Lessons from Pioneers - Digital Mammography

Buying smart in digital mammography means a lot more than finding the best imaging system. Be sure to factor in workflow changes for going from analog to digital, integration with PACS, an efficient scheme for the reading room that integrates prior analog films and investigate new multimodality mammography workstations, too.

As the Digital Mammographic Imaging Screening Trial (DMIST) winds down (and results are expected in the next few months), experts predict that the study will demonstrate that digital and analog yield fairly comparable clinical results. Nevertheless, interest in digital mammography systems remains fairly high, and it continues to gains converts in the breast imaging world. There are multiple reasons behind digital's appeal.

For starters, many sites report workflow, efficiency and throughput gains after transitioning to digital. Digital improves contrast resolution, which can translate into improved detection. It also offers a better assessment tool for women with dense breasts who may be at greater risk for breast cancer. And the immediate availability of results and ability to post-process the mammogram can reduce callbacks. Another plus? Digital mammography provides mammography a ticket into the PACS environment, which facilitates immediate image distribution and review across and beyond the enterprise. (Although a good hybrid reading plan is needed for smooth reviewing of prior studies.) Finally, digital will serve as the platform for upcoming, promising applications such as tomosynthesis and contrast-enhanced mammography.

"Digital mammography should be thought of as a beginning, not an end," recommends Elizabeth Rafferty, MD, associate director of breast imaging, Avon Comprehensive Breast Center at Massachusetts General Hospital in Boston.

Facilities eyeing digital mammography should consider some critical questions as they investigate the technology, including:

• What are the pros and cons of digital mammography?
   
• What are the options and challenges associated with bringing mammography into the PACS arena?
   
• How can the facility optimize the reading room for comparison of prior film mammograms to current digital mammograms?
   
• How can the site reconfigure workflow to capitalize on digital technology?

Weighing the pros and cons

The advantages of digital mammography fall into the areas of quality of care and efficiency. In many imaging centers, hospitals and women's clinics, mammograms represent the only patient images that can not be accessed on a workstation. The implementation of digital mammography brings sites closer to the anytime/anywhere distribution of mammograms.

Take for example, St. Vincent Breast Center of Indianapolis, Ind., which implemented three Fischer Imaging SenoScan full-field digital mammography systems when it moved to a new location in December 2003. Workflow and patient care across the enterprise are improved as the new digital systems allow oncologists to view and evaluate digital mammograms at their desks instead of tracking down films. Decisions can be made more quickly, which allows patients to receive treatment in a more timely manner, explains Julie Howerton, MSN, MBA, director of St. Vincent Breast Center.

Rafferty, who relies on a Hologic Selenia and a GE Healthcare Senographe to complete her site's digital workload, adds to the list. "There are no more lost films, radiologists can see images immediately, and we can send and discuss images in their original format," she says.

John Nelson, MD, medical director of Battlefield Imaging in Ringgold, Ga., says the ability to view images immediately on the Siemens Medical Solutions Mammomat Novation digital mammography system enables radiologists to screen mammograms for abnormalities that might have initiated a callback in the analog environment. Depending on the findings, the radiologist can magnify the image, apply a filtration algorithm or order additional views or an ultrasound study. As a result, Battlefield has experienced a 30 percent drop in callbacks since implementing digital.

Image quality also is improved with digital mammo. Laurent Levy, MD, radiologist with Institut de Radiologie de Paris in France, explains, "Our [GE Senographe] systems provide consistent, reproducible quality from one patient to another, from one view to another and over time. Contrast resolution is excellent as well." Nelson says the enhanced contrast resolution may translate into better detection. "Anecdotally, I've clearly identified lesions and calcifications on digital mammograms that were faintly present on the previous analog study."

Facilities that have invested in digital mammography report some tantalizing findings on the efficiency front. For example, St. Vincent has increased its patient load from 55 to 65 patients a day to 150 since installing its three digital systems. One word of caution-gains are not universal among users, and the digital learning curve can be lengthy. "Digital mammography can be almost treated as a new modality," opines Rafferty. Avon Breast Center has not increased its patient load since implementing digital. "We are more efficient on the front end, so techs can spend more time with the patient. But the rate limiting factor is the interpretation on the back end as digital reading does take our radiologists about 25 percent longer than analog reading," explains Rafferty.


Putting PACS to Work

While PACS does prompt some hefty benefits, the-last-holdout mammography has stood as film's last stronghold for a number of reasons. "We almost had to wait for PACS technology to catch up to the needs of mammography," says Rafferty. For starters, files sizes are quite large; a routine four-view screening mammogram is in the 140 to 160 megabyte (MB) range. Battlefield Imaging addressed storage needs upfront by upgrading its long-term archive and RAID when it installed its digital mammography system.

