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ARLINGTON, Va., July 23, 2004 -- A
light-sensitive probe is being developed to help doctors spot breast
cancer in some of the 70,000 American women each year whose
malignancies fail to show up in needle biopsies.
The technology also holds the potential of minimizing the trauma
associated with the procedure, in which a hollow needle the width of
a pencil is used to collect small tissue samples for testing.
Doctors now rely on X-rays or ultrasound images to guide the needle
to the area in question. They may take a dozen tissue samples to be
sure they do not miss anything. Yet sometimes they do.
"If you're in the wrong spot and you don't get the cancer, then
you're basically concluding that this woman doesn't have a disease
that needs to be treated," said Nirmala Ramanujam, Ph.D., assistant
professor of biomedical engineering at the University of
Wisconsin-Madison.
Missed diagnoses occur in as many as 70,000 American women each
year, she said. Another 60,000 women have repeat biopsies because
the initial results are inconclusive.
Ramanujam, graduate students Carmalyn Lubawy and Changfang Zhu, and
radiologist Elizabeth Burnside, M.D., have developed thin,
fiber-optic probes that can be threaded through the hollow channel
of a biopsy needle to its tip. The probe, together with X-ray or
ultrasound images, could ensure that the biopsy needle accurately
reaches its target. If successful, Ramanujam's optical probes could
be used as an adjunct to standard biopsies.
The probe emits light at specific wavelengths and then collects the
reflected light and fluorescence for analysis. The researchers look
at how much light is absorbed by tissue and reemitted as
fluorescence. They also measure how much light is scattered. Various
components of tissue --- such as amino acids, proteins, enzymes and
blood --- absorb and scatter light in specific ways. Tumors interact
with light differently than normal tissue does.
Preliminary testing in 56 breast tissue samples from 37 women showed
that the optical analysis correctly identified cancer with more than
90 percent accuracy. Further testing will begin in August on 250
patients. The research group has fine-tuned the optical probe in
preparation for the new study and has won $1.2 million in support
for the ongoing research from the National Cancer Institute and the
National Institute of Biomedical Imaging and Bioengineering.
The probes can be trimmed thin enough to fit through a needle
smaller than the current 1/4-inch biopsy device. This would make the
entire procedure less invasive. Ramanujam has also simplified the
analysis by carefully reducing the number of light wavelengths
needed to make a diagnosis.
"Minimizing the number of wavelengths analyzed is advantageous
clinically because it lends speed to the process and should require
a less complex, more economical instrument," Ramanujam's group
reported in a recent issue of the journal Annals of Surgical
Oncology.
Ramanujam received a Whitaker Foundation Biomedical Engineering
Research Grant in 2001 for research in this area. |
