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Gastrointestinal Imaging |
1 From the Department of Radiology, Universidad de Antioquia, Hospital Universitario San Vicente de Paúl, Medellín, Colombia. Received September 8, 2000; revision requested October 26; revision received January 3, 2001; accepted January 16. Address correspondence to J.E.L., Department of Radiology, Louisiana State University, 1542 Tulane Ave, New Orleans, LA 70112 (e-mail: jloper@lsuhsc.edu).
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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MATERIALS AND METHODS: Twenty-nine patients with malignant hilar and perihilar biliary obstruction were examined with MR cholangiography. Two radiologists evaluated MR images and determined the extent of biliary ductal involvement. A hypothetical plan for biliary drainage was established prior to any intervention. All patients underwent percutaneous cholangiography, and 27 of 29 patients also underwent biliary drainage and/or stent placement within 7 days after MR cholangiography. By using direct cholangiography as the standard of reference, the usefulness of MR cholangiography in defining the extent of biliary ductal involvement was determined. The type of drainage performed was compared with the type that had been anticipated at MR cholangiography.
RESULTS: MR cholangiography was adequate in helping predict the extent of biliary ductal involvement in 28 (96%) of 29 patients and led to underestimation of the extent of the disease in one patient. The therapeutic plan anticipated with MR cholangiography matched the one actually used in 24 (83%) of 29 patients.
CONCLUSION: The high accuracy of MR cholangiography for defining extent of ductal involvement in patients with malignant hilar and perihilar obstruction allows adequate planning of percutaneous interventions in a majority of patients.
Index terms: Bile duct radiography, 768.1226 • Bile ducts, interventional procedures, 768.1263, 768.1267 • Bile ducts, MR, 768.121411 • Bile ducts, neoplasms, 768.321, 768.323 • Bile ducts, stenosis or obstruction, 768.143 • Bile ducts, stents and prostheses, 768.1267
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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Accurate predrainage demonstration of the status of the biliary ducts and location and extent of the stricture would be beneficial to select patients who will benefit from a drainage procedure and to avoid invasive diagnostic procedures in patients with advanced complex strictures who are poor candidates for biliary drainage. Ultrasonography (US) and helical computed tomography (CT) are limited in their usefulness in helping to make these determinations (5–9). Although percutaneous transhepatic cholangiography and endoscopic retrograde cholangiopancreatography are the best methods for assessing biliary anatomy, injection of contrast medium through high-grade stenoses and subsequent drainage failure may result in severe complications such as cholangitis and sepsis (10).
In recent years, use of magnetic resonance (MR) cholangiography has increased steadily for many patients suspected of having biliary abnormalities (11–14). Ductal dilatation, strictures, stones, and anatomic variants are well depicted with this noninvasive imaging technique. MR cholangiography is well suited to provide the information required to plan the optimal therapeutic approach for these patients. The purpose of this study was to determine the usefulness of MR cholangiography in defining the extent of biliary ductal involvement in patients with malignant hilar and perihilar biliary obstruction and to evaluate whether findings at MR cholangiography alone are sufficient to plan percutaneous interventions in these patients.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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Histologic or cytologic proof of the type of tumor was available in patients with primary biliary ductal, hepatocellular, and gallbladder carcinoma. This proof was obtained by means of percutaneous biopsy (n = 11), surgery (n = 4), or endoscopic or percutaneous brushing (n = 6). Patients with metastatic lymphadenopathy had histologically proved extrahepatic primary tumors and imaging findings considered typical for hilar or periportal metastatic disease. On the basis of clinical, imaging, and/or surgical findings, tumors were considered nonresectable because of the degree of intrahepatic ductal involvement, presence of extrahepatic metastases, or vascular encasement or poor medical condition that precluded surgery. The study was approved by the investigations review board of our institution (Universidad de Antioquia, Hospital Universitario San Vicente de Paúl, Medellín, Colombia), and we obtained informed consent from all patients prior to MR examinations and biliary drainage.
