CAD: The Emerging Standard of Care in Breast Imaging

Seven years after it tiptoed onto the mammography market, breast CAD (computer-aided detection) has emerged as a standard of care. Practices and facilities that have implemented mammography CAD report a number of pluses. For starters, CAD increases clinical confidence by providing a second read and identifying suspicious areas for further review. And today, mammography CAD has been joined by CAD for breast MRI and breast ultrasound that increase accuracy and save time in making diagnoses.

Recent findings to be published in the October issue of the American Journal of Roentgenology reinforce the case for CAD. That is, it correlates with a higher rate of breast cancer detection particularly of small, earlier stage tumors. "Our experience with CAD shows a substantial increase in the cancer detection rate, a demonstrable decrease in the size of the cancer and a corresponding decrease in a woman's age at the time of diagnosis," says Tommy E. Cupples, MD, breast imaging and interventional specialist with ImageCare, LLC in Columbia, S.C. Sites that have implemented mammography CAD report that it can differentiate a practice since referring physicians and patients have become increasingly aware of CAD.

In the MRI world, CAD provides a viable solution for reviewing the 1,200 to 2,000 images generated by breast MRI studies. CAD systems provide image review and reporting tools to streamline the process. Finally, ultrasound CAD has arrived on the market. Cedara Software Corp.'s B-CAD solution received clearance earlier this summer. The new application promises to improve the breast ultrasound process with automated classification tools and standard report formats.

Mammography CAD at a glance

Most radiology departments and breast imaging centers cite similar rationales for deploying CAD. The radiology department at Hudson Valley Hospital Center (Westchester County, N.Y.) performs 15,000 mammograms annually and turned to mammography CAD in June for fairly typical reasons. "Improved patient care is the No. 1 reason for deploying CAD. No radiologist is perfect, and CAD offers another way to provide a 'second look' interpretation. We use iCAD's SecondLook, which has a very good sensitivity for microcalcifications. It also helps us review areas that might be missed," explains Maurice Poplausky, MD, director of imaging and radiology.

Other sites are implementing CAD because it has become a standard of care. Take for example Fremont Medical Center in Fremont, Neb. The center deployed Kodak Mammography CAD system in January. Mark Johannsen, MD, radiologist, explains, "We had been looking at CAD for a few years. As a community hospital, we are usually not the first to adopt a new technology, but it seemed like the time was right. Other local hospitals are using CAD, and it is becoming a standard of care [locally]."

Hudson Valley uses Second Look in conjunction with analog mammography. The system easily integrates into mammography workflow. First, a tech digitizes the mammogram. Then, Second Look uses a computer algorithm to mark suspicious areas. After the radiologist reads the film, he or she turns to the iCAD workstation, immediately dictating the report if there are no discrepancies between the findings and the CAD image. If there is an area of discrepancy, the radiologist reviews the images a second time. Second Look incorporates a variety of tools like magnification and isolation to aid image review.

Image storage is fairly straightforward. Second Look holds images on the system, and the radiology department prints and saves hard copies in the patient files. Fremont Medical Center estimates that the hard drive on its Kodak Mammography CAD system can hold four to five years' worth of studies (25,000 to 30,000 studies). The center downloads images to DVD, aiming to store studies on an optical drive in the future.

The workflow processes are similar across other analog departments. It begins with scanned films, which are routed to a CAD display placed next to a lightbox for streamlined review. Most CAD systems can be integrated with mammography tracking and reporting software, enabling radiologists to view CAD results from existing software and eliminating the need for a separate workstation.

Poplausky admits that CAD does add a few minutes to workflow for both techs and radiologists. Techs must scan the images and add stickers to charts, while radiologists must review an additional set of images. Johannsen agrees, estimating that CAD adds about three minutes to the mammography process at Fremont Medical Center.

The benefits, however, outweigh the minor workflow impact. "We have found some calcifications [thanks to CAD] that required other imaging studies and more frequent follow-up mammograms. And there are definitely marketing benefits as women are aware of the technology," Poplausky says.

"Physician perception of CAD is positive, and primary [care] physicians are pleased that we implemented CAD. It increases their confidence in results," points out Johannsen.
Reimbursement is a non-issue, with local carriers reimbursing approximately $20 per study, says Poplausky. A final motivation for CAD comes from the malpractice end. "I don't think any mammography practice should be without CAD. It's important to have from a legal standpoint because mammography is high-risk for malpractice. Eventually, insurers will give a discount to radiologists who use CAD," sums Poplausky.

