pavone and coworkers30 used MRCP to examine 24 patients with biliary-enteric anastomoses and noted a sensitivity of 100% in detecting anastomotic strictures and of 90% in detecting biliary tract stones proximal to the anastomoses MRCP is also 100% sensitive in demonstrating the choledochojejunal anastomosis after a whipple procedure5 (Fig 12) Figure 12 Coronal thick slab image CBD is seen draining into the jejunum following choledochojejunostomy and remnant pancreatic duct is seen draining into the jejunum, after pancreaticojejunostomy in a patient who underwent whipple operation due to pancreatic head adenocarcinoma Pancreatic Trauma Traumatic injuries to the pancreatic duct may be related to penetrating or blunt trauma The pancreatic duct may also be injured during surgery, particularly splenectomy Barkin and coworkers31 reported a sensitivity and specificity of 100% for ERCP for the detection of pancreatic duct disruption In some instances, MRCP may show the duct disruption as well as associated fluid collections Houben and coworkers32 conducted a retrospective study including 15 children who had pancreatic trauma Both computed tomography (CT) and MRCP were performed MRCP was performed in seven children with four who were also subjected to ERCP for comparison MRCP correctly predicted the nature of the duct injury It was also useful in correctly predicting absence of duct injury in one patient whose CT findings were suggestive of a pancreatic duct injury The authors concluded that a minimally invasive approach avoiding the need for open surgery is possible but relies on accurate definition of the degree of pancreatic trauma using a combination of contrast-enhanced CT and MRCP imaging, predicting the need for ERCP Soto and coworkers33 in their series including seven trauma patients accurately demonstrated the status of pancreatic duct and the site of duct injury in all patients by MRCP Advantages and Limitations Figure 11 Coronal MIP image Both CBD and pancreatic duct dilation is seen in this patient who has peri-ampullary carcinoma The contraindications to MRCP are the presence of specific ferro-magnetic objects within the body, such as pacemakers or aneurysms clips Claustrophobia is the most common cause of unsuccessful examination MR cholangiopancreatography Reduced spatial resolution of MRCP in comparison with ERCP can cause difficulty in some situations With MRCP, it may be challenging to detect the early changes in sclerosing cholangitis, with a tendency to either overlook or, conversely, overestimate the length of short strictures Similarly, in the assessment of pancreatitis, more subtle side branch changes are sometimes not resolved by MRCP in comparison with ERCP The major advantage of MRCP is the lack of invasiveness The other advantages are operator independence, easily implementation of pulses sequences, and application for patients with altered anatomy where ERCP cannot be performed 289 12 13 14 15 16 17 Conclusion MRCP is a noninvasive important tool in the diagnosis of pancreatico-biliary diseases and a promising alternative to ERCP In many institutions, MRCP is replacing diagnostic ERCP as the modality of choice for pancreatico-biliary imaging However, it should be remembered that, unlike ERCP, MRCP does not allow the opportunity to simultaneously perform therapeutic intervention Knowledge of the advantages and disadvantages of each technique is needed to determine the appropriate workup of patients with pancreatico-biliary disease 18 19 20 21 22 References Ueno E, Takada Y, Yoshida I, et al: Pancreatic diseases: evaluation with MR cholangiopancreatography Pancreas 16:418-426, 1998 Halefoglu AM: Magnetic resonance cholangiopancreatography: a useful tool in the evaluation of pancreatic and biliary disorders World J Gastroenterol 13:2529-2534, 2007 Irie H, Hoda H, Tajima T, et al: Optimal MR cholangiopancreatographic sequence and its clinical application Radiology 206:379-387, 1998 Yamashita Y, Abe Y, Tang Y, et al: In vitro and clinical studies of image acquisition in breath-hold MR cholangiopancreatography: single-shot projection technique versus multislice technique AJR Am J Roentgenol 168:1449-1454, 1997 Fulcher AS, Turner MA, Capps GW, et al: Half-Fourier RARE MRCP in 300 objects Radiology 207:21-32, 1998 Vitellas KM, Keogan MT, Spritzer CE, et al: MR cholangiography of bile and pancreatic duct abnormalities with emphasis on the single-shot fast spin-echo technique Radiographics 20:939-957, 2000 Soto JA, Barish MA, Yucel EK, et al: Magnetic resonance cholangiography: comparison to endoscopic retrograde cholangiopancreatography