Detection of bile duct leaks using MR cholangiography with mangfodipir trisodium (Teslascan)

Magnetic resonance cholangiography: Current and future perspectives

Magnetic resonance cholangiography (MRC) has become the standard of reference for imaging of the biliary ducts. The use of three-dimensional (3D) sequences has resulted in improved spatial resolution with virtually isotropic voxel and improved signal/noise ratio. In addition to MRC images, 3D fat suppressed T1-weighted MR images should be systematically obtained to search for intrahepatic calculi. MRC plays a major role in the diagnosis of cholangiocarcinoma and assessment of its resectability. With modern MR systems the performance of MR is basically the same that of CT for evaluation of arterial and portal vein extent. MRC is a key imaging modality for the diagnosis of primary sclerosing cholangitis. Different imaging patterns may be observed including multifocal intra- and extrahepatic strictures alternating with slightly dilated ducts. Focal signal abnormality of the liver parenchyma and focal parenchymal atrophy represent the consequences of biliary duct obstruction on liver parenchyma. Diagnosis of biliary lithiasis is performed by combination of MRC and T1-weighted MR imaging. MRC can be performed for the diagnosis of secondary cholangitis including ascending cholangitis, ischemic cholangitis and IgG4-related sclerosing cholangitis. Hepatobiliary contrast agents could be used for demonstrating the site of biliary duct leakage after surgery and for functional imaging. MR imaging can also be used to determine the prognosis of PSC. The inherent limitations of MRC of bile ducts are still the suboptimal spatial resolution for evaluation of distal intrahepatic biliary ducts.

Early phase detection of bile leak after hepatobiliary surgery: value of Gd-EOB-DTPA-enhanced MR cholangiography

PURPOSE

To assess the value of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MR cholangiography for the detection of bile leaks after hepatobiliary surgery.

METHODS

Twenty-three patients with symptoms suggestive of bile leak underwent conventional fat-suppressed T1- and T2-weighted MR cholangiography followed by Gd-EOB-DTPA-enhanced MR cholangiography using gradient-echo (GRE) T2-weighted sequences and fat-suppressed T1-weighted 3D gradient-echo sequences 20 min after an intravenous bolus of Gd-EOB-DTPA. The results of Gd-EOB-DTPA-enhanced MR cholangiography correlated with clinical findings, surgical repair, and the results of endoscopic retrograde cholangiopancreatography and percutaneous transhepatic cholangiography.

RESULTS

The results of Gd-EOB-DTPA-enhanced MR cholangiography were negative in 13 patients (cholecystectomy 5, liver transplantation 2, liver resection for focal lesions 2, cholangiocarcinoma 1, and partial hepatectomy after liver injury 1). In 10 patients in whom bile leaks were detected, this complication occurred after liver resection for focal lesions in 3, cholecystectomy in 4, liver transplantation in 2, and liver resection for intrahepatic cholangiocarcinoma in 1. The diagnostic accuracy of Gd-EOB-DTPA-enhanced MR for the detection or exclusion of bile leaks was 100%.

CONCLUSIONS

Gd-EOB-DTPA-enhanced MR cholangiography is a highly reliable technique for the detection of bile leaks after hepatobiliary surgery and may avoid the use of other, potentially risky invasive diagnostic techniques.

MR imaging in gastrointestinal emergencies

Accurate and rapid diagnostic imaging is essential for the appropriate management of acute gastrointestinal conditions. Computed tomography (CT) is the modality most often used in this setting because of its widespread availability and the relative speed, ease, and uniformity with which evaluations can be performed. CT allows the diagnosis of a wide spectrum of acute gastrointestinal diseases with the adjustment of only a few variables in the acquisition protocol. For example, the contrast material volume, injection rate, and delay before image acquisition can be manipulated to enhance vascular or organ-specific contrast for myriad gastrointestinal diagnoses. Magnetic resonance (MR) imaging has similarly robust potential, although its integration into the acute care setting requires greater technical and logistical effort. Improved MR imaging sequences, advances in coil technology, streamlined imaging protocols, and increased technical and professional familiarity with the modality make it an increasingly attractive option when there is concern about patient radiation exposure or allergy to iodinated contrast material. A variety of acute abdominal conditions, including pancreatic and biliary tract trauma, choledocholithiasis, gallbladder disease, acute pancreatitis, and appendicitis can be rapidly and accurately demonstrated with MR imaging. MR imaging also can play a vital role in the follow-up assessment of treatment response and in the diagnosis of indeterminate findings at CT or ultrasonography. Nevertheless, incompatibility of patient monitoring devices with the MR magnet, lack of MR imaging system availability, and the acuity of illness may limit the use of the modality.

