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BIBTEX RIS

Magnetic Resonance Cholangiopancreatography: Current Use and Future Applications

2008; Elsevier BV; Volume: 6; Issue: 9 Linguagem: Inglês

10.1016/j.cgh.2008.05.017

ISSN

1542-7714

Autores

V. Anik Sahni, Koenraad J. Mortelé,

Tópico(s)

Pancreatic and Hepatic Oncology Research

Resumo

Magnetic resonance pancreatography (MRCP) is now established as a robust noninvasive tool for the evaluation of biliary and pancreatic pathology. Its diagnostic performance is comparable with endoscopic retrograde cholangiopancreatography without the associated risks. This article aims to familiarize the reader with the technique, clinical indications, and limitations of the investigation. Common pitfalls in interpretation also are addressed. Emerging applications and techniques are discussed that include recent advances in technology and the development of functional imaging. Magnetic resonance pancreatography (MRCP) is now established as a robust noninvasive tool for the evaluation of biliary and pancreatic pathology. Its diagnostic performance is comparable with endoscopic retrograde cholangiopancreatography without the associated risks. This article aims to familiarize the reader with the technique, clinical indications, and limitations of the investigation. Common pitfalls in interpretation also are addressed. Emerging applications and techniques are discussed that include recent advances in technology and the development of functional imaging. Magnetic resonance cholangiopancreatography (MRCP) is a noninvasive diagnostic technique that was developed for the visualization of the biliary and pancreatic ducts. Its use was first reported in 1991,1Wallner B.K. Schumacher K.A. Weidenmaier W. et al.Dilated biliary tract: evaluation with MR cholangiography with a T2-weighted contrast-enhanced fast sequence.Radiology. 1991; 181: 805-808Crossref PubMed Scopus (371) Google Scholar and since then the method has evolved along with the advances in magnetic resonance imaging (MRI) hardware and imaging sequences. MRCP does not expose the patient to the risks associated with endoscopic retrograde cholangiopancreatography (ERCP) or percutaneous cholangiography. These can occur in up to 5% of ERCP procedures.2Masci E. Toti G. Mariani A. et al.Complications of diagnostic and therapeutic ERCP: a prospective multicenter study.Am J Gastroenterol. 2001; 96: 417-423Crossref PubMed Google Scholar In addition, there is no use of ionizing radiation or iodinated contrast. It has, therefore, become the investigation of choice for many conditions when evaluating pancreaticobiliary ductal disease. Invasive cholangiography remains the investigation of choice when intervention is required. This review aims to familiarize the reader with current techniques, indications, limitations, pitfalls, and future applications of MRCP.TechniquePatient preparation initially involves excluding any condition that may preclude an MRI. Patients are required to fast for 4 to 6 hours before the examination, to permit gallbladder filling and promote gastric emptying. T2-negative oral contrast can be administered to reduce the signal from the overlapping stomach and duodenum.3Hirohashi S. Hirohashi R. Uchida et al.MR cholangiopancreatography and MR urography: improved enhancement with a negative oral contrast agent.Radiology. 1997; 203: 281-285PubMed Google Scholar Pineapple juice has been used successfully as a negative oral contrast agent because of its high manganese content.4Riordan R.D. Khonsari M. Jeffries J. et al.Pineapple juice as negative oral contrast in magnetic resonance cholangiopancreatography: a preliminary evaluation.Br J Radiol. 2004; 77: 991-999Crossref PubMed Scopus (79) Google Scholar, 5Coppens E. Metens T. Winant C. et al.Pineapple juice labeled with gadolinium: a convenient oral contrast for magnetic resonance cholangiopancreatography.Eur Radiol. 