Assessment of pancreatic parenchymal invasion by bile duct cancer using intraductal ultrasonography

Recent Advancement in Diagnosis of Biliary Tract Cancer through Pathological and Molecular Classifications

Biliary tract cancers (BTCs), including intrahepatic, perihilar, and distal cholangiocarcinomas, as well as gallbladder cancer, are a diverse group of cancers that exhibit unique molecular characteristics in each of their anatomic and pathological subtypes. The pathological classification of BTCs compromises distinct growth patterns, including mass forming, periductal infiltrating, and intraductal growing types, which can be identified through gross examination. The small-duct and large-duct types of intrahepatic cholangiocarcinoma have been recently introduced into the WHO classification. The presentation of typical clinical symptoms, as well as the extensive utilization of radiological, endoscopic, and molecular diagnostic methods, is thoroughly detailed in the description. To overcome the limitations of traditional tissue acquisition methods, new diagnostic modalities are being explored. The treatment landscape is also rapidly evolving owing to the emergence of distinct subgroups with unique molecular alterations and corresponding targeted therapies. Furthermore, we emphasize the crucial aspects of diagnosing BTC in practical clinical settings.

Endoscopic Perspective in Cholangiocarcinoma Diagnostic Process

Cholangiocarcinoma is a malignancy arising from the epithelial lining of the intrahepatic or extrahepatic biliary tract. Timely diagnosis is challenging due to its silent clinical course. As reliable laboratory markers are lacking, diagnostic imaging plays a pivotal role. While cross-sectional imaging studies are usually conclusive for intrahepatic lesions, endoscopy plays an essential role in cases of extrahepatic tumors. Rational utilization of different diagnostic methods based on available evidence is needed. This article focuses on the diagnostic role of advanced biliary endoscopy, including endoscopic retrograde cholangiopancreatography, cholangioscopy, endoscopic ultrasonography, and intraductal sonography.

Asia-Pacific consensus recommendations for endoscopic and interventional management of hilar cholangiocarcinoma

Hilar cholangiocarcinoma (HCCA) is one of the most common types of hepatobiliary cancers reported in the world including Asia-Pacific region. Early HCCA may be completely asymptomatic. When significant hilar obstruction develops, the patient presents with jaundice, pale stools, dark urine, pruritus, abdominal pain, and sometimes fever. Because no single test can establish the definite diagnosis then, a combination of many investigations such as tumor markers, tissue acquisition, computed tomography scan, magnetic resonance imaging/magnetic resonance cholangiopancreatography, endoscopic ultrasonography/intraductal ultrasonography, and advanced cholangioscopy is required. Surgery is the only curative treatment. Unfortunately, the majority of HCCA has a poor prognosis due to their advanced stage on presentation. Although there is no survival advantage, inoperable HCCA managed by palliative drainage may benefit from symptomatic improvement. Currently, there are three techniques of biliary drainage which include endoscopic, percutaneous, and surgical approaches. For nonsurgical approaches, stent is the most preferred device and there are two types of stents i.e. plastic and metal. Type of stent and number of stent for HCCA biliary drainage are subjected to debate because the decision is made under many grounds i.e. volume of liver drainage, life expectancy, expertise of the facility, etc. Recently, radio-frequency ablation and photodynamic therapy are promising techniques that may extend drainage patency. Through a review in the literature and regional data, the Asia-Pacific Working Group for hepatobiliary cancers has developed statements to assist clinicians in diagnosing and managing of HCCA. After voting anonymously using modified Delphi method, all final statements were determined for the level of evidence quality and strength of recommendation.

Endoscopic diagnosis of extrahepatic bile duct carcinoma: Advances and current limitations

