An Ultrasound Contrast Agent Microbubble in a Microvessel: A Numerical Approach
Pourquoi ce travail est dans la base
Une base qui oublie comment elle a trouvé un travail ne peut pas être vérifiée. Voici les voies qui ont admis celui-ci.
Notice bibliographique
Résumé
The blood brain barrier (BBB), a selective barrier separating blood from the parenchyma of the central nervous system, restricts more than 98% of neurotherapeutics from traveling into the brain. Focused ultrasound (FUS) exposure combined with circulating microbubbles is an emerging technique capable of safely opening the BBB locally, transiently, and non-invasively, enabling targeted drug delivery in the brain. However, the mechanisms of the microbubble-vessel interactions central to this process are not fully understood. \nIn this thesis, a comprehensive numerical model of a microbubble within a microvessel was developed aiming to shed light on bubble-vessel interactions, vessel wall mechanical stresses and acoustic emissions during FUS-induced BBB opening. An upward shift in the bubble's resonance frequency relative to unbound bubbles was calculated, whose magnitude was dependent on the vessel elasticity. The synergistic effects of acoustic frequency and vessel elasticity on wall stresses were investigated. Vessel wall stresses were found to be maximal when the bubble was driven above resonance. The numerical model was validated with ex vivo high-speed optical imaging experiments. Resultant amplitudes of bubble oscillation were within 15% of corresponding experimental measurements. Vessel wall stresses calculated during bubble compression (and vascular invagination) were larger than those during bubble expansion, implying that vascular damage could occur during this phase. The acoustic emissions from the ultrasound-stimulated microbubble were calculated, and their correlation with the vessel wall stresses was investigated. The normalized second harmonic decreased as a function of pressure until reaching a minimum, "transition point", after which point it was found to increase. The second and fourth harmonics of confined bubbles at this point were larger than those of unbound bubbles. Above the transition point, stresses induced by larger bubbles increased with a steeper slope. The results presented in this thesis could help in enhancing contrast imaging strategies, understanding bubble-vessel interactions, and optimizing ultrasound pulse parameters to maximize vessel wall stresses to improve drug delivery efficacy. Furthermore, the calculated acoustic emissions could provide feedback to online monitoring techniques and enable calibration of in vivo pressures.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,003 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découle