Dr. Destounis is a Radiologist at Elizabeth Wende Breast Care, LLC, Rochester, NY, and a Clinical Associate Professor of Radiology, University of Rochester School of Medicine and Dentistry, Strong Memorial Hospital, Rochester, NY.
According to the American College of Radiology Imaging Network (ACRIN) and the results of the Digital Mammography Imaging Screening Trial (DMIST), which was conducted between July 2001 and November 2003, overall digital and film-screen mammography are comparable methodologies. However, full-field digital mammography (FFDM) was found to be better for diagnosing cancers in certain subgroups including younger women, those with dense breast tissue, and premenopausal women. 1 With the promise of improved detection and higher viewing quality indicated by the DMIST results, breast centers and mammography sections within radiology practices rushed to convert to digital mammography.
Many mistakes occurred during these somewhat impulsive early ventures into FFDM. The conversion to FFDM should be a stepwise, well thought-out, and informed process. Unfortunately, it did not happen this way for many of the early adopters, including the author's practice (Elizabeth Wende Breast Care [EWBC], Rochester, NY). The principal goal of this article is to assist others in making a more seamless transition to FFDM.
Moving into digital mammography: Initial steps
First, taking the time to educate staff and radiologists is the most important step in any transition. Researching the products and soliciting and answering questions before a purchase helps minimize the difficulties of transitioning to digital mammography. Before committing to a vendor for any equipment, make sure you complete a request for proposal (RFP) and stand by it. This document helps ensure equipment compatibility throughout your digital network. Choosing an administrator (or administrators) and a lead digital technologist for a picture archiving and communication system (PACS) are key decisions. These people will troubleshoot problems, develop solutions, and educate the staff about any needed changes. These positions should be filled early in the transition process so these individuals can assist in researching products and participate in decision making, as they will have the greatest responsibility for incorporating this new technology into your practice and teaching other staff to use it properly.
Before selecting a system, you must understand your practice's existing electronic technology. If your practice is within a hospital, it is important to plan for any new devices to be compatible with the radiology information system (RIS), hospital information system (HIS), and PACS. If any of these hospital-based systems are being acquired in conjunction with digital mammography, you must verify seamless compatibility. While vendor sales representatives can help in this process, one should include visits to sites where this integration has occurred and perhaps also consult with independent information technology experts to verify compatibility between systems. You must understand your existing technology in order to choose the mammography system that best fits your current and future needs. 2
Unfortunately, it is not unusual for vendors to promise everything to get your business. Comments such as, That software is scheduled for release at a future date, or We know about that conflict and are working through it should be regarded with suspicion. Such pending product fixes or enhancements are often referred to as vaporware, as they may never happen. Beware the vendor who promises everything, don't jump at the lowest price, and take the time to do the hard research work in advance. In this way, one can determine what information is really required and can separate useful information from sales hype.
Early going: The nightmare begins
Initially, the transition to FFDM, starting in 2003, was a nightmare for EWBC. The scale of the equipment change-out alone was well beyond our expectations. On the most fundamental level, it was necessary to retrain radiologists in the interpretation of mammograms. Acquiring a working understanding of computer systems and graphical interfaces presents a new world to many traditional mammographers. It was difficult for the radiologists in our practice to learn how to select appropriately, but not excessively, from the variety of image optimization tools (such as magnification and window/leveling), use hanging protocols, and annotate and review the computer-aided detection (CAD) images. Initially, this learning curve slows interpretations down dramatically, and this effect should be anticipated.
Since we are a large, freestanding private practice, the transition to digital mammography could not occur all at once given the expenseinvolved. Therefore, we had 2 completely different mammographic interpretation systems in operation simultaneously. Since we began the process as a multivendor center already using 3 different film-screen systems, the transition process was even more complex. Initially, one FFDM unit and its softcopy review (SCR) workstation were obtained; later, a second FFDM unit and its workstation (from a different manufacturer) were added. Having 2 separate and different systems required learning 2 different interfaces and made comparing softcopy images challenging at best. Images from the same patient looked quite different on the 2 systems.
