Synopsis  

This chapter describes the wide range of equipment available for EUS—processors, echoendoscopes, and accessories—and discusses their roles and limitations in EUS procedures.

 Introduction   

Endoscopic ultrasound (EUS) was initially developed in the early 1980s primarily to overcome the limitations of transabdominal ultrasound in imaging the pancreas. EUS combines endoscopy with high-frequency ultrasound by incorporating a small ultrasonic transducer at or close to the tip of a modified endoscope. EUS transducers can be either single element, where the transducer must be mechanically rotated to produce an image, or phased array, where multiple piezoceramic crystals are stimulated by electronic pulses. Phased arrays can incorporate Doppler ultrasound, which can be used to identify active blood flow. Single-element transducers were initially the mainstay of EUS; however, there is an increasing move towards phased arrays in the newest generation of instruments being developed.

 Radial and linear endosonographic probes   

Early echoendoscopes used mechanical radial scanning, where the transducer is orientated perpendicular to the shaft of the endoscope and generates a radial image of 360°(Figs 1–3). Some, although not all authors, feel that this type of imaging gives a better overview of the GI wall and paramural structures [1]. More recently, electronic radial instruments have been developed (Fig. 4). At the same time as mechanical radial endoscopes were being developed, curved linear array (CLA) echoendoscopes were also produced. These generate ultrasound images along the long axis of the echoendoscope(Fig. 5), allowing real-time visualization of fine-needle aspiration (FNA) biopsy of lesions. Very few studies have compared the accuracy of these two types of imaging; however, those that have found similar accuracies for pancreatic and esophageal cancer staging [2,3]. Figure 6 lists commonly used echoendoscopes, but a more detailed list of all available instruments can be found in Rosch [1].

 Contrast-enhanced ultrasonography   

Objects moving towards an US beam augment reflection from their surface, which increases the frequency of the returning wave. Conversely, if the motion is away from the receiver, the received wave has a lower frequency compared with its incident frequency. The importance of this equation is that the velocity of the object is directly related to the change in frequency of the US beam. This is called the Doppler shift effect and can be used to determine if an anechoic structure is a vessel with active blood flow. It is only possible to measure the Doppler effect with phased array transducers.

Contrast-enhanced sonography was initially described using carbon dioxide microbubbles which were infused into the celiac or superior mesenteric artery [4,5]. More recently Levovist, a sonography contrast agent, has been used in Doppler ultrasound studies. However, several limitations of this technique have been found, including blooming artifacts, poor spatial resolution, and low sensitivity to slow flow [6–14]. Coded phase inversion harmonic imaging is a newly available sonographic technique which is based on a combination of phase inversion harmonics and coded technology [15–17]. With the use of a microbubble contrast agent (a suspension of monosaccharide microparticles in sterile water), it depicts signals from microbubbles in very slow flow without Doppler related artifacts, and enables visualization of slow flow in microscopic vessels. A recent study by Kitano et al. [18] identified tumor vessels in 67% of pancreatic ductal carcinomas using contrast-enhanced ultrasonography, although most were relatively hypovascular compared with the surrounding pancreatic tissue. Interestingly, although contrast-enhanced ultrasonography was clearly superior in its sensitivity in identifying pancreatic tumors of 2 cm or less in size compared with contrast-enhanced computed tomography (95% vs. 68%), it was no better than routine endosonography (95% sensitivity). This is an interesting new technique; however, further studies are required to delineate its exact role and potential.

 Catheter-based EUS probes (miniprobes)   

EUS is typically performed using an echoendoscope. This often entails two procedures: an initial endoscopy to identify the lesion or area of interest, followed by EUS to evaluate it further. EUS probes are larger than regular endoscopes and are not always able to cross tight strictures. Standard echoendoscopes may also have difficulty visualizing small or early lesions due to their relatively low imaging frequency and oblique forward-viewing optics.

Catheter- or 'mini' probes have been developed, which overcome some of these problems. They consist of a cable with a mechanical transducer at its end (Fig. 7). The majority of miniprobes use a radial transducer; however, dual-plane reconstruction probes (UM-DP-12-25R, 12 MHz and UM-DP20-25R, 20 MHz; Olympus) are also available and these allow the user to scan simultaneously in both linear and radial planes. The miniprobes come in a variety of diameters and lengths with probes of over 2 m being used for colonic and pancreatico-biliary imaging (Fig. 8). They are also available in a variety of frequencies. The higher the frequency, the greater the image resolution, with up to nine gut-wall layers visualized with high-frequency probes [19,20]. However, this higher resolution comes at the expense of limited depth of penetration, with an average of 1 cm penetration with a 30-MHz probe compared with 2.9 cm for a 12-MHz probe.

