Georges Chabouh

Agents de contraste ultrasonores : des oscillations sphériques et de la dynamique de flambage à la nage: Les micro-nageurs intelligemment conçus ont attiré une attention croissante et se sont révélés très prometteurs pour diverses applications biomédicales.Dans cette étude, nous proposons un nouveau mécanisme de propulsion dans les fluides à l'échelle microscopique, en utilisant un mécanisme de flambage activé par des ondes de pression.Nous avons considéré une coquille élastique creuse de taille micrométrique composée d'une enveloppe lipidique renfermant une bulle de gaz. De telles micro coquilles sont approuvées pour une utilisation clinique comme agents de contraste ultrasonores (UCA).Nous étudions, de manière expérimentale, la dynamique de flambage des micro-enveloppes lors d'une augmentation de la pression externe. L'effet de la fréquence d'excitation est étudié, ainsi que celui de la taille et des propriétés mécaniques des micro-coquilles. Nous confrontons les résultats aux théories existantes sur la dynamique de flambage qui considèrent des coquilles constituées d'un matériau isotrope et incompressible.En parallèle, nous mettons en évidence que de telles hypothèses sont trop restrictives pour rendre compte avec précision de la dynamique de tels UCAs à coquilles lipidiques. Pour ce faire, nous considérons les oscillations sphériques de ces coquilles. Dans cette configuration plus simple, nous dérivons un nouveau modèle théorique qui inclut la compressibilité de la coquille et son anisotropie élastique dans la direction radiale. Nous offrons ainsi une meilleure description des oscillations sphériques qui ont été largement étudiées théoriquement et expérimentalement au cours des trois dernières décennies.Enfin, nous mettons en évidence un déplacement non nul lors d'un cycle complet de dégonflage et de regonflage des micro-coquilles, qui inclut des événements de flambage.Ce mécanisme de propulsion non dépendant de la source dont la direction est contrôlée dans le cadre de référence de la coquille peut être une réponse au problème de la directivité prise en compte dans la technique de force de rayonnement acoustique utilisée dans l'imagerie moléculaire ultrasonore et l'administration de médicaments ciblés.

We present an open-source code for 3D super-resolution ultrasound imaging. Open-3DULM was applied to transcranial imaging in habituated awake mice. Comparative analysis reveals that isoflurane anesthesia induces significant vasodilation and increased cerebral blood flow (CBF) in veins, while only a subset of arteries exhibits these effects compared to the awake state. This method could serve as a reference for developing new types of 3D vascular quantifications, particularly emphasizing the importance of awake and 3D imaging for accurate cerebral blood flow measurement in neuroscience research.

Aneurysmal subarachnoid hemorrhage (aSAH) is a life-threatening condition with high rates of secondary complications such as delayed cerebral ischemia (DCI). Early detection of perfusion deficits is critical but remains challenging with conventional imaging modalities that are intermittent, non-portable, and provide limited temporal resolution. Here, we evaluate a novel investigational platform for volumetric acoustic angiography and bedside cerebral perfusion imaging using three-dimensional contrast-enhanced ultrasound (3D CEUS). In a prospective feasibility study, eleven aSAH patients underwent bilateral 3D CEUS at admission, day 5, and day 10 in the neurocritical care unit. The system enabled reconstruction of 3D microvascular volumes and time-intensity evolution (TIE) curves for cerebral blood flow (CBF) assessment. Global perfusion measurements were successful in 95% of acquisitions. Notably, TIE-derived perfusion patterns at day 5 showed strong correlation with poor neurological outcome (88.9% accuracy) suggesting the prognostic potential of the technique. This study demonstrates, for the first time, the feasibility of bedside volumetric CEUS for dynamic assessment of cerebral perfusion in patients with aSAH. The method offers high spatial and temporal resolution, real-time feedback, and correlation with clinical trajectory. These findings position three dimensional CEUS-based acoustic angiography as a promising tool for early detection of DCI and improved neuromonitoring in the intensive care unit.

We present an open-source code for 3D super-resolution ultrasound imaging. Open-3DULM was applied to transcranial imaging in habituated awake mice. Comparative analysis reveals that isoflurane anesthesia induces significant vasodilation and higher cerebral blood flow compared to the awake state. This method could serve as a reference for developing new types of 3D vascular quantifications, particularly emphasizing the importance of awake and 3D imaging for accurate cerebral blood flow measurement in neuroscience research.

Super-resolution ultrasound (SRUS) has evolved significantly with the advent of Ultrasound Localization Microscopy (ULM). This technique enables sub-wavelength resolution imaging using microbubble contrast agents. Initially confined to 2D imaging, ULM has progressed towards volumetric approaches, allowing for comprehensive three-dimensional visualization of microvascular networks. This review explores the technological advancements and challenges associated with volumetric ULM, focusing on key aspects such as transducer design, acquisition speed, data processing algorithms, or integration into clinical practice. We discuss the limitations of traditional 2D ULM, including dependency on precise imaging plane selection and compromised resolution in microvasculature quantification. In contrast, volumetric ULM offers enhanced spatial resolution and allowed motion correction in all direction, promising transformative insights into microvascular pathophysiology. By examining current research and future directions, this review highlights the potential of volumetric ULM to contribute significantly to diagnostic across various medical conditions, including cancers, arteriosclerosis, strokes, diabetes, and neurodegenerative diseases.

We present an open-source code for 3D super-resolution ultrasound imaging. Open-3DULM was applied to transcranial imaging in habituated awake mice. Comparative analysis reveals that isoflurane anesthesia induces significant vasodilation and higher cerebral blood flow compared to the awake state. This method could serve as a reference for developing new types of 3D vascular quantifications, particularly emphasizing the importance of awake and 3D imaging for accurate cerebral blood flow measurement in neuroscience research.