MR Imaging
All MR cholangiograms were obtained with a 1.5-T imager (ACS-NT; Philips Medical Systems, Best, the Netherlands) by using the following sequences: non–breath-hold three-dimensional fast spin-echo with respiratory triggering and breath-hold single- and multisection half-Fourier rapid acquisition with relaxation enhancement (RARE) sequences. The three MR sequences were used in 16 patients; in 12 patients, only the breath-hold sequences were used; in the remaining patient, only the non–breath-hold sequence was used. The differences in MR cholangiographic techniques used are due to changes in the MR protocols during the study period, with increased use of non–breath-hold sequences with shorter imaging times.
Imaging parameters used for the three-dimensional fast spin-echo sequence were as follows: 2,000–2,300/240 (repetition time msec/effective echo time msec); partition thickness, 2 mm (40 partitions, eight slabs); two acquisitions; matrix, 186 x 256; echo train length, 39–43; echo spacing, 12 msec; nominal acquisition time, 5 minutes 40 seconds to 6 minutes 20 seconds. For the single-section half-Fourier RARE sequence, imaging parameters were as follows: 
/300; section thickness, 30 mm; one acquisition; matrix, 128 x 256; echo train length, 128; echo spacing, 9.9 msec; acquisition time, 2.5 seconds per section. Parameters used for the multisection half-Fourier RARE sequence were as follows: /290; section thickness, 5 mm; 10 sections; one acquisition; matrix, 128 x 256; echo train length, 128; echo spacing, 9 msec; acquisition time, 20 seconds. We applied a 65% partial k-space filling factor for both half-Fourier RARE sequences.
Image Interpretation
MR images were interpreted at an independent workstation (EasyVision; Phillips Medical Systems). All studies were interpreted by two radiologists (J.A.S., F.M.) by means of consensus. Both radiologists were fellowship trained in cross-sectional abdominal imaging and had experience with interpretation of hepatobiliary images. The radiologists were aware of the main clinical indication for performing the MR examination (ie, suspected biliary obstruction), but results of other diagnostic studies were withheld. At the workstation, the radiologists interpreted MR cholangiograms in an interactive manner. Images obtained with the three-dimensional fast spin-echo and multisection half-Fourier RARE sequences were postprocessed by using the maximum intensity projection algorithm. For interpretation of the MR studies, the radiologists evaluated the complete sets of source images and projectional renderings individually and/or in cine mode.
The radiologists determined the severity of biliary ductal involvement by using the classification proposed by Bismuth and Corlette (15). According to this classification system, type I obstruction occurs distal to the confluence of the right and left hepatic ducts (primary confluence), type II involves the primary confluence but not the secondary confluences, type III involves the primary confluence and either the right (type IIIA) or left (type IIIB) secondary confluence, and type IV involves the secondary confluence of the both the right and left hepatic ducts.
On the basis of MR cholangiographic findings, a hypothetical drainage plan was established by the radiologists (J.A.S., F.M.) who obtained the cross-sectional images and an interventional radiologist who was not involved in the biliary drainage procedures. For type I lesions, unilateral access to the biliary ductal system through a duct from either the right or the left lobe was considered appropriate. Type II lesions would be treated with bilateral drainage of the biliary ducts by using either a unilateral T-shaped access or a bilateral Y-shaped access. The left biliary ductal system for type IIIA lesions, or the right biliary ductal system for type IIIB lesions, was the primary target for drainage. However, for patients with cholangiocarcinoma and/or cholangitis, an aggressive approach with drainage of a majority of the dilated ducts was planned for internal brachytherapy and/or drainage of infected bile, respectively. For type IV lesions, unilateral or bilateral access was planned only if a dominant dilated duct was seen at MR cholangiography. For patients with advanced disease and extensive intrahepatic involvement and multiple isolated biliary ducts at percutaneous cholangiography, no drainage would be performed.
