Endoscopic Ultrasonography

Frank G. Gress, Thomas J. Savides, Frank G. Gress, Thomas J. Savides

• Publisher: Wiley-Blackwell
• Year: 2016
• Print ISBN: 9781118781104
• eBook ISBN: 9781118781081
• Edition: 3
• Topic: Medicine
• Subtopic: Gastroenterology & Hepatology

Year on year, there continue to be dramatic changes in endoscopic ultrasonography (EUS) since it was first introduced 30 years ago. Advances in technology have meant that as well as being used in the diagnosis of gastrointestinal disorders, EUS is now one of the primary diagnostic and therapeutic modalities used in GI endoscopy.

 

Back and improved for a new edition, Endoscopic Ultrasonography is the market-leading book covering the topic.  Written by leading experts in the field, it provides a technical how-to approach to learning this advanced endoscopic procedure. The highly-acclaimed authors provide step-by-step guidance to the fundamentals of EUS, giving clear instructions on the instruments involved, the correct sedation procedures to follow and how EUS should be performed safely and effectively.

Every chapter discusses a specific aspect of EUS as it relates to a particular gastrointestinal disorder or organ system.   Brand new to this edition are:

1)                  Seven new chapters on the hottest topics in EUS: Learning Anatomy for EUS; Elastography; Lung Cancer; Autoimmune Pancreatitis; EUS for Liver Disease; Biliary Access; Pancreatic Fluid Collection Drainage

2)                  A complete update of all previous chapters to reflect the most current clinical recommendations

3)                  A host of new color images in every chapter 

 Endoscopic Ultrasonography 3^rd edition is the ideal tool to consult to improve EUS skills and improve patient management, and an essential purchase for all gastroenterologists and endoscopists.

Chapter 1
Endoscopic ultrasonography at the beginning: a personal history

Michael V. Sivak, Jr.

University Hospitals Case Medical Center, Cleveland, OH, USA

The first report of endoscopic ultrasonography (EUS), to my knowledge, is that of DiMagno et al., published in 1980 [1]. These investigators described a prototype echoendoscope assembled by attaching a transducer to a duodenoscope. Although images were obtained only in dogs, this work established the feasibility of EUS. As with nearly all seminal advances in endoscopy, EUS was basically an amalgamation of existing technologies. But in 1980, the potential of this hybrid technology was scarcely apparent to anyone – probably including these first endosonographers, who did not expand on their demonstration of the feasibility of EUS.

For practical purposes, the inception of EUS as a clinical entity in the United States can be traced to a meeting I had with Mr. Hiroshi Ichikawa of the Olympus Optical Company. Neither of us can remember the exact date, but it was most likely 1981. Olympus was developing several new technologies, and Hiroshi offered me a choice between EUS and enteroscopy. The only other thing I recollect from that meeting is that, for some unknown reason, I did not ponder the choice very long before I selected EUS, largely because the idea of endosonography seemed especially intriguing; it offered a greater challenge, but also the promise of a much wider range of prospective applications. I certainly gave little thought to – indeed, did not appreciate – the formidable obstacles to the clinical realization of this potential, nor to the investment of time and effort I would need to reach this goal, which was much more distant than I realized. Hiroshi did, in fact, lay emphasis on the obstacles, warning that the instrumentation was in the early stages of development (a euphemism for crude, barely usable). Because of the scope and difficulty of the project, Hiroshi advised that Olympus proposed to work with two investigators in the United States (actually, the western hemisphere), the other being Dr. Charles Lightdale in New York City, as well as a few individuals in other countries. I already knew Charlie, and thought him an excellent choice. As it turned out, this was the beginning of a long and rewarding professional association, for which EUS became the basis. Thus, EUS in the United States began with me and Charlie Lightdale.

Given the technical sophistication of present-day EUS systems, it is important to recognize that during the early years, the viability of endosonography was far from certain. Until about 1985, there was substantial skepticism concerning the future of EUS, even among those of us most closely involved with and committed to its development. The ample tribulations facing the very small cadre of nascent endosonographers became strikingly evident with the arrival of the first EUS system, a prototype in the truest sense. Despite the obvious problems, however, I do not believe that any of us were ever truly discouraged; the best description of our mindset during these formative years might be “doggedly enthusiastic.”

I began by writing a simple, all-encompassing protocol that would allow me to use the instrument as an investigational device in patients. The protocol, essentially, had no hypothesis, other than the assertion that EUS was going to be a good thing. It listed almost every possible indication I could conceive, and minimized the risks – which were unknown, in any case – to such a degree that I doubt it would be approved by any institutional research committee today.