The accurate diagnosis of extrahepatic bile duct carcinoma is difficult, even now. When ultrasonography (US) shows dilatation of the bile duct, magnetic resonance cholangiopancreatography followed by endoscopic US (EUS) is the next step. When US or EUS shows localized bile duct wall thickening, endoscopic retrograde cholangiopancreatography should be conducted with intraductal US (IDUS) and forceps biopsy. Fluorescence in situ hybridization increases the sensitivity of brush cytology with similar specificity. In patients with papillary type bile duct carcinoma, three biopsies are sufficient. In patients with nodular or infiltrating-type bile duct carcinoma, multiple biopsies are warranted, and IDUS can compensate for the limitations of biopsies. In preoperative staging, the combination of dynamic multi-detector low computed tomography (MDCT) and IDUS is useful for evaluating vascular invasion and cancer depth infiltration. However, assessment of lymph nodes metastases is difficult. In resectable cases, assessment of longitudinal cancer spread is important. The combination of IDUS and MDCT is useful for revealing submucosal cancer extension, which is common in hilar cholangiocarcinoma. To estimate the mucosal extension, which is common in extrahepatic bile duct carcinoma, the combination of IDUS and cholangioscopy is required. The utility of current peroral cholangioscopy is limited by the maneuverability of the “baby scope”. A new baby scope (10 Fr), called “SpyGlass” has potential, if the image quality can be improved. Since extrahepatic bile duct carcinoma is common in the Far East, many researchers in Japan and Korea contributed these studies, especially, in the evaluation of longitudinal cancer extension.

Intraductal ultrasonography (IDUS) for the diagnosis of biliopancreatic diseases

Intraductal ultrasonography (IDUS) is an imaging modality having unique characteristics and suitable for imaging of a narrow ductal cavity, its wall and the neighbouring structures. As IDUS uses high-frequency ultrasound (12-30MHz), its image quality is very high within approximately 2-cm range of radius. The bile duct and the pancreatic duct, therefore, are good targets for the assessment by IDUS. Biliopancreatic IDUS is mainly performed through the papilla of Vater in the same session as endoscopic retrograde cholangiopancreatography (ERCP). Biliary IDUS is possible through the percutaneous transhepatic route as well. Not many comparative studies on biliopancreatic IDUS have been published. Gallbladder IDUS as well as most pancreatic IDUS are still at the level of clinical research. Constant delineation of Oddi's sphincter with the improvement of instruments will expand the use of IDUS for the assessment of the papilla of Vater lesions.

Evaluation of normal bile duct and cholangitis by intraductal ultrasonography

BACKGROUND

The intraductal ultrasonographic findings of normal bile duct and cholangitis were examined.

METHODS

We studied 9 autopsy cases and evaluated the clinical records of 76 patients who had been subjected to papillotomy for bile duct stones removal retrospectively.

RESULT

In vitro study: Under a low pressure, the bile duct wall was thick, and the inner surface and outer contour were irregular. The wall became thinner, and the inner surface and outer contour became smooth as the pressure was increased. The thickness was 0.68 +/- 0.12 mm (mean +/- SD) all along the duct at all pressure, and 0.55 +/- 0.12 mm at a pressure above 15 cm H(2)O. The internal echo was homogenous regardless of the internal pressure used. In vivo study: We could evaluate in 70 patients (92.1%). The wall was 1.30 +/- 0.77 mm thick. There was no relationship between the severity of cholangitis and the wall thickness. The irregular inner surface, heterogeneous internal echo, and irregular outer contour correlated with the severity of cholangitis.

CONCLUSION

The normal bile duct wall was between 0.31 and 0.79 mm thick, the inner and outer surfaces were smooth, and internal echo was homogenous. An irregular inner surface, heterogeneous internal echo and an irregular outer contour were important findings of severe cholangitis.

Nonoperative imaging techniques in suspected biliary tract obstruction

Evaluation of suspected biliary tract obstruction is a common clinical problem. Clinical data such as history, physical examination, and laboratory tests can accurately identify up to 90% of patients whose jaundice is caused by extrahepatic obstruction. However, complete assessment of extrahepatic obstruction often requires the use of various imaging modalities to confirm the presence, level, and cause of obstruction, and to aid in treatment plan. In the present summary, the literature on competing technologies including endoscopic retrograde cholangiopancreatography (ERCP), percutaneous transhepatic cholangiopancreatography (PTC), endoscopic ultrasound (EUS), intraductal ultrasonography (IDUS), magnetic resonance cholangiopancreatography (MRCP), helical CT (hCT) and helical CT cholangiography (hCTC) with regards to diagnostic performance characteristics, technical success, safety, and cost-effectiveness is reviewed. Patients with obstructive jaundice secondary to choledocholithiasis or pancreaticobiliary malignancies are the primary focus of this review. Algorithms for the management of suspected obstructive jaundice are put forward based on current evidence. Published data suggest an increasing role for EUS and other noninvasive imaging techniques such as MRCP, and hCT following an initial transabdominal ultrasound in the assessment of patients with suspected biliary obstruction to select candidates for surgery or therapeutic ERCP. The management of patients with a suspected pancreaticobiliary condition ultimately is dependent on local expertise, availability, cost, and the multidisciplinary collaboration between radiologists, surgeons, and gastroenterologists.

