- Email: [email protected]
Ultrasonic probes for pancreaticobiliary strictures
Ultrasonic probes for pancreaticobiliary strictures Kenjiro Yasuda, MD Intraductal ultrasonic scanning of the pancreaticobiliary system has become possible with the development of small-diameter ("mini") ultrasonic probes. At present the clinical applications of ultrasonic probes with respect to the bile and pancreatic ductal systems are limited because intraductal scanning is not suitable for the detection of lesions. Rather, it is performed for a more precise assessment of lesions detected by other imaging methods, such as endoscopic retrograde cholangiopancreatography (ERCP). Despite the limited range of applications at present, it is reasonable to expect that further indications for use of the miniprobe within the biliary and pancreatic ductal systems will be developed. Some currently available ultrasonic miniprobes that are suitable for scanning the bile and pancreatic ducts are shown in Figure 1. These include a 7.5 MHz 3.4 mm diameter probe, a 2.4 mm diameter miniprobe that permits scanning at 12 MHz or 20 MHz, and a 1.8 mm diameter probe with a scan frequency of 20 MHz.
CLINICAL APPLICATION Ultrasound examinations by intraductal placement of a miniprobe can be performed through the papilla of Vater under duodenoscopic guidance or through a percutaneous route when external biliary drainage has been established. 1 From J a n u a r y 1992 to June 1995, 141 patients underwent intraductal scanning in our hospital. The procedure was performed to assess the extent of tumor and the nature of cystic lesions and to evaluate the degree of ductal and parenchymal changes in chronic pancreatitis. Adequate scanning of the pancreatic duct and adjacent pancreatic parenchyma is sometimes ditticult or even impossible because of the winding nature and small diameter of the main duct and the presence of ductal obstruction. Recently introduced miniprobes have diameters of 2 mm or less so it is usually possible to pass these instruments through the intact papilla of Vater. Nevertheless, it is necessary in some patients to perform an endoscopic sphincterotomy to insert the probe. Miniprobe scanning is usually performed in conjunction with ERCP. From Kyoto Second Red Cross Hospital, Kyoto, Japan. Reprint requests: Kenjiro Yasuda, MD, Kyoto Second Red Cross Hospital, Kamaza-dori, Marutamachi, Kamigyo-ku, Kyoto 602, Japan. 0016-5107/96/4302-0S3555.00 + 0 GASTROINTESTINAL ENDOSCOPY Copyright 9 1996 by the American Society for Gastrointestinal Endoscopy 37/0/70315 VOLUME 43, NO. 2, P A R T 2, 1996
B
tll 21
:i84 ii 84184184 31
Illl4
Figure 1.
Ultrasonic probes: A, diameter of 3.4 mm with 7.5 MHz transducer; B, 2.4 mm diameter with 12 or 20 MHz transducer; C, 1.8 mm diameter with 20 MHz transducer.
Biliary tract Intraductal scanning in the biliary tract is not difficult with or without prior endoscopic sphincterotomy, because the diameter of the bile duct is usually larger than that of a miniprobe. Determination of the extent of biliary tumors is the primary indication for miniprobe scanning within the bile duct; the probe must be inserted through the stricture. An example of carcinoma of the bile duct is shown in Figure 2. Images of a tumor of the papilla of Vater obtained with an echoendoscope and miniprobe are shown in Figure 3. Fifty-three cases of biliary tract carcinoma were examined by endoscopic ultrasonography (EUS); histologic confirmation was obtained in all cases. Of these 53 tumors, 18 lesions were examined by intraductal miniprobe scanning. Tumor invasion and lymph node status were assessed according to the TNM classification. The accuracy rate for assessment of T stage (depth of invasion) by the probe was 70% (EUS, 70%) in cancer of papilla of Vater and 83% (EUS, 75%) in carcinoma of the extrahepatic bile duct. The sensitivGASTROINTESTINAL ENDOSCOPY
S35
Figure 3. Carcinoma of papilla of Vater. A, Images obtained with the ultrasonic endoscope (GF-UM200, Olympus Optical, Ltd., Tokyo, Japan) scanning at 7.5 MHz with a combination of balloon and water-filling techniques demonstrate hypoechoic mass (arrow) in the papilla of Vater. B, Images obtained by inserting the miniprobe percutaneously demonstrate the tumor mass with no invasion of the muscularis propria of the duodenal wall (arrow).
