Ultrafast, broadband and multi-pulse transmissions for ultrasonic imaging

Mehdi Yanis Benane 1, 2
2 Imagerie Ultrasonore
CREATIS - Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé
Abstract : Ultrasound imaging is a diagnostic tool widely used thanks to such virtues as real-time data acquisition / processing, ease of use and safety for the patient / practitioner during examination. However, when compared to other imaging methods such as X-ray tomography and Magnetic Resonance Imaging, the echography has the disadvantage to provide relatively low image quality. In this thesis, we study a method that is able to increase the ultrasound image quality, thus paving the way towards improved diagnostics based on echography and novel ultrasound applications. In order to increase the echo signal to noise ratio of the received signals, we propose to use linear frequency modulated signals, also called chirps. To avoid the negative effect of the bandlimited acquisition probe, we apply a pre-enhancement step on the probe excitation signals in order to boost the signal energy in the frequency bands where the probe is less efficient. To compress the echo energy in reception, we use Wiener filters that allow obtaining a good trade-off between the spatial resolution and noise stability. We apply the previously detailed pipeline, also called REC (Resolution Enhancement Technique) on ultrafast imaging schemes. We show promising results in simulation and in-vitro, ex-vivo, in-vivo acquisitions. Furthermore, we adapt REC in such way that the frequency dependent tissue attenuation effect is compensated for. This improvement is validated in simulation and phantom experiments. We also adapt REC to the nonlinear propagation of ultrasound waves, by proposing a pulse inversion technique that uses REC to provide a better image resolution and contrast to noise ratio. Then, we demonstrate the generality of the REC method by applying it to different acquisition schemes such as diverging wave compounding and Multi Line Transmit (MLT). We also show that the image quality can be increased more by taking into account the spatial impulse response of the ultrasound probe when REC and MLT are combined
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Submitted on : Thursday, July 11, 2019 - 3:23:10 PM
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  • HAL Id : tel-02072384, version 2

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Mehdi Yanis Benane. Ultrafast, broadband and multi-pulse transmissions for ultrasonic imaging. Acoustics [physics.class-ph]. Université de Lyon, 2018. English. ⟨NNT : 2018LYSE1268⟩. ⟨tel-02072384v2⟩

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