[Imaging of the postoperative biliary tract]

For a long time, imaging of the biliary tract after surgical procedures was performed with invasive procedures such as endoscopic retrograde cholangiopancreatography or percutaneous transhepatic cholangiography. Due to recent advances in diagnostic imaging, non-invasive techniques are now favored. While US remains the initial imaging modality, it is frequently followed by CT and/or MRCP. Image interpretation should always be performed in keeping with clinical and laboratory findings as well as the type of surgical procedure. The most appropriate imaging modality is selected based on these data. In patients with jaundice or biliary tract stenosis, MRCP, with use of an optimal technique and 3D acquisition, is the imaging modality of choice. In non-jaundiced patients with non-distended biliary tract and suspected bile leak, MRCP should be completed by the injection of a liver-specific contrast agent with biliary excretion to achieve non-invasive biliary tract opacification. In patients with malignancy, CT is preferred due to its high spatial resolution and ability to demonstrate small anastomotic tumor recurrences. CT should also be performed in patients with suspected hepatic artery or portal vein injury in addition to biliary tract injury or to detect distant complications.

Diagnosis and classification of pancreatic and duodenal injuries in emergency radiology

Pancreatic and duodenal injuries after blunt abdominal trauma are rare; however, delays in diagnosis and treatment can significantly increase morbidity and mortality. Multidetector computed tomography (CT) has a major role in early diagnosis of pancreatic and duodenal injuries. Detecting the often subtle signs of injury with whole-body CT can be difficult because this technique usually does not include a dedicated protocol for scanning the pancreas. Specific injury patterns in the pancreas and duodenum often have variable expression at early posttraumatic multidetector CT: They may be hardly visible, or there may be considerable exudate, hematomas, organ ruptures, or active bleeding. An accurate multidetector CT technique allows optimized detection of subtle abnormalities. In duodenal injuries, differentiation between a contusion of the duodenal wall or mural hematoma and a duodenal perforation is vital. In pancreatic injuries, determination of involvement of the pancreatic duct is essential. The latter conditions require immediate surgical intervention. Use of organ injury scales and a surgical classification adapted for multidetector CT enables classification of organ injuries for trauma scoring, treatment planning, and outcome control. In addition, multidetector CT reliably demonstrates potential complications of duodenal and pancreatic injuries, such as posttraumatic pancreatitis, pseudocysts, fistulas, exudates, and abscesses.

Computed tomography and magnetic resonance cholangiography

In patients with biliary obstruction, determining the level and the cause of the obstruction is essential because it can be a key factor for the next step in diagnostic or therapeutic intervention. Noninvasive cholangiography, such as computed tomography (CT) cholangiography or magnetic resonance (MR) cholangiography, allows the diagnosis of cause and level of biliary disease with minimal risk. Traditional magnetic resonance cholangiopancreatography (MRCP) is an established and effective noninvasive diagnostic modality particularly for extrahepatic biliary tract evaluation. Intrahepatic biliary duct evaluation and functional MR, including evaluating for leaks and gallbladder dyskinesia and outlet obstruction, are evolving diagnostic techniques that show promising results. CT cholangiography techniques are especially useful when MRI is not available or contraindicated or when the quality of MRCP images is suboptimal. CT cholangiography is particularly useful as an adjunct to surgery or postsurgical cases. The primary limitation of cholangiographic contrast-enhanced CT cholangiography (the most prevalent type of CT cholangiography) is its hindrance by poor liver function and/or high-grade biliary obstruction. In this setting MRCP is clearly superior. There are different types of CT cholangiography and MRCP. This article discusses the types of CT cholangiography and MRCP techniques and their clinical applications.

Magnetic resonance cholangiopancreatography: current use and future applications

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.

[Contrast-enhanced magnetic resonance cholangiography using gadolinium-EOB-DTPA. Preliminary experience and clinical applications]

Magnetic resonance cholangiopancreaticography (MRCP) with heavily T2-weighted RARE and HASTE sequences has become an important imaging modality for the morphologic evaluation of intra- and extrahepatic bile ducts. However, for the diagnosis of functional biliary disorders, cholangiopancreaticography (ERCP) and endoscopic manometry, two invasive techniques with considerable morbidity and mortality, remain the standard. Biliary scintigraphy, secretin-stimulated MRCP, and secretin-stimulated endoscopic ultrasound have not proven to be sufficient to replace these techniques as they lack diagnostic accuracy and correlate poorly with manometry results. Contrast-enhanced magnetic resonance cholangiography (CE-MRC) uses hepatocyte-selective contrast agents that are eliminated by the biliary system. Therefore, these substances can serve as biliary contrast agents in T1-weighted MR imaging. This method makes a noninvasive functional evaluation of the hepatobiliary system possible. In the present article, our preliminary experience with Gd-EOB-DTPA-enhanced MRC is summarized and potential clinical applications of this method are discussed. Additionally, the article reviews publications evaluating a possible benefit of CE-MRC with other hepatobiliary contrast agents such as mangafodipir trisodium.