Percutaneous Transhepatic Cholangiography and Drainage
All patients underwent percutaneous transhepatic cholangiography, and 27 of 29 patients also underwent biliary drainage and/or stent placement 1–7 days (mean, 4.2 days) after MR cholangiography. Percutaneous interventions were performed by a fellowship-trained interventional radiologist (J.E.L.) who was blinded to MR cholangiographic findings. However, results of other imaging examinations such as US, CT, and/or endoscopic retrograde cholangiopancreatography were provided. The best access route for drainage was established by the interventional radiologist (J.E.L.) by using results of these imaging examinations, and the specific type of drainage procedure performed was established with percutaneous transhepatic cholangiographic findings. Drainage was performed after the patients had received general or epidural anesthetic. Patients received prophylaxis with broad-spectrum antibiotics. US guidance was used for puncture and access to the biliary ductal system when necessary.
After puncture and opacification of a dilated peripheral duct, biliary drainage was performed by using a coaxial system (Accustick; Boston Scientific, Natick, Mass). The stricture was traversed by using hydrophilic guide wires (Glidewire, Boston Scientific). For catheter drainage, 8.5- or 10-F internal-external drains (Ultrathane; Cook, Bloomington, Ind) were used. Metallic stents (Song Biliary Stent; Biomed, Medellín, Colombia) or plastic stents were placed when required. The technique for placing stents in a Y- or T-shaped configuration has been described previously (16,17). Any procedure-related complications were recorded by the interventional radiology service, and patients were followed up clinically with physical examination and/or telephone calls every 4 weeks after the biliary intervention. In addition, bilirubin levels were measured 4 weeks after the procedure.
We determined the usefulness of MR cholangiography in defining the extent of biliary ductal involvement by comparing MR cholangiographic findings with those of percutaneous cholangiography; the latter was considered the standard of reference. Percutaneous cholangiograms were interpreted by the radiologist (J.E.L.) who performed the procedure and who was unaware of MR cholangiographic findings. For determination of severity of biliary ductal involvement, the interventional radiologist used the same Bismuth classification system that had been used by the radiologists who obtained the cross-sectional MR cholangiograms. We also compared the specific type of drainage procedures performed in the patient population in our study with the type of procedures that would have been selected if MR cholangiograms had been used to plan drainage.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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All patients (n = 9) with MR cholangiograms showing a Bismuth type I obstruction underwent successful drainage with a unilateral approach, as initially planned. Owing to operator preference, biliary drainage was accomplished by means of a right lobe approach in these nine patients (Fig 1). Six of these patients were treated with a metallic stent (Fig 1), and three patients were treated with an internal-external drainage catheter only.
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One of the 11 patients with type IIIA obstruction was initially treated with unilateral (left side) drainage but developed cholangitis soon after the drainage procedure. He eventually required a bilateral Y-shaped configuration of metallic stents. In one of the 11 patients with type IIIA obstruction (a patient with periportal metastatic disease), a left-side approach was initially attempted, but it was technically unsuccessful; the patient was treated with a right drain only.
One patient with cholangiocarcinoma and type IV obstruction had a single dominant dilated duct in both lobes and was treated with bilateral drainage and stents with a Y-shaped configuration. Another patient with type IV obstruction had a single dominant duct and was treated with unilateral drainage of only the dilated duct in the right lobe. Conservative treatment, with no drainage, was preferred for the remaining two patients with type IV obstruction and advanced disease.
In summary, the type of palliative treatment that would have been performed on the basis of MR cholangiographic findings matched the one that was eventually performed in 24 (83%) of 29 patients: nine of nine patients with MR cholangiograms showing type I obstruction, two of five with type II obstruction, nine of 11 with type IIIA obstruction, and all four with type IV obstruction.
The mean total bilirubin level was 13.9 mg/dL (237.7 µmol/L; range, 6.9–31.8 mg/dL [118.0–543.8 µmol/L]) prior to biliary drainage procedures and 1.9 mg/dL (32.5 µmol/L; range, 1.0–5.4 mg/dL [17.1–92.3 µmol/L]) 4 weeks after biliary drainage. A reduction of 50% or more in bilirubin level was observed in 20 (74%) of 27 patients who underwent biliary drainage. The procedure was considered successful in these patients. Bilirubin levels decreased by less than 50% in the remaining six patients: two patients with type II, three patients with type IIIA, and one patient with type IV obstruction. There was one procedure-related death in a patient with periportal metastases and type I obstruction, who accidentally dislodged the biliary drain after he was discharged. The patient refused to be readmitted for therapy and died 2 days later; although the cause of death was not confirmed, we believe it was probably caused by massive peritoneal bleeding. Other procedure-related complications occurred in four other patients: cholangitis (n = 2), pleural biliary leak (n = 1), and peritoneal biliary leak (n = 1).
