'Sounding Out the Future of Breast Imaging
Sonography's reputation in cancer screening is growing
Vol. 21, Issue 19, Page 18
By Heather Simons
Cynthia Rapp, BS, RDMS, FAIUM, FSDMS, still remembers the first time she was asked to perform a breast sonography exam.
It was 25 years ago at Riverside Community Hospital in Riverside, Calif., where she first began her career as a sonographer.
"I told the doctor I had never scanned a breast before," Rapp recalled in a recent interview. "He said, 'Do not worry, all we want to know is if it is cystic or solid.'"
In those days, ultrasound transducers were still mechanically driven and the internal components often wobbled. Wary and inexperienced, Rapp only attempted to view breast lesions "a couple of times" using ultrasound.
"I remember my doctor saying, 'If it has enhancement behind it, then it is a cyst,'" she said. "Boy, were we wrong! Breast cancer can enhance as much as a cyst does."
Indeed, breast sonography has come a long way in the past quarter-century. Widely adopted as a diagnostic tool in the examination of targeted palpable breast lumps or lesions, sonography today provides a closer look for physicians and, in many cases, cause for relief for women.
"Any woman with a lump in her breast thinks that she may have breast cancer," said Rapp, now a veteran breast sonographer who co-authored the book Breast Ultrasound in 2003 and trained extensively with respected breast imager A. Thomas Stavros, MD, medical director for clinical site sonographer training program, University of Colorado, and assistant clinical professor, University of Colorado School of Medicine. "Ultrasound [imaging] is a quick and easy way of letting her know things are all right."
"Education is key"
To be sure, certain signs of breast cancer, like microcalcifications, cannot be detected with sonography. In addition, false positives have proven an issue with breast sonography, leading to potentially unnecessary biopsies. For these reasons, most experts recommend the modality as a complement to mammography. When the two modalities are combined, sonography has shown substantial potential in breast cancer screening.
"I have personally found many cancers on screening ultrasound as small as 4 or 5 millimeters in size," said Rose Heller-Savoy, MD, director of mammography services at Montclair Breast Center in Montclair, N.J. Dr. Heller-Savoy added that the many benefits of breast ultrasound include its low cost, wide availability and lack of ionizing radiation. She noted that the modality is especially helpful in detecting cancers in women with dense breasts.
"We know that in women with dense breasts, up to 40 percent of malignancies will not show up on a mammogram," she said. "After explaining to patients [that] they're limiting themselves to only finding certain types of early signs of malignancy, they usually will have both [a sonogram and a mammogram]."
In a recent clinical trial, the American College of Radiology Imaging Network (ACRIN) tested the value of adding breast sonography to routine mammography. The study showed that the combination detected more cancers during initial screenings, but it also significantly increased the risk of false positives and unnecessary biopsies.
"That's a risk I'm willing to take to find cancers earlier," said Dr. Heller-Savoy, whose confidence in breast sonography is linked to the skill of those performing the examination.
"That's a very important point—someone who does the occasional breast ultrasound is not going to do as well picking up small subtle cancers as someone who is fellowship-trained or spends their whole day doing it," she said.
Montclair Breast Center has a sonographer dedicated to breast sonography, Dr. Heller-Savoy said, and all images are "completely back scanned" by experienced physicians.
Rapp agreed that "education for breast ultrasound is key" because sonography is so user-dependent. "Ultrasound is only as good as the person holding the transducer," Rapp said, echoing Daniel A. Merton, BS, RDMS, FSDMS, FAIUM, technical coordinator of research at the Jefferson Ultrasound Research and Education Institute. He deemed sonography's user-dependency "the nature of the beast," but added that "there are a lot of specific approaches for how to minimize missing something or maximize the quality of your exam." (see sidebar)
Innovative technology
The latest developments in practice and technology suggest greater accuracy, standardization and efficiency of care are on the horizon for breast sonography. For example, the Somo.v Automated 3D Breast Ultrasound (U-Systems, Inc., San Jose, Calif.) aims to condense and improve the scanning process. According to U-Systems CEO Ron Ho, the Somo.v utilizes a wide field-of-view, high-frequency transducer to acquire large format images that include the nipple for accurate anatomic reference, and the total scan lasts for approximately 60 seconds.
In a recent phone interview, Ho emphasized consistent results and reduction of operator dependency. Acknowledging that mammography remains the gold standard in breast cancer screening, he said U-Systems is working toward a screening designation for the Somo.v, which is currently approved by the FDA only for diagnostic purposes.
Currently, 40 to 50 Somo.v units are in the field, but Ho predicted the number would grow "exponentially" if a screening designation is granted. He also noted that, with a list price of around $200,000, the Somo.v costs significantly less than MRI or digital mammography systems.
Not surprisingly, the question of who should perform automated breast scans has emerged. Merton said he thinks mammography technologists could be cross-trained, since the level of expertise needed to perform an automated breast scan is lower than that needed for a traditional breast sonogram.
"You could say it's an upside, because there are limited sonographers trained in breast sonography," he said.
Rapp said she hoped that sonographers or physicians would operate the system. She predicted that automated breast ultrasound scanning would be "an everyday occurrence in the near future."
