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Beyond simulation: can adjunctive technologies accelerate learning in gastrointestinal endoscopy?
Techniques in Gastrointestinal Endoscopy (2011) 13, 146-150
Techniques in GASTROINTESTINAL ENDOSCOPY www.techgiendoscopy.com
Beyond simulation: can adjunctive technologies accelerate learning in gastrointestinal endoscopy? Tyler M. Berzin, MD, Douglas K. Pleskow, MD, AGAF, FASGE Center for Advanced Endoscopy, Division of Gastroenterology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts. KEYWORDS: Endoscopy; Colonoscopy; Endoscopic ultrasound; Computer simulation; Endoscopy; Education; User– computer interface
Gastrointestinal endoscopy is a complex manual task with an extended learning curve. Numerous technologies are emerging that may accelerate the acquisition of endoscopic skills for trainees and experienced practitioners in gastroenterology. A wide variety of endoscopic simulators are available, ranging from ex vivo porcine models to computer simulators with haptic feedback. In parallel with endoscopic simulation, innovations are also occurring in “adjunctive” technologies for live endoscopy (ie, technologies that aim to provide more detailed visual or even 3-dimensional information streams to the endoscopist during a procedure). Such adjunctive technologies include live torque and force monitoring during colonoscopy and 3-dimensional views of scope positioning with respect to patient anatomy during linear endosonography. These innovations are spurred on by potential improvements in patient safety, procedural efficiency, and the possibility of expanded therapeutic applications in endoscopy. Additionally, providing more robust visual displays of key data such as scope position, overlaid on or adjacent to the endoscopic image, has the potential to alter the learning curve for gastroenterology trainees. © 2011 Elsevier Inc. All rights reserved.
The acquisition of procedural skills in gastrointestinal endoscopy remains heavily reliant on an apprenticeship model, centered on hands-on training in the endoscopy suite under the supervision of a more experienced endoscopist. A variety of recommendations have been published regarding the number of supervised procedures required to attain “proficiency.” The American Society for Gastrointestinal Endoscopy recommends that 130 upper endoscopies and 140 colonoscopies are required to attain proficiency in each procedure,1 although recent data suggest higher numbers. More complex procedures such as endoscopic retrograde cholangiopancreatography and endoscopic ultrasound (EUS) are generally felt to require more extensive training to achieve proficiency. The current guidelines suggest that trainees perform 180-200 endoscopic
The authors report no direct financial interests that might pose a conflict of interest in connection with the submitted manuscript. Address reprint requests to Tyler M. Berzin, MD, Division of Gastroenterology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215. E-mail: [email protected] 1096-2883/11/$-see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.tgie.2011.03.002
retrograde cholangiopancreatographies and at least 150 EUS examinations to achieve proficiency.2,3 Endoscopic simulation technologies offer the possibility of developing basic manual skills or learning new techniques, away from the patient. Despite the potential benefits of moving the early part of the learning curve away from the endoscopy suite or operating room, widespread adoption of simulation in medicine has been slow. Endoscopic simulators, ranging from plastic colon models to advanced computer simulators with haptic feedback, have been available since the 1970s4; however, many gastroenterology training programs have not yet incorporated simulator training. Cost barriers and inadequate space for simulator equipment are among the potential hurdles to widespread adoption of endoscopy simulator technologies, particularly at smaller hospitals. Beyond simulation, new avenues are emerging by which cutting-edge technology may enhance, and perhaps accelerate, endoscopic training. Devices that allow precise mapping of scope position or real-time information regarding torque and pressure may bring certain core advantages of computer simulator training (eg, immediate feedback, ob-
Berzin and Pleskow
Adjunctive Technologies in Gastrointestinal Endoscopy
147
jective measurements of personal progress) back to the endoscopy suite. When live feedback regarding scope position, torque, and other factors can be effectively incorporated into the endoscopy display (in a manner similar to the “heads-up display” used by pilots), then interest in such adjunctive technologies may take a major step forward, particularly if benefits can be demonstrated for routine clinical endoscopic practice.
