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The field of breast imaging is rapidly advancing at the beginning of the 21st
century. While mammography remains the only exam
approved by the U.S. Food and Drug Administration (FDA) to help screen for breast cancer in women with no signs or symptoms of the
disease, there are several exciting developments in diagnostic breast imaging. Many of
these technologies were showcased at the annual meeting of the Radiological Society of
North America (RSNA) held this week in Chicago.
Full-Field Digital Mammography
One of the most recent advances in the field of mammography is digital mammography. Full-field digital (computerized)
mammography is similar to standard mammography in that x-rays are used to produce detailed
images of the breast. Digital mammography uses essentially the same mammography system as
conventional mammography, but the system is equipped with a digital receptor and a
computer instead of a film cassette. Full-field digital mammography has the potential to
offer several advantages over traditional film mammography, including: faster image
acquisition, shorter exams, easier image storage, easy transmission of images to other
physicians, and computer processing of breast images for more accurate detection of breast
cancer.
The first full-field digital mammography system approved for use by FDA is the
Senographe 2000D, made by General Electric (GE) Medical Systems. GE recently obtained FDA
approval for "soft copy" reading of digital mammograms. Soft copy images are
digital images that are interpreted on a computer monitor. Such soft-copy interpretation
allows radiologists to use a high-resolution monitor and make adjustments for contrast and
light intensity to better view the images. Currently, approximately 35 Senographe 2000D
digital mammography systems are installed at locations across the United States and
internationally.
Several other manufacturers, including Siemens Medical Systems and Fischer Imaging
Corporation, also introduced their digital mammography solutions at the annual meeting of
the RSNA this November. Siemens Medical Systems will offer a mammography system equipped
with both film/screen and digital capabilities. The digital component, developed together
with Fuji Medical Systems, will allow mammography facilities to begin offering digital
mammography by adding the digital component to their existing standard mammography system,
thus eliminating some of the high cost associated with converting completely to digital
mammography. Fischer Imaging introduced its SenoScan full-field digital mammography system
at the RSNA. Both Siemens Medical and Fischer Imaging are applying for FDA approval for
their digital mammography solutions.
Other companies that are offering digital mammography solutions include Instrumentarium
Imaging Inc., Hologic Inc., and Agfa Corp. In addition, Sectra-Imtec introduced its
digital MicroDose Mammography system at the RSNA, which is still under development. The
MicroDose system reduces the mammography radiation dosage by 20%.
Click here to learn more about digital
mammography.
Computer-Aided Detection for Mammography
Computer-aided detection (CAD) is a new technology
designed to help radiologists reduce interpretative errors by identifying and marking
suspicious features on mammography films that may be associated with breast abnormalities.
After the CAD technology marks possible breast abnormalities on a digitized mammogram
film, the radiologist can review the film again, examining those suspicious regions more
closely. Radiologists then decide whether additional diagnostic testing is necessary (such
as ultrasound or biopsy). Many
radiologists predict that CAD will gain more acceptance as digital mammography becomes
widely available.
Currently, the Imagechecker, made by R2 Technology, Inc. is the only FDA approved CAD
system. Approximately 80 facilities worldwide are equipped with the R2 Imagechecker. In
addition, CADx introduced its Second Look CAD workstation at the RSNA conference this
November. The Second Look system also digitizes mammogram films and highlights suspicious
areas for the radiologist to review. Scanis also showcased its Mammex TR CAD system, which
is awaiting FDA approval.
Click here to learn more about computer-aided detection
for mammography.
T-Scan Breast Imaging
Transscan (also called T-scan, electrical impedance
scanning or EIS) received FDA approval in 1999 as a new, non-invasive breast imaging exam.
T-scan measures low level bioelectric currents to produce real-time images of the
electrical impedance properties of the breast. The resulting impedance images of the
breast tissue can be used to help determine if the region of interest is normal tissue or
a cancerous tumor. Supplementing mammography with T-scan imaging or other breast imaging
exams (such as ultrasound) may reduce the number of unnecessary breast biopsies and create
savings in healthcare costs. Currently, T-scan is available at approximately 35 facilities
worldwide.
Click here to learn more about T-scan.
Computerized Thermal Imaging
Computerized thermal imaging (CTI) is a new
breast imaging exam being developed to help detect breast cancer, when used in conjunction
with mammography and other breast imaging exams. CTI is seeking pre-market approval, and
at this time, they have received approval for three out of five modules of their
application. The fourth and fifth modules will include clinical trial results.
CIT is a non-invasive, heat sensing and processing system that uses a thermal sensitive
camera to capture a digital image based on heat radiating from the body. A
computer-assisted interpretation of the digital image helps to determine whether a local
abnormality in breast tissue temperature is present, which may indicate the presence of
disease. CTI is currently conducting clinical trials at five U.S. locations.
Click here to learn more about computerized
thermal imaging.
Computed Tomography Laser Mammography
Currently under development, computed tomography laser mammography (CTLM) is a breast
imaging system that uses advanced laser technology to produce a near three-dimensional
perspective of the breast. This detailed view may help radiologists see the extent and
involvement of breast disease that is not visible in traditional two-dimensional imaging.
According to Imaging Diagnostic Systems, Inc., the maker of CTLM, the system may be
advantageous to physicians when deciding whether to recommend a patient for further
diagnostic imaging or biopsy.
To perform CTLM, the breast is placed in a scanned chamber. Without compressing the
breast, a laser beam moves 360 degrees around the breast and acquires images in
three-millimeter intervals. After all of the images are taken, they are reconstructed into
a three-dimensional image of the breast, allowing the radiologist to view images of the
breast from any plane.
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