Miniprobe technique   

The miniprobe is inserted down the working channel of a regular endoscope. Air is removed from the lumen, which is then filled with water to allow transmission of the ultrasound. Particular care should be taken in imaging the esophagus, where the head of the bed should be raised to at least 30° to prevent aspiration. A catheter balloon sheath (UM-BS20-26R; Olympus), which consists of a small water-filled balloon that inflates around the transducer tip, can be used in combination with the miniprobe. This improves acoustic coupling and has been shown to improve the clarity of the image and the depth of penetration for esophageal imaging [21,22]. In pancreatico-biliary imaging a catheter balloon sheath is not required as bile and pancreatic juice provide a fluid-filled lumen.

Intraductal ultrasound (IDUS) can be performed either through a percutaneous or retrograde transpapillary route. In the case of a retrograde procedure, an ERCP is performed first and a guidewire is passed proximal to the lesion. A wire-guided probe (Fig. 9) is then advanced under fluoroscopic guidance. Alternatively, a non-wire-guided intraductal ultrasound probe may be used; however, up to 20% of patients will require a sphincterotomy using this technique [23]. The IDUS probe can also be inserted into the pancreatic duct. This can be a more difficult procedure, particularly if the duct is tortuous or not dilated, with intubation rates falling from between 94% and 97% in the head to 89% to 90% in the body, and only 45% in the tail [24,25].

Miniprobes in cancer   

Miniprobes have been used to stage several cancers, including esophageal, gastric, duodenal, colorectal, ampullary, and pancreatico-biliary. The accuracy of miniprobes for staging cancers varies depending on the organ. Miniprobes provide better visualization and higher T-staging for esophageal cancer than standard EUS probes [26–30]. For gastric cancer, miniprobes have again been shown to be superior in overall staging accuracy compare with standard EUS (72% vs. 65%) [31]. However, miniprobes are less reliable for advanced cancer staging due to limited depth of ultrasound penetration [27]. They have also been shown to be superior to standard EUS in the visualization and diagnosis of ampullary tumors (100% vs. 59.3%) [32] with nodal staging accuracy varying from 66.7% to 93% [32,33].

Other uses of miniprobes   

Miniprobes have also been used to examine Barrett's esophagus [34,35], achalasia [36–38], esophageal varices [39], MALToma, Menetrier's disease, linitis plastica [40], and inflammatory bowel disease [41–43].

Miniprobe limitations   

Although miniprobes offer high resolution of small lesions in a single procedure, they do have some disadvantages. These include the limited penetration, which can make lymph node staging difficult. Unless a balloon sheath is used, the lumen needs to be filled with water, which may increase the risk of aspiration. Although the probes are reusable, they have a limited lifetime and undergo image deterioration after a certain number of cases.

 Needles and accessories for EUS   

Fine-needle aspiration   

The ability to sample tissue using EUS has greatly increased the sensitivity for diagnosing malignant lesions. It also overcomes some of the limitations of transcutaneous US- and CT-guided needle aspiration, which are limited when the lesions are small or no safe 'skin to lesion' route for the needle can be found. EUS-FNA is now part of the investigative algorithms for patients with pancreatic, esophageal, rectal, and lung cancer [44–46], and also for patients with submucosal tumors.

Different types of needles   

An EUS-FNA needle (Fig. 10) is a stainless steel echogenic needle with a bevelled edge. A stainless steel or nitinol stylet is inserted inside the needle, which prevents tissue or blood from clogging the needle while it is being advanced into the lesion (Figs 11–14). These stylets can be either bevelled to fit flush with the needle's tip or they can protrude a short distance from the needle tip with a sharp or a blunt tip. The needles come in a variety of diameters from 18 to 25 G, with 22 G being the most commonly used. The use of larger needles (18 or 19 G) is helpful if viscous fluid or large volumes are being aspirated. Spring-loaded needle designs are also available to help penetrate difficult-to-pierce lesions. There are as yet no studies comparing spring-loaded needles with routine EUS-FNA needles.

FNA technique   

EUS-FNA is performed using a linear echoendoscope, which allows visualization of the entire needle in real time. The needle is inserted through the instrument channel of the echoendoscope and into the lesion, and the stylet is removed and the needle moved through the lesion with a rapid inward thrust and slower backwards motion. Suction is usually used except when initial aspirates are bloody. In this case the use of suction may decrease the sensitivity [47] of FNA and tissue should be aspirated without suction. Up to 10 back-and-forth movements are usually used [48]; suction is released, the tip of the needle is withdrawn back into the needle sheath, the needle is removed, and the contents are spread thinly on slides for examination by a cytopathologist. The exact number of needle passes required depends on whether a cytopathologist is available at the procedure, and the type of lesion being biopsied. If a cytopathologist is present the number of passes needed will be determined by the adequacy of sample obtained. If a cytopathologist is not available most series suggest that 3–4 passes [49–53] are sufficient to ensure a cellular sample, although up to 10 passes may be required in well-differentiated tumors or solid pancreatic masses [54].

