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NEW IMAGING TECHNOLOGY DECIPHERS TUMORS
| Spring 2003: Scroll to Page 11 | ||
| October, 2003 |
BY DARLA
BROWN
What if an image could tell if a breast tumor were malignant or benign?
Today a biopsy is needed to make such a determination; but tomorrow, elastography may provide the answer in a gentle, noninvasive way.
Elastography, an imaging technique for soft tissue invented by radiology professor Jonathan Ophir, Ph.D., is poised to take the ancient art of physician palpitation to the next level and reduce the need for some types of painful biopsies.
“Through our work with elastography, we’re trying to find differences in the mechanical properties of benign-versus malignant breast diseases so that we can avoid doing unnecessary breast biopsies,” said Dr. Ophir, director of Ultrasonic Laboratories in the Department of Radiology. “Nine out of 10 breast biopsies turn out to be benign, so this technology can make a huge impact on the patient and health-care system.”
Using the existing technology of ultrasound, elastography involves two pictures of the tissue in question – the first in a normal “before” state and the second after a slight compression. The word“ compression” might make patients nervous; however, Dr. Ophir points out that with a mammogram a 40 percent compression of the tissue is rather routine, compared to just a 1 percent compression with elastography. From these two images, a new image, called an elastogram, is generated. This image displays the local hardness or softness of tissue elements.
“Most cancerous tissues are much harder than normal tissues because they are compacted and stiff, so they show up well on an elastogram. Malignant breast tumors are 10 to 100 times stiffer than other breast tissues,” Dr. Ophir said.
These structural changes in malignant tissues are the basis for palpation, however a tumor can be too small or too deep in the body to be felt by a physician. The elastogram allows the physician to see what he cannot feel.
Dr. Ophir’s discovery of elastography began when he was doing research on a National Cancer Institute grant in the 1980s to measure the speed of sound in various tissues. Adding an image into the equation, Dr. Ophir said he couldn’t get a good resolution of the tissue because the sound changes were small and hard to detect and because different tissues have different elasticity. “So we turned the tables – we started measuring the tissue’s elasticity, assuming the speed of sound in constant,”he explained.
Turning the tables on the experiment, Dr. Ophir and his collaborators found it was possible to measure mechanical changes in soft objects, such as sponges. When he wrote an application for a National Institutes of Health (NIH) grant in 1991,“ they basically laughed at us.” Undaunted, they tried again a couple of years later, this time vying for a highly selective NIH Program Project Grant. The perseverance paid off, as they have been funded by a multimillion dollar NIH Program Project Grant for nine years now. The multi-institutional grant covers engineering, basic science, and clinical research aspects and involves collaborators from Thomas Jefferson University, University of Montreal, University of Vermont, Baylor College of Medicine and the National Institutes of Health in France. Dr. Ophir and his group at the Medical School concentrate on the basic science aspect of the project.“ We are totally consumed by this work,” Dr. Ophir said. Dr. Ophir, an electrical engineer by training, has been very busy in his 22 years at the Medical School – he holds 16 patents in the area of ultrasound instrumentation and measurement techniques and is quick to point out that his students have been co-inventors on many of these patents. The elastography technology has been licensed to one of the largest ultrasound companies in the world, and Dr. Ophir said patients can expect to see elastography to image breast cancer, prostate New imaging technology deciphers tumors cancer, vulnerable plaque, and cardiac muscle in the next several years. A clinical trial soon will enroll 750 women who have been diagnosed with a breast lump via mammography.
Dr. Ophir’s group has four modified ultrasound machines that include the elastography instrumentation, but he said its use is not limited to ultrasound and that magnetic resonance imaging may be a future vehicle for this technology as well.
Elastography is catching on worldwide– last year, Dr. Ophir and his group put on an international conference that attracted 100 registrants from 12 different countries.“
We’re committed to advancing the state-of-the-art imaging and creating professionals in the field,” he said. “And with elastography, we know we can make a contribution.”
Dr.
Jonathan Ophir has invented technology to measure a tissue’s
elasticity. |
