(Radiographics. 1999;19:25-44.)
© RSNA, 1999
MR Cholangiography: Technical Advances and Clinical Applications
Ann S. Fulcher, MD1,
Mary Ann Turner, MD1 and
Gerald W. Capps, MD1
1 Department of Radiology, Medical College of Virginia, Virginia Commonwealth University, 401 N 12th St, Richmond, VA 23298-0615.
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Abstract
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Magnetic resonance (MR) cholangiography is a fast, accurate, noninvasive alternative to endoscopic retrograde cholangiography (ERC) in the evaluation of biliary tract disease. Technical improvements in imaging sequences (eg, half-Fourier rapid acquisition with relaxation enhancement) and use of phased-array coils allow high-quality imaging comparable to that available with ERC. In choledocholithiasis, common bile duct stones as small as 2 mm can be detected with MR cholangiography and appear as low-signal-intensity foci within the high-signal-intensity bile. MR cholangiography may help establish the diagnosis of malignant obstruction and is useful in the evaluation of patients in whom ERC was unsuccessful or incomplete. The role of MR cholangiography in the evaluation of intrahepatic duct disease continues to evolve. MR cholangiography plays a crucial role in evaluating postsurgical biliary tract alterations and can be used to demonstrate a variety of congenital anomalies of the biliary tract (eg, aberrant ducts, choledochal cysts, pancreas divisum). In addition, intentional or incidental imaging of the gallbladder with MR cholangiography can be used to identify calculi or help determine the presence and extent of neoplastic disease.
Index Terms: Bile duct radiography, 760.122, 774.122 • Bile duct radiography, technology, 760.122, 774.122 • Bile ducts, MR, 760.1214, 774.121419 • Magnetic resonance (MR), half-Fourier imaging • Pancreatic ducts, 774.121419
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INTRODUCTION
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Magnetic resonance (MR) cholangiography has emerged as an accurate, noninvasive alternative to diagnostic endoscopic retrograde cholangiography (ERC) in the evaluation of diseases of the biliary tract. MR cholangiography is performed with the use of heavily T2-weighted sequences that demonstrate the fluid-containing bile ducts as high-signal-intensity structures. The accuracy of MR cholangiography has been enhanced by increasing experience with the technique and by improvements in image quality made possible by technical modifications in sequences and the use of phased-array imaging coils.
The accuracy of MR cholangiography has been demonstrated in the evaluation of choledocholithiasis, malignant obstruction, variant biliary anatomy, and postsurgical alterations of the biliary tract (1–12). In this article, we discuss and illustrate the utility of MR cholangiography in these settings as well as in the evaluation of failed or incomplete ERC, intrahepatic duct disease, and gallbladder disease.
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MR CHOLANGIOGRAPHIC TECHNIQUE
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We performed MR cholangiography with a half-Fourier rapid acquisition with relaxation enhancement (RARE) sequence and a circularly polarized phased-array coil. Initially, 7-cm thick-slab coronal and axial images of the upper abdomen were obtained to localize the extrahepatic bile duct. Next, images were acquired in the coronal oblique plane along the longitudinal axis of the bile duct with a thin-slab multisection technique. Parameters for this technique were as follows: repetition time msec/effective echo time msec = 
/88.0; flip angle, 140°; section thickness, 5.0 mm with no gap; field of view, 270 x 270 mm; number of signals acquired, 1; matrix, 240 x 256; and acquisition time, 18 seconds. Thirteen images were obtained during the single-breath-hold acquisition. Because of the orientation of the normal bile duct, the biliary tract is usually partially visualized on each of several images rather than visualized in its entirety on a single image (Fig 1). The gallbladder and cystic duct are visualized even in the nonfasting patient (Fig 2).
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Figure 1a. Figures 1, 2. (1) Normal bile duct. (a) MR cholangiogram demonstrates the proximal extrahepatic duct (arrow) and the proximal right and left hepatic ducts. (b) MR cholangiogram obtained 5 mm anterior to a demonstrates the middle and distal thirds of the extrahepatic bile duct (arrows). (2) Normal gallbladder and cystic duct. MR cholangiogram shows the gallbladder (G) and cystic duct (arrow). The extrahepatic bile duct is also seen (arrowheads).
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Figure 1b. Figures 1, 2. (1) Normal bile duct. (a) MR cholangiogram demonstrates the proximal extrahepatic duct (arrow) and the proximal right and left hepatic ducts. (b) MR cholangiogram obtained 5 mm anterior to a demonstrates the middle and distal thirds of the extrahepatic bile duct (arrows). (2) Normal gallbladder and cystic duct. MR cholangiogram shows the gallbladder (G) and cystic duct (arrow). The extrahepatic bile duct is also seen (arrowheads).