Cholangiocarcinoma and intraductal sonography

The instruments and processing systems of intraductal ultrasonography (IDUS) and 3D-IDUS are developing. IDUS is a reliable method for the evaluation of cholangiocarcinoma, and accurate staging is the most significant role of IDUS. DPR images produced by 3D-IDUS are useful to assess the tumor extension and the relationship with surrounding organs. 3D-IDUS is more useful for the precise diagnosis of cancer extension in cholangiocarcinoma, especially in invasion into the portal vein and pancreas, than CT scan and angiography. Tumor volume calculated with 3D-IDUS should determine the prognosis for the patients and facilitate the evaluation of efficacy of laser therapy.

Catheter-based intraluminal sonography

With the development of interventional and minimally invasive surgical techniques in the last decade, a strong interest in intraluminal sonography has arisen because of the need for better imaging information and management of the interventional procedure. High-resolution intraluminal sonography is a unique approach for the evaluation of a wide range of abnormalities within the luminal structures throughout the body. This imaging technique has been able to obtain information not available with even the most sophisticated percutaneous sonography, CT, or MRI. The uniqueness of this approach has led to extensive research, establishing a variety of clinical applications. These miniature catheter-based transducers have become important supplemental tools in the evaluation of the urinary and gastrointestinal tracts. Other areas need to be evaluated more thoroughly before efficacy is established, but the concept of using miniature transducers has shown promise in many areas of the body. This should lead to the provision of important information for decision making relative to patient care and surgical intervention. In the future, with projected technical progress, intraluminal sonography should substantially improve its diagnostic capabilities.

[Diagnosis of biliary tract carcinoma]

There are several diagnostic tools available in the diagnosis of bile duct cancer. Tumors of the middle and distal part of the extrahepatic bile duct are accessible to endosonography. Endoscopic retrograde cholangiopancreatography (ERC) and percutaneous transhepatic cholangiography (PTC) are the most invasive procedures for diagnosis of bile duct cancer. However, they offer the opportunity to obtain material for cytological or histological investigation. Moreover, bile flow can be assured by inserting endoprostheses during the procedure. Cholangioscopy and/or intraductal ultrasonography can be performed during ERC. They confer to the diagnosis of a malignant bile duct tumor and are the most accurate methods to diagnose the extent of longitudinal spread. Magnetic resonance imaging-cholangiography is an efficient diagnostic procedure which should be used first, if the bile duct tumor is located in the hilar region.

Evaluation of indeterminate bile duct strictures by intraductal US

BACKGROUND

Cholangiography and tissue sampling (brush cytology, biopsy) are the standard nonsurgical techniques for determining whether a bile duct stricture is benign or malignant. The aim of this study was to determine whether intraductal US is of assistance in distinguishing benign from malignant biliary strictures.

METHODS

A retrospective review was undertaken of 30 patients with indeterminate bile duct strictures who underwent ERCP and tissue sampling from September 1999 to November 2000. A 20 MHz over-the-guidewire intraductal US catheter probe was used during ERCP for further examination of the strictures. Final diagnoses of malignant strictures (18 patients) were confirmed histopathologically; confirmation of benign stricture (12 patients) was based on negative tissue sampling plus extended clinical follow-up.

RESULTS

Based on retrospective blinded review, the diagnosis by ERCP was correct in 67% of patients, by tissue sampling in 68%, by combined ERCP/tissue sampling in 67%, and by intraductal US in 90% (p = 0.04 vs. ERCP/tissue sampling) of cases. No complication of intraductal US or ERCP was recorded.

CONCLUSIONS

Intraductal US is safe and can improve on the ability at ERCP to distinguish benign from malignant biliary strictures.

Endoluminal sonography of the genitourinary and gastrointestinal tracts

OBJECTIVE

Endoluminal sonography with high-frequency catheter-based transducers is a technique well suited to imaging structures beyond the lumen of the hollow viscus. The purpose of this article was to review some aspects of endoluminal sonography, including instrumentation, clinical applications in the gastrointestinal and genitourinary tracts, and its three-dimensional reconstruction.

METHODS

The development of 6F to 10F catheter-based ultrasonic probes has made this technique available for use within a variety of lumina. Endoluminal sonography with frequencies of 9 to 20 MHz has been used for evaluation of a wide range of abnormalities in both the genitourinary and gastrointestinal tracts.

