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Previous work has indicated the potential of magnetically functionalized microbubbles to localize and enhance cavitation activity under focused ultrasound exposure in vitro. The aim of this study was to investigate magnetic targeting of microbubbles for promotion of cavitation in vivo. Fluorescently labelled magnetic microbubbles were administered intravenously in a murine xenograft model. Cavitation was induced using a 0.5-MHz focused ultrasound transducer at peak negative focal pressures of 1.2-2.0 MPa and monitored in real-time using B-mode imaging and passive acoustic mapping. Magnetic targeting was found to increase the amplitude of the cavitation signal by approximately 50% compared with untargeted bubbles. Post-exposure magnetic resonance imaging indicated deposition of magnetic nanoparticles in tumours. Magnetic targeting was similarly associated with increased fluorescence intensity in the tumours after the experiments. These results suggest that magnetic targeting could potentially be used to improve delivery of cavitation-mediated therapy and that passive acoustic mapping could be used for real-time monitoring of this process.

Original publication

DOI

10.1016/j.ultrasmedbio.2016.08.002

Type

Journal article

Journal

Ultrasound in medicine & biology

Publication Date

12/2016

Volume

42

Pages

3022 - 3036

Addresses

Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK.

Keywords

Animals, Mice, Inbred BALB C, Mice, Neoplasms, Disease Models, Animal, Sulfur Hexafluoride, Phospholipids, Contrast Media, Image Enhancement, Ultrasonic Therapy, Microbubbles, Acoustics, Fluorescence, Female, Magnetic Resonance Imaging, Interventional