One of the most apparent problems with our first FFDM unit was making the fundamental adjustment required in moving from film-screen to digital image interpretation. Selecting the best window/level proved to be a challenge, since background density changes occurred with each adjustment and were very distracting (Figure 1). The images were not justified properly ie, there was a black space between the mediolateral oblique images when viewing them side to side (Figure 2). The skin line edge was jagged and irregular as opposed to the fine and very smooth line that is typically seen with mammography (Figure 3), which also proved very distracting. When the second FFDM was installed, the group had a better idea of what was needed to optimize images. We found that even changes in room temperature affected the units and how they performed. For example, if the room became too warm, the unit would shut down or give error codes that would not allow the next exposure to be taken.
Next, an in-house connectivity study between our PACS and each digital mammography system was conducted and verified well before images were interpretated on the PACS workstation. In transitioning to PACS, the film hanging protocols and hanging order had to be preset to automatically display as desired for each radiologist (Figure 4). Some examinations (ie, when a patient has had prior surgery or implant placement) require an individualized hanging scheme different from that of the standard 4-view mammogram. Unfortunately, not every patient study conforms to these preset hanging protocols. Therefore, additional staff was hired or reassigned to the task of sitting at a quality assurance (QA) workstation to make certain that any additional images were hung properly before the radiologist interpreted the study.
The current system and workflow issues
As of 2008, our practice has grown and currently uses 6 direct digital radiography mammography systems and 4 computed radiography units integrated with the PACS system with little downtime. Even today, EWBC still requires screen-film mammography. As the DMIST results have proven, the benefits of digital mammography over film-screen are limited to specific groups of women. We have had to add staffing positions and change some job descriptions to maintain workflow in this dual-imaging environment. To maximize the benefits of FFDM and efficiently use the equipment, all patients are initially triaged. Prior images, if available, are reviewed to determine a patient's breast density and size. The patient's chart is sent to the mammography unit that will best image her tissue. This triage is performed by a staff member trained to recognize the specific advantages of each unit. This individual delivers the chart to the delegated room, allowing the technologist to be more efficient and patient-oriented. Although eventually the paper chart and film file will be eliminated, it is now still required for film-screen interpretation.
Throughout the office a worklist is generated by the RIS with a drop-and-drag dashboard to view a patient's information as she movesthrough the system. The staff member performing triage sends the patient's information to the designated mammography system. In the mammography room, the technologist moves the patient's information to a completed column when the examination is finished. For FFDM, the triage staff member then picks up the patient's chart and delivers it to the QA workstation for hanging protocol review, and to ensure that CAD has been applied and that the images are prepared for the radiologist's review.
At EWBC, all studies are double-read and the PACS is set up to show both first and second interpretations. The PACS allows the study to be open simultaneously at more than 1 workstation. Each day, designated readers are assigned for the screening population. Patients who choose to stay for their results are given the names of the 2 doctors who interpreted their studies when the results are provided.
Advantages of digital mammography
The primary advantage of digital mammography is that the image acquisition is separated from the image display. This means that the image is available almost instantly for the technologist at acquisition and that the study is available on any PACS workstation as soon as it has been completed (Figure 5). Once the acquisition is completed, an electronically saved image can be manipulated by the radiologist. For example, an area can be magnified or the contrast and density can be changed to enhance the image. Digital images are more tolerant of over- and underexposure, which minimizes the need for repeat studies for incorrect technique. Since FFDM was initiated at EWBC, our recall rates have decreased, in part because of our ability to electronically manipulate images. Utilizing computer enhancements has endless possibilities, and technical progress continues. Currently, the same examination can be viewed from any PACS workstation in the office. Computer-aided detection is automatically applied through a server, eliminating the need for additional staff and equipment. Each radiologist can change hangings by dragging and dropping images as needed. Radiologists can view all modalities used for diagnosis (such as ultrasound, MRI, and the postbiopsy clip mammogram) at the SCR station after the examinations are performed (Figure 6). Difficulties performing double readings have been solved. Initially, after a single read, a particular case would disappear, or, if both readers had the same case open simultaneously at different workstations, the images would come up very slowly or not at all. The PACS administrators have been instrumental in teaching us and solving many initial difficulties.