Accuracy and safety   

The accuracy of EUS-FNA is dependent on the technique used [55,56], the experience of the endosonographer [48,52], and the cytopathologist [54]. Even in the most challenging scenario of hard pancreatic masses, EUS-FNA can provide a cytological diagnosis in 80–94% of pancreatic lesions [57–61].

EUS-FNA has a low complication rate of 1–2% [50,53,62–65], similar to that reported for CT- or US-guided FNA or biopsy [66–69]. The major complications are infection in cystic lesions [50], bleeding [62], pancreatitis [53,70,71], and duodenal perforation [63]. Clinically significant bacteremia after EUS-FNA is rare but, because of the small but documented risk of infecting cystic lesions at EUS-FNA, intravenous broad-spectrum antibiotics are often used with EUS-FNA of cystic lesions [72–74] and puncture of any lesion through the colonic wall [75]. To date two deaths have been reported with EUS-FNA [62,76]. Needle-tract seeding is a potential complication; however, the risk is minimal in EUS-FNA, with only one case reported to date [77], as the needle travels from the gut lumen to the lesion, a pathway that usually does not cross peritoneal or pleural surfaces. In addition, the complete needle tract is usually included should the lesion subsequently undergo resection.

Core tissue biopsies   

Technique   

One of the disadvantages of FNA is that tissue architecture is not preserved. This is particularly important for the diagnosis of stromal tumors and lymphomas [78,79]. Core biopsies allow tissue to be obtained with preservation of underlying architecture. A modified Trucut biopsy needle has been developed, consisting of a 20-mm tissue tray, with a 19 G outer cutting sheath and a spring-loaded mechanism built into the handle that automates collection of specimens (Fig. 15). The biopsy needle is prepared before introduction into the endoscope by pulling back the spring handle until it clicks into the 'firing' position. This action draws the outer cutting sheath back and allows the inner needle tissue tray to be advanced. The inner needle remains in the withdrawn position until the specimen is obtained. The sheath assembly is advanced through the echoendoscope and then securely screwed into the accessory port channel with the Luer-lock adapter. The needle assembly is advanced into the lesion under EUS visualization. Once the lesion is entered, the tissue tray is further advanced into the tissue. Once the tray has exited the cutting sheath, the spring is released, which causes the cutting sheath to deploy rapidly over the tissue tray. The needle is withdrawn into the sheath and the entire assembly is removed from the endoscope. Samples up to 20 mm long can often be obtained with this device (Fig. 16).

Accuracy and safety   

The overall accuracy of EUS core biopsies is 85–94% [80–82]. However, there is substantial variation in the accuracy, depending on whether biopsies are performed through the stomach or through the duodenum. In a study by Gines [82] the diagnostic yield was 57% with a transduodenal approach, compared with 89–100% for transesophageal or transgastric biopsies, which is comparable with findings from other studies [83,84]. The reason for higher failure rate with transduodenal biopsies has not been fully investigated but may be due to the increased angulation of the echoendoscope in the setting of a stiffer 19 G TCB needle. EUS-guided core biopsy is a relatively safe procedure with a complication rate of 2%, which is similar to that of EUS-FNA [85].

 Outstanding issues and future trends   

Several new imaging techniques are being developed. A curved linear array echoendoscope for endobronchial ultrasound-FNA (EBUS) (Fig. 17) and 360° electronic radial echoendoscopes have been launched recently. Three-dimensional EUS probes and software are being developed to evaluate esophageal, colorectal, and pancreatico-biliary lesions [86,87]. Preliminary results show that this is feasible for pancreatic evaluation and may enhance the evaluation of pancreatic lesions, especially in the setting of established chronic pancreatitis [88]. In animal studies, unresectable pancreatic tumors have been ablated using a modification of the EUS needle as a radiofrequency catheter [89]. EUS can also provide minimally invasive targeted delivery of specific therapies to tumors. EUS-guided FNA has been used to deliver a local immunotherapy (Cytoimplant) in patients with advanced pancreatic carcinoma with no procedure-related complications [90], and has also been used to inject a modified adenovirus into pancreatic adenocarcinomas [91]. Case reports of EUS-guided photodynamic therapy have been reported and studies of EUS-guided brachytherapy are awaited with interest. Finally, a specially designed applicator permeable to sound waves has been developed to apply radiation directly by needles under ultrasound guidance for anal cancer [92]. In a study of 18 patients with anal cancer EUS-guided chemotherapy produced complete initial remission in all patients with 13.9% recurrence at mean follow-up of 44 months [93]. More studies are required to assess these technologies further but they point the way forward for EUS, and hopefully the next few years will see further growth in the field of EUS-guided therapy in a range of gastrointestinal and mediastinal diseases.

 References  

 1 Rösch, T. (2005). Endoscopic ultrasonography: equipment and technique. In: Endoscopic ultrasound (ed. Fockens P), pp. 13–31. Elsevier, Philadelphia.

