Computer-aided
detection (CAD) technology is a recent advance in the
field of breast imaging. The CAD technology basically works
like a second pair of eyes, reviewing a patient's mammogram
film after the radiologist has already made an initial interpretation.
If the computer software detects any breast abnormalities
or "regions of interest" on the mammogram film,
it marks them. The radiologist can then go back and review
the mammogram film again to determine whether the marked areas
are suspicious and require further examination (with additional
imaging tests or biopsy). With the CAD technology, the radiologist
still makes the final interpretation of the mammogram.
Based
on clinical studies of the CAD technology, researchers estimate
that for every 100,000 breast cancers currently detected with
screening mammograms, the CAD technology could result in the
detection of an additional 20,500 breast cancers.
Mammography
can help detect breast cancer at an early stage, when the
chances for successful treatment and survival are the greatest.
While mammography detects approximately 85% to 90% of breast
cancers, mammogram films can be difficult for radiologists
to read. Thus, radiologists can occasionally overlook breast
cancers that are present on mammogram films. The CAD technology
works as a "second reading" for radiologists, alerting
them to areas on films that may require more attention.
How
Does the CAD Technology Work?
In
essence, the CAD technology works like a "spell-checker."
The computer marks abnormalities on the digitized films similar
to the way a computer program might alert a writer to a misspelled
word. After reviewing the computers marking, the radiologist
can decide whether the marked area is indeed an abnormality
that needs follow-up or if the computer has alerted him or
her to a normal area, such as a blood vessel, that is no cause
for concern. The final interpretation is still made by the
radiologist.
To use
the CAD technology, mammogram films are first loaded into
a special processing unit that digitizes the mammogram images.
The CAD unit then highlights any detected breast abnormalities
on the digitized mammograms using special pattern recognition
computer software. The digitized mammogram files are then
transmitted to monitors on a motorized film viewer so the
radiologist can compare the original film to the digitized
mammogram image on the small monitor.
In the
meantime, the radiologist reviews the patients original
mammogram films and makes his or her interpretation as to
whether any breast abnormalities are present (and whether
they are cause for concern). After the radiologist finishes
analyzing the mammogram films, he or she can view the digitized
mammograms on the small monitor to determine whether the computer
marked any abnormalities on the films. Based on the results
of the CAD marker information, the radiologist may choose
to reexamine the original mammogram films and modify his or
her interpretation when appropriate.
The CAD
technology marks breast abnormalities on digitized mammography
films using a special coding system. For example, the R2 Imagechecker
marks clusters of calcifications with a small triangle and
breast masses with an asterisk. (See the mammogram image below).
CAD marks are only made on the digitized mammograms; the original
films are not altered.