2005; 15: 2122-2129Crossref PubMed Scopus (33) Google Scholar It is widely available and cheaper than commercially produced superparamagnetic preparations. No intravenous contrast or antispasmodics are administered routinely.MRCP ideally is performed on a high field system with high performance gradients and a phased-array torso coil.6MacEneaney P. Mitchell M.T. McDermott R. Update on magnetic resonance cholangiopancreatography.Gastroenterol Clin North Am. 2002; 31: 731-746Abstract Full Text Full Text PDF PubMed Scopus (13) Google Scholar MRCP uses heavily T2-weighted sequences to return high signal from slow moving fluid in the biliary and pancreatic ducts, which have long T2 relaxation times.7Vitellas K.M. Keogan M.T. Spritzer C.E. et al.MR cholangiopancreatography of bile and pancreatic duct abnormalities with emphasis on the single-shot fast spin-echo technique.Radiographics. 2000; 20: 939-957Crossref PubMed Scopus (144) Google Scholar Signal from background tissue is suppressed because of its shorter T2 relaxation time. This maximizes duct visibility and contrast. Ultra-fast T2-weighted imaging is optimally performed by using single-shot fast spin echo sequences.8Irie H. Honda H. Tajima T. et al.Optimal MR cholangiopancreaticographic sequence and its clinical application.Radiology. 1998; 206: 379-387PubMed Google Scholar These sequences can be performed in a breath-hold and, therefore, reduce breathing and motion artifact.9Miyazaki T. Yamashita Y. Tsuchigame T. et al.MR cholangiopancreatography using HASTE (half-Fourier acquisition single-shot turbo spin-echo) sequences.AJR Am J Roentgenol. 1996; 166: 1297-1303Crossref PubMed Scopus (260) Google Scholar The data obtained can be displayed in a variety of formats that usually involve the axial, coronal, and oblique coronal planes. The coronal images can be viewed as either thin collimation (3–5 mm) source images or thick slabs (30–50 mm) (Figure 1A). In addition, the thin collimation images can be manipulated to produce maximum intensity projection 3-dimensional reconstructions (Figure 1B). Both the thick slab and the maximum intensity projections produce cholangiogram-like projectional images. These, however, have inferior spatial resolution compared with the thin collimation images and can miss abnormalities such as stones.10Yamashita 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. 1997; 168: 1449-1454Crossref PubMed Scopus (107) Google Scholar The thin collimation images should always be reviewed to avoid missing pathology. By optimizing techniques, ducts with diameters of less than 1 mm can be visualized.11Fayad L.M. Kowalski T. Mitchell D.G. MR cholangiopancreatography: evaluation of common pancreatic disease.Radiol Clin North Am. 2003; 41: 97-114Abstract Full Text Full Text PDF PubMed Scopus (28) Google ScholarA relatively recent adjunct to routine MRCP has been functional imaging. This involves dynamic pancreatography after intravenous (IV) stimulation by human or porcine secretin12Matos C. Metens T. Deviere J. et al.Pancreatic duct: morphological and functional evaluation with dynamic MR pancreatography after secretin stimulation.Radiology. 1997; 203: 435-441PubMed Google Scholar (Figure 2). Secretin leads to stimulation of the exocrine pancreatic gland. In addition, it temporarily increases the tone of the sphincter of Oddi during the first 5 to 6 minutes after injection, thereby inhibiting release of fluid through the papilla of Vater. After this the tone decreases.13Geenen J.E. Hogan W.J. Dodds W.J. et al.Intraluminal pressure recording from the human sphincter of Oddi.Gastroenterology. 1980; 78: 317-324PubMed Google Scholar Secretin, therefore, initially improves delineation of the pancreatic duct, facilitating the demonstration of anatomic variants or morphologic changes in the normal or diseased pancreas.14Lee N.J. Kim K.W. Kim T.K. et al.Secretin-stimulated MRCP.Abdom Imaging. 2006; 31: 575-581Crossref PubMed Scopus (20) Google Scholar The exocrine function of the pancreas also can be evaluated, by qualitatively or semiquantitatively assessing the increase in fluid in the duodenum after the sphincter of Oddi relaxes.15Cappeliez O. Delhaye M. Deviere J. et al.Chronic pancreatitis: evaluation of pancreatic exocrine function with MR pancreatography after secretin stimulation.Radiology. 