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Figure 2. Figures 1, 2. (1) Normal bile duct. (a) MR cholangiogram demonstrates the proximal extrahepatic duct (arrow) and the proximal right and left hepatic ducts. (b) MR cholangiogram obtained 5 mm anterior to a demonstrates the middle and distal thirds of the extrahepatic bile duct (arrows). (2) Normal gallbladder and cystic duct. MR cholangiogram shows the gallbladder (G) and cystic duct (arrow). The extrahepatic bile duct is also seen (arrowheads).
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Although all diagnostic decisions were made on the basis of the source images, three-dimensional images were generated with maximum-intensity-projection algorithms and multiplanar reformatting techniques. Three-dimensional images provide a road map of the obstructed ductal system, delineate complex strictures, and assist in the planning of percutaneous, surgical, and endoscopic procedures as well as radiation therapy.
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TECHNICAL ADVANCES
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Since the introduction of MR cholangiography in 1991, a variety of techniques and sequences have been used to generate images of the biliary tract (1–17). MR cholangiography may be performed with a multisection technique involving the acquisition of multiple 3–5-mm-thick source images of the pancreaticobiliary tract with or without breath holding (1–13). Three-dimensional images may be generated from the source images with a maximum-intensity-projection algorithm as in this study. Alternatively, a single-shot projection technique has been used in which a single 30–70-mm-thick image is generated during a 2-second acquisition (14,17). This projection technique obviates maximum-intensity-projection postprocessing.
In addition to multisection and single-section techniques, a number of sequences have been used in MR cholangiography, including steady state free precession, two-dimensional and three-dimensional fast spin-echo, and half-Fourier RARE sequences (10, 13–16). With each sequence, the ducts appear as high-signal-intensity structures owing to the inherent contrast provided by fluid in the duct lumen. In comparing these four sequences, Irie et al (13) found that half-Fourier RARE afforded the highest contrast and spatial resolution.
Technical advances such as half-Fourier RARE have been instrumental in generating high-resolution images that compare favorably with images obtained with ERC. Because only half the lines in k space are acquired during a single echo train length of 128, half-Fourier RARE allows extremely rapid image acquisition such that the entire biliary tract and pancreatic duct can be imaged during a single 18-second breath hold. 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 signal-to-noise ratios. Because of improvements in image quality, MR cholangiography is capable of showing ducts as small as 1 mm (2,13).
An additional advantage of the half-Fourier RARE sequence is the ability to reduce susceptibility effects from surgical clips, metallic biliary and vascular stents (Figs 3, 4), biliary drainage catheters (Fig 5), spinal fixation rods, and bowel gas to a negligible level owing to the narrow spacing of the radio-frequency pulses. The reduction of susceptibility effects is important because MR cholangiography is often performed in patients who have
multiple clips secondary to cholecystectomy, biliary-enteric anastomosis, or liver transplantation.
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Figure 3a. Metallic biliary stent in a 69-year-old woman with pancreatic carcinoma. (a) Endoscopic retrograde cholangiopancreatogram obtained prior to injection of contrast material into the bile duct reveals a metallic biliary stent (arrows). (b) MR cholangiogram demonstrates the fluid-filled bile duct (arrows) despite the presence of the stent. The filling defects within the stent represent adherent debris and may be distinguished from stones by their indistinct margins and their peripheral location within the duct on axial images.
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Figure 3b. Metallic biliary stent in a 69-year-old woman with pancreatic carcinoma. (a) Endoscopic retrograde cholangiopancreatogram obtained prior to injection of contrast material into the bile duct reveals a metallic biliary stent (arrows). (b) MR cholangiogram demonstrates the fluid-filled bile duct (arrows) despite the presence of the stent. The filling defects within the stent represent adherent debris and may be distinguished from stones by their indistinct margins and their peripheral location within the duct on axial images.
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Figure 4a. Absence of artifacts secondary to a transjugular intrahepatic portosystemic shunt and spinal fixation rods in a 51-year-old man with elevated alkaline phosphatase levels. MR cholangiography was performed to assess for bile duct obstruction. (a) Digital angiogram obtained during placement of a transjugular intrahepatic portosystemic shunt shows the metallic shunt (arrows) and spinal fixation rods (arrowheads). (b, c) Subsequent MR cholangiograms demonstrate the proximal (b) and distal (c) extrahepatic bile duct (arrows) and help exclude biliary obstruction despite the presence of the transjugular intrahepatic portosystemic shunt and the spinal fixation rods. Note the signal void (*) caused by the shunt.
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Figure 4b. Absence of artifacts secondary to a transjugular intrahepatic portosystemic shunt and spinal fixation rods in a 51-year-old man with elevated alkaline phosphatase levels. MR cholangiography was performed to assess for bile duct obstruction. (a) Digital angiogram obtained during placement of a transjugular intrahepatic portosystemic shunt shows the metallic shunt (arrows) and spinal fixation rods (arrowheads). (b, c) Subsequent MR cholangiograms demonstrate the proximal (b) and distal (c) extrahepatic bile duct (arrows) and help exclude biliary obstruction despite the presence of the transjugular intrahepatic portosystemic shunt and the spinal fixation rods. Note the signal void (*) caused by the shunt.
