CLINICAL SIGNIFICANCE OF INTRADUCTAL ULTRASONOGRAPHY FOR DIAGNOSIS OF INTRADUCTAL PAPILLARY MUCINOUS NEOPLASM OF THE PANCREAS

Intraductal ultrasonography (IDUS) is useful for evaluating the horizontal spread along the main pancreatic duct in cases of intraductal papillary mucinous neoplasm (IPMN) of the pancreas, thus providing valuable information for the determination of the resection line at surgery. Differentiation between benign and malignant IPMN is also indispensable for management decisions. Measurement of the height of mural nodules by IDUS is expected to be useful for differential diagnosis of IPMN. Because IDUS cannot always demonstrate whole lesions, especially in branch duct IPMN, endoscopic ultrasonography plays a complementary role in such cases.     

PERORAL PANCREATOSCOPY AND INTRADUCTAL ULTRASONOGRAPHY IN DETERMINING THE RESECTION LINES OF INTRADUCTAL PAPILLARY MUCINOUS TUMORS OF THE PANCREAS

In patients with malignant intraductal papillary–mucinous tumors (IPMT), the tumor spread along the main pancreatic duct is generally inspected as mural nodules within the ducts by peroral pancreatoscopy (POPS). Even the lower mural nodules including fish‐eggs‐like lesions and granular mucosa continued to the main taller mural nodules should be resected. Mural nodules along the main duct and cystic dilation of the branch ducts observed by intraductal ultrasonography (IDUS) are regarded as the tumor spread. Although POPS is superior to IDUS in identifying mural nodules along the main duct, POPS has limitations to detect mural nodules within the branch ducts. Therefore, the accuracy of the diagnosis by POPS is higher in main duct IPMT, whereas that by IDUS is higher in branch duct IPMT. These modalities should be performed as complementary tests in determining the resection lines preoperatively.     

IDUS IN THE DIAGNOSIS OF IPMT

Intraductal papillary mucinous tumor of the pancreas (IPMT) is considered as having low‐grade malignant potential, and malignancy is not infrequent. Therefore, accurate diagnosis is indispensable for appropriate patient care. IPMT is classified mainly into two categories based on the distribution of tumor, the main duct type and the branch duct type. In the diagnosis of IPMT, there are four important points: differentiation of IPMT from other pancreatic pathologies; differentiation of malignancy from benign lesions; evaluation of tumor extent along the MPD; and investigation of duct cell carcinoma coexistent with or derived from IPMT. IPMT should be distinguished from chronic pancreatitis, ductal adenocarcinoma, or cystic neoplasms. IPMT often requires pancreaticoduodenectomy for cure, but such invasive surgery should be avoided in patients with benign hyperplasia. Mural nodules in the MPD can be clearly visualized by intraductal ultrasonography (IDUS). Measurement of the height of the tumor mass by IDUS is useful in distinguishing benign from malignant IPMT. Intraductal spread of IPMT along the MPD is demonstrated by IDUS as irregular thickening of the MPD wall. To achieve a tumor‐free margin in surgery, evaluation by IDUS of the extent of the tumor along the MPD is important. The expected accuracy of IDUS in the diagnosis of invasive IPMT is reportedly over 90%.     

COMPARISON OF THE HEIGHT OF PAPILLARY TUMOR IN INTRADUCTAL PAPILLARY MUCINOUS NEOPLASM OF THE PANCREAS BETWEEN MEASURED PREOPERATIVE IMAGES AND RESECTED MATERIAL

The height of the mural nodules and papillary tumors in main pancreatic duct or dilated branch duct is the most important factor for diagnosis of intraductal papillary mucinous neoplasm (IPMN). In this study, the authors compared the height of the papillary lesions and mural nodules between the height of resected tissues and the height detected by the preoperative imaging tools (endoscopic ultrasonography [EUS] and intraductal ultrasonography [IDUS]) in 38 patients with IPMN. In 21 out of 23 cases of adenoma, and in cases with the non‐invasive cancer, the difference of the height of operative and preoperative analysis measured by EUS and IDUS was within 1–2 mm. EUS and IDUS are useful for diagnosis of degree of malignancy in IPMN.     

