Enhancement and Passive Acoustic Mapping of Cavitation from Fluorescently Tagged Magnetic Resonance-Visible Magnetic Microbubbles In Vivo.
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.
Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK.
Calum
C
Crake
Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK.
Joshua
J
Owen
Gray Institute for Radiation Oncology and Biology, Radiobiology Research Institute, Churchill Hospital, Oxford, UK.
Sean
S
Smart
Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK.
Christian
C
Coviello
Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK.
Constantin-C
CC
Coussios
Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK.
Robert
R
Carlisle
Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK. Electronic address: eleanor.stride@eng.ox.ac.uk.
Eleanor
E
Stride
D000162:Acoustics; D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage*; D004195:Disease Models, Animal; D005260:Female; D005453:Fluorescence; D007089:Image Enhancement / Q000379:methods*; D053783:Magnetic Resonance Imaging, Interventional / Q000379:methods*; D051379:Mice; D008807:Mice, Inbred BALB C; D045423:Microbubbles; D009369:Neoplasms / Q000628:therapy*; D010743:Phospholipids / Q000008:administration & dosage; D013459:Sulfur Hexafluoride / Q000008:administration & dosage; D014464:Ultrasonic Therapy / Q000379:methods*
D003287:Contrast Media; D010743:Phospholipids; C420843:contrast agent BR1; D013459:Sulfur Hexafluoride
Cavitation; Drug delivery; Fluorescence; Magnetic microbubbles; Magnetic resonance imaging; Passive acoustic mapping; Ultrasound