Torque and force monitoring The appropriate and safe application of linear insertion force and torque is a core skill of colonoscopy, but these concepts can prove difficult to explain or demonstrate to a trainee. Increased or abnormal amounts of force during endoscope insertion can increase patient discomfort and may be associated with a higher risk of injury such as mucosal bruising or perforation.5 The use of excessive linear force may also result in the development of a loop that must be reduced prior to further advancement of the colonoscope. Several computer simulators for colonoscopy incorporate immediate feedback on excessive force to help trainees adjust and learn to distinguish between appropriate and excessive force.6,7 Devices have also been developed to measure linear and torque forces applied during live colonoscopy.8,9 Currently available devices attach to the colonoscope shaft and must be gripped with the right hand during colonoscopy. The devices are somewhat bulky and must be progressively repositioned along the shaft of the colonoscope as the instrument is advanced to the cecum (Figure 1). The forces applied to the colonoscope are measured using “load cells” and the results may be transmitted wirelessly to a computer. These devices can display and analyze data including peak pull force, push force, and torque force. Chronologic recordings of a specific case can be reviewed, and the forces that an individual endoscopist/trainee applies could be compared against average results or perhaps the “ideal” patterns of force recorded from expert colonoscopists. Force monitoring technology needs to advance further before any significant impact on endoscopy training is likely. Specifically, normal or acceptable ranges of linear forces and torque forces must be established by further study. Force sensors could eventually be incorporated directly into the colonoscope shaft, replacing the current external clamp devices. Proponents of force monitoring suggest that this technology may represent a step beyond common yardsticks such as cecal intubation time toward more quantitative approaches to measuring technical skill and progress.
Colonoscope 3-dimensional positioning Developing a 3-dimensional (3-D) understanding of colonoscope positioning is a core challenge for trainees in gastrointestinal endoscopy. The ability to quickly recognize
Figure 1 Colonoscope force monitor attached to an Olympus PCF-160 colonoscope in the open (A) and closed (B) position. Reprinted with permission.9
and successfully reduce colonoscope “loops,” particularly in the sigmoid colon, is a key factor differentiating endoscopic novices from experts. Colonoscopic loops can both prolong the procedure and be a primary cause of patient discomfort during colonoscopy.10 Despite the central importance of recognizing and managing loops, it can be a significant challenge for a mentor to convey concepts of scope positioning to a novice endoscopist. In the early days of colonoscopy, concepts of scope positioning and looping could be visually demonstrated by fluoroscopy. With the development of more flexible colonoscopes, greater range of motion, and high-definition optics, the use of fluoroscopy has disappeared and with it the routine opportunity for trainees to connect tactile information with visual images of colonoscope position. Today’s computers simulators for colonoscopy routinely provide information on scope position to help trainees develop a 3-D understanding of endoscope positioning, but information on colonoscope position is not routinely available in the endoscopy suite.6,7 More recently, magnetic endoscope imaging (MEI) technology has been developed to provide accurate information regarding colonoscope positioning, without the risks of radiation exposure and bulky fluoroscopy equipment.10,11 One approach to MEI is the use of a 200-cm catheter that is
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Techniques in Gastrointestinal Endoscopy, Vol 13, No 2, April 2011
Figure 2 Magnetic endoscope imaging. Anteroposterior (AP) and lateral views of a colonoscope inserted to splenic flexure with a sigmoid loop. The splenic flexure (dark blue marker) and hepatic flexure (light blue marker) are identified. The purple sphere represents the position of an assistant’s hand, placing pressure on the sigmoid loop. Reprinted with permission.10
inserted through the instrument channel of a standard colonoscope. The MEI catheter has multiple electromagnetic coils, which generate pulsed magnetic fields. During colonoscope insertion, these signals are registered by small receiving devices and the information is processed to create a precise 3-D representation of colonoscope positioning (Figure 2). Colonoscopes are now being developed with built-in MEI functionality, obviating the need for a separate MEI catheter. Initial results suggest that the use of a colonoscope with built-in MEI technology (vs standard colonoscopy) may increase cecal intubation rates and reduce patient discomfort.12 Scope positioning technology is also at the root of an early-phase device in which independent electromagnetic elements within the colonoscope shaft articulate to follow the shape of the colon in a “follow-the-leader” fashion.13 If more robust trial data and user experience demonstrate that the benefits of precise information on colonoscope position extend into the clinical realm, this will surely spur more aggressive development of this technology. Indeed, because more colonoscopies may be performed for directed removal of polyps detected on computed tomography (CT) colonography, precise spatial positioning information may be valuable and could conceivably reduce the time spent searching for a previously identified polyp. For trainees, routine use of MEI or similar scope position technologies may once again demystify colonoscope looping and other spatial concepts, as fluoroscopy once did at the advent of colonoscopy.
