PhD, University of Toronto
Ultrasound imaging is a widely used method for anatomic assessment, as well as for providing information about blood flow within the body. It is also under investigation in therapeutic applications to ablate tissue or, increasingly, to promote local drug delivery to regions of interest. For both imaging and therapeutic applications there is a growing interest in the use of microbubble contrast agents. Injected into the blood stream, these micron sized encapsulated bubbles can be stimulated by ultrasound to produce distinct acoustic signatures that can be exploited for the purposes of improving blood flow detection or, when targeted, enable molecular imaging. They may also be stimulated to induce bioeffects within tissue and blood vessels.
One area of research is to examine the basic behaviour of microbubble contrast agents in response to ultrasound. An improved understanding of the physical behaviour of microbubbles is central to developing new imaging techniques, or for optimizing the safety and efficacy of therapeutic applications. High frequency ultrasound contrast behaviour and imaging has been one aspect of this that we have explored extensively.
A second research topic is to investigate the use of microbubbles to enhance drug delivery and efficacy in tumours. In particular, we are examining the vascular flow response to therapeutically stimulated microbubbles, and how it can be exploited to promote drug uptake. A third topic of interest is the use of ultrasound to aid the breakdown of vascular occlusions. In stroke for example, ultrasound has recently been shown to accelerate the activity of clot lysing drugs. We are examining the mechanisms of these effects with the objective of developing more effective and optimized approaches for achieving lysis; the use of microbubbles will likely play a key role in this new area.
- D. E. Goertz, M. E. Frijlink, D. Tempel, V. Bhagwandas, A. Gisolf, R. Krams, N. de Jong, A. F. van der Steen. "Subharmonic Contrast Intravascular Ultrasound for Vasa Vasorum Imaging." Ultrasound in Medicine and Biology 33 (11) (2007).
- M. Emmer, A. Van Wamel, D. E. Goertz, and N. De Jong, "The onset of microbubble vibration," Ultrasound in Medicine and Biology 33 (6), 941-949 (2007).
- D. E. Goertz, M. E. Frijlink, D. Tempel, L. C. A. van Damme, R. Krams, J. A. Schaar, F. J. ten Cate, P.W. Serruys, N. de Jong, and A. F. W. van der Steen, "Contrast harmonic intravascular ultrasound - A feasibility study for vasa vasorum imaging," Investigative Radiology 41 (8), 631-638 (2006).
- D. E. Goertz, M. E. Frijlink, N. De Jong, and A. F. W. van der Steen, "High frequency nonlinear scattering from a micrometer to submicrometer sized lipid encapsulated contrast agent," Ultrasound in Medicine and Biology 32 (4), 569-577 (2006).