[New possibilities to study biliary tree and gallbladder: functional magnetic resonance cholangiography contrast-enhanced with mangafodipir trisodium (Mn DPDP)]

Mangafodipir trisodium (Teslascan) is a hepatobiliary contrast agent that provides noninvasive opacification of the bile ducts. Using this contrast medium combined with a T1-weighted gradient echo enhanced sequence provides functional imaging of the bile ducts. Second-intention MRI was obtained after the usual morphological study of the bile ducts using heavily T2-weighted sequences (SS-FSE Te eff long and SS FSE Te eff short). This method can detect many biliary duct anomalies: biliary leakage in the postoperative context, mapping of bile ducts and the gallbladder in the search for anatomical variants, analysis of biliodigestive or biliobiliary anastomoses, or a dynamic study of bile secretion and excretion. Opacification of the bile ducts has only been possible until now with invasive tests aggravated by a certain co-morbidity rate and their functional study using biliary scintigraphy limited by mediocre spatial resolution. This new possibility provides access not only to morphological imaging, but also to functional imaging with excellent spatial resolution.

Magnetic resonance cholangiopancreatography: A useful tool in the evaluation of pancreatic and biliary disorders

Magnetic resonance cholangiopancreatography (MRCP) is being used with increasing frequency as a noninvasive alternative to diagnostic retrograde cholangiopancreatography (ERCP). The aim of this pictorial review is to demonstrate the usefulness of MRCP in the evaluation of pancreatic and biliary system disorders. Because the recently developed techniques allows improved spatial resolution and permits imaging of the entire pancreaticobiliary tract during a single breath hold, MRCP is of proven utility in a variety of pancreatic and biliary disorders. It uses MR imaging to visualize fluid in the biliary and pancreatic ducts as high signal intensity on T2 weighted sequences and is the newest modality for pancreatic and biliary duct imaging. Herein, we present the clinical applications of MRCP in a variety of pancreaticobiliary system disorders and conclude that it is an important diagnostic tool in terms of imaging of the pancreaticobiliary ductal system.

Bile leak after laparoscopic cholecystectomy

Laparoscopic cholecystectomy is commonly performed as the treatment of choice for symptomatic gallstone diseases. Bile leak is a potential complication of this procedure and the cystic duct stump is the most common site of leakage. Early diagnosis and treatment of bile leak is crucial in decreasing the morbidity and mortality related to this complication. Endoscopic retrograde cholangiopancreatography with stent placement and/or sphincterotomy is highly effective in the diagnosis and treatment of this problem.

Percutaneous Transhepatic Biliary Drainage in the Management of Postsurgical Biliary Leaks in Patients with Nondilated Intrahepatic Bile Ducts

PURPOSE

To assess the feasibility of percutaneous transhepatic biliary drainage (PTBD) for the treatment of postsurgical biliary leaks in patients with nondilated intrahepatic bile ducts, its efficacy in restoring the integrity of bile ducts, and technical procedures to reduce morbidity.

METHODS

Seventeen patients out of 936 undergoing PTBD over a 20-year period had a noncholestatic liver and were retrospectively reviewed. All patients underwent surgery for cancer and suffered a postsurgical biliary leak of 345 ml/day on average; 71% were in poor condition and required permanent nutritional support. An endoscopic approach failed or was excluded due to inaccessibility of the bile ducts.

RESULTS

Established biliary leaks and site of origin were diagnosed an average of 21 days (range 1-90 days) after surgery. In all cases percutaneous access to the biliary tree was achieved. An external (preleakage) drain was applied in 7 cases, 9 patients had an external-internal fistula bridging catheter, and 1 patient had a percutaneous hepatogastrostomy. Fistulas healed in an average of 31 days (range 3-118 days ) in 15 of 17 patients (88%) following PTBD. No major complications occurred after drainage. Post-PTBD cholangitis was observed in 6 of 17 patients (35%) and was related to biliary sludge formation occurring mostly when drainage lasted >30 days and was of the external-internal type. Median patient survival was 17.7 months and in all cases the repaired biliary leaks remained healed.

CONCLUSIONS

PTBD is a feasible, effective, and safe procedure for the treatment of postsurgical biliary leaks. It is therefore a reliable alternative to surgical repair, which entails longer hospitalization and higher costs.

Intérêt de l’IRM avec perfusion de mangafodipir trisodium dans la détection des fuites biliaires

PURPOSE

To assess the value of contrast-enhanced magnetic resonance cholangiography with Teslascan perfusion for the detection and localization of trauma-induced and postoperative bile leaks.

MATERIALS AND METHODS

Between October 2002 and December 2004, 7 patients with suspected bile duct leaks after trauma (n = 2) or surgery (n = 5) requiring morphological evaluation were included. MRI examination included single shot fast spin- echo T2 weighted and gradient echo T1 weighted images prior to and 112 minutes in average after IV administration of mangafodipir trisodium. The results of contrast enhanced MR cholangiography were correlated to surgery (n = 3), clinical course (n = 3) and percutaneous drainage (n = 1).

RESULTS

Mangafodipir trisodium-enhanced imaging showed extravasated Teslascan in collections in 6 patients (86%) whereas the combination of T2 weighted images and mangafodipir trisodium enhanced images revealed biliary collections in 7 patients (100%). The fistula between bile duct and collection was visualized in 4 patients (57%) before mangafodipir trisodium perfusion and in 3 patients (43%) after injection. In one patient the fistula was visible only after injection. Combination of both pre- and post injection MR correctly depicted the origin of bile leak in 5 cases (71%).