Full-field digital mammography has improved the productivity of the technologist; having fewer steps in the examination processallows more examinations per unit time. Fewer mammography units are needed, and the difficulties of chemical processing have been eliminated. When a radiologist needs extra views from the diagnostic workstation, the technologist sees that request almost instantly. The radiologist can annotate on the screen, and the technologist can view this in the examination room. Monitors in the FFDM X-ray rooms expedite workflow. Initially, the technologists in our practice had a hard time detecting motion on the digital images and required extra training in that regard. The technologists frequently double-team to enrich their experience and comfort level. The need for a study repeat or reject is quickly viewed at acquisition.
Recently, a dictation system was integrated with our PACS. With this system, a bar code is scanned, linking the patient's information to the transcription. Dictation can occur from any workstation in the center. Depending on insurance carriers, the reimbursement for a digital mammogram is higher than its film-screen counterpart.
As a bonus, there is now a robust data set for research projects. Folders are easily created within the PACS to hold interesting cases with specific pathology or other topics of interest, and there is a vendor collection for trouble-shooting.
Disadvantages of digital mammography
Although there are many advantages in making the switch to FFDM, there are also some drawbacks. The radiologist interpretation time takes approximately twice as long or longer as compared with film-screen. While the advantages of manipulating the images are priceless, the capability slows interpretation tremendously. Initially, interpretation times are very long as radiologists learn to maneuver around the SCR station. Persistence and experience with using the technology speeds interpretation time.
The comparison of new studies with prior imaging studies has been problematic. Hanging protocols are needed to display multiple previous digital studies along with the current examination; protocols should be standardized for all radiologists interpreting mammograms. Prior studies obtained outside the practice that were performed on an FFDM unit need to be imported into the PACS from CD or DVD media by a staff member. These images must be DICOM (Digital Imaging and Communications in Medicine) compatible. The images need to be reconciled ie, the medical record number from the outside facility needs to be changed to match the medical record at the new facility. It isimportant to be certain that prior images performed on different vendors' systems all display similarly. Different processing algorithms andimage pixel/matrix size among the vendors' systems result in different looks on images, which can make comparisons to prior studies in the same patient challenging. Images must be displayed in the correct orientation without degradation. These challenges make extra demands on staff time to maintain a smooth daily workflow.
When a digital system goes down or when a portion of the PACS is not working properly, workflow is severely impacted. Staff members (often a technologist or the PACS administrator) may be tied up for a considerable time consulting with repair services. Some issues can be corrected remotely by the vendor via a virtual private network. If a problem cannot be corrected remotely, the room is down and the patients scheduled for that unit need to be redirected to the other rooms, slowing workflow. Hardware failures within the PACS are also problematic. For example, a server going down can cause all work within the facility to be affected. The EWBC's vendor has recommended clustered servers; this minimizes downtime but does not completely eliminate it. A storage area network (SAN) houses multiple/redundant disks that can serve as a hot spare or extra disk, in case one goes down. Once, all digital imaging at our practice was down for 5 days because 2 disks failed. Fortunately, this event occurred early in our practice's digital conversion, and film-screen units were still in use.
The conversion to digital mammography is very expensive, with an FFDM unit cost approaching $500,000. The FFDM unit itself is just the beginning of the costs, however. A PACS purchase or lease is necessary, as well as a laser printer or third-party printing service, and network connections need to be made. Along with all of this new equipment, FFDM service contracts and continual upgrades are also more expensive than those for film units. Increased information technology (IT) support staff is also necessary to keep everything working smoothly.