The major problems that had to be addressed in the beginning divided into four categories: the technical limitations and deficiencies of the equipment, the development of efficient and safe techniques for the use of the echoendoscope in patients, interpretation of the ultrasound images, and the need to define and establish indications for EUS in clinical practice. More issues, some even more complicated, became evident over time.

The prototype echoendoscope itself was, by modern standards, incredibly cumbersome. The electronic (video) endoscope had not been introduced into clinical practice, so the prototype echoendoscope was a fiberoptic instrument; the optical (endoscopic) component consisted of an ocular lens and focusing ring, coupled to a coherent fiberoptic bundle, with another lens at the distal end of the insertion tube to focus an image on the bundle. The latter provided a limited, 80° field of view, oriented obliquely at an angle of 70° to the insertion tube. Of these two parameters, the narrow field of view was more of a limitation than the oblique orientation, which was not especially problematic for endoscopists accustomed to the side-viewing duodenoscope.

The ultrasound component of early echoendoscopes consisted of a transducer coupled to a rotating acoustic mirror at the distal tip of the insertion tube. The mirror was turned by means of an electric motor within a motor housing situated between a standard design control section and the insertion tube; thus the designation, “mechanical, sector-scanning echoendoscope.” Because the mirror turned around the long axis of the insertion tube, the ultrasound scanning plane was oriented perpendicular to the insertion tube. In retrospect, this was the best choice, because it seemed to simplify the problems of image interpretation. But this arrangement also had its limitations; mainly that it was unsuitable for guiding a needle to a target. Needle aspiration was, in fact, attempted with the sector-scanning instrument, albeit unsuccessfully, because the width of the tissue within the circular scan was much too narrow.

Unfortunately, the ultrasound imaging sector provided by the first instruments was not a full 360°, but only 180°. To obtain a complete, circumferential sector scan of the surrounding tissue – a circumferential esophageal tumor, for example – it was necessary to rotate the insertion tube 180°, while maintaining the same scanning plane. This was a considerable feat, especially with the instrument deeply inserted, for example in the third part of the duodenum. In truth, it was largely impossible, because any application of torque to the insertion tube invariably altered the scanning plane. This was but one among many difficulties.

Owing to the mechanical components, principally the motor and its housing, the instrument was much heavier than a standard endoscope. I don't think I ever tried to weigh it, but it probably tipped the scale at more than one pound. Because EUS had no established clinical purpose, the first procedures can only be described as exploratory. Consequently, procedure length was determined largely by patient endurance, and with an especially tolerant patient, the weight of the instrument seemingly increased exponentially. After two or three examinations, it was often difficult (and painful) to straighten your left arm.

The combination of optical and acoustical components at the distal end of the insertion tube conferred other penalties, including some potential hazards. The diameter of the insertion tube was 13 mm; that is, substantially greater than that of the upper endoscopes of the time. To make matters worse, the distal end was rigid over a length of 4.5 cm; that is, the distance from the tip to the bending section. Together with the limited field of view, this increased the difficulty of inserting the instrument through the mouth and pharynx and into the esophagus. Although we assumed that the risk of complications with EUS was no greater than that with upper endoscopy, and informed our patients the same, in reality the risk of perforating the pyriform sinus was probably greater – a fact subsequently substantiated. Moreover, attempts at insertion of the large-diameter echoendoscope through a constricting tumor in the esophagus were no doubt associated with an appreciable risk of perforation.

In addition to developing technique for the safe insertion of the echoendoscope, the learning curve for EUS imaging can only be described as long and steep, a line with a slope approaching straight up. According to Yogi Bera, “ninety percent of everything is half mental,” and this was definitely true of EUS. The first quandary was the need to uncouple endoscopic imaging from ultrasonography. This related to the need for acoustic coupling; that is, the creation of a suitable interface between the tissue and the transducer (in this case, the acoustic mirror). We discovered in short order that ultrasound images can't be obtained through air. The obvious solution: remove the air. But this proved impractical, for several reasons. The alternative was to interpose water between tissue and “transducer,” which could be accomplished in two ways: by placing a balloon over the transducer section of the instrument and filling it with water, or by filling the gut with water. However, it was not simply a matter of choosing between these two options. Depending on the circumstances, including location within the gastrointestinal tract, one or the other was usually a better choice. With the balloon method in particular, the endoscopic view was lost as the balloon was brought into contact with the gut wall, meaning that ultrasound imaging could only proceed by abandoning the endoscopic view. For technical reasons, therefore, EUS imaging was, of necessity, endoscopically blind. Although this decoupling might seem inconsequential today, it was a mental leap of faith in the early days, inasmuch as endoscopic dogma deemed “blind” use of an endoscope hazardous.

