New ways to identify cells in a precancerous state well before they become numerous and metastasize hold the potential to prevent many cases of cancer which now are not discovered until they reach a fatal state of development. Researchers at MIT's George R. Harrison Spectroscopy Laboratory in the School of Science have just received a $7.2 million dollar grant from the National Institutes of Health (NIH) to develop a method using optical fibers to detect precancerous lesions more accurately, cheaply, quickly, and easily.
Clinical screening for cervical and oral precancer are multibillion-dollar industries which currently rely on visual detection of suspicious areas followed by invasive biopsy and microscopic examination. Given that visually identified suspicious areas do not always correspond to clinically significant lesions, spectroscopic imaging and diagnosis could prevent unnecessary invasive biopsies and potential delays in diagnosis.
Furthermore, real-time detection and diagnosis of lesions could pave the way for combined diagnosis and treatment sessions, thus preventing unnecessary follow-up visits.
Michael S. Feld, professor of physics and director of the Spectroscopy Lab, says the laboratory has developed a portable instrument that delivers weak pulses of laser light and ordinary white light from a thin optical fiber probe onto the patient’s tissue through an endoscope. This device analyzes tissue over a region around 1 millimeter in diameter and has shown promising results in clinical studies. It accurately identified invisible precancerous changes in the colon, bladder and esophagus, as well as the cervix and oral cavity.
The second device, which has not yet been tested on patients, can image precancerous features over areas of tissue up to a few centimeters in diameter.
The researchers hope that these new methods, which can provide accurate results in a fraction of a second, may one day replace tissue biopsies in diagnosing certain types of cancers.
Feld predicted that in a couple of years, these devices will lead to a new class of endoscopes and other diagnostic instruments that will allow physicians to obtain high-resolution images. These easy-to-read images will map out normal, precancerous and cancerous tissue the way a contour map highlights elevations in reds, yellows and greens.
The optical fiber probe instrument employs a method called trimodal spectroscopy, in which three diagnostic techniques—light-scattering spectroscopy (LSS), diffuse reflectance spectroscopy (DRS) and intrinsic fluorescence spectroscopy (IFS)—are combined.
IFS provides chemical information about the tissue, LSS provides information about the cell nuclei near the tissue surface and DRS provides structural information about the underlying tissue. The information provided by the three techniques is complementary and leads to a combined diagnosis, though the imaging technique is based on LSS alone.
This brings to mind a different effort aimed at making cancer cells show up with greater contrast versus normal cells. Shuming Nie at Georgia Tech is doing work to develop quantum dot labelling techniques for cancer cells.
Cancer cells have certain characteristics or markers. After targeting and labeling these markers with color-coded quantum dots, Nie's computer-based algorithm converts the optical information into biological data. He then knows which markers are present, as well as their distribution over the surface of a cell. The patterns formed by the optical information may indicate the presence of cancer.
One can imagine how a liquid or paste containing quantum dots could be spread on a target tissue surface such as a cervix as a preparation to enhance the contrast for the spectroscopic device being developed by MIT.
|Share |||Randall Parker, 2003 September 24 12:06 PM Biotech Assay Tools|