Ultrasound Elastography

By Deana Totzke

A new twist on an old technology to help doctors diagnose cancer earlier

When a woman discovers a lump in her breast, one of the first steps in diagnosis is a biopsy. But results can take up to two weeks and create sleepless nights for the patient.

Elastography, a procedure developed a decade ago, is providing a faster, more accurate picture of what's going on inside the patient.

Raffaella Righetti, assistant professor in the Biomedical Imaging and Genomic Signal Processing area of the Department of Electrical and Computer Engineering at Texas A&M University, has studied the technology since its inception.

A twist on the traditional ultrasound technique, ultrasound elastography uses sound waves to detect tumors by indicating tissue stiffness.

"Many cancers do not possess a sonographic contrast that will make them detectable using standard ultrasound imaging methods, but they are much stiffer than the surrounding tissue," Righetti says. "The idea is to create a new contrast mechanism that provides additional tissue information that can help a physician to diagnose and stage diseases or assess tissue physiological states."

Both techniques use sound waves. Traditional ultrasound creates an image based on tissue echogenicity. The elastogram combines two views: the regular ultrasound image and a compression image — that is, an image produced while a technician presses on the tissue in question. How that tissue reacts speaks volumes.

A tumor can be five to 100 times stiffer than normal soft tissue. When a mechanical compression or vibration is applied, the tumor deforms less than the surrounding tissue. Elastography takes advantage of this characteristic to quickly diagnose breast cancer without the use of a needle or a scalpel.

An early interest
Righetti became involved with elastography as a student in Florence, Italy, while fulfilling a requirement to finish her undergraduate thesis. After reading some early publications by Jonathan Ophir from the University of Texas Health Science Center at Houston on elastography, she says she decided to go to Houston to learn more about the technique.

"The idea is to create a new contrast mechanism that provides additional tissue information that can help a physician to diagnose and stage diseases or assess tissue physiological states."

"I was fascinated by this new technology, which seemed to be very promising — although still at its very early stages — so I decided to take a trip to Houston to meet Dr. Ophir and his group," she says. "That trip marked the beginning of my collaboration with them."

After working with Ophir for eight months, Righetti went back to Italy to write her thesis and present her work before flying back to Houston a few days after her defense.

"That thesis is the first official Italian document on elastography," she says. "I ended up staying in Dr. Ophir's lab for eight years until joining Texas A&M in 2007."

Elastography has become a well-developed field since Righetti began her research. Several companies have developed elastography scanners that are now used worldwide with standard ultrasound methods to diagnose several diseases. These techniques are used clinically to detect breast and prostate cancer and differentiate between malignant and benign lesions. In an effort to reduce the number of biopsies performed, researchers are also studying the feasibility of using a set of features to compare the appearance of tumors in sonograms and in elastograms.

Ultrasound elastography may also be used in the early detection of lymphedema, a condition involving an abnormal accumulation of lymphatic fluid in the interstitial space that causes swelling, often related to cancer. Elastography could help assess the efficacy of current lymphedema treatments by imaging the tissue properties before and after treatment and could help in the design of more and better lymphedema treatments.

And ultrasound elastography's cost-effectiveness is a major advantage.

"The technique is easy, safe, real-time, noninvasive; it doesn't require a lot of training; and it has all the advantages of ultrasound-based imaging methods, including the fact that it could potentially be implemented in small portable devices," Righetti says. "And it's relatively inexpensive compared to MRI and other imaging methods."

On the horizon
Righetti says she joined the Texas A&M faculty so she could take advantage of the university's facilities and research labs, allowing for more comparative studies. Her current collaborations within the electrical and computer engineering department include projects with Arum Han in the NanoBio Systems Laboratory and Steve Wright in the Magnetic Resonance Systems Laboratory.

Other collaborators at Texas A&M include J.N. Reddy in the Department of Mechanical Engineering's Advanced Computational Mechanics Laboratory; Kristen Maitland in the Department of Biomedical Engineering's Biomedical Optics Laboratory; Steven Riechman in the Human Countermeasures Laboratory of the health and kinesiology department; and Theresa W. Fossum, director of the Texas A&M Institute for Preclinical Studies.

"It's exciting because you can find a lot of experts in any other field," Righetti says. "The potential is great because the facilities at Texas A&M are amazing and there is a large number of people working on different things. That kind of collaboration makes a big difference. That's what's so exciting about working at Texas A&M, that there are a lot of opportunities."

Righetti also collaborates with medical doctors, who she says are excited about elastography and its possibilities.

However, she says she gets the most satisfaction from working with her students, who have already generated three master's theses, several conference publications and three peer-reviewed articles, among several other publications in preparation. Two of her master's students working on this project have decided to continue their work in this field to pursue their Ph.D. degrees.

"I can see the light in their eyes when they're talking about all the different applications and possibilities, and I have students come up to me and say, ‘I didn't know ultrasound could be used in so many applications,'" she says. "It makes me happy to see how excited they are about the possibilities in the field that can help medicine."

And she says that one day she hopes to expand the uses of elastography to include novel orthopedic applications, a new research area at Texas A&M that the Defense Advanced Research Projects Agency is sponsoring. The motivation behind these applications is that ultrasound imaging techniques have some distinctive characteristics (such as lack of radiation, portability and real-time imaging) that make them an attractive alternative to standard orthopedic diagnostic methods.

"The potential is great because the facilities at Texas A&M are amazing and there is a large number of people working on different things. That kind of collaboration makes a big difference. That's what's so exciting about working at Texas A&M, that there are a lot of opportunities.

"Elastography is a very exciting field," Righetti says. "I've seen it grow from the moment it was born until the moment in which it has become clinical, and we have made tremendous improvements on image quality, signal and image processing techniques involved in the modality.

"I think that as a scientist and an engineer, it's really an amazing experience to be able to observe the technological development of an idea and be part of it."

Dr. Raffaella Righetti
Dr. Raffaella Righetti
Assistant Professor
Electrical & Computer Engineering
979.862.8586