CONCLUSION

Mangafodipir trisodium-enhanced magnetic resonance cholangiography is a non invasive technique that can successfully detect the presence of bile duct leaks. The combination of T2 weighted MR cholangiography and mangafodipir trisodium-enhanced T1 weighted MR cholangiography increases the sensitivity in detection and localization of the site of bile leak.

Bile duct complications after liver transplantation

Complications involving the biliary tract after orthotopic liver transplantation (OLT) have been a common problem since the early beginning of this technique. Biliary complications have been reported to occur at a relatively constant rate of approximately 10-15% of all deceased donor full size OLTs. There is a wide range of potential biliary complications which can occur after OLT. Their incidence varies according to the type of graft, type of donor, and the type of biliary anastomosis performed. The spectrum of biliary complications has changed over the past decade because of the establishment of split liver, reduced-size, and living donor liver transplantation. Apart from technical developments, novel diagnostic methods have been introduced and evaluated in OLT, the most prominent being magnetic resonance imaging (MRI). Treatment modalities have also changed over the past years towards a primarily nonoperative, endoscopy-based strategy, leaving the surgical intervention for lesions which otherwise are not curable. The management of biliary complications after OLT requires a multidisciplinary approach. Conservative, interventional, and endoscopic treatment options have to be weighed up against surgical re-intervention. In the following the spectrum of specific bile duct complications after OLT and their treatment options will be reviewed.

Blunt trauma of the pancreas and biliary tract: a multimodality imaging approach to diagnosis

Injuries of the pancreas, gallbladder, and bile ducts due to blunt trauma are relatively uncommon and difficult to detect but are associated with high morbidity and mortality, especially if diagnosis is delayed. Accurate and early diagnosis is imperative, and imaging plays a key role in detection. Knowledge of the mechanisms of injury, the types of injuries, and the roles of various imaging modalities is essential for prompt and accurate diagnosis. Early recognition of disruption of the main pancreatic duct is important because such disruption is the principal cause of delayed complications. Computed tomography (CT) can demonstrate pancreatic parenchymal injuries and complications such as abscess, fistula, pancreatitis, and pseudocyst. CT findings can also suggest disruption of the pancreatic duct; however, the ability of CT to indicate this finding depends on the degree of parenchymal injury. Magnetic resonance (MR) cholangiopancreatography allows direct imaging of the pancreatic duct and sites of disruption. Gallbladder injuries can be detected with CT, ultrasonography, hepatobiliary scintigraphy, or MR cholangiopancreatography. CT findings include a collapsed gallbladder, wall thickening, inhomogeneous mural enhancement, and pericholecystic fluid. Bile duct injuries can be suggested with CT, which may show ascites and associated liver injuries, and can be confirmed with hepatobiliary scintigraphy.

MR Imaging of the Gallbladder and Biliary System

MR imaging is an established technique for the diagnosis of a spectrum of biliary and gallbladder pathologies and continues to improve with the advent of technologic advances, including new contrast agents and new sequences that are capable of improving upon the contrast resolution and signal-to-noise that are afforded by conventional MR imaging. These improvements already have shown promise for the increasing role of MRC as the initial modality in assessing living liver donors and evaluating post-operative hepato-biliary complications. Improved spatial resolution and the added functional or physiologic information afforded by MR imaging promise ever expanding clinical applicability and usefulness.

Early biliary complications of laparoscopic cholecystectomy: evaluation on T2-weighted MR cholangiography in conjunction with mangafodipir trisodium-enhanced 3D T1-weighted MR cholangiography

OBJECTIVE

Our aim was to assess preliminary experience with combined conventional T2-weighted and mangafodipir trisodium (MnDPDP)-enhanced T1-weighted MR cholangiography in evaluating early biliary complications of laparoscopic cholecystectomy.

SUBJECTS AND METHODS

Conventional heavily T2-weighted MR cholangiography with MnDPDP-enhanced T1-weighted MR cholangiography and ERCP were performed in seven patients with high clinical suspicion of biliary complications after laparoscopic cholecystectomy. The final diagnoses of complications were classified according to the presence and degree of bile duct injury, bile leakage, and retained stones.

RESULTS

The diagnoses on MR cholangiography were as follows: complete transection and occlusion of the common bile duct with bile leakage (n = 3), partial strictures of the common bile duct with bile leakage (n = 1), cystic duct leakage (n = 1), partial ligation of an aberrant right hepatic duct (n = 1), and hemorrhage without biliary complication (n = 1). The final diagnoses at surgery (n = 2) and ERCP (n = 5) were as follows: complete transection and occlusion of the common bile duct with bile leakage (n = 2), partial strictures of the common bile duct with bile leakage (n = 2), cystic duct leakage (n = 1), partial ligation of an aberrant right hepatic duct (n = 1), and hemorrhage without biliary complication (n = 1). MR cholangiography accurately yielded the same findings as the final diagnoses, except in one case with partial stricture of the bile duct with bile leakage (overdiagnosed as complete occlusion on MR cholangiography).

