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Gregory Czarnota, PhD, MD

Senior scientist

Sunnybrook Health Sciences Centre
2075 Bayview Ave., Room T2 167
Toronto, ON
M4N 3M5

Phone: 416-480-6128
Fax: 416-480-6002

Administrative Assistant: Ram Mohabir
Phone: 416-480-6128
Fax: 416-480-6002


  • B.Sc., 1991, biochemistry, McMaster University, Canada
  • PhD, 1995, medical biophysics, University of Toronto, Canada
  • MD, 2000, University of Toronto, Canada

Appointments and Affiliations:

  • Senior scientist, Physical Sciences, Odette Cancer Research Program, Sunnybrook Research Institute
  • Radiation oncologist, Sunnybrook Health Sciences Centre
  • Associate professor, departments of radiation oncology and medical biophysics, University of Toronto

Research Foci:

  • Ultrasound imaging
  • Spectroscopy of cancer therapy responses

Research Summary:

Dr. Czarnota is conducting research focused on using ultrasound imaging and spectroscopy at conventional and high frequencies to detect apoptosis and other forms of cell death in response to chemotherapy and radiation therapy. In addition to being a scientist in the imaging discipline he is an MD in the department of radiation oncology with applied research in breast cancer patients. His basic science research interests include studies in biochemistry, chromatin biology, biophysics, medicine and oncology.

Dr. Czarnota, along with his collaborator Dr. Michael Kolios, discovered that ultrasound could be used to detect apoptosis. This finding has since been applied to important questions in oncology and organ transplantation. Our research group has demonstrated that this special form of cell death may be detected using ultrasound imaging and spectroscopy in vitro, in situ, and in vivo. The use of ultrasound to detect apoptosis and other forms of cell death has numerous applications listed below.

Cell and molecular biology:

Despite the use of medical ultrasound for decades, the features inside cells that contribute to ultrasound backscatter at conventional and high frequencies remain unknown. We are systematically probing how subcellular constituents such as DNA, RNA, protein and lipids contribute to backscatter. In particular we are interested in how nuclear and chromatin structure affects ultrasound signals since we have found it to be a dominant structure in the formation of backscatter signals.

Image and spectroscopic analysis:

We are collaboratively investigating a number of spectroscopic parameters for characterizing tumours and tumour responses to chemotherapy and radiation therapy at conventional and high frequencies. We are developing these methods to generate colour-coded ultrasound parameteric maps to aid in assessing tumour responses to therapy. Since these spectroscopic signals are potentially linked to nuclear structure and chromatin structure which differs between normal and neoplastic tissue there is potential to develop our spectroscopic methods not only into a method to track tumour responses but a potentially important diagnostic tool.

Clinical evaluations of ultrasound imaging and spectroscopy:

We are instituting a number of clinical evaluations of our spectroscopic detection of cell death. Our main investigational site is breast cancer patients with large “locally advanced” breast cancers who receive neoadjuvant combined chemotherapy and radiation therapy. We hope to rapidly distinguish responding tumours from those that are non-responding so that the latter may be treated with different chemotherapy regimens or with radiation sensitizers to hopefully improve outcomes.

Selected Publications:

See current publications list at PubMed.

  1. Tunis AS, Czarnota GJ, Giles A, Sherar MD, Hunt JW and Kolios MC. Monitoring structural changes in cells with high frequency ultrasound signal statistics. Ultrasound Med Biol. 2005 Aug; 31(8):10411049.
  2. Czarnota GJ. Role of ultrasound in the detection of apoptosis. Eur J Nucl Med Mol Imaging. 2005 May; 32(5):622632.
  3. Kolios MC, Czarnota GJ, Lee M, Hunt JW, Sherar MD. Ultrasonic spectral parameter characterization of apoptosis. Ultrasound Med Biol. 2002 May; 28(5): 589597.
  4. Czarnota GJ, Kolios M, Abraham J, Portnoy M, Sherar MD, Ottensmeyer FP and Hunt JW. Ultrasound imaging of apoptosis: high resolution non-invasive monitoring of programmed cell death in vitro, in situ, and in vivo. Br J Cancer. 1999 Oct; 81(3):520527.
  5. Czarnota GJ, Kolios M, Vaziri H, Benchimol S, Ottensmeyer FP and Hunt JW. Ultrasound biomicroscopy of living, dead, and apoptotic cells. Ultrasound Med Biol. 1997; 23(6):961–965.

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