Published online Sep 14, 2020. doi: 10.3748/wjg.v26.i34.5169
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
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.
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.
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.
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).
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)
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.
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.