Digital Mammography & Beyond

In November 2006, Fujifilm Medical Systems introduced its Synapse version 3.2 PACS with additional digital mammography capabilities that include reader-specific preferences to be set.

Breast imaging is in the midst of a perfect storm. Digital mammography is well-established and still growing fast. About 3,000 facilities now have digital technology, according to the FDA. And the Digital Mammographic Image Screening Trial (DMIST) results that two years ago demonstrated digital’s superiority for pre- and peri-menopausal women and patients with dense breasts are fueling digital sales. FDA approval for CR mammography is further feeding the fire by bringing the digital price tag into range for more sites, particularly lower volume facilities.

But the breast imaging resurgence transcends mammography. Breast MRI is making further inroads into clinical practice, and digital tomosynthesis seems to be right around the corner. New additions to the breast imaging arsenal provide radiologists with tools to help pinpoint breast cancers at earlier and more treatable stages and accurately evaluate the extent of disease to best steer treatment.

This month, Health Imaging & IT visits with state-of-the-art breast imaging sites across the nation to learn about the clinical and operational issues associated with various solutions.

Digital mammo proves itself

When digital mammography first hit the market earlier this decade, most sites eyed the technology cautiously. But over the last two years, that initial wariness has been transformed into enthusiasm. Digital is the wave of the future—from clinical and workflow perspectives. It is the platform for next-generation applications such as breast tomosynthesis. Plus it boosts efficiency, and the recent FDA approval of a CR option puts the digital price tag within reach of most mammography sites. And more systems are pending approval.

Seattle Cancer Care Alliance in Washington is a digital pioneer; the center opened in 2001 as a digital mammography site outfitted with GE Healthcare Senographe DS systems. The advantages of digital are significant, says Connie Lehman, MD, director of radiology. It offers superior image quality, faster image acquisition and fewer retakes.

Still, digital mammography can be a somewhat challenging transition, particularly for radiologists accustomed to rapidly reviewing large stacks of analog mammograms. “It can take more time to review digital images, especially at first, but there are ways to drop interpretation time,” Lehman says. For example, a radiology assistant can be added to help radiologists with digital and film image management. The goal, says Lehman, is to make radiologists as efficient as possible, which means minimizing the time they spend managing and manipulating images.

On the technologist side, Seattle Cancer Care Alliance organizes the digital mammography worklist to coordinate comparison films and information and minimize extraneous movement by radiologists. Image sorting and ordering are automated, which brings digital workflow closer to the analog ideal with the clinical advantage of additional information.

Some of the major beneficiaries of early adopters’ efforts are later adopters like Metro Imaging in St. Louis, Mo. The five-site practice began, deploying Siemens Medical Solutions Mammomat Novation DR in November 2006. “We planned on staging a full implementation over one year, but after the first installation we saw reimbursement increase with CAD and digital mammography, and decided to accelerate the deployment,” says COO Deanne Blume. The practice replaced all of its analog systems with five digital systems in just more than six months, and reaped benefits beyond the reimbursement increases.

Exam times have dropped; in fact, the more rapid digital throughput made it possible for one facility to replace two analog systems with a single digital unit. But what about radiologist productivity? “We were a little apprehensive because we were told it would be slower,” says Blume. Most radiologists have adjusted well with only a slight increase in interpretation time and the added benefit of improved image quality. Digital mammography also helps facilitate Metro Imaging’s commitment to patient care. “We treat most patients as diagnostic patients with radiologists reviewing and sharing results with patients before they leave,” explains Blume.

The advantages of digital mammography run the gamut from improved efficiency to enhanced patient care. The key to a successful transition, says Lehman, is to develop a team that includes administrators, techs, radiologists and IT personnel. One of the first tasks is to understand the challenges of the analog-to-digital switch and use a team-approach to address issues like workflow. Equally important, says Lehman, is selecting a digital mammography vendor with a strong track record for proactively addressing challenges and helping steer the transition to digital mammography.

The CR option

Last summer, the FDA approved Fujifilm Medical Systems’ Fuji Computed Radiography for Mammography (FCRm) system, providing hospitals and imaging centers a new digital mammography option. The primary advantage of the CR approach is cost; it allows sites to use existing equipment.