Figure 2. Bile duct carcinoma. A, ERCP demonstrates stricture at liver hilus (arrow). B, After ERCP, the ultrasonic probe is inserted through the papilla of Vater (arrow) and into the stricture. C, A hypoechoic mass invading the cystic duct is clearly demonstrated (arrow).
ity and specificity for N stage (lymph node metastasis) by the probe were 57% and 82%, respectively (EUS, 73% and 77%). These results suggest that the additional examination of these tumors with the miniprobe increases the accuracy of TNM staging. S36
GASTROINTESTINAL ENDOSCOPY
Pancreatic duct
The advantage of the miniprobe in the investigation of pancreatic lesions relates to its ability to obtain high-frequency ultrasound images of specific ductal lesions. However, it is sometimes not possible to obtain satisfactory images with the miniprobe if the pancreatic duct has a small diameter, the course of the duct in the head of the gland is tortuous, or the lesion (e.g., a malignant tumor) completely obstructs the duct. A small intraductal papillary adenoma is shown in Figure 4. VOLUME 43, NO. 2, P A R T 2, 1996
Fifty cases of pancreatic carcinoma were examined by EUS before surgery; histologic confirmation of the EUS findings was obtained in all cases. Of these 50 lesions, 10 were studied with miniprobes, and the findings were described according to the TNM classification. The diagnostic accuracy for T stage was 70% with the probe and 92% by EUS. Sensitivity and specificity for diagnosis of metastatic lymph nodes (N) were 40% and 100%, respectively, with the probe and 53% and 90%, respectively, by EUS. The staging of pancreatic cancer by means of miniprobes was therefore less accurate than by EUS. Bile duct and pancreatic duct structures
The differential diagnosis of biliary and pancreatic duct strictures, that is, whether malignant or benign, is an anticipated indication for scanning with a miniprobe. However, it has been difficult to distinguish malignant from benign stenosis because both lesions appear as a thickened wall in the bile duct. If the tumor mass invades neighboring organs, such as the portal vein or liver, or enlarged lymph nodes are detected in the region of the tumor, a diagnosis of a malignant stricture may be made with confidence. With regard to the pancreatic duct, it is possible to make a diagnosis of a malignant stricture when a hypoechoic mass is demonstrated surrounding the stricture. However, it is not possible to differentiate a fibrotic malignant structure from benign fibrosis. Figure 4. Intraductal papillary adenoma of the pancreas. A,
REFERENCE l. Yasuda K, Mukai H, Nakajima M, Kawai K. Clinical application of ultrasonic probes in the biliary and pancreatic duct. Endoscopy 1992;24(suppl 1):370-5.
Endoscopic ultrasonography and gallstone disease Marcia Canto, MD
Approximately 10% to 15% of adults in the United States, more than 20 million people, have gallstones. Gallstone disease is the most common and most costly digestive disease causing hospitalization in the United States. 1 From the University Hospitals of Cleveland, Ohio. Reprint requests:Marcia Canto, MD, University Hospitals of Cleveland, 11100 Euclid Ave., Cleveland, OH 44106. 0016-5107/96/4302-0S3755.00 + 0 GASTROINTESTINAL ENDOSCOPY Copyright 9 1996 by the American Society for Gastrointestinal Endoscopy 37/0/70316 VOLUME 43, NO. 2, P A R T 2, 1996
Miniprobe inserted into main pancreatic duct in stenotic segment as demonstrated by ERCP. B, Images obtained by intraductal scanning demonstrate a hypoechoic lesion, less than 10 mm in size. Bright (hyperechoic) echoes near the tumor are caused by mucus within the duct. C, Photomicrograph of resection specimen.