Use of the balloon with early-model echoendoscopes was so exasperating that it deserves a digressive paragraph of its own. The latex material that constituted the balloon was not of uniform quality, which made it nearly impossible to place the balloon on the echoendoscope without tearing it. When expanded, the balloon had an asymmetric bulge, and according to the instructions the bulge was to be placed over the transducer on the same side as the optical component; this was never accomplished. Assuming that the balloon could be maneuvered intact into the correct position, it was next necessary to tie it in place with small sutures. The design of the instrument was such that the proximal end of the balloon sometimes occluded the opening of the channel for air insufflation and water irrigation, which would not be evident until it was securely tied in place and tested. Subsequent attempts to nudge the balloon into proper position usually resulted in tearing. Since the objective was to create a water–tissue interface, it was necessary to remove all the air from the balloon (without breaking it). The balloon, if not placed exactly, could occlude the tiny-diameter channel provided for this purpose. Once all of the delicate parameters were attained, and the balloon was in gloriously correct position and functioning properly, the most maddening occurrence was rupture of the ill-fated bag in the middle of an examination, usually at the most inopportune moment. I dealt with some of these frustrations by persuading a gentleman from the biomedical engineering department (designated the “balloon man”) to take on the task of balloon placement prior to each procedure.

During the examination, the balloon was filled with water via a Luer lock fitting located between the control section and the motor housing. Unfortunately, this design meant that the attached syringe protruded in perpendicular fashion. Accordingly, as the endosonographer moved his right hand from the control section to the insertion tube, he invariably broke the syringe. In order to fill the balloon, it was necessary to set a small lever on the motor housing to the balloon-filling position, clearly labeled as “B.” The other choice was “G,” which when selected channeled the water into the gut. Since it was not possible to see this lever, it was advisable to remember which position it was in. Otherwise, the balloon might be filled with water beyond its capacity.

One of the most gratifying aspects of endosonography, readily apparent at the very first examination, was the ability to obtain a structured image of the gut wall. Believe me, all of us knew intuitively and immediately that this was going to be very big. But the interpretation of these images was something else again. There was a natural tendency to assume, to hope, that the five-layer structure corresponded in exact fashion to the actual layers of the gut wall as seen microscopically in a histological section. This betrays a near total ignorance of the principles of ultrasound imaging, and over time it became evident that the physical basis for the endosonographic representation of the bowel wall is much more complex. For reasons unknown to me, the main ultrasound frequency selected for the first EUS systems was 7.5 MHz, a frequency that happens, under the usual conditions, to render the wall structure of the stomach as five layers. I suspect that this choice of frequency was based on technical considerations, rather than experimental data. In any case, it took some time to work out the actual physical basis for the ultrasound images of the gut wall.

One thing that occurred to me during my first discussion of EUS with Hiroshi Ichikawa, and which probably influenced my choice of EUS as opposed to enteroscopy, was the possibility that EUS might have a positive impact on the problem of pancreatic cancer. By 1980, it was clear that endoscopic retrograde cholangiopancreatography (ERCP) could never alter the natural history of this disease, but perhaps EUS might provide an opportunity, under certain circumstances, for earlier detection and therefore improved survival. In retrospect, this was a worthy but naïve notion. Nevertheless, I resolved to pursue EUS of the pancreas. Charlie Lightdale, on the other hand, took a more sensible and practical path by studying the applications of EUS in staging esophageal cancer. Given the limitations of the first EUS systems, my focus on pancreatic imaging was not the wisest decision.