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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The type of palliative management provided for malignant hilar biliary obstruction depends on many factors, including the patient’s general condition, quality of life, life expectancy, and residual hepatic function (2). The approach is usually determined on an individual basis and depends on the location of the stricture and the extent of intrahepatic ductal involvement. For patients with type I obstruction, percutaneous or endoscopic drainage with a single stent is highly effective for relieving jaundice. For patients with type II, III, or IV obstruction, percutaneous drainage has a higher success rate and is associated with a lower risk of cholangitis than is use of a retrograde approach (1).
Several options exist for percutaneous drainage; these include draining only one ductal system, draining both systems through separate transhepatic tracts by using drains in a Y-shaped configuration, or draining both systems through a single transhepatic tract by using a T-shaped configuration (16,17,22). A single percutaneous access is used for lesions limited to the common hepatic duct when the obstruction is limited to one ductal system or when there is atrophy of the contralateral lobe (1). For lesions affecting the confluence of the hepatic ducts, there is controversy regarding the need for bilateral drainage. According to some authors (23), draining only 30% of the hepatic parenchyma (ie, a single lobe) will palliate the clinical and metabolic sequelae of biliary obstruction. Other authors (4,17,22), however, believe that draining both sides is necessary to provide adequate palliation and to prevent cholangitis in the side left without drainage.
Direct injection of iodinated contrast material into the biliary ducts with percutaneous transhepatic, endoscopic retrograde, or T-tube cholangiography (ie, direct cholangiography) is considered the best method for demonstrating the presence, site, and cause of biliary obstruction and for providing a road map for drainage procedures (24). Percutaneous transhepatic cholangiography is generally considered superior to endoscopic retrograde cholangiopancreatography for evaluation of the biliary ducts in hilar obstruction, especially when there is a complete obstruction of the biliary duct. However, incomplete opacification of intrahepatic ducts is not an uncommon event (25). Multiple projections with tilting and rolling of the patient are often necessary to improve the diagnostic accuracy of percutaneous transhepatic cholangiography (24). For patients with noncommunicating intrahepatic segments of the biliary tree, multiple punctures of individual ducts are necessary. Failure to opacify the biliary ducts after five or six punctures does not exclude biliary obstruction; in some cases, 15–20 punctures may be required (26).
Although percutaneous transhepatic cholangiography is considered safe, serious and even fatal procedure-related complications have been reported. The rate of serious complications after percutaneous transhepatic cholangiography varies between 3.4% and 4.8% (26). For patients with high-grade stenoses, drainage failure after injection of contrast material may result in cholangitis and severe sepsis (27,28). Given the limitations and complications associated with direct cholangiography, it would be useful to have a noninvasive test that can provide an accurate map of the biliary tract. Such a test would result in adequate planning of percutaneous drainage in these patients. US and helical CT have considerable limitations for estimation of the magnitude of malignant hilar strictures. Underestimation of disease occurs commonly owing to failure to detect nonunion of intrahepatic ductal branches (5–9).
MR cholangiography is now commonly used as a noninvasive diagnostic tool in many patients suspected of having biliary and pancreatic disorders (11–14). For patients with neoplastic obstruction of the biliary ducts, MR cholangiography can be used to establish the presence and severity of biliary and pancreatic ductal dilatation, as well as the exact location of the obstructing lesion (10,14). However, it is not clear whether this test alone is sufficient to define the severity of biliary ductal involvement and, specifically, the proximal extent of the strictures. A detailed definition of the extent and severity of biliary ductal involvement is necessary to adequately plan biliary drainage procedures in patients with malignant hilar obstruction.