CAD in the digital realm

ImageCare, LLC in Columbia, S.C., was an early adopter of CAD, deploying R2 Technology, Inc.'s ImageChecker to aid in the detection of breast lesions on film-based mammograms in 1998. When the practice transitioned to Siemens Medical Solutions Mammomat Novation DR full field digital mammography system earlier this year, it also installed R2's ImageChecker DMax. DMax accommodates dual mammography environments, accepting both film and digital mammograms.

The premise of CAD is unchanged in the digital world; however, the process is tighter as techs no longer need to digitize mammograms before the CAD system can apply the algorithm. "The CAD algorithm is applied directly to the digital mammogram at the time of acquisition, so the biggest time savings is the elimination of the scanning step," confirms Cupples of ImageCare. Cupples estimates that the entire scanning process can take four to five minutes per mammogram. The analog CAD workflow process includes film scanning and prepping film jackets with a sticker to correlate with the digitized CAD images. ImageCare, which completes 15,000 mammograms annually, employs one FTE to scan and handle films. Although the position has not been eliminated yet because the practice operates in a dual film/digital environment, the digital mammography-CAD combination provides a hefty workflow savings and allows the practice some flexibility.

Similarly, the reading process is more streamlined with DMax. Because CAD marks are applied directly to the digital image, the radiologist no longer compares separate CAD images and film mammograms. Instead, marks are overlaid on the digital mammogram and can be switched on and off with the push of a button. What's more, the radiologist views the exact location of suspicious spots at full digital resolution. "CAD and full-field digital mammography are the future. Digital resolution is spectacular and excels at finding small microcalcifications. Integrated CAD further improves the system," explains Cupples.

Image storage is straightforward with CAD for digital mammography. With DMax, CAD-marked digital mammograms are archived directly to PACS. "The images are always there if we need them," says Cupples. On the patient safety front, the rare but possible error of pairing a CAD image with the wrong film mammogram can never happen with integrated digital mammography CAD.

The CAD-digital mammography combination could have a marketing impact, continues Cupples. He explains, "We are investigating remote reading for out-of-town facilities. The facilities would install a Siemens acquisition unit, and ImageCare would provide reading services on our office's display unit. If we can institute this arrangement, CAD would be a value-added for the remote sites."

MRI CAD drives workflow, betters accuracy

While mammography CAD focuses on aiding breast cancer diagnosis by marking suspicious lesions for further review, the premise behind MRI CAD is quite different. "MRI CAD is your post-processing best friend. It helps radiologists process and read cases with tools like MIPs, MPRs and automated measurements," explains Andrew Osiason, MD, director of abdominal imaging for Hackensack University Medical Center and New Century Imaging in Oradell, N.J.
Osiason and his colleagues turned to Confirma's CADstream breast MRI CAD system in 2003. He recalls, "Our breast MRI volume was increasing, and we were developing applications and protocols. There was a clear need for this system given the lack of breast MRI post-processing tools on our workstation."

CADstream facilitates breast MRI workflow by allowing radiologists to quickly and efficiently review breast MRI images, which can number 2,000 for a standard study. The system readily integrates into the breast MRI workflow. Images are sent from an MRI scanner to the CADstream server, which separates phases into series. Radiologists view cases on the CADstream workstation, employing a variety of tools - contrast kinetics, automatic measurement, customized hanging protocols, subtraction images - to streamline and improve reading and allow users to dynamically interrogate the exam. "The newest release lets users look at other digital images in addition to MRI studies, so radiologists can view mammograms next to MRI images," explains Osiason.

Confirma's system is web-enabled, which means New Century Imaging - a multi-site practice - purchased a single server and relies on clients across the practice. "This translates into a lower price tag because we didn't have to invest in multiple workstations," sums Osiason. Various sites are connected by high-bandwidth lines to facilitate communication and image transfer among radiologists and with referring physicians. "We communicate our findings to referring physicians in a number of ways. We can show them exactly where an abnormality is by putting everything in a PDF and emailing it to them or burning a CD with a copy of the viewer," explains Osiason. CADstream's auto-send feature automatically transmits images to the practice's PACS.

On the IT front, Osiason says CADstream is as close to plug and play as possible. Confirma provides on-site set up and training. "The system is user-intuitive, so radiologists come up to speed quickly," notes Osiason. The upshot? "CAD should be the standard of care for breast MRI. It's more efficient, increases accuracy and reduces inter-radiologist variability," concludes Osiason.

