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T-scan (also called electrical impedance scanning or
EIS) was approved by the U.S. Food and Drug Administration (FDA) in 1999
to be used as an adjunct tool to mammography
in helping to detect breast cancer. T-scan uses the electrical impedance principal to
measure the way electrical current passes through breast tissue and helps detect cancerous
tumors. Conversely, T-scan imaging can also confirm when tumor tissue is benign (non-
cancerous).
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The 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.
T-scan impedance imaging of the breast does not use
radiation such as x-rays or radionuclides, does not require compression of
the breast, and does not require an injection or biopsy sampling of the
breast tissue via needle or surgical incision. T-scan impedance imaging is
the first completely new imaging method to receive US Food and Drug
Administration (FDA) clearance since magnetic
resonance (also
called MRI) imaging was approved in 1984.
The T-scan works by creating an image "map" of the
breast using a small electrical current. One-volt of continuous
electricity (approximately the same as holding a flashlight battery by its
ends) is transmitted into the body, either through an electrode patch
attached to the arm or a hand-held cylinder. The electric current travels
through the breast where it is then measured at skin level by a probe
placed on the breast. The T-scan probe is similar to those used for ultrasound
exams. Since cancerous tissue conducts electricity differently than healthy tissue,
cancerous tumors may show up on the resulting images as bright white spots. A real-time
image or "map" of the electrical properties of the breast is shown on the T-scan
system monitor.
X-ray mammography became clinically available in the
early 1970s and is the gold standard in screening and breast cancer
diagnosis. Mammography can detect approximately 85% of breast cancers and
is the only FDA approved screening tool to help detect cancer in women
with no signs or symptoms of the disease. However, mammography can miss up
to 15% of breast cancers. A number of adjunctive tools including
ultrasound, magnetic resonance and sestamibi nuclear medicine
imaging have been developed to assist in determining when a breast biopsy may used in
conjunction with mammography. T-scan breast imaging is a promising new development in
breast cancer diagnosis. T-scan imaging, used in conjunction with mammography, may be more
sensitive than mammography alone.
As with every new medical test, multi-center clinical trials
of the T-scan system were performed as part of the FDA approval process to evaluate the
safety and effectiveness of this new modality. The results indicate that the T-scan is a
cost-effective solution for increasing diagnostic accuracy and compliance for breast
cancer diagnosis. As an adjunct to mammography, the T-scan may provide information for use
in patient management and may help the physician determine whether or not to recommend
biopsy. Other supplemental tests to mammography—magnetic resonance and nuclear
medicine/sestamibi imaging of the breast—are both significantly more expensive and
less patient friendly than T-scan imaging. Currently, T-scan is only available at
approximately 35 facilities worldwide. As T-scan becomes more widely available, it may help
to accurately diagnose more breast cancers in women.
Updated: October 31, 2000
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