EUS mapping to CT scans EUS is one of the most challenging procedures to learn in gastrointestinal endoscopy. Understanding the position of the ultrasound transducer with respect to adjacent organs in the thoracic, abdominal, and pelvic regions requires extensive practice and a thorough understanding of local anat-
omy. Compared with radial endoscopic ultrasonography, linear endoscopic ultrasonography is particularly difficult because of the limited field of view and highly variable views of anatomic structures. Only one commercially available endoscopy simulator has attempted to address the inherent complexity of linear EU (GI Mentor, Symbionix USA Corp, Cleveland, OH). Understanding and interpreting the EUS imaging plane is the principal challenge of EUS. Technologies that provide a 3-D representation of the position and angle of the ultrasound transducer and resultant image have the potential to significantly improve the educational experience in EU. Of particular note is a recently developed system termed image-registered gastroscopic ultrasound.14 A 3-D reconstruction of the patient’s anatomy is first constructed based on a previously acquired CT scan. At present, this process is somewhat time intensive and requires manual identification and outlining of relevant organs on the CT scan by a trained technologist. For the EUS procedure, the linear echoendoscope tip is fitted with a commercially available microscopic position sensor that does not interfere with the ultrasonographic image. The sensor transmits precise information on scope position and orientation to a central processor. In addition to the ultrasound image, two real-time images are then displayed on additional monitors for the endoscopist; one image provides a 3-D orientation display that shows a representation of the position of the scope within the abdominal cavity, and a second image provides a matched oblique slice image of the CT scan, directly corresponding to the linear ultrasound image (Figure 3). In an early study using the image-registered gastroscopic ultrasound system, both novice and experienced endosonographers demonstrated significant improvements in identifying structures in a porcine model.14 Ongoing clinical studies will determine whether similar improvements are seen when this technology is applied to patients. EUS with image mapping to CT/magnetic resonance imaging stands out as a technology with numerous potential advantages both for training and for clinical practice and we suspect development of this technology will continue at a rapid pace.
Future Directions There is ample opportunity for adjunctive technologies to alter the landscape for training and clinical practice in gastrointestinal endoscopy. For trainees, developing an earlier understanding of endoscope forces and the relative position of the scope tip and shaft may help accelerate the learning curve, particularly in colonoscopy. Such measurements may also lay the groundwork for more quantitative assessments of individual technical skill and learning progress. In clinical practice, precise information on colonoscope position may be particularly useful for “difficult”/ redundant colons and for locating polyps or suspected lesions from previous imaging studies or procedures. In the
Berzin and Pleskow
Adjunctive Technologies in Gastrointestinal Endoscopy
149
Figure 3 Representative example of image-registered gastroscopic ultrasound. (Top left) EUS image. (Top right) Corresponding reconstructed orthogonal view from CT scan. (Bottom) Representation of scope tip (blue) and imaging plane (green) with respect to 3-D representation of landmark organs (based on CT scan). (Courtesy of Kirby Vosbough, PhD, Brigham and Women’s Hospital, Boston, MA.)