Other issues to consider
Compliance with the Health Insurance Portability and Accountability Act (HIPAA) regulations is extremely important. Patient information stays on the server. Securing the computer files to protect this information is expensive and extremely time-consuming. Our IT department holds training sessions and constantly reminds the staff to maintain awareness of possible security breaches. Internet access should be blocked from staff personal use, and e-mail warnings should be reviewed.
One of the major disadvantages of FFDM is the high cost of image archiving. Short-term, or Tier 1, storage will almost always be on-site. The files are quite data-intensive and require a large and secure storage system. Archiving needs special consideration. The practice needs to determine how much storage will be needed for Tier 1 (online and quickly accessible for current patients), Tier 2 (nearline and reasonably fast to access for recall patients), and Tier 3 (offline storage of images that won't be needed again for a long time) storage. Data in Tier 3 storage are slower to access and thus should be images of patients who probably won't be seen again until next year. The more accessible the files are, the more expensive the storage costs. In addition, a disaster recovery file that is located off-site is necessary to protect patient information as part of HIPAA regulation compliance.
Workflow advantages and disadvantages of a mixed imaging environment
Currently, EWBC is working at approximately 99% digital and 1% analog interpretations, with conversion to 100% digital fastapproaching. As peculiar as it may seem, there are advantages to this mixture as well as disadvantages. All patients at EWBC are triaged to properly choose the most appropriate modality for that individual. Breast density, prior examination modality, and patient age are allconsidered. If the patient has completely fatty replaced breast tissue, she can remain with analog imaging, allowing comparison of applesto apples. Once the patient has been transitioned to FFDM, every effort is made to continue performing her future mammograms with FFDM, making for easier annual comparisons. If there is a problem with the PACS network, analog mammography serves as a backup, which maintains workflow.
However, maintaining this mixed environment requires extra staffing. Staff is still needed for chart preparation, triage, processing of films through the digitizer for CAD, and hanging films for analog interpretation (Figure 6). In our practice, double reading is the standard of care, meaning it is necessary to leave the workstation to interpret analog studies. Since only one physician at a time can interpret analog studies, the process and patient waiting times are longer.
When a patient is imaged digitally for the first time, the most obvious disadvantage is making the comparison of apples to oranges,softcopy to hardcopy images. The ergonomics of comparing analog to digital images ie, twisting and turning from the workstation to thefilm viewer with the images positioned at different heights can literally be a pain in the neck (Figure 7). Once the patient's examination is digitized and images can be compared softcopy to softcopy, CAD can easily be applied, and more than one radiologist can read the study simultaneously, thus promoting a much more efficient workflow. Currently, patients' charts are available for historical films, if needed, but the oldest prior examinations have been digitized and are available on PACS. Digitization of prior analog films assists study comparison. Eventually, when several years of digital studies have been acquired, the analog studies will no longer need to be hung. But the chart will still be available at the time of interpretation in case an older film is needed in a particular situation.
The conversion to FFDM is a huge undertaking, whether your facility is small or large. To ensure a smooth transition, it is essential that participants are well educated and prepared for the process. The switch to FFDM technology is both exciting and intimidating. The potential for earlier diagnosis is real, yet it will take time to become proficient with the many new tools available to aid interpretation.
The author would like to thank Valerie Andolina and Renee Morgan, technologists at Elizabeth Wende Breast Care for their assistancein the preparation of this article.
- Pisano ED, Gatsonis C, Hendrick E, et al. Diagnostic performance of digital versus film mammography for breast cancer screening. N Engl J Med. 2005;353;1773-1783.
- Andolina V, Wade T. Digital Mammography: A How-To Manual for Seamless Implementation . Marblehead, MA: HCPro, Inc.; 2006.