Last month Carl DOrsi, 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, DOrsi 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
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
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
Part of what we are working on here is a reduction in the
number of recalls we have, DOrsi said. We
often see something on radiographic film that we cant 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.
DOrsi 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, DOrsi 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.