Institut National De La Sante Et De La Recherche Medicale

Universite Claude Bernard – Lyon1

Centre Leon Berard

Rémi Souchon

Jean-Yves Chapelon

Kazuhiro Matsui

Stefan Catheline

William Apoutou N'Djin

Cyril Lafon

Françoise Chavrier

Ali Zorgani

Pol Grasland-Mongrain

This method for imaging in real time the propagation of a mechanical wave in an acoustically propagative medium comprises steps of: a) emitting () a mechanical wave in an acoustically propagative medium, using an acoustic source being placed in an emission region of the acoustically propagative medium, b) measuring () voltage signal waveform values at a reception region, using an acoustic measurement unit; c) calculating () acoustic field values in the acoustically propagative medium, between the emission region and the reception region, using a reconstruction algorithm implemented in a signal processing unit, and the signal waveform values measured during step b) d) generating an image, using an image generation device and using the calculated acoustic field values.

Method and apparatus for imaging in real time the propagation of a mechanical wave in an acoustically propagative material

This method, for determining the local intensity (I) of an acoustic field propagating in a target region of a soft solid, at a position located within said target region, includes at least the following steps: determining () a value of an ultrasound attenuation coefficient (&#x3b1;) of the soft body in the target region; determining () a value of the shear modulus (&#x3bc;) of the soft body in the target region; determining () a value of the speed of sound (c) in the target region of the soft body; and building (), with the values determined in steps a), b) and c), a viscoelastic model (M) of a steady-state displacement induced by an acoustic field having a time invariant shape or a viscoelastic model of a difference between two steady-state displacements induced by an acoustic field having a time invariant shape. Moreover, this method also includes the following steps: applying () to the target region the acoustic field emitted by an ultrasound source, for a duration such that the acoustic field induces a steady-state localized deformation (Formula (I)) of the soft body in the target region; measuring () at least one steady state displacement induced by the acoustic field at a given position in the target region; and computing () the amplitude of the intensity of the acoustic field at said given position by inverting the viscoelastic model (M) at said given position, for the displacement(s) measured at step f).

Method and apparatus for determining local acoustic field intensity within a soft solid

Method for generating a shear wave in a target region of a soft solid, includes the following steps: a) generating at least two shear waves with a first and a second source of shear waves in the target region; b) detecting a propagation pattern of the shear wave in the target region with a detector unit including a row of ultrasonic transducers aligned on a first direction perpendicular to a detection direction of each or a single ultrasonic transducer movable along a first direction perpendicular to its detection direction; c) proceeding to a time reversal of the detected propagation pattern; and d) submitting the target region to an inverted excitation set of forces based on the temporally inverted propagation pattern. During step b), a first propagation pattern is detected when only the first source is active and a second propagation pattern is detected when only the second source is active.

Shear wave generation method, shear wave imaging method and thermal mapping or treating method utilizing such a generation method and installation for generating at least one shear wave

This shear wave imaging method, for collecting information on a target region (R) of a soft solid (S), comprises at least the steps a) of generating at least one shear wave (SW) in the target region, and b) of detecting a propagation pattern of the shear wave in the target region. Step a) is realized by applying to particles of the target region (R) some Lorentz forces resulting from an electric field (E) and from a magnetic field (B). At least one of the electric field (E) and the magnetic field (B) is variable in time, with a central frequency (f) between 1 Hz and 10 kHz. Alternatively, both the electric and magnetic fields (E, B) are variable in time, with a central difference frequency (&#x394;f) between 1 Hz and 10 kHz. The shear wave imaging installation comprises a first system () for generating at least one shear wave (SW) in the target region (R) and a second system () for detecting a propagation pattern of the shear wave. The first system includes first means () to apply an electric field (E) through the target region (R) and second means () to apply a magnetic field (B) through the target region. The first and second means are configured to apply to particles of the target region some Lorentz forces resulting from the electric field (E) and the magnetic field (B), where at least one of these fields is a quantity variable in time, with a central frequency (f) between 1 Hz and 10 kHz, or both fields are quantities variable in time, with a central difference frequency (&#x394;f) between 1 Hz and 10 kHz.

Shear wave imaging method and installation for collecting information on a soft solid

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Lyons, France

Rémi Souchon