Physical Sciences

Researchers in the physical sciences platform at Sunnybrook Research Institute (SRI) use physics, mathematics and engineering to develop and improve ways to visualize molecules, cells, tissues, organs and whole organisms. They also create image databases and devise new ways to extract and interpret information from images.

Their aims are to develop and improve imaging technologies to diagnosis and assess disease, and to guide and monitor therapies.

Main areas of focus include ultrasound, including high- and low-intensity focused ultrasound; magnetic resonance imaging, structural and functional; digital mammography; X-ray technology; and optical and positron emission tomography. Scientists in this platform routinely partner with many medical device companies in the development and assessment of new technologies. Major partners include GE Healthcare, Philips, Toshiba, Insightec and many others.

Select advances in Physical Sciences

Dr. Charles Cunningham is developing an MRI contrast agent that enables noninvasive metabolic imaging in the body. To do this, carbon 13-labelled pyruvate is prepared in a strong magnetic field and injected into a person undergoing MRI. It works by visualizing biochemical reactions within tissue as cells metabolize the carbon-13-labelled substance. In 2016, Cunningham and colleagues became the first in the world to demonstrate noninvasive metabolic MRI of the human heart. He will use this method to characterize the metabolism of damaged heart muscle to detect early stages of heart failure.

Dr. Greg Czarnota has developed an imaging technique that is able to show a person’s response to cancer treatment very early on. The method uses the raw data produced by ultrasound machines to detect whether tumour cells are dying. In a study of 100 women with an aggressive form of breast cancer, Czarnota and colleagues showed they could predict tumour response with 82% accuracy using the technique after just one week of chemotherapy. The aim is to translate the technology clinically, so that oncologists may one day be able to personalize care through early therapy response monitoring.

Dr. Kullervo Hynynen is a pioneer in the field of MRI-guided focused ultrasound. Under Hynynen’s leadership, the focused ultrasound research program at SRI has made significant advances. Among these are the first use of focused ultrasound to open the blood-brain barrier in patients with Alzheimer’s disease; and the first application of focused ultrasound through the blood-brain barrier to deliver chemotherapy into the brain of patients with aggressive brain cancer. He is also exploring the use of focused ultrasound in other clinical areas and devising new technical methods to develop the next generation of the technology.

Dr. Bojana Stefanovic is developing new methods for imaging brain function. Her research uses MRI to measure brain activity and study blood flow in specific brain regions. She is using preclinical models of stroke and Alzheimer’s disease to understand changes in brain structure and function in these conditions. In preclinical models of early-stage Alzheimer’s disease, she has shown that blood vessels around areas of impairment do not function normally, and thus impede blood flow. With SRI senior scientist Dr. JoAnne McLaurin, she studied mice with Alzheimer’s disease and found that beta-amyloid accumulation on the blood vessels changed their structure and function. In response to carbon dioxide, the affected vessels failed to widen to increase blood flow.