RESULTS

Uses in the gastrointestinal tract include quantification of esophageal varices, distinguishing between various submucosal lesions, and measuring the degree of fibrosis in scleroderma. In the genitourinary system, endoluminal sonography has been used to guide collagen injection, to diagnose urethral diverticula and upper tract neoplasms, to locate crossing vessels and septa for guiding endopyelotomy, and to identify submucosal calculi.

CONCLUSIONS

High-resolution endoluminal sonography is a new sonographic approach for evaluation of the genitourinary and gastrointestinal tracts. This should lead to the expansion of the diagnostic capabilities of sonography, providing important information for decision making relative to patient care and minimally invasive interventional procedures. Reconstructed three-dimensional endoluminal sonography has the potential to become a valuable tool in both the research and clinical areas.

The role of endoscopic ultrasound in hepatobiliary disease

The evaluation of hepatobiliary disease continues to change as new technologies are introduced. One of the more recent advances in hepatobiliary imaging has been the application of endoscopic ultrasound (EUS). Endoscopic retrograde cholangiopancreatography, computed tomography, conventional ultrasound, and magnetic resonance imaging were previously the primary means of evaluating hepatobiliary disease. The role of EUS as both a substitute and a complement for these historical imaging modalities continues to evolve. This review examines the current literature on EUS in the evaluation of hepatobiliary diseases, including choledocholithiasis, microlithiasis, biliary strictures, obstructive jaundice, cholangiocarcinoma, gallbladder polyps, and liver lesions.

Intraductal ultrasonography for hepatocellular carcinoma with tumor thrombi in the bile duct: comparison with polypoid cholangiocarcinoma

BACKGROUND AND AIM

Tumor thrombi in the bile duct caused by hepatocellular carcinoma (HCC), and cholangiocarcinoma show polypoid lesions on cholangiographic findings. This study prospectively compared the images of intraductal ultrasonography between HCC and polypoid cholangiocarcinoma.

METHODS

In five patients with tumor thrombi in the bile duct caused by HCC, a 2.0 mm diameter ultrasonic probe with a frequency of 20 MHz was inserted into the bile duct via the transpapillary route (n = 4) or the transhepatic route (n = 1). The images were compared to that of 65 patients with cholangiocarcinoma.

RESULTS

In all patients with HCC, intraductal ultrasonography showed a 'polypoid tumor with a narrow base'. In 16 of 65 patients with cholangiocarcinoma, it showed a 'polypoid tumor with a narrow base'. When intraductal ultrasonography showed a 'polypoid tumor with a narrow base', the findings of a positive 'nodule within a nodule' (40 vs 0%; P < 0.05), and the absence of a 'papillary-surface pattern' (80 vs 13%; P < 0.05) were more highly associated with tumor thrombi caused by HCC than to polypoid-type cholangiocarcinoma.

CONCLUSIONS

Intraductal ultrasonography was useful to distinguish between tumor thrombi caused by HCC and polypoid-type cholangiocarcinoma.

Intraductal ultrasound in the biliary tract

Although endoscopic ultrasonography (EUS) represents a major advance in endoscopic imaging, endosonography using dedicated echoendoscopes has some serious drawbacks, including the diameter of the echoendoscope (12 to 13 mm), the lack of intraluminal examination of the pancreatobiliary duct system due to the size of the instrument, unsatisfactory image quality and resolution for small lesions, and the need for a second examination separate from the previous routine endoscopy. Recently developed ultrasonographic miniprobes (diameter, about 2 mm; frequency, 12 to 20 MHz) can be passed through the working channel of standard endoscopes to provide high-frequency ultrasound images. These miniprobes may overcome some of the noted drawbacks and add to the safety and convenience of patients. Moreover, in various diseases of the gastrointestinal tract and the pancreatobiliary ductal system, the diagnostic accuracy of miniprobe ultrasonography has been proven to be superior to that of EUS. Miniprobe ultrasonography is a promising tool that adds new capabilities to the armamentarium of gastroenterologic diagnostic assessment.

Multiple bile duct biopsies using a sheath with a side port: usefulness of intraductal sonography

OBJECTIVE

We clarified the number of biopsies required to determine malignancy of the biliary tract on the basis of the type of bile duct tumor.