future, adapting image-registration technology to colonoscopy could even lead to the use of a 3-D image of the colonoscope overlaid against a rough “map” created by CT colonography. This would have the potential to substantially increase the efficiency of colonoscopy for targeted polypectomy after CT colonography. In EU, the potential advantages of tracking the position and angle of the endoscope in relation to major anatomic landmarks are particularly evident. Novice and expert endosonographers are both likely to benefit from having additional confirmation of scope position to guide diagnostic and therapeutic interventions. The additional screen “real-estate” afforded by larger, high-definition monitors in the endoscopy suite should allow for the creative incorporation of additional live information streams (scope position, torque/force monitoring) on the endoscopy display. Outside the field of medicine, there have been rapid advancements within the realm of augmented reality (ie, superimposing computer-generated, context-specific information onto a real-time view of the physical environment). We expect that over time, augmented reality will have applications in gastrointestinal endoscopy as well, both in education and in clinical practice. Scope force and position information are just two examples of the types of information that could be incorporated into a visual display during endoscopy. Eventually, it may be possible to
overlay information obtained from confocal or spectroscopic analysis on the live endoscopic image, allowing the endoscopist to rapidly perform a highly targeted biopsy or local resection of dysplastic tissue. The next generation of trainees in gastrointestinal endoscopy will likely be able to adapt rapidly to using multiple visual information streams during endoscopy and will no doubt wonder how endoscopy was performed effectively in the days when the only information on the screen was a high-definition camera image.
References 1. Principles of training in gastrointestinal endoscopy. From the ASGE. American Society for Gastrointestinal Endoscopy. Gastrointest Endosc 49:845-853, 1999 2. Jowell PS, Baillie J, Branch MS, et al: Quantitative assessment of procedural competence. A prospective study of training in endoscopic retrograde cholangiopancreatography. Ann Intern Med 125:983-989, 1996 3. Eisen GM, Dominitz JA, Faigel DO, et al: Guidelines for credentialing and granting privileges for endoscopic ultrasound. Gastrointest Endosc 54:811-814, 2001 4. Williams CB: Fiberoptic colonoscopy: Teaching. Dis Colon Rectum 19:395-399, 1976 5. Wu TK: Occult injuries during colonoscopy. Measurement of forces required to injure the colon and report of cases. Gastrointest Endosc 24:236-238, 1978
150
Techniques in Gastrointestinal Endoscopy, Vol 13, No 2, April 2011
6. Koch AD, Buzink SN, Heemskerk J, et al: Expert and construct validity of the Simbionix GI Mentor II endoscopy simulator for colonoscopy. Surg Endosc 22:158-162, 2008 7. Kruglikova I, Grantcharov TP, Drewes AM, et al: Assessment of early learning curves among nurses and physicians using a high-fidelity virtual-reality colonoscopy simulator. Surg Endosc 24:366-370, 2010 8. Appleyard MN, Mosse CA, Mills TN, et al: The measurement of forces exerted during colonoscopy. Gastrointest Endosc 52:237-240, 2000 9. Korman LY, Egorov V, Tsuryupa S, et al: Characterization of forces applied by endoscopists during colonoscopy by using a wireless colonoscopy force monitor. Gastrointest Endosc 71:327-334, 2010 10. Shah SG, Brooker JC, Thapar C, et al: Patient pain during colonoscopy: An analysis using real-time magnetic endoscope imaging. Endoscopy 34:435-440, 2002
11. Saunders BP, Bell GD, Williams CB, et al: First clinical results with a real time, electronic imager as an aid to colonoscopy. Gut 36:913917, 1995 12. Hoff G, Bretthauer M, Dahler S, et al: Improvement in caecal intubation rate and pain reduction by using 3-dimensional magnetic imaging for unsedated colonoscopy: A randomized trial of patients referred for colonoscopy. Scand J Gastroenterol 42:885-889, 2007 13. Eickhoff A, van Dam J, Jakobs R, et al: Computer-assisted colonoscopy (the NeoGuide Endoscopy System): results of the first human clinical trial (“PACE study”). Am J Gastroenterol 102:261-266, 2007 14. Vosburgh KG, Stylopoulos N, Estepar RS, et al: EUS with CT improves efficiency and structure identification over conventional EUS. Gastrointest Endosc 65:866-870, 2007
Techniques in GASTROINTESTINAL ENDOSCOPY www.techgiendoscopy.com
