DISPOSABLE SYSTEM FOR IN-VIVO MECHANICAL CHARACTERIZATION OF SOFT TISSUES BASED ON VOLUME MEASUREMENT

Abstract

In-vivo characterization of soft tissues is a key step toward biomechanical simulation and planning of intra-operative assisted surgery. To achieve this, aspiration method is a standard technique: tissue is aspirated through a hole while measuring the pressure and associated apex height. An inverse problem is then solved to identify the material mechanical properties. In the literature, the apex height is usually measured using a camera, which induces design difficulties, in particular in regards on the required sterilization process for in-vivo measurements. In this paper, the idea is to replace the apex height optical measurement by the measurement of the aspirated tissue volume. The proposed method enables to reduce the system head to a simple tube: sterilizations becomes easy and the system is disposable after use. The proposed system is thus the simplest, lightest and cheapest one could achieve. It is also to the authors knowledge the first time ever in aspiration method that the aspired volume is the extracted data. As the data signal-to-noise ratio is the main factor impacting any applied inverse method when extracting the mechanical properties, the aim of this work is to assess and compare the experimental signal-to-noise ratio in the raw volume measurements obtained either optically or with the method proposed. Explicit results of inverse methods using volumes as input data are not presented in this paper for concision purpose. The effects on accuracy of various experimental parameters has been investigated and quantified: the volume measurement has proved to present a same order or even better signal-to-noise ratio compared to optical measurements.

In-Vivo Soft Tissues Mechanical Characterization: Volume-Based Aspiration Method Validated on Silicones

“…As experimentally demonstrated in [25], decreasing the Syringe Diameter of Sy1 (SD in Fig. 1a) improves the measurement precision and repeatability:…”

“…The aspiration system and volume-based method will be briefly presented in this section. Details can be found in [25]. An aspiration head was applied on a soft material (Fig.…”

“…These limitations motivated the authors to design a new disposable system for in-vivo mechanical characterization of soft tissues based on volume measurement [25]. In this novel method, apex height measurement was replaced by measurement of the aspirated tissue volume.…”

“…This volume-based method measures the negative pressure in the chamber and the associated volume of the soft tissue aspirated through the device✬s aperture [25]: the pressure is thus known as a function of the volume. The material properties of the tissue can be identified with these experimental data using an inverse updated Finite Element (FE) method [17].…”

Thin deformable tissues modeling for simulation of arthroscopic knee surgery

“…Data driven methods have been successfully applied in the animation of many objects, such as cloth [115], facial [116], and body [117]. For the surgical simulation, although there are some methods to capture the material properties indirectly [114,118], it is generally unethical to sample human organ data in vivo. Seiler et al [119] proposed to use high resolution nonlinear simulation results as example data and to enhance low resolution linear simulation based on a nonlinear mapping.…”