2000; 215: 358-364Crossref PubMed Scopus (173) Google Scholar T2-weighted single-shot fast spin echo images are obtained every 30 seconds after IV secretin stimulation (0.2 mcg/kg of body weight) for at least 10 minutes.Figure 2Oblique coronal, thick slab MRCP images (A) before, (B) 5 minutes after, and (C) 10 minutes after intravenous injection of secretin. (B) Normal early mild dilatation of the pancreatic duct (black arrow) with (C) return to baseline shows normal pancreatic duct compliance. (A–C) Progressive filling of the duodenum (white arrows) shows normal exocrine pancreatic function.View Large Image Figure ViewerDownload Hi-res image Download (PPT)MRCP often is combined with conventional abdominal MRI to provide extraductal and parenchymal evaluation. MR angiography also can be performed in the same session if indicated. This has been referred to as the all-in-one technique or the one-stop-shopping technique.Classic IndicationsDelineation of AnatomyThe diagnosis of congenital and developmental biliary and pancreatic anomalies is an important indication for MRCP. Liver resection, living related donor transplantation, biliary intervention, and laparoscopic cholecystectomy are several procedures in which the prospective identification of congenital biliary variants may prevent inadvertent injury. Normal biliary anatomy is present only in 58% of the population14Lee N.J. Kim K.W. Kim T.K. et al.Secretin-stimulated MRCP.Abdom Imaging. 2006; 31: 575-581Crossref PubMed Scopus (20) Google Scholar; the most common anomaly is drainage of the right posterior duct into the left hepatic duct in 13% to 19% of the population.16Puente S.G. Bannura G.C. Radiological anatomy of the biliary tract: variations and congenital abnormalities.World J Surg. 1983; 7: 271-276Crossref PubMed Scopus (150) Google Scholar, 17Gazelle G.S. Lee M.J. Mueller P.R. Cholangiographic segmental anatomy of the liver.Radiographics. 1994; 14: 1005-1013Crossref PubMed Scopus (60) Google Scholar, 18Mortele K.J. Ros P.R. Anatomic variants of the biliary tree: MR cholangiographic findings and clinical applications.AJR Am J Roentgenol. 2001; 177: 389-394Crossref PubMed Scopus (107) Google Scholar The right posterior duct drains into the right anterior duct in 12%17Gazelle G.S. Lee M.J. Mueller P.R. Cholangiographic segmental anatomy of the liver.Radiographics. 1994; 14: 1005-1013Crossref PubMed Scopus (60) Google Scholar and there is a triple confluence of the right anterior, right posterior, and left hepatic ducts in 11%16Puente S.G. Bannura G.C. Radiological anatomy of the biliary tract: variations and congenital abnormalities.World J Surg. 1983; 7: 271-276Crossref PubMed Scopus (150) Google Scholar (Figure 3). Common cystic duct anomalies include low or medial insertion into the common hepatic duct and a long parallel course with the common hepatic duct.19Mortele K.J. Rocha T.C. Streeter J.L. et al.Multimodality imaging of pancreatic and biliary congenital anomalies.Radiographics. 2006; 26: 715-731Crossref PubMed Scopus (202) Google Scholar Identification of these variants is important before laparoscopic cholecystectomy, in which the risk of duct injury is twice that of open cholecystectomy.20Deziel D.J. Millikan K.W. Economou S.G. et al.Complications of laparoscopic cholecystectomy: a national survey of 4,292 hospitals and an analysis of 77,604 cases.Am J Surg. 1993; 165: 9-14Abstract Full Text PDF PubMed Scopus (1132) Google Scholar MRCP is 98% accurate in the diagnosis of aberrant hepatic ducts and 95% accurate in the diagnosis of cystic duct variants.21Taourel P. Bret P.M. Reinhold C. et al.Anatomic variants of the biliary tree: diagnosis with MR cholangiopancreatography.Radiology. 1996; 199: 521-527PubMed Google ScholarFigure 3Oblique coronal, thick slab MRCP image shows triple confluence of the right anterior, right posterior, and left hepatic ducts (arrow).View Large Image Figure ViewerDownload Hi-res image Download (PPT)There is also variability in the pancreatic ductal anatomy. In 91% of individuals, the duct of Wirsung is the major drainage route of the pancreas through the major papilla. A patent duct of Santorini drains through the minor papilla in 44% of the population.7Vitellas K.M. Keogan M.T. Spritzer C.E. et al.MR cholangiopancreatography of bile and pancreatic duct abnormalities with emphasis on the single-shot fast spin-echo technique.Radiographics. 