Light Interferometry Detects Precancerous Cells

Angle-resolved low coherence interferometry (a/LCI) is capable of detecting precancerous cells in the lining of epithelium of various tissues, including the esophagus and colon.

Researchers at Duke University (Durham, NC, USA) used a/LCI technology to examine samples of colon tissue that were removed from 27 patients suspected have having colon cancer. The technique was used to isolate scattering from subsurface tissue layers using spectroscopy, thus obtaining structural information at sub-wavelength scales. This allows the examination of cellular structure and the measurement of quantitative changes in the size and texture of cell nuclei, measurements that are characteristic of different pathological states.

The researchers also evaluated a/LCI performance by comparing the nuclear morphology measurements with pathological assessment of co-located physical biopsies. A significant correlation was noted between increased average nuclear size, reduced nuclear density, and the presence of dysplasia at the basal layer of the epithelium, 200 μm to 300 μm beneath the tissue surface. Using a decision line determined from a receiver-operating characteristic, a/LCI was able to separate dysplastic from healthy tissues with a sensitivity of 92.9%, a specificity of 83.6%, and an overall accuracy of 85.2%. The study was published in the October 3, 2011, issue of the Journal of Biomedical Optics.

“When light is directed at these tissues, it scatters,” said lead author associate professor of biomedical engineering Adam Wax, PhD, of the School of Engineering, who developed the device. “We can collect and analyze that scattered light looking for the tell-tale signs of dysplasia. Significantly, the technique is noninvasive, so no tissue is taken, and no dyes or contrast agents are needed.”

An Angle-resolved scattering measure captures light as a function of the scattering angle and then inverts it to deduce the average size of the scattering objects. Using a computational algorithm, the average scatter size is compared at various depths within a tissue sample. The technique is similar to optical coherence domain reflectometry (OCDR) and optical coherence tomography (OCT), but uses a broadband light source to achieve optical sectioning with a depth resolution based on far field diffraction patterns.

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