One of the early adopters of CR mammography is Gershon-Cohen Breast Clinic in Philadelphia, Penn. The breast clinic deployed digital mammography in 2004 at its main facility, but could not invest in additional digital systems at its two outpatient centers with the initial digital conversion. When DMIST results confirmed the facility’s commitment to digital mammography, the breast clinic decided to fully implement digital.

“Fuji’s CR system made sense for these lower volume sites,” states Debra Copit, MD, director of Gershon-Cohen Breast Clinic. The clinic combined a CR reader and existing equipment to balance cost-effectiveness, efficiency and patient care at the offsite facilities. “Image quality is wonderful with no difference between CR and conventional digital mammography,” says Copit.

Another advantage of the CR option is its ease of implementation. “CR is closer to film-screen mammography,” notes Copit. “It’s easier for techs to adjust, and it doesn’t require significant changes to the mammography workflow.” On the other hand, CR mammography does not yield the dramatic gains in volume and efficiency possible with digital mammography. Another slight drawback is its inability to serve as a platform for future applications such as digital tomosynthesis. 

Tomosynthesis aims high

Early results confirm the promise of digital breast tomosynthesis. “The results are pretty striking. In my mind, it’s clear that tomosynthesis is as good, if not better than, digital mammography in the diagnostic setting,” reports Steven Poplack, MD, co-director of breast imaging/mammography at Dartmouth-Hitchcock Medical Center in Lebanon, N.H., and one of a handful of researchers investigating Hologic’s digital breast tomosynthesis system. Breast tomosynthesis entails a series of low-dose exposures, which are mathematically processed into one millimeter slices to show tissue structure in three dimensions and eliminate spatial ambiguity.

Poplack’s research, recently published in the American Journal of Radiology, compared digital mammography and tomosynthesis in 98 women with abnormal or questionable screening mammograms. Two radiologists subjectively compared the image quality of the diagnostic mammogram and tomosynthesis projections. “In about 90 percent of cases, tomosynthesis was comparable or superior to diagnostic mammography. Tomosynthesis really shined with characterization of masses and asymmetries,” explains Poplack. Tomosynthesis appeared to be less effective with calcifications; however, Poplack suspects reduced acquisition time available on current tomosynthesis systems will improve image quality and produce results comparable to diagnostic mammograms for calcifications.

Although the Dartmouth study focused on diagnostic mammography and tomosynthesis, Poplack and his colleagues analyzed tomosynthesis images as screening studies to determine whether or not patients would have been called for follow-up studies if tomosynthesis had been employed as the initial screening exam. “We found a pretty substantial recall reduction. About 40 percent of callbacks would have been eliminated if tomosynthesis was used as a screening study. This shows the potential magnitude of recall reduction and can serve as a starting point for further research,” sums Poplack.

As tomosynthesis edges closer to clinical adoption, an inevitable question arises. How does tomosynthesis impact workflow? Poplack estimates that it takes him about three to four minutes to read a tomosynthesis exam—compared to two minutes for a comparable digital mammogram. “The next few years will bring improvements in workflow and efficiency, not the least of which is familiarity with reading tomosynthesis projections, which will improve workflow,” notes Poplack.

The real benefit of tomosynthesis may be its ability to maintain or improve cancer detection and also improve specificity, says Poplack. That is, tomosynthesis may help radiologists find more small breast cancers while distinguishing small abnormalities that are not cancerous.

Positron emission mammo under the microscope

One of the latest arrows in the breast cancer quiver is positron emission mammography (PEM). Early research places PEM’s niche as a pre-operative surgical staging solution. Until now, breast MRI has been the gold standard for surgical staging, but according to some experts, it isn’t a perfect solution. “There’s no uniform way to implement breast MRI or acquire images, and a single study can generate thousands of images to review,” states Kathy Schilling, MD, medical director of breast imaging and intervention at The Center for Breast Care at Boca Raton Community Hospital in Florida. PEM offers a cookbook alternative, says Schilling, who has compared both studies in patients recently diagnosed with breast cancer to determine which study better predicts the full extent of the disease. The study focused on Naviscan PET System’s PEM Flex Solo II system.