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Figure 4c. Absence of artifacts secondary to a transjugular intrahepatic portosystemic shunt and spinal fixation rods in a 51-year-old man with elevated alkaline phosphatase levels. MR cholangiography was performed to assess for bile duct obstruction. (a) Digital angiogram obtained during placement of a transjugular intrahepatic portosystemic shunt shows the metallic shunt (arrows) and spinal fixation rods (arrowheads). (b, c) Subsequent MR cholangiograms demonstrate the proximal (b) and distal (c) extrahepatic bile duct (arrows) and help exclude biliary obstruction despite the presence of the transjugular intrahepatic portosystemic shunt and the spinal fixation rods. Note the signal void (*) caused by the shunt.
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Figure 5. Percutaneous biliary drainage catheter in a 75-year-old man. MR cholangiogram demonstrates a biliary drainage catheter (arrows) that has not produced artifacts. The intrahepatic bile ducts are minimally dilated (arrowhead).
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CLINICAL APPLICATIONS
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Choledocholithiasis
MR cholangiography is well suited to the diagnosis of choledocholithiasis because common bile duct stones appear as low-signal-intensity foci within the high-signal-intensity bile (Figs 6, 7). Stones as small as 2 mm can be detected with MR cholangiography (2,5). Multiple studies performed with a variety of sequences have shown that the sensitivity and specificity of MR cholangiography in the diagnosis of choledocholithiasis range from 81% to 100% and
from 85% to 100%, respectively; positive and negative predictive values range from 82% to 100% and from 94% to 100%, respectively (1–5). In view of the high negative predictive value of MR cholangiography, the primary utility of this technique in the setting of choledocholithiasis may lie not in the detection of common duct stones but in their exclusion. Once common duct stones are excluded as a source of abdominal pain, patients may be spared unnecessary ERC with its attendant risks.
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Figure 6. Choledocholithiasis and cholelithiasis in a pregnant 33-year-old woman with right upper quadrant pain. Sonography revealed gallbladder calculi and bile duct dilatation but no common bile duct stones. MR cholangiogram demonstrates multiple calculi in both the dilated extrahepatic bile duct (arrows) and gallbladder (arrowheads).
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Figure 7a. Single, small common bile duct calculus and gallbladder calculi in an 18-year-old woman with chronic right upper quadrant pain. (a) Scout MR cholangiogram shows a 3-mm calculus (straight arrow) in the normal-caliber distal common bile duct. The gallbladder (curved arrow) is filled with multiple small calculi. (b) Endoscopic retrograde cholangiopancreatogram helps confirm the distal common bile duct calculus (arrow).
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Figure 7b. Single, small common bile duct calculus and gallbladder calculi in an 18-year-old woman with chronic right upper quadrant pain. (a) Scout MR cholangiogram shows a 3-mm calculus (straight arrow) in the normal-caliber distal common bile duct. The gallbladder (curved arrow) is filled with multiple small calculi. (b) Endoscopic retrograde cholangiopancreatogram helps confirm the distal common bile duct calculus (arrow).
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MR cholangiography assists in the diagnosis of complex manifestations of bile duct calculi such as Mirizzi syndrome (Fig 8). Mirizzi syndrome represents compression of the extrahepatic bile duct by a calculus impacted in the cystic duct. The multiplanar capability of MR cholangiography allows identification of both the obstructing calculus and the long cystic duct that parallels the bile duct and predisposes the patient to Mirizzi syndrome.
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Figure 8a. Mirizzi syndrome in a 46-year-old woman with cholangitis. (a) MR cholangiogram reveals a 1.2-cm calculus (arrow) resulting in biliary ductal dilatation. Gallbladder calculi are also seen (arrowheads). (b) MR cholangiogram obtained 5 mm anterior to a shows two calculi in the dilated cystic duct (arrowheads), which parallels the extrahepatic bile duct. The inferior calculus (arrow) corresponds to the calculus seen in a. This calculus eroded through the wall of the cystic duct into the extrahepatic bile duct, bridged the two structures, and resulted in obstruction of the bile duct (Mirizzi syndrome). (c) Endoscopic retrograde cholangiogram demonstrates a calculus in the cystic duct (arrowhead) outlined inferiorly by a small amount of contrast material, as well as the larger, inferior calculus (arrow) causing bile duct obstruction.