You CAD
When it comes to detection, computers are playing an increasing role, especially with regard to computer-aided detection (CAD). Rapp is the vice president of clinical program development at Medipattern Corp., Toronto, Canada. Medipattern has developed B-CAD, a software program intended to provide unbiased evaluation of breast sonograms, presumably reducing the risk of false positive results and providing consistent review of images.
"[B-CAD is] designed to assist the
sonographer or physician with automated border detection and analysis of breast lesion features for BI-RADS classification," Rapp said, adding that the technology relies on the expertise of the sonographer.
B-CAD is still relatively new, with approximately 50 units in the field. Medipattern is set to release a new version of the software that will apparently make operation easier for the user by providing even more detailed evaluations, Rapp said.
New kid in town
One promising new ultrasound mode, elasticity imaging, or elastography, may offer a level of protection against false biopsies, according to Richard G. Barr, MD, PhD. Unlike traditional sonography, elastography uses waves to measure the stiffness of an object. Dr. Barr, director of ultrasound and breast imaging at Forum Health in Youngstown, Ohio, said he often describes the way elastography works in terms of a marble in Jell-O.
"If you had a glass marble and it was set inside Jell-O and you compressed the Jell-O, you would be able to move the Jell-O, but you would never be able to deform the marble," Dr. Barr explained. Cysts, he said, are soft and appear white on the elastogram, while hard tumors appear black.
The procedure takes two images: a
standard B-Mode image and an elastography image, which "is based on several frames," said Dr. Barr. When elastograms are compared to traditional ultrasound images, he noted that size becomes an important indicator.
"For some reason, in breasts, malignant lesions appear larger, [almost] three times as large, on the elastogram," said Dr. Barr. "Benign lesions appear soft, but they also appear smaller." So far, he added, no malignant tumors have appeared smaller in the studies, though some "very dense, fibrous lesions" have appeared larger.
Currently, Dr. Barr uses elastography as a standard procedure in conjunction with traditional breast sonography. He is aware of 10 other facilities with elastography equipment, although he said he doesn't know how regularly it is used.
Sonographers will need to make some adjustments in their technique when learning how to perform elastography, said Dr. Barr.
"When we started this process many, many years ago we were under the assumption that you had to apply a fair amount of pressure to generate the elastography images," he said. "What we found was the technique is so sensitive that actually all we're doing is holding the probe gently on the breast and just the patient's heartbeat and respiration are adequate to generate good elastograms. If you try to apply pressure you get worse images."
According to Dr. Barr, elasticity imaging is especially helpful in detecting BI-RADS 3 lesions, isodense masses and complicated cysts, which produce a unique "bull's eye" artifact. Because the elastogram must still be compared to the traditional sonography scan on a relative scale, he
said using the technique for screening is not yet a possibility.
Even without a fixed scale, however, Dr. Barr believes elastography can effectively reduce the risk of false positives and unnecessary biopsies and has hope for its potential.
Dedication wanted
Breast sonography continues to be scrutinized and revised as a screening tool for breast cancer. The key, it seems, for those hoping to improve their breast imaging technique and widen their base of knowledge is to
continually seek experience and advice from the experts and to practice devotion to the modality.
"If you're going to be doing breast ultrasound, I think you should have a certain level
of dedication to it," said Dr. Heller-Savoy. "From the patient perspective, I would rather go to a place where people live and breathe the breast than to someone who might do the occasional
breast ultrasound."
With the addition of more accurate and efficient technology and increased opportunities for operator education, experts say breast sonography has become one of today's fastest growing modalities. Dr. Heller-Savoy's prediction for the future of breast ultrasound is clear: "Because it is highly sensitive in detecting malignancy and a no-risk, low-cost procedure," she said, "I think breast sonography will only grow in terms of usage." n
Heather Simons is an editorial assistant at ADVANCE. She can be reached at hsimons@advanceweb.com.
Get Your Hands In the Goo!
Here are some tips for maximizing your breast sonography exams:
1. Press the tissue. Make sure you gently compress the breast tissue. "When someone doesn't press hard enough, then lesions can either be missed or overcalled," said Rose Heller-Savoy, MD, director of mammography services and a clinical breast radiologist at Montclair Breast Center in Montclair, N.J. Dr. Heller-Savoy added that too little pressure can also result in the detection of false lesions. This is not true of elastography, where too much pressure can result in unclear images.
2. Position for success. Whether the patient is lying on her back or on her side can affect the quality of a breast ultrasound scan. "If I'm looking at
the outer part of the right breast, I have the patient lie at 45 degrees on her left hip to spread out the breast tissue on the outer part of the right breast," said Dr. Heller-Savoy. When scanning the inner parts of the
breast, she said, the patient can be lying flat on her back, but she does not recommend that position for outer-breast scanning.
3. Get educated. The consensus is that the quality of breast sonography is directly correlated to the imager's level of education, whether formal
or on-the-job. Higher levels of education result in more diagnostically acceptable images and fewer false positive examinations. Experts suggest learning from experienced sonographers and consider taking the ARDMS breast specialty examination for the RDMS credential.
4. Just do it. Ultimately, the difference between a good sonographer and a great one comes down to experience. "There is so much information to know about breast ultrasound," said Cynthia Rapp, BS, RDMS, FAIUM, FSDMS. "One can attend lectures, but the real way to learn is to get your hands in the goo!"
—Heather Simons
http://imaging-radiology-oncology-technologist.advanceweb.com