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- 2023_02_Post_Doc_CAVIIAR.pdf (PDF, 312 kB)
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Laboratoire des Applications Thérapeutiques des Ultrasons / Centre de Recherche En Acquisition et Traitement de l'Image pour la Santé
Description:
Therapeutic ultrasound offers great perspectives for minimally invasive surgery, enhanced drug delivery or cancer immunotherapy. It now addresses an extensive range of indications, from prostate or brain tumors to glaucoma. Among other mechanisms, various emerging applications rely on the phenomenon of ultrasound cavitation, which represents the oscillation of ultrasound-induced microbubbles. In any of these applications, monitoring the treatment in real-time is required for potential clinical applications. While active ultrasound B-mode imaging is well suited to monitor thermal or mechanical permanent alteration of tissues, the microbubble activity – directly actuated by high-intensity ultrasound – cannot be characterized in real-time using an active ultrasound scanner because of dazzling effects.
To localize and quantify the cavitation activity, Passive Acoustic Mapping (PAM) beamforming techniques have been used, but they suffer from weak spatial resolution in the axial direction, perpendicular to the array, when conventional imaging arrays are used. This is even more critical for applications requiring a 3D monitoring of the cavitation activity. Indeed, even if a few works have demonstrated the feasibility of 3D passive acoustic mapping of cavitation, especially in the context of transcranial therapy with very specific hemispherical arrays, 3D mapping with conventional matrix arrays suffers from very low axial resolutions due to diffraction effects associated to the low apertures of the probes. Adaptive beamformers have proven to be an effective way to enhance PAM resolution but do not entirely compensate for those diffraction effects and complimentary research avenues such as dual array mapping have to be considered to achieve millimetric or sub-millimetric resolutions in any direction.