Several clinical trials evaluated the safety and effectiveness of the CAD technology prior to FDA approval of the R2 Imagechecker
in June 1998. In one clinical trial, 12 breast centers (including several academic medical centers) provided case data to determine
the sensitivity of the computer algorithms. In that study, mammogram films on which cancer was detected were submitted along with the
patients' past "normal" mammogram films from the previous nine to 24 months ("normal" means that no breast abnormalities were noted). After
digitizing the past "normal" mammogram films with the CAD technology, the computer-assisted system was able to detect 90% of cancers in the
cases where cancer was overlooked by the radiologist.
A growing amount of research suggests that CAD may be useful in helping radiologists detect breast cancer on mammography films. In a review of
several studies published in the April 2002 issue of the journal, Technology in Cancer Research and Treatment, Stephen A. Feig, MD, of the Mount
Sinai Hospital in New York found that CAD can help radiologists spot breast cancer on mammogram films, particularly if the cancer is associated
with calcifications (calcium deposits). Dr. Feig also concluded that the use of CAD
does not appear to increase the risk of false positives. In other words, CAD does not appear to result in women having to undergo unnecessary
additional breast cancer screening because of an incorrect reading by CAD technology.
A study presented at the 2000 Radiological Society of North America (RSNA) meeting found that using CAD technology can increase the detection of breast
cancer by approximately 20%. Among the 12,860 women in the study, 49 cancers were detected:
- 32 cancers were detected by both CAD technology and by the radiologist, who interpreted the women's regular mammogram films
- nine cancers were detected by the radiologist alone
- eight cancers were detected by the CAD technology alone (the radiologist then reviewed the mammogram films again to find the suspicious areas)
However, some research has suggested that CAD is more helpful to radiologists with less experience interpreting
mammogram films. In a 2005 study published in the European Journal of Radiology, researchers found that CAD was able to
correctly point out cancers that junior radiologists tended to miss more often than for senior radiologists, who were more
likely to correctly find breast cancer on mammography films than their junior colleagues. The researchers conclude that CAD
may be an important educational tool as radiologists gain experience with mammogram films.
When applied to the United States population, researchers have estimated that for every 100,000 cancers currently detected with
screening mammograms (in women with no obvious signs of breast cancer, such as a lump), the use of CAD technology could result in
the detection of an additional 20,500 breast cancers. Detecting breast cancer at an early stage increases the chances of successful
treatment and survival. For example, the five-year survival rate for ductal carcinoma in situ (DCIS), a type of early-stage breast
cancer that is confined to the milk ducts of the breast, is nearly 100% with proper treatment.
Benefits and Limitations of CAD Technology
Many physicians believe that CAD will become more widespread in the coming years as more
mammography facilities acquire digital mammography and CAD
technology. Right now, using the CAD technology requires facilities to devote a great deal
of time (four to five minutes per case) and effort to digitize the films (at some
facilities, an additional employee may be needed just to digitize the mammography films).
The widespread use of digital mammography would increase efficiency because the films
would already be digitized.
Some radiologists also believe that the CAD technology tends to sometimes mark a fairly
high number of "normal" areas on mammograms as abnormalities. This may lead to
the ordering of additional unnecessary and costly breast imaging and/or biopsies. Prior to
the FDA’s approval of the R2 Imagechecker, clinical trials did not see a
statistically significant increase in additional breast imaging at centers using the CAD
technology. However, additional studies will continue to evaluate the advantages and
disadvantages of the CAD technology.
In addition, the high cost of the CAD technology may hinder its widespread use. A CAD
system costs approximately $200,000, in addition to the cost of a mammography system. The
cost of CAD technology may also raise the price of mammograms for patients who receive the
exams by $10 to $15 per exam.
Several companies are developing CAD systems and software to provide radiologist with
the technology to help them interpret mammogram films:
-
Imagechecker CAD system, made by R2 Technology - FDA approved
- CAD MammoReader software, made by ICAD, Inc. - FDA approved
-
MammoReader CAD system, made by ISSI, Inc. - FDA approved
-
Mammex Tr made by Scanis, Inc.
Mammography Digital Film Viewer
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By masking background light, the breast image becomes sharper and easier to
interpret by using the digital film viewer on the left. Image courtesy of Smartlight, Inc. |
The FDA has also approved the Digital Film Viewer which can help
radiologists when interpreting mammography films by blocking out the surrounding light on
the films. By masking background light, the breast image becomes sharper and easier to
interpret. In a large study, 1,027 radiologists agreed that using the Digital Film Viewer
significantly improves visibility when reading mammogram films.
Using the Digital Film Viewer, the average radiologist is able to detect 30% to 60%
smaller diameter objects compared to a normal light box. This reduces the likelihood that
radiologists will overlook a small suspicious area on a mammogram film. As with CAD
technology, the Digital Film Viewer technology may help radiologists to detect breast
cancer at an early stage when the chances for successful treatment and survival are
higher.
Additional Resources and References
- The June 3, 2003 Imaginis report, "FDA Approves Computer-Aided Detection of Breast Cancer on Mammograms," is available at http://www.imaginis.com/breasthealth/news/news6.03.03.asp
- R2 Technology, Inc. the maker of the R2 Imagechecker for computer-aided detection of
mammography provides information on CAD at http://www.r2tech.com/
- The November 30, 2000 Imaginis report, "Computer-Aided Detection Technology May
Help Improve Accuracy of Mammograms," is available at http://www.imaginis.com/breasthealth/news/news11.30.00.asp
- SmartLight, Inc., the manufacturer of the Digital Film Viewer, provides information on
the product at http://www.smartlight.com/
- To learn more about mammography, please visit http://www.imaginis.com/breasthealth/mammography.asp
