Abstract 4285: Development of a combined photoacoustic micro-ultrasound system for non-invasive detection of mouse lymph nodes and intra-tumoral oxygen saturation measurements
Notice bibliographique
Résumé
Abstract We have developed a photoacoustic (PA) micro-ultrasound imaging system which can be used to image tumour vasculature and derive oxygen saturation measurements from within those vessels. Additionally, the system can be used to detect contrast agents such as methylene blue (MB), which is already used in the clinic to aid in sentinel lymph node detection. Here we describe the assessment of the sensitivity of the system with respect to MB detection and compare oxygen saturation (sO2) measurements derived from our system to expected values. A modified μUS system (Vevo 2100, VisualSonics) was operated with a linear array transducer (MS-250, fc = 21 MHz), retrofitted with a housing that held rectangular fiber optic bundles (25.4 × 1.25 mm) to either side. The rectangular bundles were bifurcated ends of a single bundle that was coupled to a tuneable laser (Rainbow NIR, OPOTEK Inc., Carlsbad CA, 680-970 nm). The μUS system was synchronized with the laser and PA signals were acquired with a fluence < 20 mJ/cm2, beamformed in software, and displayed at 5 Hz. For determination of the sensitivity of the system to MB, serial dilutions of MB were performed (from 3.13E-02 mol/L to 3.13E-08 mol/L) and each dilution was imaged by drawing the solution into a 500 um diameter polyethylene tube. Signal intensity was measured at 680 nm since MB has a peak absorbance around this wavelength, and the minimum detectable concentration was determined. For determination of the presence of MB signal in vivo, PA images of the axillary lymph node were collected at 680 and 760 nm both pre- and post-infusion of MB into the forepaw of an adult CD1 mouse and a subtracted image was generated. Axillary and brachial lymph nodes were excised and imaged to verify the source of the MB signal. sO2 measurements were assessed by imaging the jugular vein of a rat and altering breathed oxygen concentration while simultaneously measuring the oxygen partial pressure (pO2) within the same jugular vein. A real-time parametric sO2 map was generated on the system with a dual wavelength measurement of 750 and 850 nm and sO2 measurements were calculated based on a selected region of interest. Sub-cutaneous tumors were also imaged in 2D and 3D and total haemoglobin and sO2 maps were generated. The minimum detectable concentration of MB was observed to be approximately 520 nM. We were able to see photoacoustic signal generated by MB in the mouse axial lymph node, as well as its afferent lymph vessel, and verify it through excision of the node and subsequent imaging. In vivo contrast enhancement was 16dB at 680 nm. Subtraction of 760 nm from 680 nm data yielded a contrast enhancement improvement of 8-10 dB. In the rat jugular vein, measured sO2 correlated well with expected sO2 values (R2 = 0.832). Within a tumor, PA signal from the vasculature was detected at depths of up to 10mm and total haemoglobin and sO2 measurements were made on these signals. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4285. doi:10.1158/1538-7445.AM2011-4285
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.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,001 |
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 découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».