Gastroenterology 110:589-597, 1996 Fulcher AS, Turner MA: MR pancreatography: a useful tool for evaluating pancreatic disorders Radiographics 19:5-24, 1999 Becker CD, Grossholz M, Becker M, et al: Choledocholithiasis and bile duct stenosis: diagnostic accuracy of MR cholangiopancreatography Radiology 205:523-530, 1997 10 Shanmugam V, Beattie GC, Yule SR, et al: Is magnetic resonance cholangiopancreatography the new gold standard in biliary imaging ? Br J Radiol 78:888-893, 2005 11 Griffin N, Wastle ML, Dunn WK: Magnetic resonance cholangiopancreatography versus endoscopic retrograde cholangiopancreatography 23 24 25 26 27 28 29 30 31 32 33 in the diagnosis of choledocholithiasis Eur J Gastroenterol Hepatol 15:809-813, 2003 Barish MA, Yucel EK, Ferrucci JT: Magnetic resonance cholangiopancreatography N Engl J Med 341:258-264, 1999 Schwartz LH, Coakley FV, Sun Y, et al: Neoplastic pancreaticobiliary duct obstruction: evaluation with breath-hold MR cholangiopancreatography AJR Am J Roentgenol 170:1491-1495, 1998 Ernst O, Asselah T, Talbodec N, et al: MR cholangiopancreatography: a promising new tool for diagnosing primary sclerosing cholangitis AJR Am J Roentgenol 168:1115-1116, 1997 Ernst O, Asselah T, Sergent G, et al: MR cholangiography in primary sclerosing cholangitis AJR Am J Roentgenol 171:1027-1030, 1998 Moff SL, Kamel IR, Eustace J, et al: Diagnosis of primary sclerosing cholangitis: a blinded comparative study using magnetic resonance cholangiography and endoscopic retrograde cholangiography Gastrointest Endosc 64:219-223, 2006 Lee SS, Kim MH, Lee SK, et al: MR cholangiography versus cholangioscopy for evaluation of longitudinal extension of hilar cholangiocarcinoma Gastrointest Endosc 56:25-32, 2002 Yeh TS, Jan YY, Tseng JH, et al: Malignant perihilar biliary obstruction: magnetic resonance cholangiopancreatographic findings Am J Gastroenterol 95:432-440, 2000 Romagnuolo J, Bardou M, Rahme E, et al: Magnetic resonance cholangiopancreatography: a meta-analysis of test performance in suspected biliary disease Ann Intern Med 139:547-557, 2003 Takehara Y: MR pancreatography Semin Ultrasound CT MR 20:324339, 1999 Sica GT, Braver J, Cooney MJ, et al: Comparison of endoscopic retrograde cholangiopancreatography with MR cholangiopancreatography in patients with pancreatitis Radiology 210:605-610, 1999 Soto JA, Barish MA, Yucel EK, et al: Pancreatic duct: MR cholangiopancreatography with a three dimensional fast spin-echo technique Radiology 196:459-464, 1995 Taourel P, Bret PM, Reinhold C, et al: Anatomic variants of the biliary tree: diagnosis with MR cholangiopancreatography Radiology 199: 521-527, 1996 Martin RF, Rossi RL: Bile duct injuries: spectrum, mechanisms of injury, and their prevention Surg Clin North Am 74:781-803, 1994 Bernard JP, Sahel J, Giovanni M, et al: Pancreas divisium is a probable cause of acute pancreatitis: a report of 137 cases Pancreas 5:248-254, 1990 Bret PM, Reinhold C, Taorel P, et al: Pancreas divisium: evaluation with MR cholangiopancreatography Radiology 199:99-103, 1996 Hidaka T, Hirohashi S, Uchida H, et al: Annular pancreas diagnosed by single-shot MR cholangiopancreatography Magn Reson Imaging 16: 441-444, 1998 Barish M, Soto J, Ferrucci J: Magnetic resonance pancreatography Endoscopy 29:487-495, 1997 Semelka R, Kelekis N, John G, et al: Ampullary carcinoma: demonstration by current MR techniques J Magn Reson Med 7:153-156, 1997 Pavone P, Laghi A, Catalano C, et al: MR cholangiography in the examination of patients with biliary-enteric anastomoses AJR Am J Roentgenol 169:807-811, 1997 Barkin JS, Ferstenberg RM, Panullo W, et al: Endoscopic retrograde cholangiopancreatography in pancreatic trauma Gastrointest Endosc 34:102-105, 1988 Houben CH, Ade-Ajayi N, Patel S, et al: Traumatic pancreatic duct injury in children: minimally invasive approach to management J Pediatr Surg 42:629-635, 2007 Soto JA, Alvarez O, Munera F, et al: Traumatic disruption of the pancreatic duct: diagnosis with MR pancreatography AJR Am J Roentgenol 176:175-178, 2001 ... biliary obstruction: magnetic resonance cholangiopancreatographic findings Am J Gastroenterol 95:432-440, 2000 Romagnuolo J, Bardou M, Rahme E, et al: Magnetic resonance cholangiopancreatography: ... stenosis: diagnostic accuracy of MR cholangiopancreatography Radiology 205:523-530, 1997 10 Shanmugam V, Beattie GC, Yule SR, et al: Is magnetic resonance cholangiopancreatography the new gold... J Radiol 78:888-893, 2005 11 Griffin N, Wastle ML, Dunn WK: Magnetic resonance cholangiopancreatography versus endoscopic retrograde cholangiopancreatography 23 24 25 26 27 28 29 30 31 32 33 in