"The real bottleneck can be the network," says Nelson. The local hospital installed a 500 MB pipe to the offsite imaging center to channel mammograms back and forth. A separate node is dedicated to digital mammography to facilitate efficient traffic.

Traffic issues are not uncommon in the digital mammography world. MD Anderson in Houston reports rapid access to digital mammograms acquired on its four Fischer SenoScan systems throughout the diagnostic imaging department, which has a one gigabyte (GB) network with 100 megabyte switches. "The rest of the hospital is having some problems accessing digital mammograms," reports Medical Physicist Bill Geiser. The campus has a hodge-podge of 10 MB to 100 MB networks, which do not facilitate rapid access to digital mammograms. Consequently, the hospital prints digital mammograms when they are required outside of the diagnostic imaging department.

The need to access and view prior mammograms is a second complicating factor. Although digitizing prior images can be cumbersome and expensive, some sites believe it is the most practical solution to the complexities of comparing film-based prior mammograms to current digital studies. Battlefield Imaging digitizes previous mammograms and hangs the newly digitized studies with current exams. "This suffices for comparison about 90 percent of the time," reports Nelson. Film jackets are available in the reading room if the radiologist needs to view prior film exams; subtle calcifications are one exception to the 'digitized is sufficient' rule. St. Vincent Breast Center plans to digitize relative priors to minimize the burden of the mixed media environment in the next year.

Bulky digital mammography files can prompt some storage issues, too. Take for example South Carolina Comprehensive Breast Center in Columbia, S.C. When the center installed two Fischer SenoScan systems last summer, its PACS was literally on its last legs. "We knew we couldn't store digital mammography files on the old PACS," says Manager Phyllis Moorer. The site opted to use InSiteOne's InDex Breast Imaging Archive for long-term storage of digital mammograms. Mammograms are stored locally for 30 days and then sent to InSiteOne for long-term storage. The center uses its existing internet connection with 1.5 MB of bandwidth dedicated to InSiteOne traffic. Moorer says the pay-as-you-go model does not burden the PACS, yet supports immediate retrieval of prior images from the archive.

The current and possibly long-term reality is that the digital mammography reading room is a hybrid, mixed-media environment. It's likely some fraction of women will have film-based prior mammograms for as long as the next 30 to 50 years. Digitization of priors may facilitate digital comparison for many cases at some sites; however, others, like Avon Breast Center, bypass the digitization process. Rafferty cites cost, storage burden and questionable quality as reasons to forego digitization. And regardless of the digitization decision, a significant portion of cases require the actual film study for an accurate clinical comparison. The upshot? The digital mammography reading room must be designed to enable reading of both digital and analog studies - not an easy task.

Analog studies are only part of the equation. Mammographers often evaluate studies completed in other modalities to make a diagnosis. Until recently, most sites were forced to squeeze a dual monitor digital mammography workstation, a PACS workstation for review of ultrasound and MRI images and an alternator in the reading room. Fitting the radiologist into the box is often the final configuration consideration. "The ergonomics can be brutal," confirms Rafferty. Many sites never consider factors such as adjusting from the bright backlit alternator to the digital review station. A general room design rule of thumb is to place the workstation and alternator as close together as possible to avoid head turning contortions.

Nelson points to one ergonomic plus of digital mammography. CAD (computer assisted detection) is superimposed on the digital image, eliminating the back and forth between the viewer and CAD workstation. He predicts, "I think the simplified CAD process will lead to greater acceptance of CAD."


The word on workstations

New vendor-neutral, multi-modality digital mammography workstations may be the next great technical leap for digital mammography. "The problem in the past has been that digital mammography sites were forced to work in a two workstation environment with the FDA-approved digital mammography workstation [from their mammography system vendor] for mammography viewing and a PACS workstation for modality image viewing," explains Christopher Comstock, MD, director of breast imaging at University of California San Diego of La Jolla, Calif. Digital mammography workstations were not geared to multi-modality viewing, nor were PACS workstations optimized for mammography hanging protocols.

UCSD relies on Cedara's I-Read Mammo Workstation for single station viewing of digital mammograms and breast ultrasound and MRI studies. The multi-modality workstation option has enabled the site to implement a single workstation mammography reading room configuration, which brings ergonomic and workflow benefits as all images are available in one location.

South Carolina Comprehensive Breast Center anticipates a similar single workstation arrangement when it installs an Agfa Impax MA 3000 in conjunction with a new Agfa Impax PACS. The new multi-modality breast imaging workstation will allow the center to wean itself away from its dedicated single-vendor.