Beyond simulation: can adjunctive technologies accelerate learning in gastrointestinal endoscopy? Tyler M. Berzin, MD, Douglas K. Pleskow, MD, AGAF, FASGE Center for Advanced Endoscopy, Division of Gastroenterology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts. KEYWORDS: Endoscopy; Colonoscopy; Endoscopic ultrasound; Computer simulation; Endoscopy; Education; User– computer interface
Gastrointestinal endoscopy is a complex manual task with an extended learning curve. Numerous technologies are emerging that may accelerate the acquisition of endoscopic skills for trainees and experienced practitioners in gastroenterology. A wide variety of endoscopic simulators are available, ranging from ex vivo porcine models to computer simulators with haptic feedback. In parallel with endoscopic simulation, innovations are also occurring in “adjunctive” technologies for live endoscopy (ie, technologies that aim to provide more detailed visual or even 3-dimensional information streams to the endoscopist during a procedure). Such adjunctive technologies include live torque and force monitoring during colonoscopy and 3-dimensional views of scope positioning with respect to patient anatomy during linear endosonography. These innovations are spurred on by potential improvements in patient safety, procedural efficiency, and the possibility of expanded therapeutic applications in endoscopy. Additionally, providing more robust visual displays of key data such as scope position, overlaid on or adjacent to the endoscopic image, has the potential to alter the learning curve for gastroenterology trainees. © 2011 Elsevier Inc. All rights reserved.
The acquisition of procedural skills in gastrointestinal endoscopy remains heavily reliant on an apprenticeship model, centered on hands-on training in the endoscopy suite under the supervision of a more experienced endoscopist. A variety of recommendations have been published regarding the number of supervised procedures required to attain “proficiency.” The American Society for Gastrointestinal Endoscopy recommends that 130 upper endoscopies and 140 colonoscopies are required to attain proficiency in each procedure,1 although recent data suggest higher numbers. More complex procedures such as endoscopic retrograde cholangiopancreatography and endoscopic ultrasound (EUS) are generally felt to require more extensive training to achieve proficiency. The current guidelines suggest that trainees perform 180-200 endoscopic
The authors report no direct financial interests that might pose a conflict of interest in connection with the submitted manuscript. Address reprint requests to Tyler M. Berzin, MD, Division of Gastroenterology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215. E-mail: [email protected] 1096-2883/11/$-see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.tgie.2011.03.002
retrograde cholangiopancreatographies and at least 150 EUS examinations to achieve proficiency.2,3 Endoscopic simulation technologies offer the possibility of developing basic manual skills or learning new techniques, away from the patient. Despite the potential benefits of moving the early part of the learning curve away from the endoscopy suite or operating room, widespread adoption of simulation in medicine has been slow. Endoscopic simulators, ranging from plastic colon models to advanced computer simulators with haptic feedback, have been available since the 1970s4; however, many gastroenterology training programs have not yet incorporated simulator training. Cost barriers and inadequate space for simulator equipment are among the potential hurdles to widespread adoption of endoscopy simulator technologies, particularly at smaller hospitals. Beyond simulation, new avenues are emerging by which cutting-edge technology may enhance, and perhaps accelerate, endoscopic training. Devices that allow precise mapping of scope position or real-time information regarding torque and pressure may bring certain core advantages of computer simulator training (eg, immediate feedback, ob-
Berzin and Pleskow
Adjunctive Technologies in Gastrointestinal Endoscopy
147
jective measurements of personal progress) back to the endoscopy suite. When live feedback regarding scope position, torque, and other factors can be effectively incorporated into the endoscopy display (in a manner similar to the “heads-up display” used by pilots), then interest in such adjunctive technologies may take a major step forward, particularly if benefits can be demonstrated for routine clinical endoscopic practice.