 2 Gress, F, Savides, T, Cummings, O, Sherman, S, Lehman, G & Zaidi, S et al. Radial scanning and linear array endosonography for staging pancreatic cancer: a prospective randomized comparison. Gastrointest Endosc 1997; 45: 138–42. PubMed CrossRef

 3 Siemsen, M, Svendsen, LB, Knigge, U, Vilmann, P, Jensen, F & Rasch, L et al. A prospective randomized comparison of curved array and radial echoendoscopy in patients with esophageal cancer. Gastrointest Endosc 2003; 58: 671–6. PubMed CrossRef

 4 Kato, T, Tsukamoto, Y, Naitoh, Y, Hirooka, Y, Furukawa, T & Hayakawa, T. Ultrasonographic and endoscopic ultrasonographic angiography in pancreatic mass lesions. Acta Radiol 1995; 36: 381–7. PubMed

 5 Koito, K, Namieno, T, Nagakawa, T & Morita, K. Inflammatory pancreatic masses: differentiation from ductal carcinomas with contrast-enhanced sonography using carbon dioxide microbubbles. Am J Roentgenol 1997; 169: 1263–7.

 6 Ueno, N, Tomiyama, T, Tano, S, Wada, S & Kimura, K. Contrast enhanced color Doppler ultrasonography in diagnosis of pancreatic tumor: two case reports. J Ultrasound Med 1996; 15: 527–30. PubMed

 7 Bhutani, M, Hoffman, BJ, van Velse, A & Hawes, RH. Contrast-enhanced endoscopic ultrasonography with galactose microparticles: Shu508a (Levovist). Endoscopy 1997; 29: 635–9. PubMed

 8 Ricke, J, Hänninen, LE, Amthauer, H, Lemke, A & Felix, R. Assessment of the vascularisation of endocrine tumors by stimulated acoustic emission of SHU 508A ultrasound contrast agent and color or power Doppler sonography. Invest Radiol 2000; 4: 253–9. CrossRef

 9 Becker, D, Strobel, D, Bernatik, T & Hahn, EG. Echo-enhanced color- and power-Doppler EUS for the discrimination between focal pancreatitis and pancreatic carcinoma. Gastrointest Endosc 2001; 53: 784–9. PubMed

10 Ding, H, Kudo, M, Onda, H, Suetomi, Y, Minami, Y & Maekawa, K. Hepatocellular carcinoma: depiction of tumor parenchymal flow with intermittent harmonic power Doppler US during the early arterial phase in dual-display mode. Radiology 2001; 220: 349–56. PubMed

11 Ding, H, Kudo, M, Maekawa, K, Suetomi, Y, Minami, Y & Onda, H. Detection of tumor parenchymal blood flow in hepatic tumors: value of second harmonic imaging with a galactose-based contrast agent. Hepatol Res 2001; 21: 242–51. PubMed CrossRef

12 Ding, H, Kudo, M, Onda, H, Nomura, H & Haji, S. Sonographic diagnosis of pancreatic islet cell tumor: value of intermittent harmonic imaging. J Clin Ultrasound 2001; 29: 411–16. PubMed CrossRef

13 Ding, H, Kudo, M, Onda, H, Suetomi, Y, Minami, Y & Maekawa, K. Contrast-enhanced subtraction harmonic sonography for evaluating treatment response in patients with hepatocellular carcinoma. Am J Roentgenol 2001; 176: 661–6.

14 Rickes, S, Unkrodt, K, Neye, H, Ocran, KW & Wermke, W. Differentiation of pancreatic tumours by conventional ultrasound, unenhanced and echo-enhanced power Doppler sonography. Scand J Gastroenterol 2002; 37: 1313–20. PubMed CrossRef

15 Ding, H, Kudo, M, Onda, H, Suetomi, Y, Minami, Y & Chung, H et al. Evaluation of post-treatment response of hepatocellular carcinoma with contrast-enhanced coded phase-inversion harmonic US: comparison with dynamic CT. Radiology 2001; 221: 721–30. PubMed

16 Minami, Y, Kudo, M, Kawasaki, T, Kitano, M, Chung, H & Maekawa, K et al. Transcatheter arterial chemoembolization of hepatocellular carcinoma: usefulness of coded phase-inversion harmonic sonography. Am J Roentgenol 2003; 180: 703–8.

17 Wen, Y, Kudo, M, Zheng, RQ, Minami, Y, Chung, H & Suetomi, Y et al. Radiofrequency ablation of hepatocellular carcinoma: therapeutic response using contrast-enhanced coded phase-inversion harmonic sonography. Am J Roentgenol 2003; 181: 57–63.