INTRADUCTAL ULTRASONOGRAPHY BEFORE BILIARY DRAINAGE AND TRANSPAPILLARY BIOPSY IN ASSESSMENT OF THE LONGITUDINAL EXTENT OF BILE DUCT CANCER

Aim: We evaluated the diagnostic efficacy of transpapillary intraductal ultrasonography before biliary drainage (IDUS‐BD) and transpapillary biopsy (TPB) for the assessment of the longitudinal extent of bile duct cancer. Methods: Between November 1999 and January 2005, we performed IDUS‐BD and TPB preoperatively in 27 patients with carcinoma of the extrahepatic bile duct. Following IDUS‐BD, TPB was performed under fluoroscopic guidance immediately after endoscopic sphincterotomy. The diagnostic efficacy of IDUS‐BD and TPB for the longitudinal extent of the cancer and the complications which accompanied the procedure were evaluated. Results: The overall success rate of sampling and the diagnostic accuracy of bile duct cancer by TPB were 85.3% (192/225) and 85% (23/27), respectively. The sensitivity, specificity and accuracy of the assessment of the longitudinal extent of cancer on the hepatic and duodenal sides by IDUS‐BD were 82%, 70%, 78% and 85%, 43%, 70%, respectively. Those by a combination of IDUS‐BD and TPB were 88%, 80%, 85% and 77%, 86%, 80%, respectively. Overestimation of the longitudinal extent of BD cancer by IDUS‐BD was mainly due to inflammation and obscure images, especially resulting from collapse of the bile duct on the duodenal side of the tumor, and was corrected by TPB in four of five patients. No serious complications occurred following the combination of IDUS‐BD and TPB. Conclusions: TPB is useful for preoperative histological diagnosis of bile duct cancer. The combination of IDUS‐BD and TPB is practical for evaluation of its longitudinal extent; basically, IDUS‐BD is sufficient on the hepatic side of the tumor, but concomitant TPB is recommended on the duodenal side.     

LATERAL SPREAD ALONG THE MAIN PANCREATIC DUCT IN BRANCH‐DUCT INTRADUCTAL PAPILLARY‐MUCINOUS NEOPLASMS OF THE PANCREAS: USEFULNESS OF INTRADUCTAL ULTRASONOGRAPHY FOR ITS EVALUATION

Background: Intraductal papillary mucinous neoplasms (IPMN) of the pancreas tend to spread intraepithelially along the pancreatic duct wall. We evaluated histopathological intraductal lateral spread (LS) along the main pancreatic duct (MPD) from branch‐duct IPMN and investigated the usefulness of intraductal ultrasonography (IDUS) for its preoperative diagnosis. Patients and Methods: Twenty‐four patients with branch‐duct IPMN who had undergone preoperative IDUS and surgery were reviewed clinicopathologically. The prevalence and histological length of LS along the MPD from branch‐duct IPMN, characteristics of the patients with LS, and efficacy of LS assessment by IDUS were examined. Results: LS along the MPD was observed in 54% of the subjects. In the group of patients with LS, its mean length was 25.2 ± 16.8 mm (5–50 mm) and the diameter of the MPD was 6 mm or greater. Of the patients with LS, those in whom the length of LS along the MPD was longer than the diameter of the cystically dilated branch accounted for 30%. The diameter of the MPD in the group with LS was significantly greater than that in the group without LS (P = 0.03). The sensitivity, specificity, and overall accuracy of IDUS in the detection of LS were 92%, 91%, and 92%, respectively. Conclusion: LS along the MPD was detected in about half of the resected cases of branch‐duct IPMN. Preoperative transpapillary IDUS may be beneficial for the determination of the resection line, especially in those branch‐duct IPMN patients in whom the MPD is 6 mm or greater in diameter.     

DIAGNOSTIC UTILITY OF PERORAL CHOLANGIOSCOPY AND TRANSPAPILLARY INTRADUCTAL ULTRASONOGRAPHY FOR BILE DUCT CARCINOMA

Recently, new diagnostic procedures such as video peroral cholangioscopy (POCS) and transpapillary intraductal ultrasonography (IDUS) have been available for diagnosis of biliary diseases. These new modalities are especially useful for diagnosis of minute bile duct lesions on cholangiogram and correct diagnosis of lateral extension of bile duct carcinoma. In this paper, showing some effective cases of POCS and IDUS, we present our diagnostic approach for bile duct carcinoma and discuss the future prospects of POCS and IDUS.     

