The research assistant in the Medical Imaging Laboratory
in the Institute of Biomedical Engineering at Université
de Montréal moves in front of a journalist with 17 electrodes
attached to his thorax. He connects some wires and suddenly,
on the screen, you can see the subject's lungs inflating
and deflating as he breathes. Even the blood flow to the
heart is audible between the lobes. The picture is astonishingly
clear.
"Air is a very bad conductor of electricity, and blood
has a much higher conductivity than an organ such as the
lung," explains Robert Guardo, a Professor in the Department
of Electrical Engineering at the École Polytechnique.
When very weak currents are applied on both sides of the
body, these electric variations can be reproduced as images
on the screen."
The technique is called the electrical impedence tomography
imaging. Professor Guardo has been working to perfect the
system for the past 15 years. Today, he is ready to
market a device that he designed from A to Z. "One
of the clinical applications of this system is to monitor
patients in intensive care," he explains. If an edema
reaches the lungs, for example, the conductivity will change
and the effect on breathing will be seen on the screen.
The electrical impedence tomography technology was initially
developed to characterize soils in geophysics, e.g., to
identify mineral deposits. It is also used in industry,
for non-destructive inspection of materials. In another
application, it has proved effective in detecting antipersonnel
mines. We are just beginning to realize its potential in
biomedical applications, and the Institute of Biomedical
Engineering is the only site in Canada working on all aspects
of the technology, from instrumentation and in vivo tests
to software. "The technology has a bright future,"
Professor Guardo predicts. "It is non-invasive and
does not cause the patient any discomfort. In addition,
it requires only relatively inexpensive, compact instrumentation.
Lastly, it produces images in real time-up to 24 per second-with
a resolution comparable to ultrasound."
Eventually, the device developed by Professor Guardo at
the École Polytechnique will be marketed to support
assisted ventilation and monitoring systems.
Researcher: Robert
Guardo
Telephone: (514) 340-4711, ext. 4365
Funding: Natural Science and Engineering Research Council,
Canadian Foundation for Innovation
