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Stuart Foster, PhD

Senior scientist

Sunnybrook Health Sciences Centre
2075 Bayview Ave., Room S6 58
Toronto, ON
M4N 3M5

Phone: 416-480-5716
Fax: 416-480-5714

Administrative Assistant: Johnson Lee
Phone: 416-480-6100 x65765
Email: johnson.lee@sunnybrook.ca

Education:

  • B.A.Sc., 1974, engineering physics, University of British Columbia, Canada
  • M.Sc., 1977, medical biophysics, University of Toronto, Canada
  • PhD, 1980, medical biophysics, University of Toronto, Canada

Appointments and Affiliations:

Research Foci:

  • Ultrasound
  • Imaging
  • Ultrasonic therapy

Research Summary:

Ultrasound is a well-established imaging modality that currently accounts for about 1/3 of all diagnostic imaging procedures and is a cornerstone in medical disciplines such as cardiology, radiology, and obstetrics. Conventional medical diagnostic imaging methods provide resolution on the order of 0.5–1 mm and penetration greater than 100 mm. Dr. Foster's lab has extended the powerful B-mode backscatter methods developed for clinical imaging in the 3–10 MHz frequency range to much higher frequencies (20–200 MHz), thereby enabling tissue micro-imaging. This technique, called micro-ultrasound (microUS), enables biological structures to be imaged with resolutions ranging from 15 to 100 micrometres over fields of view ranging from 2–15 mm.

There are numerous clinical and basic biological research applications for microUS imaging at elevated frequencies. Clinical applications include the follwing:

  • Imaging of the eye: In the eye, microUS provides images with fascinating detail not visible using any other means. Commercial instrumentation for ocular imaging has proliferated and found wide clinical acceptance as a means of assessing glaucoma and anterior segment tumours.
  • Intravascular imaging: 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.
  • Skin and cartilage imaging: Skin and cartilage imaging are natural applications of UBM as both are comprised of comparatively thin layers of tissue that undergo structural alteration when diseased. In the case of skin cancers such as malignant melanoma the stage at which the tumour changes from a lateral growth phase to a vertical growth phase is important in tumour grading. Osteoarthritis can change both the thickness, structure, and surface roughness of cartilage. Since such changes are typically only on the order of a few tens of microns, microUS may be a useful means of quantifying this process.

Micro-ultrasound imaging and other microimaging technologies are rapidly infiltrating the field of genomics. Together with other U of T colleagues we have founded the Mouse Imaging Centre (MICe) at the Hospital for Sick Children in Toronto. This is a Canada wide resource for rapid phenotyping and disease modeling in the mouse. The biological applications of UBM are being investigated in combination with micro-MR, micro-CT and optical microscopies. These techniques greatly facilitate in vivo assessment of developmental and pathophysiological processes under highly controlled conditions. Disease models ranging from glaucoma to breast cancer are under investigation. Finally, the development of high-frequency Doppler may offer a new dimension of information on blood flow at the arteriolar and capillary level to compliment the structural information in microUS images. Such developments are bound to have an important impact on the study of angiogenesis and disease progression.

Specific research areas include:

  • transducer array and imaging systems development;
  • Doppler studies of vascular morphology and hemodynamics in the microcirculation;
  • ultrasonic propagation and fundamental interactions in tissues;
  • high-frequency nonlinear propagation;
  • microbubble and Nanoparticle contrast agents; and
  • imaging for genomics and disease models.

More Information:

  • Recipient of a Terry Fox Cancer Research Scientist Award from the National Cancer Institute of Canada and has won the Ultrasound in Medicine and Biology Prize twice.
  • Distinguished lecturer of the IEEE Ultrasonics Ferroelectrics and Frequency Control Society (1995-6). He is on the editorial boards of Ultrasonic Imaging and Ultrasound in Medicine and Biology.
  • Awarded the Eadie Medal by the Royal Society of Canada in 1997 for major contributions to applied science in Canada.
  • Pioneered the development of the technology and clinical applications of high-frequency microUS in the eye. There are now more that 400 commercial systems based on our design around the world. More than 500,000 patients have been scanned with this instrumentation.
  • Developed microUS for imaging of the skin leading to a number of clinical studies on its use to visualize melanoma, basal cell carcinoma and psoriasis.
  • Performed the first application of high-frequency ultrasound to the visualization of the mouse. This work showed the ability of microUS to detect and image genetic mutations that affect neural and cardiac mouse development, noninvasively.
  • Reported the first clinical use of high-frequency (40 MHz) intravascular ultrasound in human coronary arteries. He was instrumental is establishing the benefits of high-frequency intravascular ultrasound and in developing the high-frequency transducer technology now used in commercial products.
  • Introduced the first Doppler systems and transducer arrays for high-frequency ultrasound imaging. This technology enables ultrasound to image and measure flow in the microvasculature.
  • Commercialized microUS for preclinical imaging. More than 600 laboratories around the world now use this instrumentation.

Selected Publications:

See current publications list at PubMed.

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