Observational Study
Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Sep 14, 2020; 26(34): 5169-5180
Published online Sep 14, 2020. doi: 10.3748/wjg.v26.i34.5169
Experimental model standardizing polyvinyl alcohol hydrogel to simulate endoscopic ultrasound and endoscopic ultrasound-elastography
Elymir S Galvis-García, Sergio Sobrino-Cossío, Arturo Reding-Bernal, Yesica Contreras-Marín, Karina Solórzano-Acevedo, Patricia González-Zavala, Rosa M Quispe-Siccha
Elymir S Galvis-García, Unidad de Endoscopía Gastrointestinal, Hospital General de México "Dr. Eduardo Liceaga", Mexico 06720, Mexico
Sergio Sobrino-Cossío, Unidad de Endoscopia y Fisiología Digestiva, Hospital Ángeles del Pedregal, Mexico 10700, Mexico
Arturo Reding-Bernal, Dirección de Investigación, Hospital General de México “Dr. Eduardo Liceaga”, Mexico 06720, Mexico
Yesica Contreras-Marín, Karina Solórzano-Acevedo, Unidad Profesional Interdisciplinaria de Biotecnología and Unidad de Investigación y Desarrollo Tecnológico, Instituto Politécnico Nacional and Hospital General de México "Dr. Eduardo Liceaga", Mexico 06720, Mexico
Patricia González-Zavala, Instituto de Investigaciones en Materiales and Unidad de Investigación y Desarrollo Tecnológico, Universidad Nacional Autónoma de México and Hospital General de México "Dr. Eduardo Liceaga", Mexico 06720, Mexico
Rosa M Quispe-Siccha, Unidad de Investigación y Desarrollo Tecnológico, Hospital General de México "Dr. Eduardo Liceaga", Mexico 06720, Mexico
Author contributions: Quispe Siccha RM established the design and concept of the study; Galvis García ES and Sobrino Cossío S executed the figures; Quispe Siccha RM, González Zaval P, Contreras Marín Y and Solórzano Acevedo K provided and validated the PVA phantoms; Sobrino Cossío S, Galvis García ES, Reding Bernal A and Quispe Siccha RM analyzed data from the literature, and Reding Bernal A performed the statistical analysis; Sobrino Cossío S and Quispe Siccha RM edited the first draft of the manuscript, which was critically discussed and revised in terms of intellectual content by Galvis García ES and Reding Bernal A; all authors discussed the statement and conclusions and approved the final version for publication.
Institutional review board statement: The study was reviewed and approved by the Science and Research Office of Hospital General de México “Dr. Eduardo Liceaga” (México) (Approval No. DI/12/11/04/017).
Informed consent statement: Patient details on ultrasound/elastography images have been removed to ensure anonymity.
Conflict-of-interest statement: There are no conflicts of interest to report.
Data sharing statement: No additional data are available.
STROBE statement: The authors have read the STROBE Statement-checklist of items, and the manuscript was prepared and revised according to the STROBE Statement-checklist of items.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Rosa M Quispe-Siccha, PhD, Academic Research, Research Scientist, Unidad de Investigación y Desarrollo Tecnológico, Hospital General de México "Dr. Eduardo Liceaga", Dr. Balmis 148, Doctores, Cuauhtémoc, Mexico 06720, Mexico. rosa.quispe@gmail.com
Received: April 30, 2020
Peer-review started: April 30, 2020
First decision: May 15, 2020
Revised: July 27, 2020
Accepted: August 15, 2020
Article in press: August 15, 2020
Published online: September 14, 2020
Research background

Training endoscopy by simulation facilitates practice while curtailing risk. However, the models lack realism to achieve competence. In order to have greater realism in simulated lesions, it is important to know the mechanical properties (elasticity /stiffness) of polyvinyl alcohol (PVA) hydrogels.

Research motivation

According to the American Society for Gastrointestinal Endoscopy, before trainees can be certified in advanced endoscopic techniques, they must perform a minimum number of procedures to achieve competence. It is important that endoscopic simulators recreate reality, but most do not, and require considerable investment in terms of time and resources, and do not necessarily reproduce the haptic. We need to build phantoms that recreate reality.

Research objectives

This study was designed to standardize the mechanical properties of PVA phantoms, using endoscopic ultrasound (EUS) images to simulate organs and digestive lesions, and Endoscopic Ultrasound Elastography (EUS-E) to evaluate the degree of tissue stiffness.

Research methods

PVA phantoms with different densities were prepared by changing the molecular weight (MW) and concentration (C). Ultrasound images of these phantoms were obtained to contrast them with healthy organs and digestive lesions. Stiffness/elasticity with 2-panel images in B mode of conventional grayscale (right) and an elastographic image (left) were evaluated. Two observers qualified all EUS/EUS-E images (Kappa index).

Research results

The density of PVA phantoms depended on MW and C. The stiffness of these phantoms was correlated with higher MW and C (correlation r = 0.8, P = 0.01) as well as with increasing density and M.Y. All simulated lesions were visible using EUS. We calculated elasticity and deformation parameters of solid (blue) areas, contrasting with the norm (Kappa = 0.8; high degree of satisfaction)

Research conclusions

The use of PVA phantoms with different densities allowed adequate and consistent simulation of organs and digestive lesions, visible by EUS/EUS-E. Knowledge of the elasticity coefficient made it possible to create different lesions.

Research perspectives

Training in a clinical setting has medical and legal implications. Skill and abilities depend on shortening the learning curve. However, in order to achieve this, a model must be realistic. PVA phantoms were demonstrated to be feasible, economical and realistic models for EUS/EUS-E training.