CONCLUSION

Combined conventional T2-weighted and MnDPDP-enhanced T1-weighted MR cholangiography may eliminate the use of other studies for the imaging of biliary complications after cholecystectomy if this preliminary data can be verified in a larger study.

Value of MR Cholangiography in Patients with Iatrogenic Bile Duct Injury After Cholecystectomy

OBJECTIVE

Our aim was to determine the diagnostic role of MR cholangiography in the evaluation of iatrogenic bile duct injuries after cholecystectomy.

SUBJECTS AND METHODS

Nineteen patients (14 women and five men; mean age, 47 years; age range, 24-75 years) with suspected bile duct injury as a result of laparoscopic cholecystectomy (17 patients) and open cholecystectomy (two patients) underwent MR cholangiography. MR images were evaluated for bile duct discontinuity, presence or absence of biliary dilation, stricture, excision injury, free fluid, and collections. Bile duct excision and stricture were classified according to the Bismuth classification. Final diagnosis was made on the basis of findings at surgery in 15 patients, on percutaneous transhepatic cholangiography (PTC) in one patient, and on endoscopic retrograde cholangiography (ERC) and at clinical follow-up until hospital discharge in the remaining three patients.

RESULTS

In 16 patients, injury of the bile duct was observed. Two patients had Bismuth type I injury; one patient, type II injury; 11 patients, type III injury; and one patient each, type IV and V injuries. Three patients showed findings suggestive of leakage from the cystic duct remnant, which were confirmed on ERC.

CONCLUSION

MR cholangiography is an accurate diagnostic technique in the identification of postoperative bile duct injuries. This technique allows exploration above and below the level of obstruction, a resource provided by neither ERC nor PTC, and allows the accurate classification of these injuries, which is essential for treatment planning.

Contrast-enhanced magnetic resonance cholangiography using mangafodipir compared with standard T2W MRC sequences: a pictorial essay

Mangafodipir, a manganese-containing hepatobiliary contrast agent, is excreted in bile. We review the principles and practice of a contrast-enhanced MRC technique using mangafodipir and compare it with standard T2-weighted magnetic resonance cholangiography (MRC) sequences. Potential applications include the evaluation of leaks and strictures; the assessment of drainage in normal, surgically by-passed, stented and obstructed biliary systems; the diagnosis of cholecystitis; and the evaluation of normal and variant biliary anatomy.

Magnetic Resonance Cholangiography With Mangafodipir Trisodium (Teslascan) to Evaluate Bile Duct Leaks After T-Tube Removal in Liver Transplantation

Liver transplant patients who present with abdominal pain after removal of the T-tube can be initially evaluated by contrast-enhanced magnetic resonance cholangiography (CEMRC) instead of abdominal computed tomography and hepatobiliary scintigraphy. In this article, 3 liver transplant patients who were evaluated by CEMRC after removal of the T-tube. CEMRC successfully identified the presence, location and extent of bile duct leaks, and can be performed as a diagnostic study in patients with suspected bile duct leaks.

Mangafodipir-enhanced magnetic resonance cholangiography for the diagnosis of bile duct leaks

BACKGROUND

The purpose of this prospective study was to assess the value of contrast-enhanced magnetic resonance cholangiography with mangafodipir trisodium perfusion for detection and localization of trauma-induced and postoperative bile duct leaks.

METHODS

Eleven patients with suspected bile duct leaks after trauma (n=5) or surgery (n=6) were included. Patients with suspected leaks after cholecystectomy were excluded. All patients underwent contrast-enhanced magnetic resonance cholangiography with two-dimensional axial and three-dimensional coronal gradient-echo images acquired 1 to 3 hours after intravenous administration of mangafodipir trisodium perfusion. Contrast-enhanced magnetic resonance cholangiography findings were correlated with direct cholangiography obtained in all patients, including endoscopic retrograde (n=7) and percutaneous transhepatic cholangiography (n=4).

RESULTS

Biliary tract enhancement was identified in all patients on contrast-enhanced magnetic resonance cholangiography. Peritoneal cavity fluid and bile collections that contained extravasated mangafodipir trisodium (increased signal intensity on gradient-echo sequences) were demonstrated in 6 patients. Direct cholangiography confirmed the presence of bile duct leaks in these 6 patients and the absence of bile duct leaks in 5 patients. There was no false-negative or false-positive contrast-enhanced magnetic resonance cholangiography.

CONCLUSIONS

Mangafodipir-enhanced magnetic resonance cholangiography is a noninvasive technique that can provide functional biliary information with excellent depiction of bile duct leaks.