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Figure 8b. Mirizzi syndrome in a 46-year-old woman with cholangitis. (a) MR cholangiogram reveals a 1.2-cm calculus (arrow) resulting in biliary ductal dilatation. Gallbladder calculi are also seen (arrowheads). (b) MR cholangiogram obtained 5 mm anterior to a shows two calculi in the dilated cystic duct (arrowheads), which parallels the extrahepatic bile duct. The inferior calculus (arrow) corresponds to the calculus seen in a. This calculus eroded through the wall of the cystic duct into the extrahepatic bile duct, bridged the two structures, and resulted in obstruction of the bile duct (Mirizzi syndrome). (c) Endoscopic retrograde cholangiogram demonstrates a calculus in the cystic duct (arrowhead) outlined inferiorly by a small amount of contrast material, as well as the larger, inferior calculus (arrow) causing bile duct obstruction.
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Figure 8c. Mirizzi syndrome in a 46-year-old woman with cholangitis. (a) MR cholangiogram reveals a 1.2-cm calculus (arrow) resulting in biliary ductal dilatation. Gallbladder calculi are also seen (arrowheads). (b) MR cholangiogram obtained 5 mm anterior to a shows two calculi in the dilated cystic duct (arrowheads), which parallels the extrahepatic bile duct. The inferior calculus (arrow) corresponds to the calculus seen in a. This calculus eroded through the wall of the cystic duct into the extrahepatic bile duct, bridged the two structures, and resulted in obstruction of the bile duct (Mirizzi syndrome). (c) Endoscopic retrograde cholangiogram demonstrates a calculus in the cystic duct (arrowhead) outlined inferiorly by a small amount of contrast material, as well as the larger, inferior calculus (arrow) causing bile duct obstruction.
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Malignant Obstruction
The diagnosis of malignant obstruction is usually established with sonography, computed tomography, or MR imaging. In some instances, however, MR cholangiography used in conjunction with conventional MR imaging may
provide additional diagnostic information. For example, MR cholangiography may be useful in establishing the resectability of a malignant neoplasm such as hilar cholangiocarcinoma by helping determine the proximal extent of disease (6) (Fig 9). If the lesion is determined to be resectable, the patient may undergo surgery immediately and avoid unnecessary ERC and stent placement. In addition, MR cholangiography can help delineate the biliary tract in proximal obstructions in which endoscopic retrograde cholangiopancreatography (ERCP) may not be successful (Fig 10) and in distal obstructions in which percutaneous transhepatic cholangiography may be of limited value (Fig 11).
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Figure 9a. Hilar cholangiocarcinoma with proximal extension into the right and left hepatic bile ducts in a 75-year-old man. (a) MR cholangiogram demonstrates dilatation of the intrahepatic bile ducts (arrowheads) secondary to hilar cholangiocarcinoma, which has extended proximally to involve the right and left hepatic ducts (arrows). (b) MR cholangiogram obtained after injection of contrast material into biliary drainage catheters helps confirm the obstructing hilar lesion and its proximal extent (arrows) as demonstrated in a. (Reprinted, with permission, from reference 6.)
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Figure 9b. Hilar cholangiocarcinoma with proximal extension into the right and left hepatic bile ducts in a 75-year-old man. (a) MR cholangiogram demonstrates dilatation of the intrahepatic bile ducts (arrowheads) secondary to hilar cholangiocarcinoma, which has extended proximally to involve the right and left hepatic ducts (arrows). (b) MR cholangiogram obtained after injection of contrast material into biliary drainage catheters helps confirm the obstructing hilar lesion and its proximal extent (arrows) as demonstrated in a. (Reprinted, with permission, from reference 6.)
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Figure 10. Gallbladder carcinoma with nodal metastasis in a 56-year-old man who presented with right upper quadrant pain and jaundice. Maximum-intensity-projection MR cholangiogram demonstrates a necrotic nodal metastasis (*) resulting in proximal bile duct obstruction. The mass (M) noted in the gallbladder (arrows) represents adenocarcinoma.
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Figure 11a. Pancreatic metastasis from mucinous colon carcinoma in a 34-year-old woman. (a) MR cholangiogram demonstrates obstruction of the intrapancreatic segment of the bile duct (arrow) caused by a pancreatic metastasis. Note the dilated gallbladder (G). Enlarged lymph nodes with high signal intensity (arrowheads) represent metastases from mucinous colon carcinoma. (b) Endoscopic retrograde cholangiogram helps confirm the abrupt obstruction of the intrapancreatic bile duct (arrow) and the proximal bile duct dilatation.
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Figure 11b. Pancreatic metastasis from mucinous colon carcinoma in a 34-year-old woman. (a) MR cholangiogram demonstrates obstruction of the intrapancreatic segment of the bile duct (arrow) caused by a pancreatic metastasis. Note the dilated gallbladder (G). Enlarged lymph nodes with high signal intensity (arrowheads) represent metastases from mucinous colon carcinoma. (b) Endoscopic retrograde cholangiogram helps confirm the abrupt obstruction of the intrapancreatic bile duct (arrow) and the proximal bile duct dilatation.
