LAWS Webinar 1: David Alejandro Collazos-Burbano & Nicolás Benech

UFFC-S Latin America Webinar Series - Webinar 1 (23 June 2022)

Short Early Career Talk:
David Alejandro Collazos-Burbano
Pulsed Photoacoustics: A Powerful Non-invasive and Non-contact Ultrasonic Technique for Agroindustry Applications

Talk Abstract
Pulsed photoacoustics is a technique which allows for the generation of acoustic waves at ultrasonic frequencies in several materials. It has a huge potential for agroindustry applications, e.g. remote sensing, non-contact and non-destructive characterization, massive data generation and IoT compatibility, among others. This talk presents how this technique can be used to extract elastic properties of plant leaves and to obtain acoustic vegetal indices to determine the water content in the samples under study. The presentation will cover the setting of the experimental apparatus, the determination of the dispersive behavior of the medium and the corresponding extraction of the elastic properties of the samples. This talk will conclude with a discussion about the potential applications in plant hydraulics studies and the assessment of complex biological samples, e.g. plant phenotyping.

Main Talk:
Nicolás Benech
Recent Advances in Skeletal Muscle Elastography in the LAU

Talk Abstract
In this talk, I will review the most recent work related to elastography applied to skeletal muscle, developed at the Laboratorio de Acústica Ultrasonora (LAU) in Montevideo, Uruguay. Elastography in muscles is challenging because of anisotropy and viscosity. The simplest case to deal with is the SH propagation mode where polarization of the shear wave (SW) is perpendicular to the fibers. For such mode, the shear wave velocity (SWV) depends on the angle between the propagation direction and the fibers’ direction. In US elastography, a push beam (PB) generates the SW and ultrafast imaging is used to track its propagation. The SW attenuates with distance due to diffraction and viscosity. We are working on a diffraction model for the PB, based on Green’s function for transversely isotropic solids, to discriminate those effects in the experimental data and be able to estimate the tissue viscosity.

The SW can also be generated by using external sources. For superficial muscles, most parts of the energy propagate as a surface wave. Thus, the shear elasticity can be estimated if a relationship between the velocity of surface waves and the SWV can be established. This relationship depends on the geometry of the tissue but also on near-field effects. These effects generate a dispersion curve even in a semi-infinite solid and thus, must be considered to retrieve the SWV. I will show examples of the application of surface waves in beef samples (ex vivo) as well as in biceps branchii (in vivo).

Finally, I will show the results of 3D shear elasticity imaging using an RCA probe and a Vantage Verasonics System, based in a passive elastography approach. We conducted experiments in a CIRS phantom and in the forearm muscles of a healthy volunteer. Results are encouraging but there are still some issues to be addressed.

Q&A Sesssion:
Moderator: Stefan Catheline

Видео LAWS Webinar 1: David Alejandro Collazos-Burbano & Nicolás Benech канала IEEE-UFFC