Hepatobiliary contrast agents for contrast-enhanced MRI of the liver: properties, clinical development and applications

Hepatobiliary contrast agents with uptake into hepatocytes followed by variable biliary excretion represent a unique class of cell-specific MR contrast agents. Two hepatobiliary contrast agents, mangafodipir trisodium and gadobenate dimeglumine, are already clinically approved. A third hepatobiliary contrast agent, Gd-EOB-DTPA, is under consideration. The purpose of this review is to provide an overview on the properties, clinical development and application of these three hepatobiliary contrast agents. Bolus injectable paramagnetic hepatobiliary contrast agents combine established features of extracellular agents with the advantages of hepatocyte specificity. The detection and characterisation of focal liver disease appears to be improved compared to unenhanced MRI, MRI with unspecific contrast agents and contrast-enhanced CT. To decrease the total time spent by a patient in the MR scanner, it is advisable to administer the agent immediately after acquisition of unenhanced T1-w MRI. After infusion or bolus injection (with dynamic FS-T1-w 2D or 3D GRE) of the contrast agent, moderately and heavily T2w images are acquired. Post-contrast T1-w MRI is started upon completion of T2-w MRI for mangafodipir trisodium and Gd-EOB-DTPA as early as 20 min following injection, while gadobenate dimeglumine scans are obtained >60 min following injection. Post-contrast acquisition techniques with near isotropic 3D pulse sequences with fat saturation parallel the technical progress made by MSCT combined with an unparalleled improvement in tumour-liver contrast. The individual decision that hepatobiliary contrast agent one uses is partly based on personal preferences. No comparative studies have been conducted comparing the advantages or disadvantages of all three agents directly against each other.

Functional magnetic resonance cholangiography (fMRC) of the gallbladder and biliary tree with contrast-enhanced magnetic resonance cholangiography

PURPOSE

To determine the diagnostic performance of functional magnetic resonance cholangiography (fMRC) for the evaluation of anatomic and functional biliary disorders.

MATERIALS AND METHODS

At 1.5 T, 39 MR examinations with conventional MRC and mangafodipir trisodium-enhanced fMRC were retrospectively reviewed by three observers who recorded anatomic (duct dilation, stricture, filling defects) and functional (cholecystitis, obstruction) abnormalities in three modes: MRC alone, fMRC alone, and MRC and fMRC images together (combined-MRC). Performance was determined by comparing findings with each mode to findings of invasive cholangiography (IC) and surgery.

RESULTS

Among 75 biliary segments (correlated with IC), the sensitivity/specificity for diagnosing dilation (N = 41) with MRC was 95%/97%; with fMRC, 90%/100%; with combined-MRC, 100%/97%. For stricture (N = 7), the sensitivity/specificity of MRC was 86%/98%; of fMRC, 43%/100%; of combined-MRC, 86%/100%. For filling defects (N = 9), the sensitivity/specificity of MRC was 91%/98%; of fMRC, 82%/100%; of combined-MRC, 91%/100%. For diagnosing obstruction (N = 9), the sensitivity/specificity of MRC, fMRC, and combined-MRC were 89%/100%, 100%/100%, and 100%/100%, respectively. For surgically proven cholecystitis (N = 13), positive predictive values for diagnosing acute/chronic cholecystitis for MRC were 33%/40%; for fMRC, 100%/50%; for combined-MRC, 100%/50%.

CONCLUSION

Although single-shot fast spin echo (SSFSE)-MRC is valuable, the addition of fMRC increased diagnostic performance for functional biliary disorders.

MRCP in the diagnosis of iatrogenic bile duct injury

Postoperative biliary tract lesions are becoming increasingly common. The diagnosis is made by direct cholangiography via endoscopic retrograde cholangiopancreatography (ERCP) or percutaneous transhepatic cholangiography (PTC). The present comparative study evaluates the diagnostic efficacy of magnetic resonance cholangiopancreatography (MRCP) in application to iatrogenic bile duct injury. A prospective blind study was performed, contrasting MRCP and ERCP in 10 patients with suspected postoperative biliary tract lesions. MRCP was performed less than 72 h before ERCP. Final diagnosis was made on the basis of findings at surgery and ERCP. The presence of biliary dilatation, excision injury, stricture, fluid collection and free fluid was analyzed. The mean patient age was 66.5 years. There were three males and seven females. The type of postoperative lesion (Bergman classification) are five patients type C, three type D, one type B and one type A. Diagnostic failure was recorded in two cases with ERCP, while in five patients it was unable to define a therapeutic approach. In contrast, MRCP correctly diagnosed all patients. MRCP is effective in diagnosing postoperative biliary tract lesions, and can help decide the best therapeutic approach.

Acute cholecystitis at T2-weighted and manganese-enhanced T1-weighted MR cholangiography: preliminary study

Twelve patients with symptoms of acute cholecystitis underwent heavily T2-weighted and mangafodipir trisodium-enhanced T1-weighted magnetic resonance (MR) cholangiography and cholescintigraphy before they underwent cholecystectomy. On T2-weighted MR cholangiographic images, morphologic evidence of outflow obstruction of the gallbladder was definitive in seven patients, equivocal in one, and absent in four. In all 12 patients, biliary dynamics depicted at manganese-enhanced T1-weighted MR cholangiography agreed completely with those depicted at hepatobiliary scintigraphy. T2-weighted MR cholangiography combined with manganese-enhanced T1-weighted MR cholangiography provides not only morphologic information but also functional information about the biliary system.