18 Kitano, M, Kudo, M, Maekawa, K, Suetomi, Y, Sakamoto, H & Fukuta, N et al. Dynamic imaging of pancreatic diseases by contrast enhanced coded phase inversion harmonic ultrasonography. Gut 2004; 53: 854–9. PubMed CrossRef

19 Wiersema, M & Wiersema, LM. High-resolution 25-megahertz ultrasonography of the gastrointestinal wall: histologic correlates. Gastrointest Endosc 1993; 39: 499–504. PubMed

20 Maruta, S, Tsukamoto, Y, Niwa, Y, Goto, H, Hase, S & Yoshikane, H. Evaluation of upper gastrointestinal tumors with a new endoscopic ultrasound probe. Gastrointest Endosc 1994; 40: 603–8. PubMed

21 Schembre, D, Chak, A, Stevens, P, Isenberg, G, Sivak, MV Jr & Lightdale, CJ. Prospective evaluation of balloon-sheathed catheter US system. Gastrointest Endosc 2001; 53: 758–63. PubMed CrossRef

22 Wallace, M, Hoffman, BJ, Sahai, AS, Inoue, H, Van Velse, A & Hawes, RH. Imaging of esophageal tumors with a water-filled condom and a catheter US probe. Gastrointest Endosc 2000; 51: 597–600. PubMed CrossRef

23 Menzel, J & Domschke, W. Gastrointestinal miniprobe sonography: the current status. Am J Gastroenterol 2000; 95: 605–16. PubMed CrossRef

24 Furukawa, T, Tsukamoto, Y, Naitoh, Y, Hirooka, Y & Hayakawa, T. Differential diagnosis between benign and malignant localized stenosis of the main pancreatic duct by intraductal ultrasound of the pancreas. Am J Gastroenterol 1994; 89: 2038–41. PubMed

25 Menzel, J & Domschke, W. Intraductal ultrasonography (IDUS) of the pancreato-biliary duct system: personal experience and review of literature. Eur J Ultrasound 1999; 10: 105–15. PubMed CrossRef

26 Hasegawa, N, Niwa, Y, Arisawa, T, Hase, S, Goto, H & Hayakawa, T. Preoperative staging of superficial esophageal carcinoma: comparison of an ultrasound probe and standard endoscopic ultrasonography. Gastrointest Endosc 1996; 44: 388–93. PubMed CrossRef

27 Hunerbein, M, Ghadimi, BM, Haensch, W & Schlag, PM. Transendoscopic ultrasound of esophageal and gastric cancer using miniaturized ultrasound catheter probes. Gastrointest Endosc 1998; 48: 371–5. PubMed CrossRef

28 Menzel, J, Hoepffner, N, Nottberg, H, Schulz, C, Senninger, N & Domschke, W. Preoperative staging of esophageal carcinoma: miniprobe sonography versus conventional endoscopic ultrasound in a prospective histopathologically verified study. Endoscopy 1999; 31: 291–7. PubMed CrossRef

29 Yanai, H, Yoshida, T, Harada, T, Matsumoto, Y, Nishiaki, M & Shigemitsu, T. Endoscopic ultrasonography of superficial esophageal cancers using a thin ultrasound probe system equipped with switchable radial and linear scanning modes. Gastrointest Endosc 1996; 44: 578–82. PubMed CrossRef

30 Kawano, T, Ohshima, M & Iwai, T. Early esophageal carcinoma: endoscopic ultrasonography using the Sonoprobe. Abdom Imaging 2003; 28: 477–85. PubMed CrossRef

31 Akahoshi, K, Chijiwa, Y, Hamada, S, Sasaki, I, Nawata, H & Kabemura, T. Pretreatment staging of endoscopically early gastric cancer with a 15 MHz ultrasound catheter probe. Gastrointest Endosc 1998; 48: 470–6. PubMed CrossRef

32 Menzel, J, Hoepffner, N, Sulkowski, U, Reimer, P, Heinecke, A & Poremba, C. Polypoid tumors of the major duodenal papilla: preoperative staging with intraductal US, EUS, and CT—a prospective, histopathologically controlled study. Gastrointest Endosc 1999; 49: 349–57. PubMed CrossRef

33 Itoh, A, Goto, H, Naitoh, Y, Hirooka, Y, Furukawa, T & Hayakawa, T. Intraductal ultrasonography in diagnosing tumor extension of cancer of the papilla of Vater. Gastrointest Endosc 1997; 45: 251–60. PubMed CrossRef

34 Adrain, AHC, Cassidy, MJ, Schiano, TD, Liu, JB & Miller, LS. High-resolution endoluminal sonography is a sensitive modality for the identification of Barrett's metaplasia. Gastrointest Endosc 1997; 46: 147–51. PubMed CrossRef

35 Waxman, I. Endosonography in columnar-lined esophagus. Gastroenterol Clin North Am 1997; 26: 607–12. PubMed CrossRef

36 Schiano, T, Fisher, RS, Parkman, HP, Cohen, S, Dabezies, M & Miller, LS. Use of high-resolution endoscopic ultrasonography to assess esophageal wall damage after pneumatic dilation and botulinum toxin injection to treat achalasia. Gastrointest Endosc 1996; 44: 151–7. PubMed CrossRef

37 Miller, L, Liu, JB, Barbarevech, CA, Baranowski, RJ, Dhuria, M & Schiano, TD. High-resolution endoluminal sonography in achalasia. Gastrointest Endosc 1995; 44: 545–9. CrossRef