2000; 20: 939-957Crossref PubMed Scopus (144) Google Scholar Pancreas divisum and annular pancreas are important conditions to diagnose. Pancreas divisum occurs in 4% to 10% of the population.22Agha F.P. Williams K.D. Pancreas divisum: incidence, detection and clinical significance.Am J Gastroenterol. 1987; 82: 315-320PubMed Google Scholar The ventral and dorsal pancreatic ducts fail to fuse, with the majority of the pancreatic secretions emptying through the duct of Santorini and the minor papilla. The clinical importance of pancreas divisum is its possible association with recurrent pancreatitis.23Cotton P.B. Congenital anomaly of pancreas divisum as cause of obstructive pain and pancreatitis.Gut. 1980; 21: 105-114Crossref PubMed Scopus (392) Google Scholar, 24Mortele K.J. Wiesner W. Zou K.H. et al.Asymptomatic nonspecific serum hyperamylasemia and hyperlipasemia: spectrum of MRCP findings and clinical implications.Abdom Imaging. 2004; 29: 109-114Crossref PubMed Scopus (9) Google Scholar MRCP diagnosis is made by visualizing 2 separate ducts with independent drainage sites. The dominant dorsal duct lies anterior to the common duct and enters into the minor papilla (Figure 4). MRCP has been shown to be 100% accurate in diagnosing pancreas divisum.25Bret P.M. Reinhold C. Taourel P. et al.Pancreas divisum: evaluation with MR cholangiopancreatography.Radiology. 1996; 199: 99-103Crossref PubMed Scopus (268) Google Scholar Annular pancreas, characterized by pancreatic tissue encircling the second part of the duodenum, also can be diagnosed by MRCP26Hidaka T. Hirohashi S. Uchida H. et al.Annular pancreas diagnosed by single-shot MR cholangiopancreatography.Magn Reson Imaging. 1998; 16: 441-444Abstract Full Text Full Text PDF PubMed Scopus (15) Google Scholar (Figure 5).Figure 4Oblique coronal, thick slab MRCP image shows pancreas divisum. The dorsal duct (short solid white arrow) crosses anterior to the common bile duct (open arrow) to empty into the minor papilla. An incidental intraductal papillary mucinous neoplasm is seen to arise from the ventral duct (long solid white arrow).View Large Image Figure ViewerDownload Hi-res image Download (PPT)Figure 5Annular pancreas. (A) Oblique coronal, thick slab MRCP image shows a pancreatic duct (solid white arrow) that encircles the second part of the duodenum (open arrow). (B) Axial T1-weighted, unenhanced, 3-dimensional spoiled gradient-echo fat-suppressed MR image shows pancreatic parenchyma (arrow) encircling the duodenum.View Large Image Figure ViewerDownload Hi-res image Download (PPT)CholedocholithiasisStones within the common duct are identified as low-signal filling defects within high-signal intensity bile on MRCP examinations (Figure 6). Stones as small as 2 mm have been identified, even in nondilated ducts.27Bret P.M. Reinhold C. Magnetic resonance cholangiopancreatography.Endoscopy. 1997; 29: 472-486Crossref PubMed Scopus (79) Google Scholar, 28Fulcher A.S. Turner M.A. Capps G.W. et al.Half-Fourier RARE MR cholangiopancreatography: experience in 300 subjects.Radiology. 1998; 207: 21-32PubMed Google Scholar The performance of MRCP for common duct stones is superior to ultrasound and computerized tomography (CT),29Fulcher A.S. Turner M.A. MR cholangiopancreatography.Radiol Clin North Am. 2002; 40: 1363-1376Abstract Full Text Full Text PDF PubMed Scopus (45) Google Scholar and comparable with ERCP.30Fulcher A.S. MRCP and ERCP in the diagnosis of common bile duct stones.Gastrointest Endosc. 2002; 56: S178-S182Abstract Full Text Full Text PDF PubMed Google Scholar Studies have yielded sensitivities ranging from 81% to 100%, and specificities ranging from 96% to 100%.28Fulcher A.S. Turner M.A. Capps G.W. et al.Half-Fourier RARE MR cholangiopancreatography: experience in 300 subjects.Radiology. 