An acoustical camera for in vitro characterization of contrast agent microbubbles

Guillaume Renaud , Johan G. Bosch , Antonius F.W. van Der Steen , Nico de Jong (1)

1 ErasmusMC- ThoraxCentruum

We report on a new experimental method, termed acoustical camera, to retrieve the radial response of single microbubbles to a pressure wave by means of a low-amplitude wave called the probing wave. If the frequency of the latter is much higher than the resonance frequency of the microbubble, the relative amplitude modulation observed in the signal scattered by a bubble in response to the probing wave is quasi-equal to the radial strain experienced by a microbubble in response to a pressure wave. An experimental setup allowing the dual-frequency and dual-focused-beam insonification of single microbubbles was developed to demonstrate the feasibility of the technique. A 300 \mu s 11MHz probing wave is employed to investigate the radial response of BR-14 microbubbles (Bracco) to a 100 \mu s 0.5MHz pressure wave. The 100 \mu s parts of the probing signal situated before and after the transmission of the low-frequency excitation provide a reference to calculate the relative amplitude modulation. Therefore asymmetry in the radial oscillation can be assessed. Compression-only behavior is observed for some microbubbles whereas other microbubbles exhibit a symmetric response, in agreement with literature. We believe this technique is a simple and practical approach to measure the response of single microbubbles to a pressure wave.

Mots clés: ultrasound contrast agent; microbubble; acoustical camera; asymmetric vibrations

Domaines: Acoustique [physics.class-ph]

Guillaume Renaud, Johan G. Bosch, Antonius F.W. van Der Steen, Nico de Jong. An acoustical camera for in vitro characterization of contrast agent microbubbles. Acoustics 2012, Apr 2012, Nantes, France. ⟨hal-00811015⟩