Imaging the spectrum of biliary tract disease

An understanding of underlying biliary pathology and the corresponding subtle changes reflected at imaging can greatly improve imaging accuracy in evaluating the biliary tract. The optimal demonstration of biliary tract imaging findings requires attention to specific imaging and contrast techniques, regardless of the modality used.

Update on magnetic resonance cholangiopancreatography

MRCP is a useful tool in the diagnosis of a wide variety of pathologic entities including congenital anomalies, biliary obstruction and stricture, biliary calculi, pancreatitis, neoplasms, and trauma. ERCP and MRCP both have important roles in the management of patients with suspected pancreaticobiliary disease. Knowledge of the advantages and disadvantages of each technique is needed to determine the appropriate work-up of patients with these pathologies.

Using contrast-enhanced MR cholangiography with IV mangafodipir trisodium (Teslascan) to evaluate bile duct leaks after cholecystectomy: a prospective study of 11 patients

OBJECTIVE

The purpose of our study was to determine whether contrast-enhanced MR cholangiography using IV mangafodipir trisodium can accurately detect the presence and location of bile duct leaks in patients who have undergone cholecystectomy.

SUBJECTS AND METHODS

Our study group included 11 patients with suspected bile duct leaks after cholecystectomy. Axial single-shot fast spin-echo and gradient-echo images were acquired in all patients before and 1-2 hr after IV administration of mangafodipir trisodium. The contrast-enhanced MR cholangiograms were evaluated for image quality, degree of ductal or small bowel opacification, and the presence and location of bile duct leaks, strictures, and stones. MR cholangiograms were correlated with conventional contrast-enhanced cholangiograms obtained in all patients, including endoscopic retrograde cholangiography (n = 10) and percutaneous transhepatic cholangiography (n = 1).

RESULTS

Excretion of mangafodipir trisodium was noted in the intrahepatic and extrahepatic bile ducts in all patients from 1 to 2 hr after IV administration. Bile ducts and fluid collections that contained excreted mangafodipir trisodium showed increased signal intensity on gradient-echo sequences and decreased signal intensity on single-shot fast spin-echo sequences. Conventional contrast-enhanced cholangiography showed the presence of bile duct leaks in six patients and the absence of bile duct leaks in five patients, with false-negative findings in one patient and false-positive findings in one patient for bile duct leak (sensitivity, 86%; specificity, 83%).

CONCLUSION

Contrast-enhanced MR cholangiography with IV mangafodipir trisodium can successfully detect the presence and location of bile duct leaks in patients suspected of having such leaks after undergoing cholecystectomy. More research is necessary before acceptance of this examination as routine in the workup of these patients.

On the appearance of bile in clinical MR cholangiopancreatography

PURPOSE

To study the appearance of bile in clinical MR cholangiopancreatography (MRCP) with special reference to its chemical and physical properties.

MATERIAL AND METHODS

Gallbladder bile was collected during surgery from 38 patients and studied with respect to chemical constituents. The relaxation rates 1/T1 and 1/T2 of bile were also determined in vitro. In 16 of these 38 patients, abdominal imaging was performed using MRCP as well as T1-weighted GE sequences.

RESULTS

For 9 of the 13 chemical parameters studied, a positive significant correlation with 1/T1 as well as 1/T2 was found. The median relaxation rates 1/T1 and 1/T2 were 0.76 and 1.48 s-1, respectively. The corresponding ranges were 0.38-3.13 s-1 and 0.70-5.75 s-1, respectively. On the MRCP images a few patients showed gallbladder of poor visibility due to low signal-to-noise ratio. This coincided with a high relaxation rate 1/T2 of bile. On the T1-weighted GE sequences a few patients showed hyperintense gallbladder relative to liver, coinciding with high relaxation rates 1/T1 of bile.

CONCLUSION

Bile was found to show a large interindividual variation with respect to relaxation rates 1/T1 and 1/T2. The relaxation rates increased with increasing amounts of substances in the bile. For some patients (11%) MRCP imaging is unsuccessful due to high relaxation rate of bile.

Biliary Complications After Liver Transplantation

The incidence of biliary complications after liver transplant is estimated to be 8% to 20%. Post-liver transplant biliary complications may lead to acute and chronic liver injury. The early recognition and prompt treatment of such complications improves the long-term survival of the patient and graft. An understanding of the type of biliary reconstruction, the rationale for creating a particular anastomosis, and the technical difficulties in reconstructing the biliary tract are important in assessing and managing complications after liver transplant. Because the clinical presentation of these patients may be subtle, the physician must be aggressive and thoughtful in ordering and interpreting the diagnostic tests. Important points to remember are 1) that noninvasive examinations may fail to detect small obstructions or leaks, 2) a liver biopsy often is performed prior to cholangiography to exclude rejection and ischemia, and 3) the liver biopsy can miss an extrahepatic obstruction by misinterpreting portal inflammation as rejection. Biliary leaks and strictures are the most common biliary complications following liver transplant. Less common complications include ampullary dysfunction and stone/sludge formation. The effective management of biliary complications following a liver transplant depends on understanding the natural history, the prognosis, and the available therapeutic options for each type of complication.