While my comprehension of the EUS image of the gut wall was next to zero, this knowledge was encyclopedic by comparison with my understanding of EUS of the pancreas. In truth, the only thing I could identify with certitude was a gallstone, and only if it was over 1 cm in diameter and solidly calcified. After a while, optimism becomes a poor substitute for know-how, and it was soon obvious that the only way to move forward was to seek the advice of a radiologist with expertise in ultrasonography. Many of the first endosonographers adopted a similar approach. And so, a radiologist by the name of Craig George came to my assistance. Our idea was that Craig would look over my shoulder during the EUS procedure and essentially interpret the images. By this time, we had a second-generation prototype EUS system. In contrast to the first prototype, the second system included an extremely bulky image processor with a tiny display screen, probably no more than 8 inches on the diagonal. Moreover, the quality of the image was poor, which made it necessary to get close to the screen to see anything. Furthermore, the screen was placed in the box such that it was only about 4 feet above the floor. So, Craig sat on a low stool in front of the box. But all of these limitations were inconsequential to me because Craig is a big guy with a correspondingly large head; most of the time the only thing I could see was the back of it. Somehow, we evolved a set of hand signals to deal with this problem. It worked like this: if Craig (face pressed to the screen) saw something he recognized, he would make certain motions with his hand, either the left or the right depending on the direction he wanted me to move the transducer, in an effort to obtain the best possible image (I always think of Craig whenever I watch a jet plane being guided to its parking place by the guy with the long, orange flashlights). When he got the image he wanted, Craig would hit the “freeze” button, quickly move his head out of the way so I could see it, and then place a camera in front of the screen to obtain a photograph (the permanent image in those days).

Although this arrangement was cumbersome, I learned most of what I know about pancreatic imaging, and the principles of ultrasonography, from Craig George. After about 6 months, our partnership gradually dissolved, partly because it was difficult to coordinate our schedules, but mostly because I had acquired, so I thought, enough knowledge to proceed on my own.

Until June 1982, the struggle to develop EUS was a lonely one; only a handful of endoscopists had any practical experience with EUS, and all were working essentially alone. This changed that June, when Olympus sponsored the first “International Workshop on Endoscopic Ultrasonography” at the Grand Hotel in Stockholm, Sweden – a time and venue selected to coincide with the World Congress of Gastroenterology. We met in a very small room, as there were, according to my notes, only about 15 active participants, including two invited guests with expertise in areas of digestive ultrasonography other than EUS, and excluding about a half dozen representatives from Olympus.

Keichi Kawai (Kyoto, Japan), who organized the meeting, asked me to speak on “Arrangement of Endoscopic Ultrasonography.” I never did discover exactly what my assigned topic entailed. Nevertheless, compared to the many EUS meetings in which I participated in subsequent years, this first gathering was by far the most important. For, by the time of the meeting, each participant had discovered many things about EUS, but none had a complete picture, whether of its limitations or of its true potential. Thus, there was a remarkable and exhilarating exchange of information and ideas that, in retrospect, amounted by aggregation to a significant advance. I led a long discussion on EUS of the pancreas that solidified the concept of stationed withdrawal of the echoendoscope from the duodenum. Essentially, we made a list of the organs and structures that should be imaged at each station. But, most importantly, I think each of the dozen participants left the meeting with a revitalized sense of purpose, as well as a stronger sense of confidence in the future of EUS.

Another aspect of EUS that was clarified by the 1982 meeting...

Table of contents

• Cover
• Title page
• Copyright
• Table of contents
• List of contributors
• Preface
• Acknowledgments
• Chapter 1: Endoscopic ultrasonography at the beginning: a personal history
• Chapter 2: Basic principles and fundamentals of EUS imaging
• Chapter 3: Learning EUS anatomy
• Chapter 4: EUS instruments, room setup, and assistants
• Chapter 5: EUS procedure: consent and sedation
• Chapter 6: The EUS report
• Chapter 7: Radial EUS: normal anatomy
• Chapter 8: Linear-array EUS: normal anatomy
• Chapter 9: EUS elastography
• Chapter 10: Fundamentals of EUS FNA
• Chapter 11: EUS FNA cytology: material preparation and interpretation
• Chapter 12: High-frequency ultrasound probes
• Chapter 13: EUS: applications in the mediastinum
• Chapter 14: EBUS and EUS for lung cancer diagnosis and staging
• Chapter 15: EUS for esophageal cancer
• Chapter 16: EUS of the stomach and duodenum
• Chapter 17: Gastrointestinal subepithelial masses
• Chapter 18: EUS for the diagnosis and staging of solid pancreatic neoplasms
• Chapter 19: EUS for pancreatic cysts
• Chapter 20: The role of EUS in inflammatory diseases of the pancreas
• Chapter 21: Autoimmune pancreatitis
• Chapter 22: EUS for biliary diseases
• Chapter 23: EUS in liver disease
• Chapter 24: Colorectal EUS
• Chapter 25: Therapeutic EUS for cancer treatment
• Chapter 26: EUS-guided biliary access
• Chapter 27: Pancreatic fluid collection drainage
• Chapter 28: EUS-guided drainage of pelvic fluid collections
• Chapter 29: EUS hemostasis
• Chapter 30: Training in EUS
• Chapter 31: The future of EUS
• Index
• End User License Agreement