LASTIC: A Light Aspiration Device for in vivo Soft TIssue Characterization

Abstract

Abstract. This paper introduces a new Light Aspiration device for in vivo Soft TIssue Characterization (LASTIC). This device is designed to be used during surgery, and can undergo sterilization. It provides interactive-time estimation of the elastic parameters. LASTIC is a 3cm x 3cm metallic cylinder divided in two compartments. The lower compartment is a cylindrical chamber made airtight by a glass window in which a negative pressure can be applied. Put in contact with soft tissues, it can aspirate the tissues into the chamber through a circular aperture in its bottom side. The upper compartment is clinched onto the lower part. A miniature digital camera is fixed inside the upper chamber, focusing on the aspirated soft tissue. LASTIC is operated by applying a range of negative pressures in the lower compartment while measuring the resulting aspirated tissue deformations with the digital camera. These measurements are used to estimate the tissue elasticity parameters by inverting a Finite Element model of the suction experiment. In order to use LAS-TIC during surgical interventions, a library-based optimization process is used to provide an interactive time inversion.

Soft Tissue Finite Element Modeling and Calibration of the Material Properties in the Context of Computer-Assisted Medical Interventions

“…However, most of the papers rarely address the important issue of sterilization to any great depth of detail whereas such sterilization can be very important in case of the aspiration of human living tissues. In such a perspective, our group has developed a sterilizable device ( (Schiavone et al, 2010) To be able to improve the planning of the outcome of an aesthetic or maxillo-facial surgery, it is necessary to estimate the stiffness of the facial soft tissues in several places. Four locations with presumably different tissue thicknesses and different amounts of fat and muscle were consequently chosen: the cheek, the cheekbone, the forehead, and the lower lip.…”

Validation of a Light Aspiration Device for In Vivo Soft Tissue Characterization (LASTIC)

“…Based on a prototype aspiration device quantitatively evaluated during surgery on the brain [4] and during more classical experiments on other organs such as tongue, cheeks and forearm skin, we designed a more elaborate device, called LASTIC (Light Aspiration device for in vivo Soft Tissue Characterization) [5]. LASTIC is intended to be used in operating rooms and therefore to meet the very rigorous sterilization and handling process imposed during surgery.…”

“…This implied that (1) the device had to undergo a full sterilization and (2) the data processing to be sufficiently fast to provide an interactive estimation of the tissues constitutive equation. These two constraints have encouraged us to propose a new version of LASTIC [5]. This chapter aims at validating this new version by comparing, for synthetic materials, the constitutive parameters it estimates with the parameters provided by usual tensile test machines.…”

Biomechanics for computer-assisted surgery

“…It is built in a very compact metallic cylinder of 33 mm in height and 34 mm in diameter [9]. The surgeon holds the instrument and establishes contact with the tissues surface while the device measures the negative pressures and displacement responses.…”