38 Miller, L & Schiano, TD. The use of high frequency endoscopic ultrasonography probes in the evaluation of achalasia. Gastrointest Endosc Clin N Am 1995; 5: 635–47. PubMed

39 Schiano, T, Adrain, AL, Cassidy, MJ, McCray, W, Liu, JB & Baranowski, RJ. Use of high-resolution endoluminal sonography to measure the radius and wall thickness of esophageal varices. Gastrointest Endosc 1996; 44: 425–8. PubMed CrossRef

40 Buscarini, E, Stasi, MD, Rossi, S, Silva, M, Giangregorio, F & Adriano, Z. Endosonographic diagnosis of submucosal upper gastrointestinal tract lesions and large fold gastropathies by catheter ultrasound probe. Gastrointest Endosc 1999; 49: 184–91. PubMed

41 Soweid, A, Chak, A, Katz, JA & Sivak, MV Jr Catheter probe assisted endoluminal US in inflammatory bowel disease. Gastrointest Endosc 1999; 50: 41–6. PubMed CrossRef

42 Tsuga, K, Haruma, K, Fujimura, J, Hata, J, Tani, H & Tanaka, S. Evaluation of the colorectal wall in normal subjects and patients with ulcerative colitis using an ultrasonic catheter probe. Gastrointest Endosc 1998; 48: 477–84. PubMed CrossRef

43 Higaki, S, Nohara, H, Saitoh, Y, Akazawa, A, Yanai, H & Yoshida, T. Increased rectal wall thickness may predict relapse in ulcerative colitis: a pilot follow-up study by ultrasonographic colonoscopy. Endoscopy 2002; 34: 212–19. PubMed

44 Detterbeck, F, De Camp, MM, Kohman, LJ & Silvestri, GA. Lung cancer: invasive staging: the guidelines. Chest 2003; 123: 167S–75S. PubMed

45 Green, F, Page, DL, Fleming, ID, Fritz, AG, Balch, CM & Haller, DF. (2002). Esophagus. In: AJCC cancer staging handbook, 6th edn (ed. Greene FL et al.), pp. 103–XX. Springer-Verlag, New York.

46 Green, F, Page, DL, Fleming, ID, Fritz, AG, Balch, CM & Haller, DF. (2002). Exocrine pancreas. In: AJCC cancer staging handbook, 6th edn (ed. Greene FL et al.), pp. 182–XX. Springer-Verlag, New York.

47 Wallace, M, Kennedy, T, Durkalski, V, Eloubeide, MA, Etamad, R & Matsuda, K. et al. Randomized controlled trial of EUS-guided fine needle aspiration techniques for the detection of malignant lymphadenopathy. Gastrointest Endosc 2001; 54: 441–7. PubMed CrossRef

48 Mertz, H & Gautam, S. The learning curve for EUS-guided FNA of pancreatic cancer. Gastrointest Endosc 2004; 59: 33–7. PubMed CrossRef

49 Erickson, R, Sayage-Rabie, L & Beissner, RS. Factors predicting the number of EUS-guided fine-needle passes for diagnosis of pancreatic malignancies. Gastrointest Endosc 2000; 51: 184–90. PubMed CrossRef

50 Wiersema, M, Vilmann, P, Giovannini, M, Chang, KJ & Wiersema, LM. Endosonography-guided fine-needle aspiration biopsy: diagnostic accuracy and complication assessment. Gastroenterology 1997; 112: 1087–95. PubMed

51 Gress, F, Gottlieb, K, Sherman, S & Lehman, G. Endoscopic ultrasonography-guided fine-needle aspiration biopsy of suspected pancreatic cancer. Ann Int Med 2001; 134: 459–64. PubMed

52 Harewood, GC, Wiersema, LM, Halling, AC, Keeney, GL, Salamao, DR & Wiersema, MJ. Influence of EUS training and pathology interpretation on accuracy of EUS-guided fine needle aspiration of pancreatic masses. Gastrointest Endosc 2002; 55: 669–73. PubMed CrossRef

53 O'Toole, D, Palazzo, L, Arotcarena, R, Dancour, A, Aubert, A & Hammel, P. et al. Assessment of complications of EUS-guided fine-needle aspiration. Gastrointest Endosc 2001; 53: 470–4. PubMed

54 Lin, F & Staerkel, G. Cytologic criteria for well differentiated adenocarcinoma of the pancreas in fine-needle aspiration biopsy specimens. Cancer 2003; 99: 44–50. PubMed

55 Chang, K. Maximizing the yield of EUS-guided fine-needle aspiration. Gastrointest Endosc 2002; 56: S28–34. PubMed

56 Binmoeller, K & Rathod, VD. Difficult pancreatic mass FNA: tips for success. Gastrointest Endosc 2002; 56: S86–93. PubMed

57 Erickson, R, Sayage-Rabie, L & Beisner, RS. Factors impacting endoscopic ultrasound-guided fine needle aspiration passes for pancreatic malignancies. Gastrointest Endosc 2000; 51: 184–90. PubMed

58 Chang, K. Endoscopic ultrasound-guided fine needle aspiration in the diagnosis and staging of pancreatic tumors. Gastrointest Endosc Clin North Am 1995; 5: 723–34.