Torque and force monitoring The appropriate and safe application of linear insertion force and torque is a core skill of colonoscopy, but these concepts can prove difficult to explain or demonstrate to a trainee. Increased or abnormal amounts of force during endoscope insertion can increase patient discomfort and may be associated with a higher risk of injury such as mucosal bruising or perforation.5 The use of excessive linear force may also result in the development of a loop that must be reduced prior to further advancement of the colonoscope. Several computer simulators for colonoscopy incorporate immediate feedback on excessive force to help trainees adjust and learn to distinguish between appropriate and excessive force.6,7 Devices have also been developed to measure linear and torque forces applied during live colonoscopy.8,9 Currently available devices attach to the colonoscope shaft and must be gripped with the right hand during colonoscopy. The devices are somewhat bulky and must be progressively repositioned along the shaft of the colonoscope as the instrument is advanced to the cecum (Figure 1). The forces applied to the colonoscope are measured using “load cells” and the results may be transmitted wirelessly to a computer. These devices can display and analyze data including peak pull force, push force, and torque force. Chronologic recordings of a specific case can be reviewed, and the forces that an individual endoscopist/trainee applies could be compared against average results or perhaps the “ideal” patterns of force recorded from expert colonoscopists. Force monitoring technology needs to advance further before any significant impact on endoscopy training is likely. Specifically, normal or acceptable ranges of linear forces and torque forces must be established by further study. Force sensors could eventually be incorporated directly into the colonoscope shaft, replacing the current external clamp devices. Proponents of force monitoring suggest that this technology may represent a step beyond common yardsticks such as cecal intubation time toward more quantitative approaches to measuring technical skill and progress.
Colonoscope 3-dimensional positioning Developing a 3-dimensional (3-D) understanding of colonoscope positioning is a core challenge for trainees in gastrointestinal endoscopy. The ability to quickly recognize
Figure 1 Colonoscope force monitor attached to an Olympus PCF-160 colonoscope in the open (A) and closed (B) position. Reprinted with permission.9
and successfully reduce colonoscope “loops,” particularly in the sigmoid colon, is a key factor differentiating endoscopic novices from experts. Colonoscopic loops can both prolong the procedure and be a primary cause of patient discomfort during colonoscopy.10 Despite the central importance of recognizing and managing loops, it can be a significant challenge for a mentor to convey concepts of scope positioning to a novice endoscopist. In the early days of colonoscopy, concepts of scope positioning and looping could be visually demonstrated by fluoroscopy. With the development of more flexible colonoscopes, greater range of motion, and high-definition optics, the use of fluoroscopy has disappeared and with it the routine opportunity for trainees to connect tactile information with visual images of colonoscope position. Today’s computers simulators for colonoscopy routinely provide information on scope position to help trainees develop a 3-D understanding of endoscope positioning, but information on colonoscope position is not routinely available in the endoscopy suite.6,7 More recently, magnetic endoscope imaging (MEI) technology has been developed to provide accurate information regarding colonoscope positioning, without the risks of radiation exposure and bulky fluoroscopy equipment.10,11 One approach to MEI is the use of a 200-cm catheter that is
148
Techniques in Gastrointestinal Endoscopy, Vol 13, No 2, April 2011
Figure 2 Magnetic endoscope imaging. Anteroposterior (AP) and lateral views of a colonoscope inserted to splenic flexure with a sigmoid loop. The splenic flexure (dark blue marker) and hepatic flexure (light blue marker) are identified. The purple sphere represents the position of an assistant’s hand, placing pressure on the sigmoid loop. Reprinted with permission.10
inserted through the instrument channel of a standard colonoscope. The MEI catheter has multiple electromagnetic coils, which generate pulsed magnetic fields. During colonoscope insertion, these signals are registered by small receiving devices and the information is processed to create a precise 3-D representation of colonoscope positioning (Figure 2). Colonoscopes are now being developed with built-in MEI functionality, obviating the need for a separate MEI catheter. Initial results suggest that the use of a colonoscope with built-in MEI technology (vs standard colonoscopy) may increase cecal intubation rates and reduce patient discomfort.12 Scope positioning technology is also at the root of an early-phase device in which independent electromagnetic elements within the colonoscope shaft articulate to follow the shape of the colon in a “follow-the-leader” fashion.13 If more robust trial data and user experience demonstrate that the benefits of precise information on colonoscope position extend into the clinical realm, this will surely spur more aggressive development of this technology. Indeed, because more colonoscopies may be performed for directed removal of polyps detected on computed tomography (CT) colonography, precise spatial positioning information may be valuable and could conceivably reduce the time spent searching for a previously identified polyp. For trainees, routine use of MEI or similar scope position technologies may once again demystify colonoscope looping and other spatial concepts, as fluoroscopy once did at the advent of colonoscopy.
