Sunnybrook imaging researchers
collaborate to support
To further improve outcomes for individuals living with cancer, the strength of research collaboration across Sunnybrook’s Odette Cancer Centre and Sunnybrook Research Institute (SRI) better propels translation to clinical care.
“In imaging research and resulting discoveries for example in breast cancer,” explains Dr. Kullervo Hynynen, director of the Physical Sciences Research Platform at SRI, “Sunnybrook is using imaging technologies, and imaging combined with novel agents, to improve detection and diagnosis, better define aggressive breast cancers, enhance treatment, and faster track treatment response.”
Detection and Diagnosis
Digital tomosynthesis is a newer technology using the strengths of digital mammography. Dr. Martin Yaffe, a senior scientist at SRI and Dr. Roberta Jong are conducting research and clinical trials on the use of digital tomosynthesis to enhance breast cancer detection and diagnosis.
“Instead of the two views in digital mammography, tomosynthesis quickly takes up to 15 low-dose images that are layered into a three-dimensional view,” says Dr. Yaffe who also helped pioneer digital mammography.
“With tomosynthesis we look at images of thin slices of the breast so that abnormalities are not obscured by other structures, and false findings are not created,” says Dr. Jong, a dedicated breast radiologist.
Sunnybrook researchers are using MRI to enhance detection and diagnosis especially for women at high risk. Recent studies led by Dr. Ellen Warner, a medical oncologist at Sunnybrook’s Odette Cancer Centre show that in high-risk women, MRI detects more than twice as many breast cancers as mammography, ultrasound or clinical breast examination, with MRI detecting the cancers at an earlier stage. To further support MRI screening in high-risk women, Dr. Anne Martel, a senior scientist at SRI is collaborating with Sunnybrook radiologists to develop computer-aided diagnosis and detection (CAD) analysis techniques and patient motion ‘correction‘ tools for better imaging quality and accuracy.
DCIS (ductal carcinoma in situ) is a non-invasive form of breast cancer representing about 20 per cent of diagnoses. “Because the cancer cells have not spread beyond the ducts in the breast, DCIS is a highly curable form however some women will develop invasive breast cancer,” says Dr. Eileen Rakovitch, head, Odette Breast Cancer Care team, and an SRI scientist with a research focus in DCIS. Dr. Rakovitch, Dr. Yaffe, Dr. Belinda Curpen, acting head of Breast Imaging, and others are evaluating if women with DCIS with dense breasts are at higher risk of recurrence after treatment. “We are working to determine who is at greatest risk, and to potentially reduce over-treatment for others.”
To detect and differentiate DCIS from more invasive disease, Dr. Yaffe with Dr. Jong and Dr. Peter Burns, are investigating two new ultrasound imaging techniques: microbubble contrast ultrasound and tissue elastography.
Microbubbles are smaller than red blood cells and pass harmlessly through the circulation following a small injection, allowing ultrasound to detect microscopic blood vessels. Dr. Burns, a senior scientist at SRI leads work in this area. As cancers develop, the formation of new blood vessels or angiogenesis, is critical for tumour growth. Their early development in DCIS may be a danger sign that ultrasound can detect. Tumours that are growing also make tissue harder. Ultrasound elastography creates shear waves or ‘wobbles’ in tissue, which enable very subtle changes in tissue stiffness to be imaged non-invasively.
Locally Advanced Breast Cancer (LABC) accounts for 15 per cent of breast cancers and involve large tumours. Before surgery, patients undergo chemotherapy and or radiation to shrink tumours and reduce the chance of recurrence after treatment.
To enhance radiation, Sunnybrook researchers are exploring microbubbles to further sensitize tumours. Dr. Gregory Czarnota, a scientist at SRI and radiation oncologist in the Odette Breast Cancer Care team is using microbubbles combined with radiation to reduce tumour volume.
Other research to sensitize tumours is being done by Dr. Jean-Philippe Pignol, also a scientist at SRI and radiation oncologist on the Odette Breast Cancer Care team. He is using gold nanoparticles loaded into tumour cells. When exposed to a novel type of x-ray, these particles produce Auger electrons that are highly damaging to breast cancer cells.
Support Tailored Treatment
Faster tracking of tumour response better tailors treatment and further reduces toxicity. Dr. Czarnota, and Dr. Greg Stanisz, a senior scientist at SRI are using ultrasound and MRI showing tumour metabolic activity in response to chemotherapy. Clinical trials using ultrasound with LABC patients shows tumour response one week into chemotherapy compared to PET (position emission tomography) and CT (computed tomography) scans which typically take several months.