Title:How Do Microbubbles and Ultrasound Interact? Basic Physical, Dynamic and Engineering Principles
Volume: 18
Issue: 15
Author(s): Mehrdad Azmin, Caroline Harfield, Zeeshan Ahmad, Mohan Edirisinghe and Eleanor Stride
Affiliation:
Keywords:
Microbubbles, ultrasound, contrast, cavitation, drug delivery, gene therapy
Abstract: Ultrasound contrast agents consisting of gas microbubbles stabilised by a polymer or surfactant coating have been in clinical
use for several decades. Research into the biomedical uses of microbubbles, however, remains a highly active and growing field. This is
largely due to their considerable versatility and the wide range of applications for which they have demonstrated potential benefits. In addition
to contrast enhancement, diagnostic applications include: perfusion mapping and quantification and molecular imaging. In drug
and gene therapy microbubbles can be used as vehicles which are inherently traceable in vivo and can provide both targeted and controlled
release. In addition, the dynamic behaviour of the microbubbles in response to ultrasound excitation contributes to the therapeutic
process. At low intensities microbubbles have been shown to mediate reversible enhancement of cell and endothelial permeability, including
temporary opening of the blood brain barrier. At higher intensities they have been used as means of increasing the efficiency of
thrombolysis, high-intensity focused ultrasound (HIFU) surgery and lithotripsy. The aim of this review is to describe the key physical
principles which determine how microbubbles and ultrasound interact and the implications for their design, preparation and exploitation
in diagnostic and therapeutic applications.
