Journal article
Comparison of in vitro and in vivo acoustic response of a novel 50:50 PLGA contrast agent
Ultrasonics, v 44(4), pp 360-367
Nov 2006
PMID: 16730047
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
A comparison between in vitro and in vivo experiments conducted to investigate the acoustic properties of a novel, 1.2μm diameter poly(lactic-co-glycolic acid) (50:50) (PLGA) ultrasound contrast agent, the development of which was described previously by us, is presented. A pulse-echo setup was used to determine enhancement in vitro. Additional in vitro studies further characterized the hollow microcapsules, including resonance frequency from attenuation measurements (from 2.25 to 15MHz) and temperature effects (25°C vs. 37°C). In vivo, four rabbits received intravenous injections of the agent (dose range: 0.005–0.13ml/kg). Quantitative in vivo dose–responses were calculated off-line using spectral power analysis of audio Doppler signals acquired from a custom-made 10MHz cuff transducer placed around the surgically exposed distal aorta. This frequency was chosen since the very shallow scanning depths encountered in rabbits, in particular for the cuff transducer placed directly around the vessel, necessitates the use of high frequency imaging devices with sufficient spatial resolution to enable meaningful measurements. For qualitative assessments, two rabbits were imaged pre- and post-contrast administration (dose: 0.1ml/kg) in power Doppler mode. Significant acoustic enhancements (up to 24dB) were reported both in vitro and in vivo. Moreover, the rabbits did not show any adverse side effects from multiple injections (>20) of the agent. Measured in vitro resonance frequency between 3.09 and 3.49MHz was lower than predicted for a similar sized free bubble, potentially due to capsule wall structure. Minimal loss of signal (∼4dB) was observed at 25°C over 20min of insonation at 5MHz but at 37°C the signal dropped close to base line within the first 5min. This temperature sensitivity could be due to loss of capsule integrity (and hence loss of gas). Potential causes include increased hydrolysis or polymer softening and increased water uptake by the shell at temperatures closer to the glass transition temperature (Tg).
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Details
- Title
- Comparison of in vitro and in vivo acoustic response of a novel 50:50 PLGA contrast agent
- Creators
- Margaret A Wheatley - School of Biomedical Engineering, Science and Health Systems, Drexel University, 3141 Chestnut Streets, Philadelphia, PA 19104, United StatesFlemming Forsberg - Department of Radiology, Thomas Jefferson University, Philadelphia, PA 19107, United StatesKelleny Oum - School of Biomedical Engineering, Science and Health Systems, Drexel University, 3141 Chestnut Streets, Philadelphia, PA 19104, United StatesRaymond Ro - School of Biomedical Engineering, Science and Health Systems, Drexel University, 3141 Chestnut Streets, Philadelphia, PA 19104, United StatesDalia El-Sherif - School of Biomedical Engineering, Science and Health Systems, Drexel University, 3141 Chestnut Streets, Philadelphia, PA 19104, United States
- Publication Details
- Ultrasonics, v 44(4), pp 360-367
- Publisher
- Elsevier
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- School of Biomedical Engineering, Science, and Health Systems
- Web of Science ID
- WOS:000241940400003
- Scopus ID
- 2-s2.0-33749511606
- Other Identifier
- 991014878057404721
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InCites Highlights
Data related to this publication, from InCites Benchmarking & Analytics tool:
- Collaboration types
- Domestic collaboration
- Web of Science research areas
- Acoustics
- Radiology, Nuclear Medicine & Medical Imaging