The prospect was announced today (Monday, Feb. 17) at the 1997 annual meeting of the American Association for the Advancement of Science (AAAS).
Called adaptive current tomography (ACT), the system can deliver real-time images of bodily functions without exposing patients to radiation or radioactivity.
Developed by a team of mathematicians, biomedical engineers, and computer scientists at Rensselaer Polytechnic Institute in Troy, N.Y., ACT uses harmless currents to measure electrical conductivity and permitivity within the body, said David Isaacson, professor of mathematics at Rensselaer.
Because breast tumors have been shown to conduct electrical currents as much as four times better than surrounding breast tissue, Isaacson believes the ACT system may have advantages over X-ray mammography. As many as 10 percent of breast tumors do not show up on X-rays. In addition, some women and doctors have expressed concern regarding the annual exposure of the breast to radiation.
Although the development of the ACT system for breast cancer detection is still in the early stages at Rensselaer, the approach has already been used to image the blood and air going in and out of human lungs and to show the blood as it enters and leaves the heart. The ACT imaging system has also been tested in clinical trials at the Albany Medical Center, Albany, N.Y.
Speaking at an AAAS session on the use of inverse mathematics in electrical impedance imaging, Isaacson explained how he and his Rensselaer colleagues developed algorithms to image the conductivity and permitivity of tissues, gasses, blood, and other fluids in the human body. Inverse mathematics is a method by which scientists can account for what is happening inside a hidden region (such as the interior of the body or the Earth) by measurements made outside the region.
Isaacson said that his algorithms for using ACT in breast cancer screening are ready to be tested. The next step is to develop electronics similar to those the team developed for imaging the heart and lungs.
The use of electrical currents to screen for breast cancer is not new, Isaacson said. Twenty years ago, E. H. Frei, an Israeli scientist, developed a commercially available system that has performed well in Israel as an adjunct in testing for breast cancer, Isaacson said.
When fully developed, Rensselaer's ACT system will not only provide better image resolution than is possible with other electrical screening systems, it may also show the size and location of the tumor in a three-dimensional reconstruction, Isaacson said.
The ACT system may also warn physicians if blood clots are forming in post-surgical patients, detect fluids building up in the brains of premature infants, and diagnose pulmonary edema.
Unlike most other imaging systems, ACT may provide safe, around-the-clock monitoring at a patient's bedside with no radiation risks and at comparatively low cost. The pictures are not as clear as X-rays or CAT scans, but do indicate fluid build-up that is often not visible with other imaging systems.
In addition to the Rensselaer team of scientists and engineers, more than 60 undergraduate and graduate students have worked on the ACT project. Funding has come from the National Institutes of Health, the National Science Foundation, and the Office of Naval Research.
Faculty Contacts: David Isaacson, Professor of Mathematical Sciences, 518-276-6900 Jonathan Newell, Professor of Biomedical Engineering, 518-276-6433
Rensselaer News Bureau Contact: Bruce Adams, 518-276-2840