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Nitrogen-filled liposomes as a vascular US contrast agent: preliminary evaluation
E C Unger1, P J Lund, D K Shen
1Department of Radiology/Magnetic Resonance Imaging, University of Arizona Health Sciences Center, Tucson 85724.
Radiology
|November 1, 1992
Summary
Nitrogen gas-filled liposomes, known as Aerosomes, show promise as ultrasound contrast agents. These Aerosomes demonstrate excellent stability and reflectivity for cardiac and blood-pool imaging with low toxicity.
Area of Science:
- Biomedical Engineering
- Nanotechnology
- Medical Imaging
Background:
- Ultrasound (US) contrast agents enhance image quality.
- Liposomes are versatile drug delivery vehicles.
- Gas-filled liposomes offer unique acoustic properties.
Purpose of the Study:
- To evaluate nitrogen gas-entraped liposomes (Aerosomes) as a novel ultrasound contrast agent.
- To assess the in vitro and in vivo performance of Aerosomes.
- To determine the safety and efficacy of Aerosomes for cardiac imaging.
Main Methods:
- Liposomes with a 1-2 micron diameter were prepared to entrap nitrogen gas.
- In vitro testing included size, stability, reflectivity, and acoustic characterization.
- In vivo studies involved acute toxicity in mice and cardiac imaging in rabbits via intravenous injection.
Main Results:
- Aerosomes exhibited significantly higher reflectivity and attenuation compared to standard liposomes.
- Acoustic properties remained stable after months of storage in aqueous media.
- Median lethal dose was approximately 2.5 mmol/kg, with an imaging dose under 5 μmol/kg, indicating a high therapeutic index (>500:1).
- Postcontrast US images showed sustained enhancement of cardiac chambers, aorta, vena cava, and hepatic veins.
Conclusions:
- Aerosomes are a promising novel ultrasound contrast agent for cardiac and blood-pool imaging.
- Their stability, high reflectivity, and favorable safety profile support further development.
- Aerosomes represent a significant advancement in ultrasound contrast technology.