SUBJECTS AND METHODS

Patients with a biliary tract malignancy (n = 33) and a benign biliary stenosis (n = 3) underwent biopsy via the percutaneous transhepatic route. We performed intraductal sonography using a 20-MHz probe with a 2.0-mm diameter. The sonographic findings were prospectively classified as polypoid, circular, or semicircular. The tip of a long 9-French sheath with a side port was wedged into the stenosis, and six specimens were obtained with a 1.8-mm-diameter forceps with serrated cups.

RESULTS

When cholangiography or intraductal sonography showed a polypoid lesion, the sensitivity of two biopsies was 100% (6/6). When cholangiography showed a stenotic lesion, the sensitivity of nine biopsies (96%, 26/27) was superior to that of two biopsies (74%, 20/27; p < 0.05). When intraductal sonography showed a circular lesion, the sensitivity of three biopsies (100%, 14/14) was superior to that of a single biopsy (64%, 9/14; p < 0.05). When it showed a semicircular lesion, the sensitivity of nine biopsies (92%, 12/13) was superior to that of two biopsies (54%, 7/13; p < 0.05).

CONCLUSION

Bile duct biopsy using a sheath with a side port has a high sensitivity. However, the number of biopsies required depends on the cholangioscopic and intraductal sonographic appearance of the tumor.

Transpapillary intraductal US prior to biliary drainage in the assessment of longitudinal spread of extrahepatic bile duct carcinoma

BACKGROUND

The utility of intraductal US via the transpapillary route prior to biliary drainage in the assessment of longitudinal extension of extrahepatic bile duct carcinoma was investigated.

METHODS

In 19 patients with extrahepatic bile duct carcinoma who underwent surgical resection, an ultrasonic probe (diameter, 2.0 mm; frequency, 20 MHz) was inserted into the bile duct via the transpapillary route prior to biliary drainage. Longitudinal cancer extension along the bile duct was prospectively determined and compared with the histologic findings in the resected specimens.

RESULTS

Results on the hepatic side were as follows: Intraductal US demonstrated more extensive longitudinal cancer spread than cholangiography in 9 of 19 patients with one instance of overdiagnosis. The accuracy of intraductal US in assessing the extent of spread (84%) was superior to that of cholangiography (47%) (p < 0.05). Results on the duodenal side were as follows: In patients with suprapancreatic bile duct cancer (n = 14), intraductal US demonstrated more extensive longitudinal cancer spread than cholangiography in 8 of 14 patients. The accuracy of intraductal US in assessing the extent of the spread (86%) was superior to that of cholangiography (43%) (p < 0.05).

CONCLUSIONS

Transpapillary intraductal US prior to biliary drainage is useful in demonstrating longitudinal extension of bile duct cancer. However, the surgical margins were inaccurate in some patients.

Comparison of intraductal ultrasonography with percutaneous transhepatic cholangioscopy for the identification of residual bile duct stones during lithotripsy

BACKGROUND

An imaging modality that can be used to identity small stones after a biliary lithotripsy is required. Intraductal ultrasonography was evaluated by using percutaneous transhepatic cholangioscopy as the gold standard.

METHODS

Lithotripsy, under percutaneous transhepatic cholangioscopy guidance, was performed in 20 patients. A thin-caliber ultrasonic probe (2.0 mm in diameter and 20 MHz frequency) was inserted into the bile duct through the percutaneous tract after lithotripsy, and residual stones were identified. This was followed by percutaneous transhepatic cholangioscopy.

RESULTS

In the extrahepatic bile ducts, intraductal ultrasonography provided images of all the stones demonstrated on cholangioscopy (n = 11). The sensitivity was superior to that of cholangiography (P < 0.005). However, in the intrahepatic bile ducts, intraductal ultrasonography only visualized the stones located in the cannulated lobe. Extrahepatic stones smaller than 5.0 mm in diameter or in a common hepatic duct larger than 15.0 mm in diameter were missed by cholangiography, but were visualized by the use of intraductal ultrasonography (P < 0.05).

CONCLUSIONS

Intraductal ultrasonography is equivalent to cholangioscopy in the extrahepatic bile ducts. Cholangiography and intraductal ultrasonography should be used in combination to image intrahepatic and extrahepatic stones.

Intraductal US in assessing the effects of radiation therapy and prediction of patency of metallic stents in extrahepatic bile duct carcinoma

BACKGROUND

We assessed the local effects of radiation therapy using intraductal ultrasonography (US) to predict the subsequent patency of metallic stents in bile duct carcinoma.

