Last month Carl D’Orsi, director of oncologic imaging at the Winship Cancer Institute (WCI), helped launch one of the largest mammography studies ever conducted in the United States.

Conducted at WCI and 19 other institutions around the country and funded by the American College of Radiology Investigative Network through a project grant from National Cancer Institute, the study will compare digital and standard (analog) mammograms on 45,000 women over the course of 18 months. Each of the 20 sites will work with approximately 2,000 women using both digital and standard mammography units in order to compare images.

“The purpose of the study,” D’Orsi said, “is to determine whether digital mammography is equal to, better or worse than standard mammography. In addition, we will attempt to determine if a particular digital unit provides better results than other units.”

Currently there are four digital mammography manufacturers: General Electric, Fisher, LoRad and Fuji (WCI uses a GE machine). The Food and Drug Administration first approved digital mammography in January 2000.

Film/screen mammography, in conjunction with physical examination and breast self-examination, remains the standard method for breast-cancer screening in women.

Digital technology, however, offers several potential advantages over the standard use of radiographic film. Unlike images on radiographic film, digital images:

• can be stored and transferred electronically, which facilitates retrieval as well as remote evaluation by distant specialists.

• can be manipulated to potentially enhance cancer detection without the necessity of taking another mammogram.

• have a wide dynamic range that allows examination of all areas of the breast, despite their varying density. The limited dynamic range of film/screen systems sometimes requires additional exposures to examine very high or very low density areas of the breast.

“Part of what we are working on here is a reduction in the number of ‘recalls’ we have,” D’Orsi said. “We often see something on radiographic film that we can’t clearly define, and we have to call the patient back in to have another look. This is time consuming, causes obvious anxiety and is expensive. If digital mammography can help us reduce unnecessary recalls, then everyone benefits, and we are taking a step in the right direction with this technology.”

D’Orsi conducted a similar study on a smaller scale three years ago at the University of Massachusetts Medical Center in Worcester, where he was professor and vice chairman of radiology.

In that study, D’Orsi collaborated with investigators at the University of Colorado; both sites worked with approximately 2,000 women. Results indicated there was no significant difference between digital and standard mammograms, and that study is being used as the basis for the current study.