Random excitation by optimized pulse inversion in contrast harmonic imaging

Sébastien Ménigot (1) , Jean-Marc Girault (1)

1 iBraiN - Imaging, Brain & Neuropsychiatry

Over the past twenty years, in ultrasound contrast imaging, new physiological information are obtained by the detection of non-linearities generated by the microbubbles. One of the most used techniques is the pulse inversion imaging. The usual command of this system is a fixed-frequency sinus wave. An optimal choice of this command requires the knowledge of the transducer and of the medium to obtain the best contrast-to-tissue ratio. However, these information are experimentally inaccessible. Our goal is to seek the command which maximizes the contrast-to-tissue ratio. Among several noises, we identified the one which maximized the contrast-to-tissue ratio. A new suboptimal control was made from the parameters of a nonlinear autoregressive filter and from suboptimal noise. The contrast-to-tissue ratio was then iteratively optimized by the method of Nelder-Mead which adjusted the filter parameters. The gain compared to the case in which we used at the optimal frequency can reach about 1 dB and 5 dB in comparison to the center frequency of the transducer. By adding a closed loop, the system automatically proposes the optimal command without any a priori knowledge of the system or of the medium explored and without any hypothesis about the shape of the command.

Domaines: Acoustique [physics.class-ph]; Acoustique [physics.class-ph]; Traitement du signal et de l'image [eess.SP]; Traitement du signal et de l'image [eess.SP]; Imagerie

Sébastien Ménigot, Jean-Marc Girault. Random excitation by optimized pulse inversion in contrast harmonic imaging. Acoustics 2012, Apr 2012, Nantes, France. pp.2895-2900. ⟨hal-00703046⟩