Elastographie pour le suivi des thérapies par ultrasons focalisés et nouveau concept de cavité à retournement temporel pour l'histotripsie

Abstract : High amplitudes of focused ultrasound can be used to generate non-invasively ablation of a pathogenic tissues, for example malignant ones. Two regimes of ablation exist: thermal ablation called HIFU ("High Intensity Focused Ultrasound") and mechanical ablation called histotripsy using focused shock waves. During my PhD, we developed methods for the real-time ultrasound monitoring of such treatments based on a quantitative elastography technique called "Supersonic Shear wave Imaging" (SSI). We will demonstrate that accurate measurements of the changes of stiffness provides monitoring and guidance with a robustness to motion during the treatments. Indeed, elastography allowed us to map temperature and to monitor the lesion formation in real time whether thermal (HIFU) or mechanical (histotripsy). We will introduce an alternative full waveform inversion applied to SSI which will improve the robustness to the loss of information due to noise and partial measurements due to hypoechoic lesions. Finally, we will present a new concept of "tunable" time-reversal cavity for high amplitude pulses generation from a limited number of transducers. Our prototype allowed to generate focused shock waves in a wide target area and to multiply by 17 the peak pressure of a conventional imaging probe. Hence, based on cheap low-power electronics, this therapeutic device could have many therapeutic applications which are limited at present by geometrical confines.
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Submitted on : Friday, February 8, 2013 - 5:34:50 PM
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Bastien Arnal. Elastographie pour le suivi des thérapies par ultrasons focalisés et nouveau concept de cavité à retournement temporel pour l'histotripsie. Acoustique [physics.class-ph]. Université Paris-Diderot - Paris VII, 2013. Français. ⟨pastel-00786523⟩

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