1998; 207: 21-32PubMed Google Scholar, 31Soto J.A. Barish M.A. Alvarez O. et al.Detection of choledocholithiasis with MR cholangiography: comparison of three-dimensional fast spin-echo and single- and multisection half-Fourier rapid acquisition with relaxation enhancement sequences.Radiology. 2000; 215: 737-745Crossref PubMed Scopus (110) Google Scholar, 32Reinhold C. Taourel P. Bret P.M. et al.Choledocholithiasis: evaluation of MR cholangiography for diagnosis.Radiology. 1998; 209: 435-442PubMed Google Scholar, 33Becker C.D. Grossholz M. Becker M. et al.Choledocholithiasis and bile duct stenosis: diagnostic accuracy of MR cholangiopancreatography.Radiology. 1997; 205: 523-530Crossref PubMed Scopus (189) Google Scholar, 34Demartines N. Eisner L. Schnabel K. et al.Evaluation of magnetic resonance cholangiography in the management of bile duct stones.Arch Surg. 2000; 135: 148-152Crossref PubMed Scopus (97) Google Scholar, 35Guibaud L. Bret P.M. Reinhold C. et al.Bile duct obstruction and choledocholithiasis: diagnosis and MR cholangiography.Radiology. 1995; 197: 109-115PubMed Google Scholar Negative predictive values are also very high (94%–100%28Fulcher A.S. Turner M.A. Capps G.W. et al.Half-Fourier RARE MR cholangiopancreatography: experience in 300 subjects.Radiology. 1998; 207: 21-32PubMed Google Scholar, 31Soto J.A. Barish M.A. Alvarez O. et al.Detection of choledocholithiasis with MR cholangiography: comparison of three-dimensional fast spin-echo and single- and multisection half-Fourier rapid acquisition with relaxation enhancement sequences.Radiology. 2000; 215: 737-745Crossref PubMed Scopus (110) Google Scholar, 32Reinhold C. Taourel P. Bret P.M. et al.Choledocholithiasis: evaluation of MR cholangiography for diagnosis.Radiology. 1998; 209: 435-442PubMed Google Scholar, 33Becker C.D. Grossholz M. Becker M. et al.Choledocholithiasis and bile duct stenosis: diagnostic accuracy of MR cholangiopancreatography.Radiology. 1997; 205: 523-530Crossref PubMed Scopus (189) Google Scholar, 34Demartines N. Eisner L. Schnabel K. et al.Evaluation of magnetic resonance cholangiography in the management of bile duct stones.Arch Surg. 2000; 135: 148-152Crossref PubMed Scopus (97) Google Scholar, 35Guibaud L. Bret P.M. Reinhold C. et al.Bile duct obstruction and choledocholithiasis: diagnosis and MR cholangiography.Radiology. 1995; 197: 109-115PubMed Google Scholar); MRCP is, therefore, a good test in patients with a low to intermediate probability of having choledocholithiasis, to exclude stones and prevent these patients from being subjected to an unnecessary ERCP procedure and its associated complications.Figure 6Oblique coronal, thick slab MRCP image shows an impacted low-signal stone in the distal common duct (*) with intrahepatic (arrows) and extrahepatic biliary dilatation.View Large Image Figure ViewerDownload Hi-res image Download (PPT)NeoplasmsMalignant disease of the biliary system and the pancreas frequently results in ductal obstruction. MRCP has been shown to be accurate in identifying the presence, cause, and level of obstruction.35Guibaud L. Bret P.M. Reinhold C. et al.Bile duct obstruction and choledocholithiasis: diagnosis and MR cholangiography.Radiology. 1995; 197: 109-115PubMed Google Scholar, 36Schwartz L.H. Coakley F.V. Sun Y. et al.Neoplastic pancreaticobiliary duct obstruction: evaluation with breath-hold MR cholangiopancreatography.AJR Am J Roentgenol. 1998; 170: 1491-1495Crossref PubMed Scopus (101) Google Scholar, 37Arslan A. Geitung J.T. Viktil E. et al.Pancreaticobiliary diseases Comparison of 2D single-shot turbo spin-echo MR cholangiopancreatography with endoscopic retrograde cholangiopancreatography.Acta Radiol. 2000; 41: 621-626Crossref PubMed Scopus (27) Google Scholar, 38Mortele K.J. Wiesner W. Cantisani V. et al.Usual and unusual causes of extrahepatic cholestasis: assessment with magnetic resonance cholangiography and fast MRI.Abdom Imaging. 2004; 29: 87-99Crossref PubMed Scopus (24) Google Scholar Cholangiocarcinoma, pancreatic ductal adenocarcinoma, liver parenchymal tumors, ampullary neoplasms, and duodenal adenocarcinoma all can cause ductal obstruction.39Mortele K.J. Ji H. Ros P.R. CT and magnetic resonance imaging in pancreatic and biliary tract malignancies.Gastrointest Endosc. 