F. Stuart Foster
PhD, University of Toronto
At A Glance
- Transducer array and imaging systems development
- Ultrasound physics and fundamental interactions in tissues
- Studies of vascular morphology and hemodynamics in the microcirculation - angiogenesis
- Microbubble and nanoparticle contrast agents
- Discovery oriented research in cancer imaging
- Molecular Imaging
F Stuart Foster is currently a senior scientist at Sunnybrook Research Institute and Professor and Canada Research Chair in Ultrasound Imaging, Department of Medical Biophysics, University of Toronto. His current research centres on the development of high frequency clinical and preclinical imaging systems, array technology, intravascular imaging, photoacoustics, and molecular imaging. Stuart is a Fellow of the American Institute of Ultrasound in Medicine and IEEE. He is the founder and former Chairman of VisualSonics Inc., a company dedicated to preclinical imaging. Dr. Foster co-founded the Mouse Imaging Centre (MICe) now at the Toronto Centre for Phenogenomics. He has served on the Board of Directors of the National Cancer Institute of Canada and as Chairman of its Committee on Research (ACOR). He has previously been the recipient of the Eadie Medal for major contributions to engineering in Canada, the Queen’s Golden Jubilee Medal, the Manning Award of Distinction for Canadian Innovation, the Ontario Premier’s Discovery Award, and the Rayleigh Award from IEEE. He serves on numerous advisory bodies and is currently on the editorial boards of Ultrasonic Imaging and Ultrasound in Medicine and Biology.
Micro-ultrasound. My lab has extended the powerful backscatter methods developed for conventional clinical ultrasound imaging in the 3 - 10 MHz frequency range to much higher frequencies (15 – 200 MHz) thereby enabling tissue microimaging. This technique, called micro-ultrasound or ultrasound biomicroscopy , enables biological structures to be imaged with resolutions ranging from 30 to 100 micrometres over fields of view ranging from 4 to 30 mm. Commercial instrumentation for ocular imaging has proliferated and found wide clinical acceptance as a means of assessing glaucoma and anterior segment tumors. Probes for invasive applications such as catheter based intravascular imaging or needle based ultrasound imaging pose an interesting engineering challenge because the imaging transducer and scanning actuation must fit within a sub-millimeter cavity. Intravascular scanners are designed to provide clinicians with quantitative information regarding the distribution and structure of atherosclerotic plaque in arterial vessels such as the coronary arteries that feed the heart.
Mouse Imaging. The second important contribution was the development of micro- ultrasound imaging and phenotyping for mice. The technology developed in our lab became the basis for applications in mouse models of cardiovascular disease, cancer, and many other conditions. The commercial version of this system has been phenomenally successful (>1500 installed units) and is now a standard at most universities, research institutions and drug companies around the world and with total sales exceeding $300 Million.
Photoacoustic imaging. The combination of optical excitation and ultrasound detection provides a new universe of imaging opportunities in which the best attributes of both fields are combined. We developed the first fully integrated photoacoustic micro-ultrasound system. Scanners based on this technology are now located around the world in leading laboratories.
Nanoparticle contrast agents. In collaboration with Mikhail Shapiro at Caltech, we identified the first genetically programmable natural ultrasound contrast agents. GVs are formed by certain species of archaea and bacteria as a means to regulate cellular buoyancy. Small pores in the protein shell allow for the inner gas to be in constant equilibrium with dissolved gas in the surrounding medium. When they interact with ultrasound they exhibit strong nonlinearities that can be exploited for imaging purposes. These new particles are an important part of our contrast and molecular imaging program. They also have the potential to unlock a “GFP” equivalent for ultrasound imaging.
Dual Frequency Ultrasound. Transducer technology is at the heart of innovation in ultrasound imaging and has been a driver extending clinical and preclinical applications. The Foster Lab in collaboration with Paul Dayton at UNC have introduced the first widely separated dual band US for ultrasound contrast angiography and other applications. A first in human clinical trial of this technology is now underway at UNC. The current devices use simple mechanical scanning of separate low and high frequency elements. We plan to develop the world first array systems in which both LF (manipulation/therapy) and HF (imaging) beams are transmitted by the same transducer through the same aperture. Widely separating the frequencies of the manipulating beam and the imaging beam offers numerous advantages for imaging and therapy applications.
Entrepreneurship. The final important contribution of the Foster lab has been to teach students (and colleagues) the mechanics of real translation which demands an understanding of entrepreneurship and all of the conflicts that go with it. Dr Foster has participated in the development of four Toronto area start-ups which have created opportunities and jobs for hundreds of people.
- F. S. Foster, J. Mehi, M. Lukacs, D. Hirson, C. White, C. Chaggares, and A. Needles, "A new 15-50 MHz array-based micro-ultrasound scanner for preclinical imaging," Ultrasound Med Biol, vol. 35, pp. 1700-8, Oct 2009.
- Needles, A. Heinmiller, J. Sun, C. Theodoropoulos, D. Bates, D. Hirson, M. Yin, and F. S. Foster, "Development and initial application of a fully integrated photoacoustic micro-ultrasound system," IEEE Trans Ultrason Ferroelectr Freq Control, vol. 60, pp. 888-97, May 2013.
- J. M. Denbeigh, B. A. Nixon, J. M. Hudson, M. C. Puri, and F. S. Foster, "VEGFR2-targeted molecular imaging in the mouse embryo: an alternative to the tumor model," Ultrasound Med Biol, vol. 40, pp. 389-99, Feb 2014.
- M. G. Shapiro, P. W. Goodwill, A. Neogy, M. Yin, F. S. Foster, D. V. Schaffer, and S. M. Conolly, "Biogenic gas nanostructures as ultrasonic molecular reporters," Nature Nanotechnol, vol. 9, pp. 311-6, Apr 2014.
- D. S. Ardelean, M. Yin, M. Jerkic, M. Peter, B. Ngan, R. S. Kerbel, F. S. Foster, and M. Letarte, "Anti-VEGF therapy reduces intestinal inflammation in Endoglin heterozygous mice subjected to experimental colitis," Angiogenesis, vol. 17, pp. 641-59, Jul 2014.
- S. E. Shelton, B. D. Lindsey, J. K. Tsuruta, F. S. Foster, and P. A. Dayton, "Molecular Acoustic Angiography: A New Technique for High-resolution Superharmonic Ultrasound Molecular Imaging," Ultrasound Med Biol, Dec 8 2015.