Common bile duct (CBD) stones may be present in 3% to 35% of patients undergoing laparoscopic cholecystectomy for symptomatic gallstones. 2 Despite the common occurrence of CBD stones, there is no consensus on the on the best approach to diagnosis and treatment ofcholedocholithiasis. 1Although gallstones are accurately diagnosed by transabdominal ultrasonography, CT, and oral cholecystography, these tests are insufficiently sensitive for diagnosing choledocholithiasis. The increasing use of laparoscopic cholecystectomy to treat cholelithiasis has therefore stimulated the investigation of other imaging techniques to evaluate possible bile duct stones, including endoscopic ultrasonography (EUS), intraoperative ultrasonography, 3 intraoperative cholangiography, 4 and magnetic resonance imaging. 5 This article focuses on the potential role of EUS in GASTROINTESTINAL ENDOSCOPY
S37
CLINICAL APPLICATION Ultrasound examinations by intraductal placement of a miniprobe can be performed through the papilla of Vater under duodenoscopic guidance or through a percutaneous route when external biliary drainage has been established. 1 From J a n u a r y 1992 to June 1995, 141 patients underwent intraductal scanning in our hospital. The procedure was performed to assess the extent of tumor and the nature of cystic lesions and to evaluate the degree of ductal and parenchymal changes in chronic pancreatitis. Adequate scanning of the pancreatic duct and adjacent pancreatic parenchyma is sometimes ditticult or even impossible because of the winding nature and small diameter of the main duct and the presence of ductal obstruction. Recently introduced miniprobes have diameters of 2 mm or less so it is usually possible to pass these instruments through the intact papilla of Vater. Nevertheless, it is necessary in some patients to perform an endoscopic sphincterotomy to insert the probe. Miniprobe scanning is usually performed in conjunction with ERCP. From Kyoto Second Red Cross Hospital, Kyoto, Japan. Reprint requests: Kenjiro Yasuda, MD, Kyoto Second Red Cross Hospital, Kamaza-dori, Marutamachi, Kamigyo-ku, Kyoto 602, Japan. 0016-5107/96/4302-0S3555.00 + 0 GASTROINTESTINAL ENDOSCOPY Copyright 9 1996 by the American Society for Gastrointestinal Endoscopy 37/0/70315 VOLUME 43, NO. 2, P A R T 2, 1996
B
tll 21
:i84 ii 84184184 31
Illl4
Figure 1.
Ultrasonic probes: A, diameter of 3.4 mm with 7.5 MHz transducer; B, 2.4 mm diameter with 12 or 20 MHz transducer; C, 1.8 mm diameter with 20 MHz transducer.
Biliary tract Intraductal scanning in the biliary tract is not difficult with or without prior endoscopic sphincterotomy, because the diameter of the bile duct is usually larger than that of a miniprobe. Determination of the extent of biliary tumors is the primary indication for miniprobe scanning within the bile duct; the probe must be inserted through the stricture. An example of carcinoma of the bile duct is shown in Figure 2. Images of a tumor of the papilla of Vater obtained with an echoendoscope and miniprobe are shown in Figure 3. Fifty-three cases of biliary tract carcinoma were examined by endoscopic ultrasonography (EUS); histologic confirmation was obtained in all cases. Of these 53 tumors, 18 lesions were examined by intraductal miniprobe scanning. Tumor invasion and lymph node status were assessed according to the TNM classification. The accuracy rate for assessment of T stage (depth of invasion) by the probe was 70% (EUS, 70%) in cancer of papilla of Vater and 83% (EUS, 75%) in carcinoma of the extrahepatic bile duct. The sensitivGASTROINTESTINAL ENDOSCOPY
S35
Figure 3. Carcinoma of papilla of Vater. A, Images obtained with the ultrasonic endoscope (GF-UM200, Olympus Optical, Ltd., Tokyo, Japan) scanning at 7.5 MHz with a combination of balloon and water-filling techniques demonstrate hypoechoic mass (arrow) in the papilla of Vater. B, Images obtained by inserting the miniprobe percutaneously demonstrate the tumor mass with no invasion of the muscularis propria of the duodenal wall (arrow).