“We’re positive PEM is as sensitive as breast MRI, and it’s more specific, so we don’t see many false positive results,” explains Schilling. In addition, PEM is fairly easily implemented. After an FDG injection, a tech acquires four PEM views, which are reconstructed into 48 tomographic images. The views mimic mammography, helping radiologists translate and correlate findings. Like other nuclear medicine studies, PEM visualizes functional abnormalities rather than structural abnormalities. “Resolution is about one to two millimeters, and the functional data provide an opportunity to detect cancers at an earlier stage,” Schilling says.

Equally important, PEM is easily implemented, says Schilling. “It costs half as much as a whole body MRI system, and there is no need for shielding. Mammography techs can complete the study. It is fairly easy for radiologists to learn to read the images,” explains Schilling.

PEM won’t replace standard breast imaging modalities, but it may be an important adjunctive tool whose role extends beyond pre-surgical planning to include high-risk screening, says Schilling.

Adding breast MRI

Breast imaging is a multimodality process with an assortment of imaging tools each playing a niche role in breast cancer detection, diagnosis and staging. MRI stands superior in a few areas, says Susan Gaskill, MD, director of Victory Breast Diagnostics and Women’s Imaging, a comprehensive breast imaging center in Houston, Tex. New research (“Cancer Yield of Mammography, MR, and US in High-Risk Women: Prospective Multi-Institution Breast Cancer Screening Study,”) published in August in Radiology indicates that screening high-risk women with breast MRI will allow detection of 23 more cancers per 1,000 women compared to mammography and ultrasound.

“There’s no question that MRI detects cancers missed by mammography and ultrasound,” says Lehman, who authored the study. Women with a greater than 20 percent risk of developing breast cancer should be screened annually via MRI, says Seattle Cancer Care Alliance’s Lehman. Other questions about appropriate use linger. For example, researchers have no concrete data to support or reject annual screening of women previously diagnosed with breast cancer. On the other hand, the data do show that women benefit from an MRI at diagnosis. It is an excellent tool for pre-operative staging, MRI-guided biopsy and monitoring response to chemotherapy.

“MRI can be particularly important in pre-operative staging,” explains Gaskill. “Mammography and ultrasound can underestimate the extent of disease. MRI helps radiologists and surgeons evaluate the extent of disease and establish clear margins. If surgery proceeds without clear margins, the patient may require a second surgery.”

“The ideal approach to breast imaging is a coordinated approach,” opines Gaskill. Victory Breast Diagnostics installed an Aurora 1.5T Dedicated Breast MRI System in October 2006 as part of its patient-centric approach. Unlike traditional magnets, the entire system—including the table, magnet and software—is designed for breast imaging. The comprehensive approach addresses patients’ emotional needs, too. “Our patients don’t need to go to a hospital and mix with other patients or face techs who aren’t accustomed to the emotions and anxiety surrounding breast disease,” explains Gaskill. She credits the system’s Rodeo software, which suppresses fat and ductal tissue, as the foundation for clear images with superior resolution.

The coordinated approach does take some adjustment on the part of the radiologist. A state-of-the-art mammogram should accompany the breast MRI, and patients with suspicious mammograms or clinical abnormalities may have ultrasound studies as well. Gaskill relies on three separate digital workstations set up side by side to interpret each patient’s results, a configuration that facilitates a reasonable workflow and comprehensive diagnosis.

The final positive associated with breast MRI is financial. “Victory Breast Diagnostic initially budgeted for a minimum of 10 to 12 breast MRIs per month,” shares Gaskill. The practice has exceeded the minimum; however, Gaskill admits that investing in a dedicated breast MRI system would not be fiscally sound for sites that aren’t comprehensive breast imaging centers offering a full selection of modalities.

The breast imaging evolution

Breast imaging has seen significant changes in the last decade.Digital mammography, CR mammography, tomosynthesis, PEM and breast MRI are coming together in the perfect storm, its eye centered on most effectively detecting and treating breast cancer.