EUS mapping to CT scans EUS is one of the most challenging procedures to learn in gastrointestinal endoscopy. Understanding the position of the ultrasound transducer with respect to adjacent organs in the thoracic, abdominal, and pelvic regions requires extensive practice and a thorough understanding of local anat-
omy. Compared with radial endoscopic ultrasonography, linear endoscopic ultrasonography is particularly difficult because of the limited field of view and highly variable views of anatomic structures. Only one commercially available endoscopy simulator has attempted to address the inherent complexity of linear EU (GI Mentor, Symbionix USA Corp, Cleveland, OH). Understanding and interpreting the EUS imaging plane is the principal challenge of EUS. Technologies that provide a 3-D representation of the position and angle of the ultrasound transducer and resultant image have the potential to significantly improve the educational experience in EU. Of particular note is a recently developed system termed image-registered gastroscopic ultrasound.14 A 3-D reconstruction of the patient’s anatomy is first constructed based on a previously acquired CT scan. At present, this process is somewhat time intensive and requires manual identification and outlining of relevant organs on the CT scan by a trained technologist. For the EUS procedure, the linear echoendoscope tip is fitted with a commercially available microscopic position sensor that does not interfere with the ultrasonographic image. The sensor transmits precise information on scope position and orientation to a central processor. In addition to the ultrasound image, two real-time images are then displayed on additional monitors for the endoscopist; one image provides a 3-D orientation display that shows a representation of the position of the scope within the abdominal cavity, and a second image provides a matched oblique slice image of the CT scan, directly corresponding to the linear ultrasound image (Figure 3). In an early study using the image-registered gastroscopic ultrasound system, both novice and experienced endosonographers demonstrated significant improvements in identifying structures in a porcine model.14 Ongoing clinical studies will determine whether similar improvements are seen when this technology is applied to patients. EUS with image mapping to CT/magnetic resonance imaging stands out as a technology with numerous potential advantages both for training and for clinical practice and we suspect development of this technology will continue at a rapid pace.
Future Directions There is ample opportunity for adjunctive technologies to alter the landscape for training and clinical practice in gastrointestinal endoscopy. For trainees, developing an earlier understanding of endoscope forces and the relative position of the scope tip and shaft may help accelerate the learning curve, particularly in colonoscopy. Such measurements may also lay the groundwork for more quantitative assessments of individual technical skill and learning progress. In clinical practice, precise information on colonoscope position may be particularly useful for “difficult”/ redundant colons and for locating polyps or suspected lesions from previous imaging studies or procedures. In the
Berzin and Pleskow
Adjunctive Technologies in Gastrointestinal Endoscopy
149
Figure 3 Representative example of image-registered gastroscopic ultrasound. (Top left) EUS image. (Top right) Corresponding reconstructed orthogonal view from CT scan. (Bottom) Representation of scope tip (blue) and imaging plane (green) with respect to 3-D representation of landmark organs (based on CT scan). (Courtesy of Kirby Vosbough, PhD, Brigham and Women’s Hospital, Boston, MA.)
