Shear Wave Generation by Remotely Stimulating Aluminum Patches With a Transient Magnetic Field and Its Preliminary Application in Elastography.

Objective: This article presents shear wave generation by remotely stimulating aluminum patches through a transient magnetic field, and its preliminary application in the cross-correlation approach based ultrasound elastography.

Methods: A transient magnetic field is employed to remotely vibrate the patch actuators through the Lorentz force. The origin, and the characteristics of the Lorentz force are confirmed using an interferometric laser probe.

Imaging of Thermal Effects during High-Intensity Ultrasound Treatment in Liver by Passive Elastography: A Preliminary Feasibility in Vitro Study.

High-intensity focused ultrasound is a non-invasive modality for thermal ablation of tissues through locally increased temperature. Thermal lesions can be monitored by elastography, following the changes in the elastic properties of the tissue as reflected by the shear-wave velocity. Most studies on ultrasound elastography use shear waves created by acoustic radiation force.

Coherent transmission of an ultrasonic shock wave through a multiple scattering medium.

We report measurements of the transmitted coherent (ensemble-averaged) wave resulting from the interaction of an ultrasonic shock wave with a two-dimensional random medium. Despite multiple scattering, the coherent waveform clearly shows the steepening that is typical of nonlinear harmonic generation. This is taken advantage of to measure the elastic mean free path and group velocity over a broad frequency range (2-15 MHz) in only one experiment.