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Failed or Incomplete ERC
MR cholangiography is useful in the evaluation of patients in whom ERC failed or was incomplete. In a group of 37 such patients, Soto et al (18) demonstrated that MR cholangiopancreatography could be performed successfully and the findings used to guide therapeutic options. Unsuccessful ductal cannulation or incomplete ductal opacification occurs in 10%–20% of all ERCP procedures (19). The majority of failures are secondary to technical factors; the remainder are caused by anatomic alterations. Such alterations include biliary-enteric anastomoses, gastric or duodenal obstructions precluding passage of the endoscope (Fig 12), and anatomic variants such as periampullary diverticula (Fig 13).
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Figure 12a. Gastric outlet obstruction preventing ERCP in a 56-year-old woman who presented with weight loss and intractable nausea and vomiting. (a) MR cholangiogram shows obstruction of the extrahepatic bile duct (straight arrow) secondary to lymphadenopathy. The scalloped appearance of the peritoneum (arrowheads) represents carcinomatosis. Gallbladder calculi are also seen (curved arrow). (b) MR cholangiogram of the stomach demonstrates marked antral wall thickening (arrows) secondary to adenocarcinoma, resulting in outlet obstruction.
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Figure 12b. Gastric outlet obstruction preventing ERCP in a 56-year-old woman who presented with weight loss and intractable nausea and vomiting. (a) MR cholangiogram shows obstruction of the extrahepatic bile duct (straight arrow) secondary to lymphadenopathy. The scalloped appearance of the peritoneum (arrowheads) represents carcinomatosis. Gallbladder calculi are also seen (curved arrow). (b) MR cholangiogram of the stomach demonstrates marked antral wall thickening (arrows) secondary to adenocarcinoma, resulting in outlet obstruction.
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Figure 13. Periampullary diverticulum resulting in failed ERCP in a 92-year-old woman with suspected common bile duct stones. MR cholangiopancreatogram reveals a periampullary diverticulum (arrowhead) and a slightly dilated extrahepatic bile duct (straight arrow) but no common bile duct stones. Minute gallbladder calculi are also seen (curved arrow).
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Intrahepatic Duct Disease
The role of MR cholangiography in the evaluation of intrahepatic duct disease (eg, primary sclerosing cholangitis, acquired immunodeficiency syndrome [AIDS] cholangiopathy) is evolving. Preliminary data suggest that MR cholangiography may be used to establish the diagnosis of primary sclerosing cholangitis (20) and obviate diagnostic ERC. The ductal stenoses, occlusions, and irregularities associated with primary sclerosing cholangitis and AIDS cholangiopathy may be demonstrated with MR cholangiography (Figs 14, 15).
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Figure 14a. Primary sclerosing cholangitis in a 51-year-old woman with increasing alkaline phosphatase levels. (a) MR cholangiogram shows stenosis of a right hepatic duct branch (arrows). (b) MR cholangiogram demonstrates stenoses and irregularities of the left hepatic ducts (arrows), indicative of primary sclerosing cholangitis, as well as third-order bile ducts (arrowheads).
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Figure 14b. Primary sclerosing cholangitis in a 51-year-old woman with increasing alkaline phosphatase levels. (a) MR cholangiogram shows stenosis of a right hepatic duct branch (arrows). (b) MR cholangiogram demonstrates stenoses and irregularities of the left hepatic ducts (arrows), indicative of primary sclerosing cholangitis, as well as third-order bile ducts (arrowheads).
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Figure 15a. AIDS cholangiopathy in a 32-year-old man with elevated alkaline phosphatase levels. (a) MR cholangiogram shows multiple ductal stenoses and irregularities of the right hepatic ducts (arrows) and beading of the left hepatic ducts (arrowheads). (b) Endoscopic retrograde cholangiogram performed with balloon occlusion (arrowhead) helps confirm the ductal stenoses (arrows) noted at MR cholangiography.
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Figure 15b. AIDS cholangiopathy in a 32-year-old man with elevated alkaline phosphatase levels. (a) MR cholangiogram shows multiple ductal stenoses and irregularities of the right hepatic ducts (arrows) and beading of the left hepatic ducts (arrowheads). (b) Endoscopic retrograde cholangiogram performed with balloon occlusion (arrowhead) helps confirm the ductal stenoses (arrows) noted at MR cholangiography.
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Recent technical advances such as breath-hold sequences have improved image quality and in many instances allow visualization of the extrahepatic and proximal intrahepatic bile ducts as well as third-order ducts. MR cholangiography can be used to show the bile ducts without the instrumentation and high injection pressures associated with ERC, thereby eliminating the risk of ERC-induced sepsis. MR cholangiography offers the added advantage of displaying the ducts in their natural degree of distention. At times, incomplete distention of the ducts during ERC may lead to underestimation of ductal involvement in both primary sclerosing cholangitis and AIDS cholangiopathy.