METHODS

Data from 16 patients with extrahepatic-suprapancreatic bile duct carcinoma were prospectively analyzed. Thin-caliber US probes (2.0 mm diameter/20 MHz frequency and 2.8 mm diameter/10 MHz frequency) were inserted into the bile duct via a percutaneous transhepatic approach pre- and postradiation therapy to evaluate the effects of treatment. When intraductal US showed a reduction in bile duct wall thickness of 30% or greater or showed a lessening of vessel (portal vein or right hepatic artery) invasion, radiation therapy was judged to be effective. Noncovered metallic stents were then inserted, and their patency was evaluated over time.

RESULTS

When radiation therapy was effective (n = 7), the metallic stent was patent for 522 +/- 571 days. When radiation was ineffective (n = 9), the metallic stent was patent for only 188 +/- 159 days. When radiation therapy was ineffective, stent obstruction occurred in 6 of 9 (66.7%) patients during this period, significantly more frequently than when radiation therapy was effective (14.3%, p < 0.05).

CONCLUSIONS

Assessment of local radiation effects by intraductal US is useful for predicting patency of metallic stents in bile duct cancer.

Gastrointestinal miniprobe sonography: the current status

Endoscopic ultrasonography (EUS) represents a major advance in endoscopic imaging. The usefulness and effectiveness of EUS have been established during the past few years. However, endosonography using dedicated echoendoscopes (7.5/12 MHz) has some serious drawbacks, as follows: 1) Combining endoscopy and ultrasonography in one instrument increases the diameter of such echoendoscopes (12-13 mm); 2) Because of the large diameter, complete passage of severe strictures is often not possible and, for examination of the pancreatobiliary duct system, is not feasible at all; 3) Image quality and resolution for small lesions is not always satisfactory; and 4) Conventional endosonography requires a second examination separate from the previous routine endoscopy. Recently developed ultrasonographic miniprobes (diameters about 2 mm; frequencies 12-20 MHz) can be passed through the working channel of standard endoscopes to provide high frequency ultrasound images. These miniprobes might overcome some of the above-mentioned drawbacks and contribute to patients' security and convenience. Moreover, in various diseases of the GI tract and the pancreatobiliary duct system, diagnostic accuracy of miniprobe ultrasonography has been shown to be even superior to that of EUS. In summary, miniprobe ultrasonography seems to be a promising tool in the armamentarium of gastroenterological diagnostics.

Preoperative diagnosis of bile duct strictures--comparison of intraductal ultrasonography with conventional endosonography

BACKGROUND

The accuracy of intraductal ultrasonography (IDUS) and endoscopic ultrasonography (EUS) were compared in diagnosing biliary obstruction and in predicting surgical resectability.

METHODS

Fifty-six patients with biliary obstruction were investigated preoperatively with both conventional EUS and IDUS. The ultrasonographic miniprobe was inserted into the bile duct system through the working channel of the duodenoscope during endoscopic retrograde cholangiopancreatography (ERCP). Conventional endosonography was performed with echoendoscopes in a standard technique. Images of endoluminal ultrasonography were prospectively reviewed and compared with intraoperative findings and resection specimen analyses.

RESULTS

IDUS exceeded EUS in terms of accuracy (IDUS, 89.1%; EUS, 75.6%; P < 0.002), sensitivity (IDUS, 91.1%; EUS, 75.7%; P < 0.002), specificity (IDUS, 80%; EUS, 75%; NS), and T-staging (IDUS, 77.7%; EUS, 54.1%; P < 0.001). In bile duct carcinomas the accuracy rate for lymph node staging using IDUS (60%) is comparable with that using EUS (62.5%). In pancreatic carcinomas, however, lymph node staging using IDUS (13.3%) is significantly (P < 0.002) inferior to EUS (69.2%). Endoluminal ultrasonography may predict the potential resectability of bile duct tumors (IDUS, 81.8%; EUS, 75.6%; P < 0.002).

CONCLUSIONS

IDUS proved to be accurate in preoperative diagnosing and T-staging of malignant biliary strictures, whereas it is not suitable for lymph node staging. IDUS using miniprobes during ERCP exceeds conventional EUS in terms of depiction of bile duct obstruction, diagnostic accuracy, and sensitivity and in the prediction of surgical tumor resectability. Additionally, different to EUS, IDUS can conveniently be performed during ERCP in one and the same session.