Three-dimensional Ultrasonography Using Ultrasonic Probes by the Transpapillary Approach for Diagnosis of Pancreatobiliary Diseases

Abstract: Three-dimensional (3D) intraductal ultrasonography (IDUS) is more useful than two-dimensional IDUS for the diagnosis of pancreatobiliary disease. We investigated the advantages and disadvantages of the transpapillary approach for 3D-IDUS using a newly developed system for pancreatobiliary application. In total 12 patients with a sufficiently wide orifice were examined, bile duct (BD) scanning being successful in 100% of attempted cases and main pancreatic duct (MPD) scanning in 85.7%. In all cases, acceptable radial and linear images were obtained and 3D diagnosis was accomplished. However, several primary problems were experienced; 1) The 3D probe is relatively inflexible, having a thick shaft and a long tip, such that insertion into the BD or MPD can be somewhat difficult; 2) Clear images of the BD or MPD wall were not always obtained because of artifacts produced by the 3D probe itself; 3) In some cases, linear images could not be reconstructed with BD or MPD scanning despite sufficiently clear radial scan images. In the future, development of new 3D probes with more flexible and thinner shafts, and shorter tips, should considerably enhance the diagnostic capacity of IDUS for the pancreatobiliary system.     

内镜超声对胰腺癌的诊断

目的 探讨内镜超声（EUS）检查对胰腺癌的诊断价值。方法 对116例胰腺癌患者行EUS检查，其中16例经管内超声（IDUS）检查并与体表B超（B超），CT，磁共振成像（MRI），内镜逆行胰胆管造影（ERCP）检查结果进行比较。结果 EUS（IDUS)诊断胰腺癌的敏感性与准确性均明显高于B超，与CT，MRI及ERCP相当，EUS诊断准确率为98．2％（114／116），IDUS为100％（16／16）；CT为85．3％（99／116）；MRI为87．0％（54／62）；ERCP为80．6％（79／98）；B超为73．2％（85／116）。结论 EUS对胰腺癌有较大的诊断价值。     

Differential diagnosis of intraductal papillary‐mucinous tumor of the pancreas by endoscopic ultrasonography and intraductal ultrasonography

Background: Intraductal papillary‐mucinous tumor (IPMT) of the pancreas has a broad spectrum of histology ranging from hyperplasia to adenocarcinoma. Therefore, it is important to differentiate between the malignant and benign lesions to determine the therapeutic strategy for IPMT. Patients and Methods: Thirty‐nine patients with IPMT (27 men and 12 women, mean age: 63.3 years) underwent surgery between January 1985 and March 2002. The size of the cystic lesion, the maximum diameter of the main pancreatic duct (MPD), and the height of the papillary tumor inside the cyst were investigated by endoscopic ultrasonography (EUS) and/or intraductal ultrasonography (IDUS) before operation. These preoperative clinical findings were compared with the pathological findings of the resected specimen. Results: The size of the cystic lesion, the diameter of MPD, and the height of the papillary tumor in cases with malignant IPMT (invasive and non‐invasive carcinoma) were larger than those in cases with benign IPMT (adenoma and hyperplasia). Analysis of the images of the lesions revealed that the following three factors are important for diagnosing IPMT: (i) the size of the cystic lesion is ≥ 30 mm; (ii) the diameter of MPD is ≥ 8 mm; (iii) the height of the papillary tumor inside the cyst is ≥ 3 mm. It was not significant to differentiate between benign and malignant IPMT based on factor (i), but statistically significant (P < 0.001) based on factors (ii) and (iii). Conclusions: EUS and IDUS are useful in the differential diagnosis of IPMT, especially in the differentiation between malignant and benign IPMT.     