59 Bhutani, M. Endoscopic ultrasonography in pancreatic disease. Semin Gastrointest Dis 1998; 9: 51–60. PubMed

60 Bhutani, M, Hawes, RH, Baron, PL, Sanders-Cliette, A, van Velse, A, Osborne, JF & Hoffman, BJ. Endoscopic ultrasound guided fine needle aspiration of malignant pancreatic lesions. Endoscopy 1997; 29: 854–8. PubMed

61 Chang, K, Katz, KD, Durbin, TE, Erickson, RA, Butler, JA & Lin, F et al. Endoscopic ultrasound-guided fine-needle aspiration. Gastrointest Endosc 1994; 40: 694–9. PubMed

62 Gress, F, Hawes, RH, Savides, TJ, Ikenberry, SO & Lehman, GA. Endoscopic ultrasound-guided fine-needle aspiration biopsy using linear array and radial scanning endosonography. Gastrointest Endosc 1997; 45: 243–50. PubMed CrossRef

63 Raut, C, Grau, AM, Staerkel, GA, Kaw, M, Tamm, EP & Wolff, RA et al. Diagnostic accuracy of endoscopic ultrasound-guided fine-needle aspiration in patients with presumed pancreatic cancer. J Gastrointest Surg 2003; 7: 118–26. PubMed CrossRef

64 Chieng, D, Jhala, D, Jhala, N, Eltoum, I, Chen, VK & Vickers, S et al. Endoscopic ultrasound-guided fine-needle aspiration biopsy: a study of 103 cases. Cancer 2002; 96: 232–9. PubMed

65 Williams, D, Sahai, AV, Aabakken, L, Penman, ID, van Velse, A & Webb, J. et al. Endoscopic ultrasound guided fine needle aspiration biopsy: a large single centre experience. Gut 1999; 44: 720–6. PubMed

66 Klein, J & Zarka, MA. Transthoracic needle biopsy. Radiol Clin North Am 2000; 38: 235–66. PubMed CrossRef

67 Schreiber, G & McCrory, DC. Performance characteristics of different modalities for diagnosis of suspected lung cancer: summary of published evidence. Chest 2003; 123: 115S–28S. PubMed

68 Brandt, K, Charboneau, JW, Stephens, DH, Welch, TJ & Goellner, JR. CT- and US-guided biopsy of the pancreas. Radiology 1993; 187: 99–104. PubMed

69 Di Stasi, M, Lencioni, R, Solmi, L, Magnolfi, F, Caturelli, E & De Sio, I et al. Ultrasound-guided fine needle biopsy of pancreatic masses: results of a multicenter study. Am J Gastroenterol 1998; 93: 1329–33. PubMed CrossRef

70 Hollerbach, S, Klamann, A, Topalidis, T & Schmiegel, W. Endoscopic ultrasonography (EUS) and fine-needle aspiration (FNA) cytology for diagnosis of chronic pancreatitis. Endoscopy 2001; 33: 824–31. PubMed CrossRef

71 Eloubeidi, M, Chen, VK, Eltoum, IA, Jhala, D, Chhieng, DC & Jhala, N et al. Endoscopic ultrasound-guided fine needle aspiration biopsy of patients with suspected pancreatic cancer: diagnostic accuracy and acute and 30-day complications. Am J Gastroenterol 2003; 98: 2663–8. PubMed

72 Hernandez, L, Mishra, G, Forsmark, C, Draganov, PV, Petersen, JM & Hochwald, SN et al. Role of endoscopic ultrasound (EUS) and EUS-guided fine needle aspiration in the diagnosis and treatment of cystic lesions of the pancreas. Pancreas 2002; 25: 222–8. PubMed CrossRef

73 Frossard, JL, Amouyal, P, Amouyal, G, Palazzo, L, Amaris, J & Soldan, M. et al. Performance of endosonography-guided fine needle aspiration and biopsy in the diagnosis of pancreatic cystic lesions. Am J Gastroenterol 2003; 98: 1516–24. PubMed CrossRef

74 Bounds, B & Brugge, WR. EUS diagnosis of cystic lesions of the pancreas. Int J Gastrointest Cancer 2001; 30: 27–31. PubMed

75 Antillon, M & Chang, KJ. Endosopic and endosonography guided fine-needle aspiration. Gastrointest Endosc Clin N Am 2000; 10 (619–36):. PubMed

76 ten Berge, J, Hoffman, BJ, Hawes, RH, Van Enckevort, C, Giovannini, M & Erickson, RA et al. EUS-guided fine needle aspiration of the liver: indications, yield, and safety based on an international survey of 167 cases. Gastrointest Endosc 2002; 55: 859–62. PubMed CrossRef

77 Paquin, S, Chua, TS, Tessier, G, Gariepy, G, Raymond, G & Bourdages, R et al. A first report of tumor seeding by EUS-FNA. Gastrointest Endosc 2004; 59: AB235.