In our study, MR cholangiography proved highly accurate for defining the extent of hilar and perihilar biliary ductal involvement. By using direct cholangiography as the standard of reference, MR cholangiography was adequate in helping predict the Bismuth grade of biliary ductal involvement in 96% (28 of 29) of the patients in our study. In one patient with type IIIA obstruction at direct cholangiography, the MR cholangiogram was interpreted as showing type II obstruction. This underestimation resulted from failure to recognize an obstructed noncommunicating right hepatic ductal branch at MR cholangiography.
Similar good results were reported by Zidi et al (10) and Yeh et al (29). In the study by Zidi et al (10), MR cholangiography was compared with endoscopic retrograde cholangiopancreatography in patients with hilar strictures; MR cholangiography enabled correct classification of the severity of involvement in 14 (78%) of 18 patients and led to underestimation of tumor extension in four (22%) patients. The usefulness of MR cholangiography in accurate demonstration of the extent of hilar involvement in these patients has important implications for therapeutic planning (10).
In the population in our study, the type of therapy provided matched the one that had been anticipated in 24 (83%) of 29 patients when only findings at MR cholangiography were used. For patients with type I obstructions, MR cholangiograms enabled prediction of a successful unilateral approach with a single drain or stent. For patients with type II, IIIA, or IV obstruction, drainage of one, two, or more biliary ducts with one or multiple punctures was anticipated, depending primarily on the underlying diagnosis, presence of cholangitis, and severity of intrahepatic ductal involvement.
For example, in patients with type IIIA obstruction in whom the single left hepatic duct was drained (ie, patients without cholangiocarcinoma or complicating cholangitis), MR cholangiographic findings could have precluded multiple punctures of isolated right ductal branches, thereby decreasing the time of the procedure and the risk of complications. Patients with type IIIA strictures and cholangiocarcinoma or cholangitis still require bilateral punctures for brachytherapy and drainage of infected bile, respectively. For these patients, in whom multiple punctures are necessary on the basis of MR cholangiographic findings, the length of the procedure and associated risks of such an aggressive approach can be anticipated. MR cholangiography could also be useful for planning technical aspects of drainage, such as proper placement of the patient on the table when puncture of the left ductal branches is anticipated; this reduces radiation exposure to the operator’s hands (30).
Enabling demonstration of anatomic variants is important, since some of these variants have important implications for percutaneous access and drainage planning (31). For example, in one of the patients included in our study, the right posterior duct drained directly into the left hepatic duct, and a left ductal approach resulted in drainage of larger volumes of the liver. MR cholangiography may demonstrate advanced disease and complex involvement of multiple ductal branches, such that a decision to not drain and treat conservatively may be made with confidence without unnecessary invasive procedures (10). This occurred in two patients in our series.
Limitations of our study include the fact that MR cholangiograms were interpreted by two radiologists by means of consensus. Independent interpretations with determination of interobserver agreement would have been preferable. Also, although our results suggest that MR cholangiography has the capability of decreasing the time of the drainage procedures and the number of punctures, this remains to be proved, since we did not actually record these data.
In summary, our results indicate that MR cholangiography is adequate in helping to define the extent of biliary ductal involvement in patients with malignant hilar and perihilar biliary obstruction and unresectable disease. On the basis of MR cholangiographic findings, a management strategy can be planned, including selection of the most appropriate side for access to the biliary ductal system and the type of biliary drainage required. MR cholangiograms alone can be used for planning palliative percutaneous therapy in these patients. However, the decision to drain one or more biliary ducts or, when necessary, to not drain, should be made on an individual basis and depends on the general condition of the patient, underlying diagnosis, residual hepatic function, presence of cholangitis, and extent of biliary obstruction.
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FOOTNOTES |
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Author contributions: Guarantor of integrity of entire study, J.E.L.; study concepts, J.E.L., J.A.S., F.M.; study design, J.E.L., J.A.S.; literature research, J.E.L., J.A.S.; clinical studies, J.E.L., J.A.S., F.M.; data acquisition, J.E.L., J.A.S., F.M.; data analysis/interpretation, J.E.L., J.A.S.; manuscript preparation, J.E.L., J.A.S.; manuscript definition of intellectual content, J.E.L., J.A.S., F.M.; manuscript editing, J.E.L., F.M.; manuscript revision/review and final version approval, J.E.L., J.A.S.
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REFERENCES |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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