future, adapting image-registration technology to colonoscopy could even lead to the use of a 3-D image of the colonoscope overlaid against a rough “map” created by CT colonography. This would have the potential to substantially increase the efficiency of colonoscopy for targeted polypectomy after CT colonography. In EU, the potential advantages of tracking the position and angle of the endoscope in relation to major anatomic landmarks are particularly evident. Novice and expert endosonographers are both likely to benefit from having additional confirmation of scope position to guide diagnostic and therapeutic interventions. The additional screen “real-estate” afforded by larger, high-definition monitors in the endoscopy suite should allow for the creative incorporation of additional live information streams (scope position, torque/force monitoring) on the endoscopy display. Outside the field of medicine, there have been rapid advancements within the realm of augmented reality (ie, superimposing computer-generated, context-specific information onto a real-time view of the physical environment). We expect that over time, augmented reality will have applications in gastrointestinal endoscopy as well, both in education and in clinical practice. Scope force and position information are just two examples of the types of information that could be incorporated into a visual display during endoscopy. Eventually, it may be possible to
overlay information obtained from confocal or spectroscopic analysis on the live endoscopic image, allowing the endoscopist to rapidly perform a highly targeted biopsy or local resection of dysplastic tissue. The next generation of trainees in gastrointestinal endoscopy will likely be able to adapt rapidly to using multiple visual information streams during endoscopy and will no doubt wonder how endoscopy was performed effectively in the days when the only information on the screen was a high-definition camera image.
References 1. Principles of training in gastrointestinal endoscopy. From the ASGE. American Society for Gastrointestinal Endoscopy. Gastrointest Endosc 49:845-853, 1999 2. Jowell PS, Baillie J, Branch MS, et al: Quantitative assessment of procedural competence. A prospective study of training in endoscopic retrograde cholangiopancreatography. Ann Intern Med 125:983-989, 1996 3. Eisen GM, Dominitz JA, Faigel DO, et al: Guidelines for credentialing and granting privileges for endoscopic ultrasound. Gastrointest Endosc 54:811-814, 2001 4. Williams CB: Fiberoptic colonoscopy: Teaching. Dis Colon Rectum 19:395-399, 1976 5. Wu TK: Occult injuries during colonoscopy. Measurement of forces required to injure the colon and report of cases. Gastrointest Endosc 24:236-238, 1978
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Techniques in Gastrointestinal Endoscopy, Vol 13, No 2, April 2011
6. Koch AD, Buzink SN, Heemskerk J, et al: Expert and construct validity of the Simbionix GI Mentor II endoscopy simulator for colonoscopy. Surg Endosc 22:158-162, 2008 7. Kruglikova I, Grantcharov TP, Drewes AM, et al: Assessment of early learning curves among nurses and physicians using a high-fidelity virtual-reality colonoscopy simulator. Surg Endosc 24:366-370, 2010 8. Appleyard MN, Mosse CA, Mills TN, et al: The measurement of forces exerted during colonoscopy. Gastrointest Endosc 52:237-240, 2000 9. Korman LY, Egorov V, Tsuryupa S, et al: Characterization of forces applied by endoscopists during colonoscopy by using a wireless colonoscopy force monitor. Gastrointest Endosc 71:327-334, 2010 10. Shah SG, Brooker JC, Thapar C, et al: Patient pain during colonoscopy: An analysis using real-time magnetic endoscope imaging. Endoscopy 34:435-440, 2002
11. Saunders BP, Bell GD, Williams CB, et al: First clinical results with a real time, electronic imager as an aid to colonoscopy. Gut 36:913917, 1995 12. Hoff G, Bretthauer M, Dahler S, et al: Improvement in caecal intubation rate and pain reduction by using 3-dimensional magnetic imaging for unsedated colonoscopy: A randomized trial of patients referred for colonoscopy. Scand J Gastroenterol 42:885-889, 2007 13. Eickhoff A, van Dam J, Jakobs R, et al: Computer-assisted colonoscopy (the NeoGuide Endoscopy System): results of the first human clinical trial (“PACE study”). Am J Gastroenterol 102:261-266, 2007 14. Vosburgh KG, Stylopoulos N, Estepar RS, et al: EUS with CT improves efficiency and structure identification over conventional EUS. Gastrointest Endosc 65:866-870, 2007