Introduction
Introduction
Training to a level of competency for EUS is challenging and involves a long learning
curve. Exposure to EUS cases may be limited and thus learning tools need to be developed
to decrease the number of supervised examinations in patients required to master this.
Also, the trainees have to reach a certain skill level in the limited period of EUS
fellowship. A few learning tools have been developed to allow a faster learning of
EUS and EUS-FNA.
Phantom
Phantom
Olympus (Olympus, Inc., Tokyo, Japan) has developed an EUS-FNA phantom, which consists
of a box (50 cm in length) with a hole in the center to simulate the esophagus and
different types and sizes of silicon block to simulate lymph nodes or cystic lesions.
(Fig. [1]) The advantage of this model is that it is simple, easy to use and conveniently
stored and transported. Sorbi et al. reported another type of phantom using commonly
available materials (barium enema bag, plastic tube, standard agar, etc.). [1] Both phantoms can aid in learning the basics of EUS-FNA - especially needle manipulation
and positioning of the echoendoscope relative to the target lesion. However, phantoms
cannot simulate or teach other EUS-related techniques, and are inadequate ”real-life”
simulators.
Fig. 1 Outlook of EUS-FNA box.
Computer-based simulator
Computer-based simulator
EUS Mentor (Simbionix, Tel Hashomer, Israel) represents an addition to a computer-based
endoscopic simulator platform and was developed for radial and linear-array EUS [2] (Fig. [2]). It provides real-time computer simulated EUS images based on human anatomy. As
of now, this system cannot create natural resistance for the tools through the working
channels and thus cannot simulate EUS-FNA. Burmester et al. reported another type
of simulator, which was especially designed for linear-array EUS with the three dimensional
integration of the real anatomy of the cadavers [3]. This interactive simulation system is very useful to learn the basic anatomic structure
using the linear array echoendoscope. However, there is no function for scope or needle
manipulation.
Fig. 2 Radial EUS images and anatomical view on EUS Mentor.
EUS RK model
EUS RK model
The Erlanger model is now widely used for training in therapeutic EGD and colonoscopy
as well as ERCP [4]. This model was modified to accommodate EUS training [5]
[6] (Fig. [3]). It consists of special made silicon case housing the ex-vivo pig stomach surrounded
by a gelatin medium to provide acoustic coupling. Grapes were embedded in gelatin
simulate lymph nodes. The whole preparation is labor intensive and takes about 6 hours
excluding preparation of pig organs, and can last 2 to 3 days in the refrigerator
after use. This model can generate real-time EUS images of tissue and is the most
realistic simulator of EUS-FNA besides the live pig model. This model has a potential
to contribute to the development of therapeutic EUS tools in the future. This model
was used in the learning center of 13th and 14th International Symposium on EUS as
well as hands-on training courses in Japan, Singapore, USA, and Europe. This model
would be suitable for relatively large training centers but needs to be simplified
and made less labor intensive.
Fig. 3 Outlook of EUS RK model.
Live pig
Live pig
The swine has been the most popular model for teaching EUS. The anatomy is similar
in many respects to the human, especially the pancreas, left kidney and celiac axis.
The live pig is realistic, however, it may be difficult to acquire, is expensive and
ethical issues often limit its availability. Bhutani et al. reported on the efficacy
of a swine model for teaching EUS tutorials [7] as well as for teaching interventional EUS by making a ”pseudo-lesion” with the
injection of saline [8]. The conclusion was that this model was helpful for understanding manipulation of
the scope and needle manipulation. The live pig can be an excellent option for teaching
EUS but requires an animal care facility.
How can we measure the efficacy of learning tools for EUS?
How can we measure the efficacy of learning tools for EUS?
For colonoscopy, Ahlberg et al. reported that endoscopic simulators actually improved
the early part of the learning curve in colonoscopy training [9]. In the field of ERCP, Sedlack et al. reported the direct comparison between the
live pig, a computer simulator and the EASIE model for ERCP [10]. The EASIE model scored the highest on indices of realism, usefulness, and performance,
although this reached statistical significance only for ”ease of use”. The computer
simulator scored significantly lower in most realism scores, although it was felt
to be the one model most easily incorporated into a training system.
In the case of EUS, there is no direct comparison demonstrating the actual efficacy
of each type of learning tool for EUS and EUS-FNA, although a few reports suggested
that they represented an overall aid in education [3]
[5]
[6]
[7]. We conducted a survey to assess the impact of the phantom, a computer simulator,
the modified Erlanger (RK) model and the live pig as a learning tool. Eight EUS experts
(Peter Vilmann, Mitsuhiro Kida, Kenneth Binmoeller, Vipulroy Rathod, Anand Sahai,
Greg Zuccaro, Robert Hawes, Koji Matsuda) were queried regarding the teaching utility
of these various tools. If they had no experience in a particular tool, no score was
counted.
Experience of each tool for educational purpose
Experience of each tool for educational purpose
The experience of each tool by eight EUS experts is shown in Table [1]. Only the ex-vivo model (RK model) had been used by all experts. The fewest number
of experts had experience with the computer simulator.