Figure 2. Bile duct carcinoma. A, ERCP demonstrates stricture at liver hilus (arrow). B, After ERCP, the ultrasonic probe is inserted through the papilla of Vater (arrow) and into the stricture. C, A hypoechoic mass invading the cystic duct is clearly demonstrated (arrow).
ity and specificity for N stage (lymph node metastasis) by the probe were 57% and 82%, respectively (EUS, 73% and 77%). These results suggest that the additional examination of these tumors with the miniprobe increases the accuracy of TNM staging. S36
GASTROINTESTINAL ENDOSCOPY
Pancreatic duct
The advantage of the miniprobe in the investigation of pancreatic lesions relates to its ability to obtain high-frequency ultrasound images of specific ductal lesions. However, it is sometimes not possible to obtain satisfactory images with the miniprobe if the pancreatic duct has a small diameter, the course of the duct in the head of the gland is tortuous, or the lesion (e.g., a malignant tumor) completely obstructs the duct. A small intraductal papillary adenoma is shown in Figure 4. VOLUME 43, NO. 2, P A R T 2, 1996
Fifty cases of pancreatic carcinoma were examined by EUS before surgery; histologic confirmation of the EUS findings was obtained in all cases. Of these 50 lesions, 10 were studied with miniprobes, and the findings were described according to the TNM classification. The diagnostic accuracy for T stage was 70% with the probe and 92% by EUS. Sensitivity and specificity for diagnosis of metastatic lymph nodes (N) were 40% and 100%, respectively, with the probe and 53% and 90%, respectively, by EUS. The staging of pancreatic cancer by means of miniprobes was therefore less accurate than by EUS. Bile duct and pancreatic duct structures
The differential diagnosis of biliary and pancreatic duct strictures, that is, whether malignant or benign, is an anticipated indication for scanning with a miniprobe. However, it has been difficult to distinguish malignant from benign stenosis because both lesions appear as a thickened wall in the bile duct. If the tumor mass invades neighboring organs, such as the portal vein or liver, or enlarged lymph nodes are detected in the region of the tumor, a diagnosis of a malignant stricture may be made with confidence. With regard to the pancreatic duct, it is possible to make a diagnosis of a malignant stricture when a hypoechoic mass is demonstrated surrounding the stricture. However, it is not possible to differentiate a fibrotic malignant structure from benign fibrosis. Figure 4. Intraductal papillary adenoma of the pancreas. A,
REFERENCE l. Yasuda K, Mukai H, Nakajima M, Kawai K. Clinical application of ultrasonic probes in the biliary and pancreatic duct. Endoscopy 1992;24(suppl 1):370-5.
Endoscopic ultrasonography and gallstone disease Marcia Canto, MD
Approximately 10% to 15% of adults in the United States, more than 20 million people, have gallstones. Gallstone disease is the most common and most costly digestive disease causing hospitalization in the United States. 1 From the University Hospitals of Cleveland, Ohio. Reprint requests:Marcia Canto, MD, University Hospitals of Cleveland, 11100 Euclid Ave., Cleveland, OH 44106. 0016-5107/96/4302-0S3755.00 + 0 GASTROINTESTINAL ENDOSCOPY Copyright 9 1996 by the American Society for Gastrointestinal Endoscopy 37/0/70316 VOLUME 43, NO. 2, P A R T 2, 1996
Miniprobe inserted into main pancreatic duct in stenotic segment as demonstrated by ERCP. B, Images obtained by intraductal scanning demonstrate a hypoechoic lesion, less than 10 mm in size. Bright (hyperechoic) echoes near the tumor are caused by mucus within the duct. C, Photomicrograph of resection specimen.
Common bile duct (CBD) stones may be present in 3% to 35% of patients undergoing laparoscopic cholecystectomy for symptomatic gallstones. 2 Despite the common occurrence of CBD stones, there is no consensus on the on the best approach to diagnosis and treatment ofcholedocholithiasis. 1Although gallstones are accurately diagnosed by transabdominal ultrasonography, CT, and oral cholecystography, these tests are insufficiently sensitive for diagnosing choledocholithiasis. The increasing use of laparoscopic cholecystectomy to treat cholelithiasis has therefore stimulated the investigation of other imaging techniques to evaluate possible bile duct stones, including endoscopic ultrasonography (EUS), intraoperative ultrasonography, 3 intraoperative cholangiography, 4 and magnetic resonance imaging. 5 This article focuses on the potential role of EUS in GASTROINTESTINAL ENDOSCOPY
S37