Making digital workflow work

"Digital mammography is not just implementing a new system, it also entails changing the practice," asserts Levy. "Sites need to change workflow to make the most of digital mammography," adds Rafferty.
 
Some sites reconfigured digital workflow includes tech assistants. The position may be somewhat analogous to the file room clerk; duties include hanging priors on the viewer, recording patient histories and escorting patients to the digital room. The tech takes over at this point. One commonly reported digital plus is that the tech can spend additional time with the patient. After explaining the procedure and answering questions about the study, the tech can complete the exam. Often, QC occurs while the patient is in the room, enabling efficient retakes. Studies are pushed to the radiology reading room, where radiologists typically batch read and compare to film priors and other modality studies as necessary.

Often sites devise site-specific plans for optimizing workflow. St. Vincent Breast Center maintains two film rooms, which can be used for longer procedures, thus avoiding tying up the higher-throughput digital rooms. Another workflow booster at St. Vincent is the Faxatron digital x-ray specimen device for use by offsite breast surgeons. When a surgeon completes a breast localization, the system captures and sends a digital image to the radiologist for review on the PACS workstation. This allows radiologists to immediately clear the area of concern, not wait for a film image.

Institut de Radiologie de Paris is a master of digital mammography efficiency, completing 240 mammograms daily. The center is organized to minimize patient time in the mammography room. Each digital room is paired with three adjacent rooms for mammography prep and follow-up procedures including changing, breast palpitations and exams and ultrasound studies. "Only mammograms are completed in the mammography rooms," explains Levy.

The Breast Unit at Helsingborg Lasarett of Helsingborg, Sweden is another master of digital efficiency, relying on Sectra's MicroDose system for screening cases. The hospital has automated all processes to drop screening time to a mere four to six minutes per patient. Patient histories are updated in the mammography information system at registration. Patient data are electronically routed to workstations in the mammography rooms where the tech verifies patient identification and history before completing the study.


Conclusion

Digital mammography can yield a host of benefits. Improved throughput and enhanced patient care top the list. Realizing these benefits, however, hinges on a thoughtful planning process that analyzes everything from an IT and image management standpoint to workflow and ergonomics. New storage and workstation options represent significant improvements for sites currently in the digital world as well as those considering digital mammography. As new clinical applications like tomosynthesis and contrast-enhanced mammography become available, and CAD gains more ground, digital mammography will gain greater traction and additional converts.

 

THE DIGITAL MAMMOGRAPHY IT CHECKLIST

IT can make a new digital mammography system hum, or it can throw a huge wrench in the operations. Here are some pointers to consider along the way:

• DICOM conformance - make sure vendors of digital solutions under consideration provide a DICOM conformance statement. This indicates the system's ability to communicate with other DICOM devices and enable essential DICOM functions like print and store.
   
• Go beyond basic DICOM. Ask if the mammography system has been verified with your current vendor's PACS, printers, etc. If the answer is no, specify in your sales contract that the system be verified prior to paying for it.
   
• Ensure that the system can be configured to communicate as fast as possible at your site. For example, MD Anderson made sure its digital mammography system could support its Cisco 100 MB/second, full duplex switches. This enables the most rapid transmission of images.
   
• Anticipate and even over-estimate the size impact of mammography files on the network and PACS. "You really need a dedicated network for digital mammography," confirms Bill Geiser, medical physicist with MD Anderson. Geiser uses a generous 200 MB file size estimate for network and storage calculations.

THE DIGITAL UPGRADE PLAN: CR GETTING IN THE MIX, TOO

One of the upcoming digital mammography options is Fujifilm Medical Systems FCR-M. Food and Drug Administration approval for the computed radiography (CR) option is anticipated in the first half of 2005.

Lenox Hill Hospital (New York City) aims to be one of the first FCR-M sites in the country. In fact, the hospital installed eight FCR-M systems last fall, using the systems for outpatient orthopedic imaging, critical care portables and ER exams. Lenox Hill plans to purchase the mammography upgrade for one of its units after FDA approval is secured.

"The advantage of this technology is that it is not dedicated to mammography. A smaller hospital can use the system for both general radiography and mammography and achieve economies of scales," explains Gerry Durney, MBA, administrative director of radiology.

The system's cost-effectiveness is based on the ability of a single CR reader to serve four mammography rooms. Existing x-ray equipment can be used with Fuji's CR cassettes and imaging plates, which replace analog cassettes, screens, films and wet processing. "The economics of mammography are marginal. If a site can reduce its capital outlay and operating costs while maintaining or increasing efficiency, it should do it," asserts Durney.

Another digital mammography upgrade option in the works is Planmed's Nuance Classic, an analog mammography system that can be upgraded to a full field-digital mammography system.