Intraductal ultrasonography (IDUS) of the pancreato-biliary duct system. Personal experience and review of literature

Endoscopic ultrasonography (EUS) represents a major advance in endoscopic imaging. Usefulness and effectiveness of EUS have been established during the past few years. However, endosonography using dedicated echoendoscopes (7.5/12 MHz) has some serious drawbacks: (1) combining endoscopy and ultrasonography in one instrument increases the diameter of such echoendoscopes (13 mm); (2) as a result of the large diameter insertion into the pancreato-biliary duct system is not feasible at all; (3) image quality and resolution for small lesions is not always satisfactory; and (4) conventional endosonography needs a second examination separate from the previous routine endoscopy. Recently developed ultrasonographic miniprobes (diameters about 2 mm; frequencies 12-20 MHz) can be passed through the working channel of standard endoscopes to provide high-frequency ultrasound images. These miniprobes might overcome some of the above mentioned drawbacks and contribute to patients' security and convenience. Moreover, in various diseases of the pancreato-biliary duct system diagnostic accuracy of miniprobe ultrasonography has been shown to be superior to that of EUS. In summary, miniprobe ultrasonography appears to be a promising addition to the armamentarium of gastroenterologic diagnostics.

Preoperative assessment of extrahepatic bile duct carcinoma using three-dimensional intraductal US

BACKGROUND

We investigated the utility of a new imaging modality, three-dimensional intraductal ultrasonography (US), for staging bile duct cancer.

METHODS

In eight patients with extrahepatic bile duct carcinoma, two- and three-dimensional intraductal US was used to assess tumor invasion of the right hepatic artery, portal vein, and pancreatic parenchyma before resection. The findings were correlated with histologic information from the resected specimen.

RESULTS

Three-dimensional intraductal US enabled accurate assessment of tumor invasion of the right hepatic artery in 88% of cases, the portal vein in 100%, and pancreatic parenchyma in 100%. Two-dimensional intraductal US enabled accurate assessment of invasion of these structures in 88%, 88%, and 88% of cases.

CONCLUSIONS

Three-dimensional intraductal US is useful in assessing tumor stage in bile duct carcinoma.

Limitation of cholangiography in assessing longitudinal spread of extrahepatic bile duct carcinoma to the hepatic side

BACKGROUND

Preoperative assessment of longitudinal spread of bile duct carcinoma (BDC) to the hepatic side remains a difficult problem for diagnostic imaging.

METHODS

We studied the accuracy of cholangiography in assessing BDC. In 54 patients with extrahepatic bile duct cancer, cholangiographic findings were compared retrospectively with the histological findings of the resected specimens.

RESULTS

Histological examination of specimens indicated longitudinal spread of the tumour to the hepatic side in 22 of 54 patients. The accuracy of cholangiography in assessing the extent of the longitudinal spread was only 34/54 (63%). When the cholangiographic images showed a main tumour with a collapsed edge, there was a significantly higher frequency of longitudinal spread compared with tumours with sharp edges (P< 0.05). In contrast, the accuracy of mapping biopsy under percutaneous transhepatic cholangioscopy (n=24) was 83%.

CONCLUSIONS

Cholangiography cannot accurately assess the extent of the longitudinal spread of bile duct cancer. When cholangiographic images show a tumour with a collapsed edge, preoperative or intraoperative histological examination is essential to determine a suitable surgical line.

Preoperative assessment of congenital bile duct dilatation using intraductal US

BACKGROUND

Although congenital bile duct dilatation is frequently associated with biliary tract cancer, conventional cholangiography often does not demonstrate small ductal tumors. This is the first prospective study of the value of intraductal ultrasonography (US) in the examination of the extrahepatic bile ducts in patients with congenital bile duct dilatation.

METHODS

Intraductal US via a transpapillary route was used in consecutive patients with congenital bile duct dilatation. A 2.0 mm diameter, 20 MHz frequency catheter probe was used. The images were correlated with the results of histologic examination of the resection specimens.

RESULTS

Intraductal US was performed successfully via the transpapillary route in 8 of 10 patients. In the other 2 patients, the percutaneous transhepatic route was used. In the 6 patients with cylindrical dilatation, intraductal US demonstrated the entire extrahepatic bile duct. In 1 patient, it showed a bile duct cancer not demonstrated by cholangiography. In 2 of the 4 patients with cystic dilatation, intraductal US did not demonstrate the entire extrahepatic bile duct because of the low penetration depth of the probe. Percutaneous transhepatic cholangioscopy was required in these patients.