2002; 56: S206-S212Abstract Full Text Full Text PDF PubMed Google Scholar MRCP, compared with contrast cholangiography, can visualize the duct before and after an obstructing lesion, thereby providing a roadmap for any future intervention. Also, the examination is noninvasive so there is no risk of cholangitis and the procedure can be combined with routine abdominal MRI to stage the tumor at the same time.6MacEneaney P. Mitchell M.T. McDermott R. Update on magnetic resonance cholangiopancreatography.Gastroenterol Clin North Am. 2002; 31: 731-746Abstract Full Text Full Text PDF PubMed Scopus (13) Google ScholarMRCP findings of cholangiocarcinoma include an abrupt biliary obstruction with dilatation of the ducts above (Figure 7). MRCP plays an important role in staging hilar (Klatskin) tumors.40Klatskin G. Adenocarcinoma of the hepatic duct at its bifurcation within the porta hepatis An unusual tumor with distinctive clinical and pathological features.Am J Med. 1965; 38: 241-256Abstract Full Text PDF PubMed Scopus (688) Google Scholar The investigation is important in determining resectable disease and providing guidance for palliative biliary intervention.41Manfredi R. Masselli G. Maresca G. et al.MR imaging and MRCP of hilar cholangiocarcinoma.Abdom Imaging. 2003; 28: 319-325Crossref PubMed Scopus (70) Google Scholar The disease has a 5-year survival rate of 1%,42Alexander F. Rossi R.L. O'Bryan M. et al.Biliary carcinoma A review of 109 cases.Am J Surg. 1984; 147: 503-509Abstract Full Text PDF PubMed Scopus (115) Google Scholar but by using diagnostic imaging to select appropriate surgical candidates a 5-year survival rate of 20% can be achieved.43Lygidakis N.J. van der Heyde M.N. Houthoff H.J. Surgical approaches to the management of primary biliary cholangiocarcinoma of the porta hepatis: the decision-making dilemma.Hepatogastroenterology. 1988; 35: 261-267PubMed Google Scholar, 44Nesbit G.M. Johnson C.D. James E.M. et al.Cholangiocarcinoma: diagnosis and evaluation of resectability by CT and sonography as procedures complementary to cholangiography.AJR Am J Roentgenol. 1988; 151: 933-938Crossref PubMed Scopus (132) Google Scholar Tumors are staged according to the Bismuth-Corlette45Bismuth H. Nakache R. Diamond T. Management strategies in resection for hilar cholangiocarcinoma.Ann Surg. 1992; 215: 31-38Crossref PubMed Scopus (705) Google Scholar classification, with MRCP showing an accuracy of 84%.46Manfredi R. Brizi M.G. Masselli G. et al.Malignant biliary hilar stenosis: MR cholangiography compared with direct cholangiography.Radiol Med. 2001; 102: 48-54Google Scholar In combination with conventional MRI, biliary, vascular, and liver involvement can be assessed to determine resectability.41Manfredi R. Masselli G. Maresca G. et al.MR imaging and MRCP of hilar cholangiocarcinoma.Abdom Imaging. 2003; 28: 319-325Crossref PubMed Scopus (70) Google ScholarFigure 7Klatskin tumor. (A) Oblique coronal, thick slab MRCP image shows an obstructing tumor (*) with intrahepatic left and right lobe biliary dilatation (arrows). (B) Contrast-enhanced late portal venous axial T1-weighted 3-dimensional spoiled gradient-echo fat-suppressed MR image shows an ill-defined enhancing mass at the liver hilum (white arrows). Dilated biliary ducts are present (black arrows).View Large Image Figure ViewerDownload Hi-res image Download (PPT)MRCP depicts obstruction and encasement of the pancreatic duct by pancreatic ductal adenocarcinoma. Smooth homogenous dilatation of the duct with an abrupt termination favors malignancy.47Pavone P. Laghi A. Catalona C. et al.MRI of the biliary and pancreatic ducts.Eur Radiol. 1999; 9: 1513-1522Crossref PubMed Scopus (32) Google Scholar If the lesion is in the head then biliary obstruction can occur; this results in the "double duct sign" in 77%,48Freeny P.C. Marks W.M. Ryan J.A. et al.Pancreatic ductal adenocarcinoma: diagnosis and staging with dynamic CT.Radiology. 1988; 166: 125-133PubMed Google Scholar which is highly suggestive of malignancy49Freeny P.C. Bilbao M.K. Katon R.M. "Blind" evaluation of endoscopic retrograde cholangiopancreatography (ERCP) in the diagnosis of pancreatic carcinoma: the "double duct" and other signs.Radiology. 