Table 1 Experience of each tool as an educational tools for EUS and EUS-FNA
| EUS-FNA box |
EUS Mentor |
EUS RK model |
Live pig |
| 7/8 |
5/8 |
8/8 |
6/8 |
Scores for realism compared with a human EUS
Scores for realism compared with a human EUS
The realism was evaluated for each system. The following criteria were scored on a
7-point Likert scale (1 = very unrealistic, 7 = very realistic): (1) anatomy of mediastinum,
(2) anatomy of pancreatic body and celiac axis (3) visualization, (4) scope manipulation,
(5) needle manipulation (Table [2]). In terms of anatomy, live pig scored best, followed by EUS Mentor and EUS RK
model. Regarding scope manipulation, the live pig and EUS Mentor scored best, followed
by EUS RK model. For needle manipulation, the live pig was best, followed by the ex-vivo
system and EUS-FNA box.
Table 2 Scores for realism compared with a human EUS
|
EUS-FNA box |
EUS Mentor |
EUS RK model |
Live pig |
| Anatomy of mediastinum |
1 (1 - 3) |
4.5 (1 - 6) |
3 (1 - 6) |
4 (1 - 6) |
| Anatomy of pancreatic body and celiac axis |
1 (1 - 3) |
4 (4 - 6) |
4 (1 - 5) |
5 (1 - 6) |
| Visualization |
4 (2 - 6) |
5 (4 - 6) |
5.5 (3 - 6) |
6 (4 - 7) |
| Scope manipulation |
3 (2 - 5) |
6 (4 - 6) |
4.5 (3 - 7) |
6 (4 - 7) |
| Needle manipulation |
5 (3 - 6) |
4 (1 - 6) |
5 (4 - 7) |
6 (5 - 7) |
| Median scores (range) are based on a 7-point Likert scale (1 = very unrealistic, 7
= very realistic). Scores in bold represent the highest score in each category. |
Scores for utility as an educational tool for EUS and EUS-FNA
Scores for utility as an educational tool for EUS and EUS-FNA
A similar scale was used to assess the utility of each tool for teaching of EUS and
EUS-FNA (1 = not useful at all, 7 = very useful) (Table [3]). In terms of overall utility for teaching EUS, the EUS Mentor scored slightly higher
than the live pig, followed by EUS RK model. In terms of usefulness in teaching EUS-FNA,
the live pig scored highest, followed by RUS RK model and EUS-FNA box.
Table 3 Scores for utility as an educational tool for EUS and EUS-FNA
|
EUS-FNA box |
EUS Mentor |
EUS RK model |
Live pig |
| Usefulness in teaching EUS |
3 (1 - 6) |
6 (4 - 6) |
4 (2 - 7) |
5.5 (4 - 6) |
| Usefulness in teaching EUS-FNA |
5 (4 - 6) |
3 (1 - 6) |
5 (4 - 7) |
6 (5 - 7) |
| Median scores (range) are based on a 7-point Likert scale (1 = not useful at all,
7 = very useful). Scores in bold represent the highest score in each category. |
Ordered rankings for four learning tools (Table [4])
Ordered rankings for four learning tools (Table [4])
Eight EUS experts directly compared the four tools by ranking them in order for the
following: (1) overall simulation realism (1 = most, 4 = least), (2) utility as an
educational modality (1 = most, 4 = least), (3) ease of use (1 = easiest, 4 = most
difficult), (4) ease of incorporation into a fellowship training program (1 = easiest,
4 = most difficult). If the experts did not have the experience using one tool, no
rank was counted.
The EUS-FNA box was rated highest in ”ease of use” and ”ease of incorporating into
fellowship training”, whereas it was lowest in ”overall simulation realism” and ”scores
for utility as an educational tool”. The live pig ranked highest in ”overall simulation
realism” and ”scores for utility as an educational tool”. However, the live pig was
inferior to the other tools for ”ease of use” and ”ease of incorporating into fellowship
training”.
Table 4 Ordered rankings for four learning tools
|
EUS-FNA box |
EUS Mentor |
EUS RK model |
Live pig |
| Overall simulation realism |
3 (3 - 4) |
2 (1 - 3) |
2 (1 - 3) |
1 (1 - 2) |
| Scores for utility as an educational tool |
3 (3 - 4) |
2 (1 - 3) |
2 (1 - 3) |
1 (1 - 2) |
| Ease of use |
1 (1 - 3) |
2 (1 - 2) |
2.5 (1 - 4) |
3 (2 - 4) |
| Ease of incorporating into fellowship training |
1 (1 - 3) |
2 (1 - 3) |
2 (1 - 4) |
3 (3 - 4) |
| Median ranking (range) are based on a 4-point hierarchy (1 = best, 4 = least). Scores
in bold represent the best median ranking in each category. |
Recommendation of learning tools in each teaching session by EUS experts
Recommendation of learning tools in each teaching session by EUS experts
The eight EUS experts marked the utility of each of the learning tools relative to
what stage the trainees were along the learning curve (Fig. [4]). EUS Mentor was recommended highest when ”doing EUS without FNA”, followed by ”before
starting EUS fellowship”, whereas the EUS RK model and phantom was recommended most
in ”just before starting EUS-FNA”. The live pig was recommended throughout the training
process. This type of study will be necessary to show the evidence of the efficacy
of learning tools from the point of trainee.
Fig. 4 Recommendation of learning tools in each teaching session by EUS experts.
Summary
Summary
There are a number of options to assist the trainee to achieve competency in EUS and
EUS-FNA. Although no randomized controlled trial with these tools have been performed
to definitely determine their role in training, this survey of EUS experts suggest
they can have a positive role. The authors believe that it is critically important
to develop practical and useful leaning tools for EUS and EUS-FNA and that these tools
will significantly aid in the teaching of EUS. Further study from the point of trainees
would be necessary.