CONCLUSIONS

Intraductal US is useful for demonstrating cancers in the extrahepatic bile ducts in patients with congenital cylindrical ductal dilatation.

Bile duct wall thickness measured by intraductal US in patients who have not undergone previous biliary drainage

BACKGROUND

We investigated the bile duct wall thickness measured on intraductal US in patients who had not undergone biliary drainage, with special attention to the influence of cancer at the distal bile duct, bile duct stones, obstructive jaundice, longitudinal cancer extension, and primary sclerosing cholangitis on wall thickness.

METHODS

The study included 183 patients. Patients who had undergone previous biliary drainage were excluded. Intraductal US was performed by the transpapillary route with use of a thin-caliber ultrasonic probe (2.0 mm diameter, 20 MHz frequency). The bile duct wall thickness (width of the inside hypoechoic layer) was retrospectively measured on US images.

RESULTS

Bile duct wall thicknesses of the common hepatic duct for the control group (n = 95), cancer at the distal bile duct group (n = 9), bile duct stone group (n = 56), and obstructive jaundice group (n = 17) were 0.6 +/- 0.3 mm (mean +/- SD), 0.8 +/- 0.5 mm, 0.8 +/- 0.6 mm, and 0.8 +/- 0. 5 mm, respectively. No significant differences (p > 0.05) were found between them. However, wall thickness for the cancer extension to the common hepatic duct group (n = 4, 2.0 +/- 0.4 mm) and sclerosing cholangitis group (n = 2, 2.5 +/- 0.4 mm) were significantly greater than in the other groups (p < 0.005).

CONCLUSIONS

In patients who have not undergone previous biliary drainage, the bile duct wall thickness was not thicker in patients with obstructive jaundice. However, the duct wall was significantly thicker in patients with either longitudinal cancer extension or primary sclerosing cholangitis compared with that of other groups.

Characterization of biliary strictures using intraductal ultrasonography: comparison with percutaneous cholangioscopic biopsy

BACKGROUND

We determined the accuracy of intraductal ultrasonography (IDUS) in distinguishing between bile duct cancer and benign bile duct disease.

METHODS

Patients (n=42) who required bile duct biopsy using percutaneous transhepatic cholangioscopy (PTCS) to evaluate bile duct strictures or filling defects were studied. A thin-caliber ultrasonic probe (2.0 mm diameter and 20 MHz frequency) was inserted into the bile duct, and its images were prospectively reviewed before PTCS.

RESULTS

Disruption of the bile duct wall structure, seen on IDUS, was associated with malignancy in 25 of 26 patients. When IDUS demonstrated a lesion with normal bile duct structure, six of nine patients were found to have no malignancy. IDUS demonstrated no intraductal lesion in seven patients, and bile duct biopsy also did not indicate cancer in any of these patients. The accuracy, sensitivity, and specificity of IDUS for diagnosing bile duct cancer were 76%, 89%, and 50%, respectively. When used in tandem with IDUS, the sensitivity of bile cytology (64%) and PTCS (93%) improved to 96% and 100%, respectively.

CONCLUSIONS

The accuracy of IDUS for diagnosing bile duct cancer was less than that of PTCS (95%). However, the sensitivity for bile cytology, or bile duct biopsy improved when performed in combination with IDUS.

Influence of biliary drainage catheter on bile duct wall thickness as measured by intraductal ultrasonography

OBJECTIVE

To determine the influence of biliary drainage catheter placement on bile duct wall thickness, we performed intraductal ultrasonography (IDUS) in patients before and after biliary drainage.

METHODS

Patients underwent IDUS before and after either short-term (n = 9, 6 to 8 days) or long-term (n = 9, 14 to 35 days) biliary drainage using a thin (2.0 mm diameter), 20 MHz probe inserted by means of a transpapillary route or a percutaneous tract. The bile duct wall thickness (mean +/- standard deviation) was retrospectively measured at the upper portion of the common hepatic duct.

RESULTS

The bile duct wall thickness increased from 0.8+/-0.4 mm (predrainage) to 2.0+/-1.6 mm (post-drainage) in the long-term group (p < 0.001) but was not significantly increased in the short-term group.

CONCLUSIONS

The bile duct wall thickness as measured on IDUS appears to be increased after placement of biliary drainage catheters.