The role of magnetic resonance cholangiopancreatography in patients with suspected biliary obstruction

Endoscopic retrograde cholangiopancreatography (ERCP) is an accepted and accurate procedure that combines the advantage of diagnosis of biliary obstruction with possible therapeutic endobiliary intervention. However, it is an operator-dependent and invasive procedure that is associated with complications and limitations. Magnetic resonance cholangiopancreatography (MRCP) is a unique noninvasive technique for the diagnosis of biliary obstruction. It is well suited to provide the information required to plan the optimal therapeutic approach for these patients. MRCP has the potential to replace or at least precede ERCP as the first-line imaging effort in the evaluation of suspected biliary obstruction. Significant advantages and some notable limitations inherent to the modality dictate its judicious use in appropriate circumstances. The present article reviews the utility of MRCP in evaluation of biliary obstruction, with brief reference to its principles and techniques.

Magnetic resonance imaging. Liver-specific contrast agents

MR imaging with new liver-specific contrast agents will probably be the imaging modality used in the future to detect focal liver lesions. The detection of HCC will probably be improved by using specific hepatobiliary agents, but the exact technique remains to be determined. New liver-specific contrast can differentiate some benign lesions from malignant ones and can assist in making a final diagnosis. In certain circumstances, liver-specific contrast agents can be used to evaluate hepatic vessels, the biliary tract, and hepatic function. New applications are also expected.

Contrast-enhanced magnetic resonance cholangiography versus heavily T2-weighted magnetic resonance cholangiography

RATIONALE AND OBJECTIVES

To investigate the feasibility of contrast-enhanced magnetic resonance cholangiography (CE-MRC) and compare it with single-shot turbo spin-echo magnetic resonance cholangiography (SSTSE-MRC).

METHODS

Fifteen patients with suspected metastatic liver disease (n = 10) or biliary tree abnormalities (n = 5) underwent a magnetic resonance imaging (1.5-T system) examination before and after mangafodipir administration. Contrast-enhanced MRC with a three-dimensional fast low-angle shot sequence after mangafodipir trisodium administration was compared with SSTSE-MRC. Four anatomic segments were evaluated: the intrapancreatic and extrapancreatic common bile duct segments, the cystic duct, and the area of hepatic bifurcation. Contrast-enhanced MRC and SSTSE-MRC were separately analyzed on a 5-point grading scale in terms of ductal segment visualization and lumen narrowing or dilatation.

RESULTS

There was no difference (P = 0.375) in segment visualization between CE-MRC and SSTSE-MRC; 56 of the 60 segments were visualized by both techniques. In the evaluation of ductal narrowing or dilatation, nonsignificant differences (P = 0.500) were observed. Contrast-enhanced MRC was not influenced by fluid superimposition and provided additional information from background tissues.

CONCLUSIONS

Contract-enhanced MRC is a feasible technique showing anatomic correlation with SSTSE-MRC, and it can in addition provide functional information. Contrast-enhanced MRC may be used in selected patients when traditional SSTSE-MRC is inconclusive.

Vascular and extravascular complications of liver transplantation: comprehensive evaluation with three-dimensional contrast-enhanced volumetric MR imaging and MR cholangiopancreatography

OBJECTIVE

Our purpose was to evaluate a comprehensive MR imaging strategy for recipients of liver transplants that relies on dynamic interpolated three-dimensional (3D) MR imaging for simultaneous vascular, parenchymal, and extrahepatic imaging.

MATERIALS AND METHODS

Twenty-three consecutive adult patients underwent 30 MR imaging examinations between 2 days and 99 months (mean, 15 months) after transplantation using a breath-hold 3D gradient-echo sequence (TR range/TE range, 3.7-4.7/1.8-1.9; flip angle, 12-30 degrees ) with an intermittent fat-saturation pulse and interpolation in the section-select direction to enable pixel size 3 mm or less in all dimensions. Unenhanced and triphasic contrast-enhanced 3D imaging (average dose, 0.13 mmol/kg of gadopentetate dimeglumine) was performed. A subset of patients (n = 13) also underwent MR cholangiopancreatography using half-Fourier single-shot turbo spin-echo imaging. MR imaging examinations were correlated with digital subtraction angiography (n = 8), contrast-enhanced cholangiography (n = 9), sonography (n = 13), and histopathology (n = 14).

RESULTS

MR imaging revealed abnormal findings in 27 (90%) of 30 examinations, including vascular disease in nine, biliary complications in four, and evidence of intra- or extra-hepatic hepatocellular carcinoma recurrence in six. Digital subtraction angiography confirmed seven MR angiography examinations but suggested disease overestimation in one. Contrast-enhanced cholangiography confirmed findings of MR cholangiopancreatography in seven cases but suggested disease underestimation in two.

CONCLUSION

Dynamic interpolated 3D MR imaging combined with dedicated MR cholangiopancreatography can provide a comprehensive assessment of vascular, biliary, parenchymal, and extrahepatic complications in most recipients of liver transplants.