If a facility has not changed the way it performs mammography in the last ﬁve years, its work probably is not state-of-the-art. Too many cancers are still being missed, especially in patients with denser breasts. Higher contrast resolution is needed. This can be achieved with either full-ﬁeld digital mammography (FFDM) or one of the new ﬁlm-screen mammography (FSM) systems that utilize double emulsion ﬁlm.
is a Women's Imaging Specialist in Chattanooga, TN and the
founder of American Mammographics, Inc.
If a facility has not changed the way it performs mammography in
the last five years, its work probably is not state-of-the-art. Too
many cancers are still being missed, especially in patients with
denser breasts. Higher contrast resolution is needed. This can be
achieved with either full-field digital mammography (FFDM) or one
of the new film-screen mammography (FSM) systems that utilize
double emulsion film.
Digital vs. Film-Screen Mammography
Is FFDM necessary in order to perform state-of-the-art
mammography? There have been four screening trials comparing FFDM
and FSM. None of these trials has shown a significant difference in
the diagnostic accuracy between the two in the population as a
whole. The latest trial was the ACRIN study (DMIST), which compared
FFDM with FSM in 42,760 women.
DMIST initially reported that FFDM showed some increased
sensitivity in heterogeneously dense or extremely dense breasts
(mainly for DCIS). However, subsequent analysis of the detected
cancers failed to show any difference in sensitivity even for
Awareness of the limitations of DMIST and the other three trials
will allow more meaningful scrutiny of their results and
conclusions. The various types of bias and limitations in
scientific investigations have been comprehensively described.
When a new test is evaluated, its efficacy is determined by
comparing its performance to that of the accepted reference test. A
single emulsion film system was the reference test with which
digital was compared in all of these trials. However, FSM
technology has subsequently been significantly improved. The new
double emulsion film-screen systems have now become the reference
test with which digital must be compared. The results of DMIST and
the other trials are not valid for comparing the performance of
FFDM with the new generation of FSM systems, which use double
emulsion film technology.
The S.O.F.T. Paddle
is one of several recently developed products that can enhance the
performance of FSM. A conventional compression paddle produces
optimum compression of only the thick posterior portion of the
breast. Several compression paddles have been developed that rotate
as compression is applied. They tilt downward over the anterior
breast, but at the same time, they rotate upward posteriorly.
Unfortunately, this causes suboptimal compression of the posterior
breast, which is where most cancers occur.
The S.O.F.T. Paddle
from American Mammographics is different (Figure 1). The
compression surface is horizontal near the chest wall, then curves
slightly to slope downward toward the nipple. It does not rotate.
Increased compression of the anterior two thirds of the breast is
achieved while maintaining excellent compression posteriorly.
Fibroglandular tissue is spread apart more effectively so that a
cancer is less likely to be obscured by superimposed structures.
There is additional reduction in breast thickness. This permits a
lower kV, which increases contrast. Exposure time is also
shortened, which eliminates motion blur. The improved image quality
with S.O.F.T. Paddle
is shown in Figure 2. S.O.F.T. Paddle
provides many potential benefits, such as increased sensitivity for
cancer detection and fewer callbacks (Table 1).
Dr. László Tabár says of the S.O.F.T. Paddle
, "the image details that are so essential in making the first and
most important decision (callback or normal) are visualized so well
and with such sharpness as I have never experienced it previously."
Improved Film-Screen Technology
Newer state-of-the-art FSM systems, such as Kodak Min-R EV,
utilize double emulsion film with smaller, more uniform cubic
silver halide grains that increase contrast and image sharpness.
This will increase detection of cancers in denser breasts. Dramatic
improvement in image quality occurs when a newer FSM system and
are used together (Figure 3).
Since cancers are most likely to be missed in dense breasts,
better penetrating, higher energy radiation should now be used
routinely for all screening mammography. kV could be increased, but
this would reduce contrast. To produce the higher energy radiation,
it is better to substitute the rhodium (Rh) filter for the
molybdenum (Mo) filter. This will result in a more penetrating beam
and will shorten the exposure.
An important study in Sweden showed that the Rh filter provided
better depiction of glandular tissue and the skin for breasts of
all size and glandular composition, while giving a lower dose.
Hendrick et al
showed that when the Rh filter is used for breasts ≥6 cm in
thickness, the exposure time is reduced by as much as 30%. The
resulting shorter exposure will reduce motion blur. It will also
permit the use of a lower kV, which will increase contrast. The Rh
filter also reduces glandular dose by ≥20% in breasts ≥6 cm in
Pros and Cons of Digital Mammography
The primary motivation for switching to FFDM is not necessarily
the superiority of detector technology but rather the intrinsic
value of the digital image format. This permits images to be
manipulated and transmitted via teleradiology. Patient throughput
also is faster, which increases technologist productivity. In an
editorial accompanying the DMIST article, Dershaw
recognized several benefits of FFDM but said that these advantages
must be weighed against the cost of FFDM systems (up to five times
as expensive as FSM systems). He also stated that "more time and
effort are often required to read digital mammograms than film
A study by Berns et al
showed that digital mammography reduced the time needed to image a
patient by 35% but increased interpretation time by 57%. Barbara
Monsees, MD, Mallinckrodt Institute of Radiology, said, "Every
single one of us at Mallinckrodt was surprised by how much longer
it takes to interpret digital images…I think time needs to be
factored into any cost-effectiveness analysis. This could become a
State-of-the-art mammography can be achieved with either digital
or film-screen mammography. Film-screen mammography has been
significantly improved by new products that were not available at
the time DMIST and the three other trials were conducted. New
generation double emulsion film-screen technology produces
increased image contrast and sharpness. Better breast compression
can be achieved with the unique S.O.F.T. Paddle
(Figure 2). Greater use of the Rh filter will generate higher
energy radiation for better penetration and reduced radiation dose.
Patients, providers, and third-party payers can be confident that
digital and state-of-the-art film-screen mammography are equally
effective for improving the detection of cancer of the breast.