Management of intraductal papillary mucinous neoplasm of the pancreas

Intraductal papillary mucinous neoplasm (IPMN) of the pancreas is a distinct entity characterized by papillary proliferations of mucin-producing epithelial cells with excessive mucus production and cystic dilatation of the pancreatic ducts. IPMNs have malignant potential and exhibit a broad histologic spectrum, ranging from adenoma to invasive carcinoma. IPMNs are classified into main duct and branch duct types, based on the site of tumor involvement. IPMN patients have a favorable prognosis if appropriately treated. The postoperative 5-year survival rate is nearly 100% for benign tumors and noninvasive carcinoma, and approximately 60% for invasive carcinoma. A main duct type IPMN should be resected. Surgical treatment is indicated for a branch duct IPMN with suspected malignancy (tumor diameter ≥ 30 mm, mural nodules, dilated main pancreatic duct, or positive cytology) or positive symptoms. Malignant IPMNs necessitate lymph node dissection (D1). IPMNs are associated with a high incidence of extrapancreatic malignancies and pancreatic ductal carcinoma.     

Preoperative evaluation of ampullary neoplasm with EUS and transpapillary intraductal US: a prospective and histopathologically controlled study

BACKGROUND: Endoscopic papillectomy is performed in selected patients with ampullary neoplasm, and, thus, accurate preoperative tumor staging is indispensable for its application. DESIGN: Prospective and histopathologically controlled study. SETTING: Single center. PATIENTS AND INTERVENTIONS: EUS and transpapillary intraductal US (IDUS) were performed in 40 patients with ampullary neoplasm before surgery (n = 30) or endoscopic papillectomy (n = 10). Ductal infiltration by a tumor into the bile duct (BD) or the pancreatic duct (PD) was also evaluated. The indication for endoscopic papillectomy was determined by findings obtained by EUS and IDUS. These findings were compared with histologic features of the resected specimens. MAIN OUTCOME MEASUREMENTS AND RESULTS: Thirty-three patients had adenocarcinoma (14 pT1, 11 pT2, 8 pT3-4) and 7 had adenoma. Tumor depiction by EUS and IDUS was achieved in 95% and 100% of the patients, respectively. The diagnostic accuracy of EUS and IDUS in T staging was 62% and 86% in adenoma and pT1, 45% and 64% in pT2, and 88% and 75% in pT3-4, respectively. The overall accuracy by EUS and IDUS in T staging was 63% and 78%, respectively (P = .14). In 10 patients who underwent endoscopic papillectomy, the accuracy of IDUS in T staging with EUS and IDUS was 80% and 100%, respectively. Ductal infiltration into the BD and the PD was correctly assessed in 88% and 90% by EUS and in both BD and the PD in 90% by IDUS, respectively. Ductal infiltration was correctly diagnosed by EUS and IDUS in all patients who had a papillectomy. CONCLUSION: Although IDUS had a tendency of overestimation in tumor staging for ampullary neoplasm, it can provide useful information for making therapeutic decisions, especially in cases appropriate for endoscopic papillectomy.     

Clinical aspects of intraductal papillary mucinous neoplasm of the pancreas

Intraductal papillary mucinous neoplasm (IPMN) is a spectrum of neoplasia in the pancreatic duct epithelium characterized by cystic dilation of the main and/or branch pancreatic duct. According to the site of involvement IPMNs are classified into three categories, i.e., main duct type, branch duct type, and combined type. Most branch duct IPMNs are benign, whereas the other two types are often malignant. A large size of branch duct IPMN and marked dilation of the main pancreatic duct indicate the presence of adenoma at least. The additional existence of large mural nodules increases the possibility of malignancy in all types. Of recent interest is the relatively high prevalence of synchronous and/or metachronous malignancy in various organs, including the pancreas. The prognosis is favorable after complete resection of benign and noninvasive malignant IPMNs. Malignant IPMNs acquiring aggressiveness after parenchymal invasion necessitate adequate lymph node dissection. On the other hand, asymptomatic branch duct IPMNs without mural nodules can be observed without resection for a considerably long time. This review addresses available data, current understanding, controversy, and future directions.     

