Digital mammography offers better imaging

Every year, over 200,000 American women receive a breast cancer diagnosis, and there are approximately 40,000 deaths caused by breast cancer. Mammography is the recommended imaging test for the early detection of breast cancer in women age 40 and older. In fact, mammography typically detects breast cancer several years before it is detectable on a clinical breast examination – at a smaller size and earlier stage. For patients with certain characteristics, digital mammography has been proven to be more effective than traditional (film-screen) mammography. 

Digital mammography is considered state of the art breast imaging. A digital mammogram unit looks the same as a traditional mammography unit (film-screen), and the mammography experience involves the same breast positioning and breast compression. However, a digital mammogram unit takes an electronic image of the breast and stores it directly on a computer. Traditional mammography (film-screen) captures an image of the breast on X-ray film.

Since the digital mammogram is displayed on a computer, the radiologist can manipulate the image for better visibility. For example, if an image is too light or too dark, the contrast can easily be adjusted on the computer monitor and subtle areas can be magnified. With film-screen mammography, the image obtained on film cannot be altered. For example, if the film is underexposed, contrast information has been lost and cannot be retrieved. 

Logically, before the widespread adoption of any new medical technology, its possible advantages or disadvantages must be evaluated by medical studies. Additionally, digital mammography equipment is significantly more expensive than traditional mammography units ”“ typically 1.5 to four times more expensive. The American College of Radiology Imaging Network conducted a two-year trial that tested the sensitivity and accuracy of digital mammography as compared with traditional film-screen mammography. The results of the trial, the Digital Mammographic Imaging Screening Trial (DMIST), were published in the New England Journal of Medicine in 2005.  

The DMIST study enrolled 50,000 asymptomatic women who were eligible for screening mammograms and who had no problems or history of prior cancer. Overall, the performance of film-screen mammography and digital mammography was found to be similar. However, digital mammography was found to be significantly more sensitive in detecting breast cancer in women with dense breast tissue, in women under the age of 50, and in premenopausal and perimenopausal women. Digital mammography was 15 percent more sensitive in detecting breast cancers in these groups of women and many of the tumors detected in the trial were high-grade, or aggressive, cancers. Although the trial was not designed to measure a survival benefit, which would take many years, the goal of screening mammography has always been the detection of precisely these types of small and aggressive cancers. 

The skill, knowledge and perception of the radiologist interpreting the films are more important than the mammographic technique used. Even if women do not have access to digital mammography, they should have annual mammograms beginning at age 40; early detection saves lives. 

Catherine S. Giess is a fellowship-trained radiologist and breast health expert. She is founder of Harrison-based Mira Women”™s Imaging, which provides personalized, comprehensive breast imaging. For additional information, visit www.mirawomensimaging.com or call 468.1000.