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Theses

Microscopie par localisation ultrasonore dans les modèles d'accidents vasculaires cérébraux

Abstract : A stroke is a sudden loss of vascularization of a part of the brain. Patients must receive medical care within the first hour to reduce neuronal loss and long-term sequelae.Most strokes are hemorrhagic or ischemic, with similar symptoms but specific treatments. Early-phase diagnosis becomes vital and requires deep brain imaging through the skull bone.The development of Ultrasound Localization Microscopy (ULM) has widened applications for microvascular imaging by improving contrast, resolution, and penetration depth. Microbubbles are injected into the blood flow and localized to reconstruct the microvessels within few minutes.The main objective of this thesis is the application of 3D ULM for non-invasive stroke diagnosis in the early phase.A first study focuses on a quantitative comparison of localization algorithms for 2D ultrasound imaging. A set of standardized metrics and unified datasets were established to evaluate various algorithms with objective and reproducible criteria. Then a volumetric ULM system was set up to overcome the elevation projection of 2D imaging and increase the field of view. We performed a 3D angiography of a rat brain in vivo with a commercial scanner and a multiplexed ultrasonic probe. A few tens of micrometers resolution was obtained through the skull bone. This method didn’t induce major modifications of the animal’s physiology and can be used for a pre-clinical study. Finally, this system was used to image induced strokes in a cohort of rats. It proved its ability to distinguish the effects of ischemia versus hemorrhage on brain vascularization. This first study shows the relevance of such imaging for the early diagnosis of stroke in humans by volumetric ULM, without the constraints and availability of MRI and CT.
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Submitted on : Friday, January 7, 2022 - 3:16:10 PM
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  • HAL Id : tel-03517012, version 1

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Arthur Chavignon. Microscopie par localisation ultrasonore dans les modèles d'accidents vasculaires cérébraux. Acoustique [physics.class-ph]. Université Paris sciences et lettres, 2021. Français. ⟨NNT : 2021UPSLS069⟩. ⟨tel-03517012⟩

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