Researchers employ infrared imaging for tumor detection


MIT researchers have designed a prize-winning breast cancer detection method which could prove to be a safe and highly accurate substitute for the mammogram and follow-up biopsy.

The Minimally Invasive Optical Biopsy System uses infrared light in conjunction with an intravenously injected dye and special computer software to create a clear, high-contrast image that the researchers believe will easily allow physicians to detect breast masses and determine if they are benign or malignant.

The researchers -- Drs. Robert Levine and Matthew Braunstein, both research scientists at Lincoln Laboratory, and Robert W. Chan, a senior in biology -- will present their findings next month at the IEEE Engineering in Medicine and Biology Conference in Chicago.

While the researchers are optimistic about the device's possibilities, Dr. Levine cautioned that the system is not yet in prototype and no clinical trials have been planned. Because the research is in a very early stage, it cannot be viewed as a current option to mammography.

The new device uses infrared light, an invisible light which is already widely used by physicians in Japan in some breast cancer diagnostic tools. But the image revealed by those infrared light instruments lacks clarity, and thus is most useful on certain types of masses when used with other diagnostic tools.

The Minimally Invasive Optical Biopsy System takes infrared imaging of the human body a step further, by using it with a dye and special computer program that improve image clarity. While the new system has yet to be clinically tested, the researchers believe that the technology would be successful in clinical practice.

"The ability of infrared light to penetrate human tissue is well known. The problem has been that the images it produced lack clarity and contrast," said Dr. Levine. "Our method would make use of an existing FDA approved dye, Indocyanine Green, which, when injected in animal tissue, accumulates near tumors. The accumulation of dye near malignant tumors is much greater than the accumulation of dye near benign tissue. So you could tell not only if there was a tumor, but if it was malignant. Without clinical trials, we really won't know for certain. Our tests have all been in vitro [outside the body]," said Dr. Levine, who emphasized that the results are tentative.

The fluorescing dye, which is currently used in angiography and liver function tests, passes through the human body in less than three minutes. Except for the injection of the dye, the remainder of the optical biopsy technique is noninvasive. Infrared light is considered safe to humans.

Mammograms are commonly used to detect breast masses which are then biopsied, a procedure that removes a portion of the tumor tissue for testing. Biopsies are performed either with a needle that draws cells from the mass and requires either local or general anesthesia, or by surgery, which requires general anesthesia.

"The anesthesia alone for a biopsy could have a higher complication rate than the drug we're using. In addition, the biopsy is highly invasive and expensive," said Dr. Levine.

Mammograms themselves have been the subject of serious debate within the medical establishment, as their potential for doing harm must be carefully weighed against their benefits as a cancer screening device in women of different ages. Mammograms rely on X-rays, which can mutate or destroy the tissue they penetrate. Because of the danger inherent in repeated exposure to X-rays, debate in the medical community continues over how often women should have mammograms and at what age they should begin.

While no one disagrees that mam-mograms and biopsies have saved thousands of lives and should be used to screen for breast cancer, the techniques have room for improvement. Because about 80 percent of biopsies reveal no malignancy, the patient's risk from injury due to the combined procedures of mammogram and biopsy may be quite high when compared with the risk of living with a nonmalignant breast condition.

"The false-alarm rate is so high that if you could come up with a technique that would be less invasive and more accurate, you would be performing a real service," said Dr. Levine.

"There's a large scientific community working on infrared imaging techniques. I think eventually something is going to be good enough to become part of the imaging commonly available for screening breast cancer. My research in this area was actually prompted by an offhand remark by a radiologist at a conference a few years ago, who suggested that a contrast agent could make infrared imaging a truly useful diagnostic tool," he said.

Mr. Chan, the student who helped design the device, recently won a BFGoodrich Collegiate Inventors Program award for the invention, which includes a $3,000 prize for the student and $1,000 for the research advisor. He was one of two undergraduates and five overall winners chosen from 106 entries. (Students wanting more information on the competition should visit the program's Web site.) A business plan based on the imaging technology was also a finalist in MIT's 1997 $50K Entrepreneurship Competition.

A version of this article appeared in MIT Tech Talk on September 24, 1997.


Topics: Health sciences and technology, Innovation and Entrepreneurship (I&E)

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