多种内镜检查方法联合应用对胆管狭窄性疾病的诊断价值

目的评估多种内镜检查方法联合应用对胆管狭窄性疾病的诊疗价值。方法回顾性分析36例胆管狭窄性疾病患者的诊断情况。36例患者均进行了超声内镜检查术（EUS）、经内镜逆行胰胆管造影术（ERCP）、胆管内超声检查术（IDUS）,胆道靶向刷检行细胞学涂片、液基薄层细胞学检查,并结合临床资料及组织学病理检查,综合诊断。结果最终诊断胆管恶性病变21例,其中胆管细胞癌9例、十二指肠乳头癌4例、胰腺癌侵犯胆总管4例、肝癌侵犯胆总管4例;胆管良性病变15例,其中胆总管结石9例、肝吸虫感染所致胆管狭窄4例、单纯胆管炎性狭窄1例、外部压迫所致胆管狭窄1例。EUS、ERCP、IDUS及ERCP＋IDUS对胆管狭窄性疾病鉴别诊断的准确率分别为77．8％、88．9％、91．7％、94．4％,ERCP、IDUS及ERCP＋IDUS均明显高于EUS（P均〈0．05）;ERCP＋IDUS对胆管狭窄性疾病鉴别诊断的敏感度、特异度、阳性预测值与阴性预测值分别为95．2％、93．3％、95．2％、93．3％,均高于EUS、ERCP及IDUS单独检查。胆道刷检细胞学、液基薄层细胞学或组织病理学检查,19例诊断为恶性狭窄,17例诊断为良性狭窄,对鉴别胆管狭窄性质诊断的敏感度为90．5％、特异度为100．0％、准确率为94．4％。结论对于胆管狭窄性病变,ERCP＋IDUS可使诊断准确率得到明显提高;联合应用ERCP＋IDUS＋病变胆管的靶向刷检等多种内镜检查方法,诊断准确率更高。     

Optimal management of the branch duct type intraductal papillary mucinous neoplasms of the pancreas

GOALS: To determine the optimal management of the intraductal papillary mucinous neoplasms (IPMNs) according to the morphologic type based on distinguishing between benign and malignant diseases. BACKGROUNDS: IPMNs are increasingly recognized clinicopathologic entity. Extended pancreatic resection with radical lymph node dissection has been recommended for treatment. STUDY: A retrospective clinicopathologic study was carried out of the 57 cases with IPMNs who were treated between 1985 and 2001. Forty-three patients with IPMNs underwent resection, and 14 patients with small IPMNs were observed without resection. RESULTS: Among the 43 resected IPMNs, 25 were benign and 18 were malignant. Malignant tumors were significantly greater in diameter than benign tumors (52.9 vs. 30.2 mm, P< 0.05). All main duct type tumors with mural nodules were malignant. All branch duct type tumors less than 30 mm in diameter and without mural nodules were benign. Twelve branch duct type IPMNs size less than 30 mm were not resected and have not progressed. CONCLUSION: These results suggest that the branch duct type IPMNs less than 30 mm and without mural nodules is benign and might be treatable with limited resection or careful observation.     

Differential diagnosis of benign and malignant branch duct intraductal papillary mucinous neoplasm using contrast-enhanced endoscopic ultrasonography

AIM: To elucidate the role of contrast-enhanced endoscopic ultrasonography (CE-EUS) in the diagnosis of branch duct intraductal papillary mucinous neoplasm (BD-IPMN).METHODS: A total of 50 patients diagnosed with BD-IPMN by computed tomography (CT) and endoscopic ultrasonography (EUS) at our institute were included in this study. CE-EUS was performed when mural lesions were detected by EUS. The diagnostic accuracy for identifying mural nodules (MNs) was evaluated by CT, EUS, and EUS combined with CE-EUS. In the patients who underwent resection, the accuracy of measuring MN height with each imaging modality was compared. The cut-off values to diagnose malignant BD-IPMNs based on MN height for each imaging modality were determined using receiver operating characteristic curve analysis.RESULTS: Fifteen patients were diagnosed with BD-IPMN with MNs and underwent resection. The remaining 35 patients were diagnosed with BD-IPMN without MNs and underwent follow-up monitoring. The pathological findings revealed 14 cases with MNs and one case without. The accuracy for diagnosing MNs was 92% using CT and 72% using EUS; the diagnostic accuracy increased to 98% when EUS and CE-EUS were combined. The accuracy for measuring MN height significantly improved when using CE-EUS compared with using CT or EUS (median measurement error value, CT: 3.3 mm vs CE-EUS: 0.6 mm, P < 0.05; EUS: 2.1 mm vs CE-EUS: 0.6 mm, P < 0.01). A cut-off value of 8.8 mm for MN height as measured by CE-EUS improved the accuracy of diagnosing malignant BD-IPMN to 93%.CONCLUSION: Using CE-EUS to measure MN height provides a highly accurate method for differentiating benign from malignant BD-IPMN.     

