Recently I considered how breast ultrasound has the potential to enhance the sensitivity of screening for breast cancer in women with dense breasts. Having dense, or fibroglandular, breasts is a benign condition affecting as many as 40 to 50 percent of middle-aged women. This matters in screening, because dense breast glands appear cloudy in mammograms, obscuring tumors.
Supplemental screening by ultrasound is a contentious issue. That's in part because among radiologists, not all agree that the sound-wave technology is the best way to check dense breasts for cancer, or that it's economically feasible.
One possible solution to lower the costs and improve screening, both, is to automate the process. Over the long haul – after a hospital or radiology practice has invested in a machine and software to go with it, and training – automated ultrasound systems can render screening faster, reliable and more accurate.
“With ultrasound we’re improving our ability to find breast cancers that are small and early-stage” said Dr. Monica Saini, a radiologist in Santa Fe. Before settling in New Mexico, the Chicago-raised physician completed a breast imaging fellowship at the University of Washington in Seattle. She’s been in private practice for approximately seven years at Santa Fe Imaging.
Last year, her practice purchased an ABUS machine from GE Healthcare. The radiology group is affiliated with Christus St. Vincent Hospital, a medical center that serves approximately 75,000 people in and around Santa Fe. It’s one of the largest hospitals in the region. Both the practice and hospital accept most forms of private insurance, Medicare and Medicaid, Saini told me in a phone interview.
Her group's decision to buy the machine came after discussion and consultation with the hospital’s board. The leadership was concerned that breast cancers in women with dense breast tissue were going undetected by mammography, Saini said. “We wanted to improve our breast cancer screening,” she said. “It came down to buying a tomosynthesis (3-D mammography) or ultrasound machine,” she added. “Neither is cheap.”
“In Santa Fe there’s a lot of concern about radiation,” Saini observed. Tomosynthesis generates 3-D images of the breast using x-rays. “After speaking with many patients, we realized that many were more amenable to an extra ultrasound exam than to tomosynthesis,” she said. “We realized that automated ultrasound would be the best for our community.”
She and four colleagues in the Santa Fe practice began using the ABUS system in July 2014. “Most patients have liked it,” she said. “It’s nice because there’s not compression as with mammography.” It does take a while, though. “It takes us a good half hour, 15 minutes per side,” she said.
Saini has received a small fee for giving a lecture on her group’s experience with the ABUS system. Otherwise she has received no compensation from GE and has not been paid to promote the ultrasound system, she told me.
In her practice the ultrasound can usually be done in the same day as the mammogram, Saini said. “It works very well for the patients. Whenever possible, it’s the same technologist all the way through.”
Some women with dense breasts have hesitated to get the ultrasound. New Mexico does not have a law mandating that women be informed about that, or that screening ultrasound be covered by insurance, Saini said. “Because the procedure is not currently covered by Medicare or local payers in the area, there are barriers,” she stated.
“I believe that giving patients more information is a better,” Saini said. “We try to educate women when they come in for their screening mammograms. We explain about dense breasts, and ultrasound. But we also have to tell them that the charges, while covered by some insurance companies, are subject to deductibles and co-pays." If it’s not covered, or doesn’t go toward the deductible or co-pay, that dissuades many patients.”
Yet not all doctors agree that it’s worth offering this sound-wave test to all women with dense breasts for supplemental screening. Some radiologists have argued against widespread implementation of the procedure.
Manpower is one issue: An editorial in the February 2015 American Journal of Roentgenology suggested the field would be “overwhelmed” if all women with dense breasts were referred for ultrasound screening. Money, too: Comparatively low reimbursement rates for ultrasound influences some radiologists’ decisions – not just about recommending the procedure to patients who might benefit, but about purchasing the equipment and learning to use it.
Many are concerned about false positives. Some radiologists have little or no training in the sound-wave method of scanning whole breasts for cancer. If they dabble in ultrasound, they wind up with an unacceptably high rates of false positives. If they lack practice – or confidence – in distinguishing malignant from benign tissue, they’ll perform too many biopsies in women who don’t have cancer.
Dr. Kevin Kelly has spent over 20 years in this area of radiology. His company, SonoCiné, has developed machines and software to automate collection and analysis of whole breast ultrasound screening images.
“The false positives are mostly due to a lack of education,” Kelly said. “Without experience, radiologists are biopsying fat and benign fibrous tissue. With experience, you learn when to say to a woman ‘you don’t need a biopsy,’” he added.
“In my first study using the automated system with an experienced group of radiologists, the positive predictive value (PPV) was 38 percent,” Kelly said. In other words, over a third of the biopsies in the study yielded a cancer diagnosis. The result, published in the European Journal of Radiology, suggests that the false positive rate – when radiologists do biopsies based on the ultrasound, but find no cancer – is not too high.
Recently Dr. Jean Weigert reported that as radiologists in Connecticut gained experience with hand-held (non-automated) whole breast ultrasound for breast cancer screening, the procedure’s specificity improved over four years. These findings support that with training, the rate of false positives can be significantly lowered, ultimately reducing costs and risks.