Postsurgical Biliary Tract Alterations
MR cholangiography plays a critical role in evaluating the surgically altered biliary tract. ERC is often difficult or impossible to perform in patients with biliary-enteric anastomoses and is associated with a greater frequency of complications in these patients than in those without altered anatomy (21). MR cholangiography is useful in delineating the anatomy of biliary-enteric anastomoses and in detecting complications such as anastomotic strictures, intraductal stones, and biliary ductal dilatation (Figs 16, 17). Pavone et al (12) used MR cholangiography 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.
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Figure 16. Stricture resulting from choledochojejunostomy in a 66-year-old man who had undergone a Whipple procedure for pancreatic carcinoma. Scout MR cholangiogram shows a stricture of the common hepatic duct (arrow) extending to the anastomosis between the duct and the jejunum (J). The intrahepatic bile ducts are dilated (arrowheads).
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Figure 17a. Stricture resulting from hepaticojejunostomy in a 33-year-old woman with jaundice. The patient had undergone hepaticojejunostomy because of a bile duct injury sustained during laparoscopic cholecystectomy. (a) MR cholangiogram shows castlike filling defects (arrows) representative of stones in the dilated bile ducts immediately above the strictured hepaticojejunostomy. A small amount of fluid in the jejunum (arrowhead) demarcates the hepaticojejunostomy. (b) Percutaneous transhepatic cholangiogram demonstrates the intraductal stones (arrows), dilated ducts, and anastomotic stricture (arrowhead).
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Figure 17b. Stricture resulting from hepaticojejunostomy in a 33-year-old woman with jaundice. The patient had undergone hepaticojejunostomy because of a bile duct injury sustained during laparoscopic cholecystectomy. (a) MR cholangiogram shows castlike filling defects (arrows) representative of stones in the dilated bile ducts immediately above the strictured hepaticojejunostomy. A small amount of fluid in the jejunum (arrowhead) demarcates the hepaticojejunostomy. (b) Percutaneous transhepatic cholangiogram demonstrates the intraductal stones (arrows), dilated ducts, and anastomotic stricture (arrowhead).
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MR cholangiography can also be used postoperatively to detect isolated ductal obstructions. Such obstructions may occur secondary to strictures or stones, and if the obstruction is high grade or complete, the isolated duct may not be opacified at direct cholangiography (Fig 18).
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Figure 18a. Isolated duct obstruction in an 18-year-old woman who sustained bile duct transection during laparoscopic cholecystectomy. The transection was repaired with a duct-to-duct anastomosis. (a) MR cholangiopancreatogram reveals a stricture (arrow) of the left hepatic duct and proximal ductal dilatation (arrowhead). (b) T-tube cholangiogram shows incomplete filling of the dilated left hepatic duct (arrowhead) and a partially retracted T tube (arrow). Note the surgical clips adjacent to the duct.
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Figure 18b. Isolated duct obstruction in an 18-year-old woman who sustained bile duct transection during laparoscopic cholecystectomy. The transection was repaired with a duct-to-duct anastomosis. (a) MR cholangiopancreatogram reveals a stricture (arrow) of the left hepatic duct and proximal ductal dilatation (arrowhead). (b) T-tube cholangiogram shows incomplete filling of the dilated left hepatic duct (arrowhead) and a partially retracted T tube (arrow). Note the surgical clips adjacent to the duct.
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During the first few months after liver transplantation, biliary catheters are often left in place to provide access to the biliary tract, after which the catheters are removed. Before the advent of MR cholangiography, visualization of the biliary tract after catheter removal was possible only with invasive procedures such as ERC and percutaneous transhepatic cholangiography. MR cholangiography provides a noninvasive means of visualizing primary duct-to-duct anastomoses and biliary-enteric anastomoses (Fig 19) as well
as complications such as ischemic strictures (Fig 20) and intraductal stones in liver transplant recipients.
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Figure 19a. Normal bile duct in a 46-year-old woman who had undergone orthotopic liver transplantation and primary duct-to-duct anastomosis. (a–c) Multiple MR cholangiograms (a most anterior, c most posterior) are required to show the entire extent of the tortuous bile duct (arrow in a and c). Arrowhead in b indicates the anastomosis. (d) Endoscopic retrograde cholangiogram helps confirm the duct tortuosity and the duct-to-duct anastomosis (arrowhead).
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Figure 19b. Normal bile duct in a 46-year-old woman who had undergone orthotopic liver transplantation and primary duct-to-duct anastomosis. (a–c) Multiple MR cholangiograms (a most anterior, c most posterior) are required to show the entire extent of the tortuous bile duct (arrow in a and c). Arrowhead in b indicates the anastomosis. (d) Endoscopic retrograde cholangiogram helps confirm the duct tortuosity and the duct-to-duct anastomosis (arrowhead).