1976; 119: 271-274PubMed Google Scholar (Figure 8). MRCP alone has been shown to be more sensitive and specific than ERCP in detecting pancreatic carcinoma.50Adamek H.E. Albert J. Breer J. et al.Pancreatic carcinoma detection with magnetic resonance cholangiopancreatography and endoscopic retrograde cholangiopancreatography: a prospective controlled study.Lancet. 2000; 356: 190-193Abstract Full Text Full Text PDF PubMed Scopus (227) Google Scholar Combining MRCP with conventional MRI and MR angiography has been reported to be superior in staging and determining resectability than the combination of ultrasound, CT, and conventional angiography.51Trede M. Rumstadt B. Wendi K. et al.Ultrafast magnetic resonance imaging improves the staging of pancreatic tumors.Ann Surg. 1997; 226: 393-405Crossref PubMed Scopus (173) Google ScholarFigure 8Pancreatic adenocarcinoma. (A) Contrast-enhanced axial T1-weighted 3-dimensional spoiled gradient-echo fat-suppressed MR image shows a hypointense mass in the head of the pancreas (arrow). Oblique coronal, thick slab (B) MRCP image and (C) ERCP image show dilatation of the common duct (open arrow) and the pancreatic duct (solid white arrow) by a pancreatic adenocarcinoma (* in B).View Large Image Figure ViewerDownload Hi-res image Download (PPT)Intraductal papillary mucinous neoplasm (IPMN) is a mucin-producing tumor of the pancreas and is thought to originate in the main pancreatic duct or its branches52Itai Y. Ohhashi K. Negai H. et al."Ductectatic" mucinous cystadenoma and cystadenocarcinoma of the pancreas.Radiology. 1986; 161: 697-700PubMed Google Scholar (Figure 9). It has either hyperplastic, dysplastic, or malignant epithelium.11Fayad L.M. Kowalski T. Mitchell D.G. MR cholangiopancreatography: evaluation of common pancreatic disease.Radiol Clin North Am. 2003; 41: 97-114Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar Multiple IPMNs may be present in 23% of patients.53Megibow A.J. Lombardo F.P. Guarise A. et al.Cystic pancreatic masses: cross-sectional imaging observations and serial follow-up.Abdom Imaging. 2001; 26: 640-647Crossref PubMed Scopus (85) Google Scholar On MRCP, segmental or diffuse dilatation of the main pancreatic duct or a unilocular or multilocular cystic lesion is typical.54Sidden C.R. Mortele K.J. Cystic tumors of the pancreas: ultrasound, computed tomography, and magnetic resonance imaging features.Semin Ultrasound CT MR. 2007; 28: 339-356Abstract Full Text Full Text PDF PubMed Scopus (37) Google Scholar Communication between the main pancreatic duct and the cystic lesion may be depicted. Papillary projections may be present. Bulging of the papilla, biliary obstruction, and large caliber of the main pancreatic duct (>1 cm) are more common in patients with malignant IPMNs.55Adamek H.E. Weitz M. Breer H. et al.Value of magnetic-resonance cholangio-pancreatography (MRCP) after unsuccessful endoscopic-retrograde cholangio-pancreatography (ERCP).Endoscopy. 1997; 29: 741-744Crossref PubMed Scopus (55) Google Scholar MRCP is considered superior to ERCP in diagnosing IPMN,56Fukukura Y. Fujiyoshi F. Sasaki M. et al.HASTE MR cholangiopancreatography in the evaluation of papillary-mucinous tumors of the pancreas.J Comput Assist Tomogr. 1999; 23: 301-305Crossref PubMed Scopus (53) Google Scholar and ERCP on occasion may not be possible because the thick mucin restricts complete opacification of the ductal system. The use of IV secretin stimulation is thought to be useful in depicting the communication of branch duct IPMNs with the main pancreatic duct.57Carbognin G. Pinali L. Girardi V. et al.Collateral branches IPMTs: secretin-enhanced MRCP.Abdom Imaging. 2007; 32: 374-380Crossref PubMed Scopus (35) Google Scholar MRCP, however, cannot differentiate fluid from mucin and sampling with ERCP may be required.Figure 9(A) Oblique coronal, thick slab MRCP image shows a cystic pleomorphic pancreatic head mass (arrow) connected to the main pancreatic duc

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