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All Together Now
Microwave Imaging Spectroscopy (MIS)
The premise: Most people think of microwave technology as having to do with "radars, World War II submarines, or something like that," says Paul Meaney, who leads the MIS breastimaging project. Engineers have considered biomedical applications for microwaves "for a long time," he adds, but the technology "never really caught on." That may be changing.
For 10 years now, Meaney has been developing an imaging system that uses microwaves and specialized software to measure the electromagnetic properties of breast tissue. Those measurements form the basis for high-contrast images that can be used to diagnose breast cancer and monitor tumors that are getting shrunk with chemotherapy prior to surgery.
Early on, Meaney and Keith Paulsen, who helped create the software, decided to patent the MIS system. They formed a small company, Microwave Imaging System Technologies (MIST), with the help of the Dartmouth Entrepreneurial Network. Recently, a government research institute in South Korea licensed MIST's software; the Korean group plans to build and market their own imaging system.
Meanwhile, Meaney and his team continue to improve the MIS software and hardware. A third generation of the system will come online soon in clinical research space at DHMC.
The procedure: During MIS, a woman lies face down on a table with one of her breasts submerged in a bath of water and glycerin. Most women find this modality to be the most comfortable one, says Christine Kogel, the project's clinical research coordinator. "We advertise it as a facial for their breast tissue," she quips. Sixteen antennas surround the breast but don't touch it. In fact, women don't feel anything but the liquid during the procedure.
The microwaves are transmitted from one antenna, hit the breast, are deflected in various patterns depending on the tissue's composition, then are received by the
A bath of glycerin and water fills the tank (shown above and below left) when a woman's breast is being examined (as shown on the bottom right). The mixture provides enough resistance so that if a signal bounces off the wall of the tank, it is too weak to interfere with the primary measurements.
other 15 antennas. The waves' power is about 1/1,000th the strength of a cell-phone signal. Each antenna takes a turn as the transmitter until the whole array is used. The array can be raised and lowered to image different planes of the breast, but for time and data manageability, usually only about seven planes of data are collected.