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Figure 19c. Normal bile duct in a 46-year-old woman who had undergone orthotopic liver transplantation and primary duct-to-duct anastomosis. (a–c) Multiple MR cholangiograms (a most anterior, c most posterior) are required to show the entire extent of the tortuous bile duct (arrow in a and c). Arrowhead in b indicates the anastomosis. (d) Endoscopic retrograde cholangiogram helps confirm the duct tortuosity and the duct-to-duct anastomosis (arrowhead).
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Figure 19d. Normal bile duct in a 46-year-old woman who had undergone orthotopic liver transplantation and primary duct-to-duct anastomosis. (a–c) Multiple MR cholangiograms (a most anterior, c most posterior) are required to show the entire extent of the tortuous bile duct (arrow in a and c). Arrowhead in b indicates the anastomosis. (d) Endoscopic retrograde cholangiogram helps confirm the duct tortuosity and the duct-to-duct anastomosis (arrowhead).
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Figure 20a. Ischemic changes of the bile duct in a 43-year-old man 6 months after orthotopic liver transplantation. (a) MR cholangiogram demonstrates smooth narrowing of the common hepatic duct and the central intrahepatic bile ducts (arrows). The more peripheral branches of the intrahepatic bile ducts are dilated. (b) Endoscopic retrograde cholangiogram shows narrowing of the right hepatic duct (arrow); the narrowing of the left hepatic duct is obscured by overlying ducts.
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Figure 20b. Ischemic changes of the bile duct in a 43-year-old man 6 months after orthotopic liver transplantation. (a) MR cholangiogram demonstrates smooth narrowing of the common hepatic duct and the central intrahepatic bile ducts (arrows). The more peripheral branches of the intrahepatic bile ducts are dilated. (b) Endoscopic retrograde cholangiogram shows narrowing of the right hepatic duct (arrow); the narrowing of the left hepatic duct is obscured by overlying ducts.
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Congenital Anomalies
MR cholangiography can be used to demonstrate a variety of congenital anomalies of the biliary tract. MR cholangiography has an accuracy of 98% in the diagnosis of aberrant hepatic ducts and of 95% in the diagnosis of anatomic variants of the cystic duct (11) (Figs 21, 22). As laparoscopic cholecystectomies have become routine, there has been heightened interest in the preoperative identification of aberrant bile ducts because these anatomic variants increase the risk of inadvertent ductal ligation.
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Figure 21a. Aberrant right hepatic duct detected incidentally in a 38-year-old woman. (a) MR cholangiogram shows an aberrant right hepatic duct (arrow) draining into the cystic duct remnant (arrowheads). (b) Endoscopic retrograde cholangiogram demonstrates communication of the aberrant right hepatic duct (arrow) with the cystic duct remnant (arrowheads). Note the surgical clips adjacent to the cystic duct remnant.
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Figure 21b. Aberrant right hepatic duct detected incidentally in a 38-year-old woman. (a) MR cholangiogram shows an aberrant right hepatic duct (arrow) draining into the cystic duct remnant (arrowheads). (b) Endoscopic retrograde cholangiogram demonstrates communication of the aberrant right hepatic duct (arrow) with the cystic duct remnant (arrowheads). Note the surgical clips adjacent to the cystic duct remnant.
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Figure 22a. Low medial insertion of the cystic duct detected incidentally in a 38-year-old woman with abdominal pain. (a) MR cholangiopancreatogram demonstrates low medial insertion of the cystic duct (arrows) into the extrahepatic bile duct (arrowhead). (b) Intraoperative cholangiogram helps confirm the insertion location (arrows).
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Figure 22b. Low medial insertion of the cystic duct detected incidentally in a 38-year-old woman with abdominal pain. (a) MR cholangiopancreatogram demonstrates low medial insertion of the cystic duct (arrows) into the extrahepatic bile duct (arrowhead). (b) Intraoperative cholangiogram helps confirm the insertion location (arrows).
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In the setting of a suspected choledochal cyst, MR cholangiography helps confirm the presence of the cyst and identify the associated anomalous union of the bile and pancreatic ducts (Fig 23). In patients who are to undergo cyst resection, MR cholangiography can be used to determine the length of duct involved by the cyst.
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Figure 23. Type 1 choledochal cyst in a 25-year-old woman. MR cholangiopancreatogram demonstrates fusiform dilatation of the suprapancreatic portion of the extrahepatic bile duct (arrow), indicative of a type 1 choledochal cyst. An anomalous union of the bile and pancreatic ducts is also seen (arrowhead).