When Radiology Associates of Brooklyn in New York City decided to add breast MRI to its practice late in 2004, radiologist Martin Elsant, MD, recognized the value of CAD and recommended the practice deploy both breast MRI and CAD at the same time. The rationale was simple. The practice required a helping hand as it was starting out. His colleagues agreed, and the decision has proven to be a wise one as 3TP Imaging Sciences' CAD system has facilitated workflow and aided accuracy.

"Like many modalities, breast MRI is very sensitive, but not very specific. Radiologists can use CAD tools to find true positives and eliminate false positives. In many cases, it provides helpful data to make the decision whether or not to biopsy," explains Elsant. Indeed, the times Elsant has disagreed with the system and recommended a biopsy, 3TP proved correct. "It's earned my respect," Elsant notes.

Like CADstream, the system creates color-coded images. It produces contrast wash-out graphs, so abnormal areas immediately stand out. "This has a very positive workflow impact. It can be very time-consuming to draw all of the wash-out graphs on a complex case," explains Elsant.

3TP put the practice on the right path as it deployed breast MRI, sending a physicist to the site to analyze the data and verify that the results were consistent with specified protocols and parameters. "3TP's basic protocol is very rigid. On the downside, if a radiologist wants to modify this there isn't as much flexibility as with other systems. But the upside is you are using a system that has been tested very extensively," explains Osiason. The company also provides overreads for the new readers to increase comfort level and accuracy and ensure results.

MRI CAD does legitimately increase confidence, but it's important not to become overly dependent on the technology, says Elsant. "Radiologists still need to use morphology as a criterion for making a decision," notes Elsant. The exclusion of morphology in breast MRI CAD systems may change in the not too distant future. One works-in-progress system focuses on morphology as well as kinetics (See sidebar on page 44.)

Ultrasound enters the CAD age

Breast imaging encompasses other modalities in addition to mammography and MRI. Ultrasound became the third modality to enter the CAD age when Cedara Software Corp.'s B-CAD breast ultrasound CAD solution received 510(k) clearance from the FDA in June.

"B-CAD helps point out worrisome features," explains Cindy Rapp, sonographer with Invision and the Sally Jobe Center in Denver. "It will benefit lesion detection - especially questionable lesions - by helping radiologists decide whether or not a biopsy is required. In many cases the software points out features users may not recognize like microlobulation."

B-CAD is designed to close the gap by identifying features indicative of a malignancy. The software aids workflow with automated segmentation, characterization, classification, annotation and report generation tools. After the user selects regions of interest, B-CAD analyzes, segments and classifies shape and orientation characteristics such as angular margins and spiculation to help the radiologist determine the appropriate course of action.

"One of the primary challenges of breast ultrasound is the lack of a standard reporting system similar to MQSA for mammography. B-CAD gets everybody speaking the same language," continues Rapp. The system can incorporate ACR BI-RADS and annotations based on the Stavros criteria to facilitate a standard reporting format.

B-CAD can be integrated into DICOM-compliant workstations and ultrasound systems and is currently available for OEM sales. According to Cedara, end-users will be able to purchase the application by mid-2006.

Conclusion

Breast CAD has proven its merit. Scores of studies show that mammography CAD helps radiologists identify smaller lesions earlier in the disease process. Although the software can have a slightly negative impact on mammography workflow in the analog environment, users agree that the clinical benefits outweigh the workflow lag. What's more, payors, referring physicians and patients recognize the value of CAD. CAD studies are typically reimbursed, and both women and physicians want access to the technology. The CAD-digital mammography combination not only improves lesion detection but also streamlines workflow by eliminating the time-consuming digitization step required in the analog CAD process.

Both MRI and ultrasound CAD promise to boost diagnostic breast imaging workflow with features like automated segmentation, characterization and subtraction images. Reporting tools also improve breast imaging by providing a standardized format for findings.


 

Breast MRI CAD in the works

Alan Penn & Associates aims to introduce a new breast MRI CAD system focused on morphology and kinetics in the next year; research units of its CADimas solution were slated to arrive to facilities in August, and the company is applying for U.S. Food and Drug Administration approval.

Company President Alan Penn explains, "Three recent studies published in the New England Journal of Medicine, Journal of the American Medical Association and Lancet point to the tremendous impact breast MRI could have on high-risk screening. Current breast MRI CAD products focus on kinetics and evaluating [contrast] uptake patterns." But morphology may be equally or more important. In fact, the European radiology community believes readers should analyze morphology before kinetics. Penn & Associates is wrapping up a three-year National Institutes of Health study, using its algorithm to look at several aspects of breast MRI images - including morphology. "We're able to provide a lot of differentiation between benign and malignant lesions," claims Penn. CADimas includes a morphology algorithm and basic kinetics algorithm to support both interpretations.