Mode of progression of intraductal papillary-mucinous tumor of the pancreas: analysis of patients with follow-up by EUS

Background We investigated the mode of progression of intraductal papillary-mucinous neoplasm of the pancreas (IPMN) in patients who underwent follow-up in order to elucidate the characteristics of malignancy and to establish an effective treatment strategy.Methods Fifty-one patients with IPMN (branch-duct type, 47; main-duct type, 4) who had undergone follow-up study by endoscopic ultrasonography (EUS) were included (mean follow-up duration, 41.0 ± 32.3 months; average number of EUS examinations performed during follow-up, 4.4). Chronological changes in EUS findings and histological findings of resected specimens were evaluated.Results Of the patients with the branch-duct type, only 2% showed enlargement of the dilated branches. In the main-duct-type group, an increase in size of the main pancreatic duct (MPD) was observed in 75% of the patients. In 14 patients with papillary protrusions, an increase in size and lateral spread was observed in 71% and 43%, respectively. No patients developed invasive cancer. In 15 patients who had thick septum-like structures (TSS), the development of papillary protrusions and that of invasive cancer were observed in 53% and 13%, respectively. Twenty-nine patients who had thin septum-like structures showed no change. Two patients with dense multilocular large cysts and TSS developed invasive cancer without change in the cystic lesions. One patient developed carcinoma with multifocal stromal invasion.Conclusions Patients with branch-duct type IPMNs without papillary protrusions or TSS are not immediate candidates for surgery. Those who have small papillary protrusions have a benign course. It is recommended that patients with the large branch-duct type with TSS should undergo surgery. Attention should be paid to the entire pancreas when performing follow-up examinations in patients with branch-duct type IPMN, as invasive ductal adenocarcinoma can develop at a site in the pancreas different from that of the IPMN.     

Intraductal ultrasonography in six patients with endoscopic biliary stenting

The development of endoscopic biliary stenting (EBS), using the Wallstent, to treat patients with obstructive jaundice secondary to unresectable tumors of the pancreas or biliary ducts has led to improved quality of life in these patients. We followed six patients with intraductal ultrasonography (IDUS) after insertion of a Wallstent. In two patients, endoscopic ultrasonography (EUS) was also performed, and in three patients IDUS was repeated every few months. IDUS allowed ingrowth of the tumor or formation of debris in the stent to be observed clearly and easily. Therefore IDUS was considered to be a powerful tool to follow patients after stenting and to decide on the next treatment when reobstruction occurred. (Received Apr. 13, 1998; accepted Aug. 28, 1998)     

超声内镜对壶腹癌及肝外胆管癌术前分期诊断

超声内镜对手术前Ｖａｔｅｒ＇ｓ壶腹癌及肝外胆管癌的原发病变范围、浸润深度、是否有区域淋巴结转移及远隔转移作出诊断及分期，将有助于选择最佳治疗方案及判断预后。对２８例Ｖａｔｅｒ＇ｓ壶腹癌及１８例肝外胆管癌于手术前进行了超声内镜检查，并按照国际ＴＮＭ分期方案进行了手术前分期。其中２２例Ｖａｔｅｒ＇ｓ壶腹癌及１８例肝外胆管癌进行了根治性切除及详细的病理组织学检查，有可能将超声内镜与病理诊断结果进行对照以检验超声内镜诊断的准确性。超声内镜判断Ｖａｔｅｒ＇ｓ壶腹癌及肝外胆管癌病变范围及浸润深度的准确性分别为８１．８％及７２．２％；判断其区域淋巴结转移的准确性分别为５９％及６１．６％。Ｖａｔｅｒ＇ｓ壶腹癌伴门静脉受侵的３例中有２例于术前超声内镜检查中获得了正确诊断，但３例肝转移均未能发现。     

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.