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Bret et al (22) found an accuracy of 100% for MR cholangiopancreatography in the detection of pancreas divisum. Patients with recurrent episodes of pancreatitis are often referred for MR cholangiopancreatography to assess for pancreas divisum. The high image quality and multiplanar capability of MR cholangiopancreatography allow visualization of the isolated ventral and dorsal ducts of the pancreas characteristic of pancreas divisum and of their entrance into the major and minor ampullae, respectively (Fig 24). MR cholangiopancreatography is especially useful in this patient population because it allows diagnosis of pancreas divisum without the risk of inducing or exacerbating pancreatitis.
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Figure 24a. Pancreas divisum in a 36-year-old man with recurrent pancreatitis. (a) MR cholangiogram shows the distal bile duct (arrowhead), which joins with the ventral pancreatic duct (arrows) to enter the major ampulla. (b) MR cholangiogram shows the dorsal pancreatic duct (arrows) entering the minor ampulla (arrowhead) cephalad to the major ampulla. Subsequent images helped confirm the absence of communication between the ventral and dorsal pancreatic ducts.
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Figure 24b. Pancreas divisum in a 36-year-old man with recurrent pancreatitis. (a) MR cholangiogram shows the distal bile duct (arrowhead), which joins with the ventral pancreatic duct (arrows) to enter the major ampulla. (b) MR cholangiogram shows the dorsal pancreatic duct (arrows) entering the minor ampulla (arrowhead) cephalad to the major ampulla. Subsequent images helped confirm the absence of communication between the ventral and dorsal pancreatic ducts.
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Gallbladder Disease
Although MR cholangiography is performed to evaluate the biliary tract, both incidental and intentional imaging of the gallbladder occur even in the nonfasting patient. Gallbladder calculi appear as low-signal-intensity filling defects within the high-signal-intensity bile (Figs 25, 26). Calculi as small as 2 mm can be identified at MR cholangiography. This technique can also help determine the presence and extent of neoplastic disease of the gallbladder (Fig 10). Adenomyomatosis of the gallbladder may be detected incidentally as fluid-filled Rokitansky-Aschoff sinuses within the gallbladder wall (Fig 27).
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Figure 25. Large gallbladder calculus in a 30-year-old man with sickle cell disease. MR cholangiogram demonstrates a large calculus in the gallbladder (arrow). Note the normal-caliber bile duct (arrowhead).
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Figure 26. Small gallbladder calculi in a 58-year-old woman with right upper quadrant pain. MR cholangiogram reveals multiple small calculi filling the gallbladder (arrows). The cystic duct (arrowhead) does not contain calculi.
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Figure 27a. Adenomyomatosis detected incidentally in a 68-year-old man. (a) MR cholangiogram that includes the gallbladder demonstrates small, fluid-filled outpouchings arising from the gallbladder (arrows), representative of Rokitansky-Aschoff sinuses characteristic of adenomyomatosis. (b) MR cholangiogram of the gallbladder fundus reveals additional fluid-filled sinuses (arrows), seen en face.
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Figure 27b. Adenomyomatosis detected incidentally in a 68-year-old man. (a) MR cholangiogram that includes the gallbladder demonstrates small, fluid-filled outpouchings arising from the gallbladder (arrows), representative of Rokitansky-Aschoff sinuses characteristic of adenomyomatosis. (b) MR cholangiogram of the gallbladder fundus reveals additional fluid-filled sinuses (arrows), seen en face.
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CONCLUSIONS
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Technical advances in imaging sequences and coils have improved image quality in MR cholangiography such that this technique has emerged as a noninvasive, accurate alternative to ERC in the evaluation of diseases of the biliary tract. MR cholangiography is particularly useful in the settings of choledocholithiasis, malignant obstruction, failed or incomplete ERC, intrahepatic bile duct diseases, postsurgical anatomic alterations, and congenital anomalies of the biliary tract.
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Footnotes
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Address reprint requests to A.S.F.
Recipient of a Certificate of Merit award for a scientific exhibit at the 1997 RSNA scientific assembly.
See also the commentary by Mitchell following this article and the article by Fulcher et al (pp 5–24) in this issue.
Abbreviations: AIDS = acquired immunodeficiency syndrome
ERC = endoscopic retrograde cholangiography
ERCP = endoscopic retrograde cholangiopancreatography
RARE = rapid acquisition with relaxation enhancement
Received for publication March 16, 1998.
Revision received April 7, 1998. April 29, 1998.
Accepted for publication April 30, 1998.
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References
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Becker CD, Grossholz M, Becker M, Mentha G, de Peyer R, Terrier F. Choledocholithiasis and bile duct stenosis: diagnostic accuracy of MR cholangiopancreatography. Radiology 1997; 205:523-530.[Abstract/Free Full Text]
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Fulcher AS, Turner MA, Capps GW, Zfass AM, Baker KM. Half-Fourier RARE MRCP i
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Abstract
INTRODUCTION
