Technique may end need for some biopsies
By Sid Perkins
UPI Science News
WASHINGTON, June 26 (UPI) -- Researchers have developed an "optical
biopsy" that may lead to a noninvasive technique to detect the early
stages of tissue damage associated with cancer and
atherosclerosis.
Optical coherence tomography (OCT), described in the journal Science, can
obtain a resolution of 10 micrometers, which is more than 10 times better
than current imaging techniques. Dr. Mark Brezinski, a cardiologist at
Massachusetts General Hospital, says the technique is similar to
ultrasound imaging except that it uses infrared light waves rather than
acoustic waves.
As an optical beam is repeatedly scanned across the tissue to be imaged,
the echo time delay of light reflected from different layers of tissue is
measured to construct the image.
OCT initially was used to image the transparent tissue of the eye and to
diagnose a wide range of retinal diseases, but researchers have recently
used the technique to obtain images at depths of up to 2 to 3 mm in
nontransparent tissue.
Brezinski and his colleagues at Massachusetts Institute of Technology and
at Sinai Samaritan Hospital in Milwaukee, Wisc., say the technique is
particularly attractive because the imaging systems can be made using
fiber optic components commonly used in telecommunications, which will
make the OCT systems relatively inexpensive and portable. When
incorporated into catheters or endoscopes, the systems can be used to
obtain high-resolution images of the structure of internal organs.
The researchers have successfully used OCT systems with a diameter of 1
mm, which is small enough to allow imaging inside a human coronary artery
or to be used in conjuction with a standard endoscope.
The "optical biopsy" could conceivably eliminate the need for conventional
surgical biopsies currently used to evaluate possible premalignant tissues
in the gastrointestinal tract. Brezinski says the technique will also be
useful in tissues where a conventional biopsy could be hazardous or cause
irreversible damage, such as the eye, the brain or a coronary
artery.
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