“With our automated system, we demonstrated over a 55 percent relative increase in detecting invasive breast cancers as compared to 2-D mammography in women with dense breasts,” said Dr. Jessie Jacob, chief medical officer of Women’s Health at GE Healthcare. Jacob, a radiologist, also has a private practice in Palo Alto, California.
“The problem with hand-held ultrasound is that it’s very user-dependent,” Jacob said. “Not just in interpretation of the images, but in how the probe is applied. There is a great deal of skill that’s required for breast ultrasound, and a huge degree of variation,” she said in a phone interview.
The ABUS system involves a probe that’s larger than most ultrasound devices, about 6 inches in width, and curved to conform to contours of the breast. Technicians are trained to apply the probe in a standardized way to capture images in three planes, or angles. The ABUS images, which typically number around 2,800, are sent to a PACS (Picture Archiving and Communication System) IT system for the radiologist to review.
When a radiologist first starts reading with ABUS it takes about three to five minutes on average to examine a study, Jacob said. With a new tool for aligning and reviewing images in “survey” mode, a radiologist can look through thousands of images very quickly, she said. “We don’t have computer-assisted detection at this time,” Jacob told me.
GE Healthcare provides FDA-required training for technologists and radiologists who use the ABUS system. “We give a three-day course for each person who does image acquisition, as required by the FDA,” Jacob said. “We actually send people for onsite training.” The radiologists go through an intensive course, too. Their training includes examining thousands of ABUS images,” she said.
“With practice, reviewing gets faster and goes better,” Jacob said. “There’s a learning curve,” she acknowledged.
“Mammography is the gold standard right now. It is especially good for women who have non-dense breasts,” Jacob said. “Using ultrasound for women with fatty breasts doesn’t make sense,” she stated. She explained that if the background appears dark, as fat looks in a mammogram, cancers show up as white. “It’s best used as a supplemental test, only in women with dense breasts,” she emphasized.
A new GE healthcare automated system typically costs between $250,000 and $300,000. Some models and older machines run considerably less, depending on their newness and features. The latest ABUS system, InveniaTM, offers higher image quality and resolution than earlier versions, Jacob said.
At this time GE Healthcare has installed more than 30 of the latest ABUS units “in a mix of hospitals and practices” around the United States, Jacob said. Older models are used around the U.S, Canada and elsewhere. Additional new systems have been placed in other countries including Japan and Thailand.
ABUS has been evaluated in a recent report involving over 15,000 women who were screened. Some data from that study informed the FDA’s approval of the system. “That testing was with an older unit," Jacob said. "Now the ABUS resolution, contrast and overall image quality are better. We’ve improved the usability, workflow and other aspects of the system.”
“The SonoCiné system is designed to overcome inconsistencies and other problems inherent in handheld whole breast ultrasound,” Kelly said in a phone interview. The device has a robotic arm with a hand-held probe. A technician applies the probe in a rote manner while receiving real-time feedback to assure good contact, pressure and the best angle for imaging.
How it works is the machine slowly gathers and records sound wave images of the breasts. The SonoCiné frames are separated by only 0.8 millimeters (800 microns). The scanning process usually takes between 15 and 20 minutes, Kelly said. For each case the system records between 3,000 and 5,000 images and creates a movie.
“It takes about five minutes for a radiologist to go through the movie,” Kelly said. “What we get looks like a really good non-automated scan, he considered. “The advantage is we can catch tumors as small as 4 to 6 millimeters, which is ideal for picking up early invasive breast cancers.”
SonoCiné provides a level of detail beyond that of other ultrasound systems, Kelly emphasized. The magnifying power is about 25-fold, he said. “It’s fantastic. When you look at a breast with ultrasound, you can see the ducts and lobular units. You can’t see the individual cells, but you can see a lot.”
Central reading by specialized radiologists – potentially in a city apart from where a woman gets scanned, upon secure transmission of the images or “movie” – should be feasible, Kelly told me. “For gynecologists, the system offers the possibility of having women get breast ultrasound in their practices,” he said.
“The images could be streamed over a network and interpreted by a radiologist in a breast center,” he added. “But if they’re breast radiologists, they should be able to use this.”
One issue in the Santa Fe community is that not all doctors, such as gynecologists and primary care physicians, are informed about the reasons and methods of whole breast ultrasound screening, Saini considered. “We have lunches where I discuss screening with other physicians. It takes a lot of time to explain,” she said. “There’s a lack of information, and also a bombardment of information.”
“A lot of primary care doctors in our area are wondering about the recommendations for screening. They’re looking for a radiologist who might explain the methods,” Saini said. “False positives are always a concern, whether it’s mammography or ultrasound,” she added.
“We want to find the cancers at a point women have options, including breast conservation surgery,” Saini said. “Who would argue with that being a good thing?”