Special Seminar on Photoacoustics: 11AM Wednesday, July 12, BRB 9th Floor Conference Room
"A contemporary ceraunoscope: probing different biological length scales using photoacoustics by listening at 1 to 1000 MHz ultrasound waves." --Dr. Michael C. Kolios, Professor, Dept. Physics, Assoc. Dean of Research & Graduate Studies, Ryerson University, Toronto, Canada.
Photoacoustic imaging relies on the generation of ultrasound waves from optically absorbing structures. The interest in the imaging modality has been steadily growing and possibly is one of the most exciting biomedical imaging techniques of this decade. The ultrasound waves produced by the absorption of light in tissue can be analyzed by methods developed to analyze ultrasound backscatter signals in the field known as ultrasound tissue characterization. In this approach, the interpretation of the signals detected is based on the physics of photoacoustic wave generation. In the absence of exogenous absorbers, blood is one of the dominant optically absorbing tissues. Hemoglobin in red blood cells is the primary endogenous chromophore in blood. The spatial distribution of red blood cells in tissue determines the frequency content of the ultrasound signals produced. Analysis of the signals can reveal information related to the tissue vasculature. We are interested in cancer treatment monitoring with this technique. Typical vessel networks are hierarchically organized, with vessels that are evenly distributed to ensure adequate oxygen and nutrient delivery. Tumor vessels are structurally different: they are torturous and typically hyperpermeable. Therapies that target the vasculature can induce changes in the vascular networks that in principle should be detected using photoacoustic imaging. This presentation will show how the frequency content of the photoacoustic signals encodes information about the size, concentration and spatial distribution of resolvable and non-resolvable blood vessels that can be used to assess treatment response and speculate how we can use photoacoustic imaging to guide drug delivery and monitor its effects on tissues. Moreover, recent work in the development of specialized contrast agents, including microbubbles and nanoemulsions, will be presented.
Dr. Michael C. Kolios is a Professor in the Department of Physics at Ryerson University, Associate Dean of Research and Graduate Studies in the Faculty of Science and Affiliate Scientist at the Keenan Research Center at St. Michael’s Hospital. He leads a large group of projects that focus on optical and ultrasound methods used to characterize tissues and disease, as well as to develop theranostic agents that will assist in both therapeutic and diagnostic applications. He currently holds funding from the NSERC, the CIHR (amongst other funding agencies) and has received numerous teaching and research awards, including the Canada Research Chair in Biomedical Applications of Ultrasound, and the Ontario Premiers Research Excellence Award. He is the 2016 recipient of the Joseph H. Holmes Basic Science Pioneer Award from the American Institute of Ultrasound in Medicine (AIUM) and a fellow of the American Institute for Medical and Biological Engineering (AIMBE). Dr. Kolios currently holds four patents (one of which is licensed), with another four under consideration. Google Scholar’s index (which includes conference papers and patents) indicates that his work has been cited over 4000 times, with an h-index of 35 and an i10-index of 87. Dr. Kolios received his B.Sc. in Honours Physics (minor in Computer Science) from the University of Waterloo and Ph.D. in Medical Biophysics from the University of Toronto.