78 Davila, R & Failgel, DO. GI stromal tumors. Gastrointest Endosc 2003; 58: 80–8. PubMed CrossRef

79 Ribeiro, A, Vazquez-Sequeiros, E, Wiersema, LM, Wang, KK, Clain, JE & Wiersema, MJ. EUS-guided fine-needle aspiration combined with flow cytometry and immunocytochemistry in the diagnosis of lymphoma. Gastrointest Endosc 2001; 53: 485–91. PubMed CrossRef

80 Levy, M, Jondal, ML, Clain, JE & Wiersema, MJ. Preliminary experience with an EUS-guided trucut biopsy needle compared with EUS-guided FNA. Gastrointest Endosc 2003; 57: 101–6. PubMed

81 Varadarajulu, S, Fraig, M, Schmulewitz, N, Roberts, S, Wildi, S & Hawes, RH et al. Comparison of EUS-guided 19-gauge trucut needle biopsy with EUS-guided fine-needle aspiration. Endoscopy 2004; 36: 397–401. PubMed CrossRef

82 Ginès, A, Wiersema, MJ, Clain, JE, Ponchron, NL, Rajan, E & Levy, MJ. Prospective study of a Trucut needle for performing EUS-guided biopsy with EUS-guided FNA rescue. Gastrointest Endosc 2005; 62: 597–601. PubMed CrossRef

83 Largi, A, Verna, EC, Stavropoulos, SN, Rotterdam, H, Lightdate, CJ & Stevens, PD. EUS-guided trucut needle biopsies in patients with solid pancreatic masses: a prospective study. Gastrointest Endosc 2004; 59: 185–90. PubMed CrossRef

84 Itoi, T, Itokawa, F, Sofuni, A, Nakamura, K, Tschida, A & Yamao, K et al. Puncture of solid pancreatic tumors guided by endoscopic ultrasonogrphy: a pilot study series comparing trucut and 19-gauge and 22-gauge aspiration needles. Endoscopy 2005; 37: 362–6. PubMed CrossRef

85 Erickson, RA. EUS-guided FNA. Gastrointest Endosc 2004; 60: 267–79. PubMed CrossRef

86 Sumiyama, K, Suzuki, N, Kakutani, H, Hino, S, Tajiri, H & Suzuki, H et al. A novel 3-dimensional EUS technique for real-time visualization of the volume data reconstruction process. Gastrointest Endosc 2002; 55: 723–8. PubMed CrossRef

87 Molin, S, Nesje, LB, Gilja, OH, Hausken, T, Martens, D & Odegaard, S. 3D-endosonography in gastroenterology: methodology and clinical applications. Eur J Ultrasound 1999; 10: 171–7. PubMed CrossRef

88 Fritscher-Ravens, A, Knoefel, WT, Drause, C, Swain, CP, Brandt, L & Patel, K. Three-dimensional endoscopic ultrasound-feasibility of a novel technique applied for the detection of vessel involvement of pancreatic masses. Am J Gastroenterol 2005; 100: 1296–302. PubMed CrossRef

89 Goldberg, SN, Mallery, S, Gazelle, GS & Brugge, WR. EUS-guided radiofrequency ablation in the pancreas: results in a porcine model. Gastrointest Endosc 1999; 50: 392–401. PubMed CrossRef

90 Chang, KJ, Nguyen, PT, Thompson, JA, Kurosaki, TT, Casey, LR & Leung, EC et al. Phase I clinical trial of local immunotherapy (Cytoimplant) delivered by endoscopic ultrasound (EUS)-guided fine needle injection (FNI) in patients with advanced pancreatic carcinoma. Gastrointest Endosc 1998; 47: AB144.

91 Bedford, R, Hecht, J, Lahoti, S, Abbruzzese, L, So, L & Kim, D. Tolerability and efficacy of direct injection of pancreatic adenocarcinomas with ONYX-015 under endoscopic ultrasound (EUS) guidance. Gastrointest Endosc 2000; 51: AB97.

92 Lohnert, M, Doniec, JM, Kovacs, G, Schroder, J & Dohrmann, P. New method of radiotherapy for anal cancer with three-dimensional tumor reconstruction based on endoanal ultrasound and ultrasound-guided afterloading therapy. Dis Colon Rectum 1998; 41: 169–76. PubMed CrossRef

93 Doniec, MJ, Loehnert, MS & Kovacs, G et al. Rectal EUS guided HDR-brachytherapy in patients with anal and peri-anal malignancies. Gastrointest Endosc 2000; 51: AB106.

Copyright © Blackwell Publishing, 2006