New Imaging Technology Deciphers Tumors

Measuring tissue elasticity may reduce the need for some biopsies

Jonathan Ophir, Ph.D.

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 palpation
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 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, 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,” 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.

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, 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 is constant,” he explained.

The research has been funded by a multi-million 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 in Philadelphia, University of Montreal, University of Vermont, Baylor College of Medicine and the National Institutes of Health in France. At two sites, clinical trials have begun with an expectation of enrolling 750 women who have been diagnosed with a breast lump via mammography.

Ophir and his group at the Medical School concentrate on the basic science aspect of the project. An electrical engineer, Ophir holds 16 patents and is quick to point out that his students have been coinventors on many of these patents.

The elastography technology has been licensed to one of the largest ultrasound companies in the world,
and Ophir says patients can expect to see elastography to image breast cancer, prostate cancer, vulnerable plaque and cardiac muscle in the next several years.

Ophir 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, Ophir and his group organized an international conference that attracted 100 registrants from 12 countries.

— By Darla Brown, Medical School