Optics-enabled endoscopy could lead to better colonoscopies

Massachusetts Institute of Technology (MIT; Cambridge, MA) researchers have developed a new endoscopy technology that could make it easier for doctors to detect precancerous lesions in the colon. The technology--photometric stereo endoscopy--can capture topographical images of the colon surface along with traditional two-dimensional images. Such images make it easier to see precancerous growths, including flatter lesions that traditional endoscopy usually misses, says Nicholas Durr, a research fellow in the Madrid-MIT M+Vision Consortium in Spain, a recently formed community of medical researchers in Boston, MA, and Madrid.

“In conventional colonoscopy screening, you look for these characteristic large polyps that grow into the lumen of the colon, which are relatively easy to see,” Durr says. “However, a lot of studies in the last few years have shown that more subtle, nonpolypoid lesions can also cause cancer.”

Originally developed as a computer vision technique, photometric stereo imaging can reproduce the topography of a surface by measuring the distances between multiple light sources and the surface. Those distances are used to calculate the slope of the surface relative to the light source, generating a representation of any bumps or other surface features. But the researchers had to modify the original technology for endoscopy because there is no way to know the precise distance between the tip of the endoscope and the surface of the colon. Because of this, the images generated during their first attempts contained distortions, particularly in locations where the surface height changes gradually.

MIT researchers have developed a new type of endoscopy that can produce three-dimensional images of the surface of the colon.

The researchers built two prototypes—one 35 mm in diameter, which would be too large to use for colonoscopy, and one 14 mm in diameter, the size of a typical colonoscope. In tests with an artificial silicon colon, the researchers found that both prototypes could create 3D representations of polyps and flatter lesions.

The new technology should be easily incorporated into newer endoscopes, Durr says. “A lot of existing colonoscopes already have multiple light sources,” he says. “From a hardware perspective all they need to do is alternate the lights and then update their software to process this photometric data.”

The researchers plan to test the technology in human patients in clinical trials at Massachusetts General Hospital (MGH; Boston, MA) and the Hospital Clinico San Carlos in Madrid. They are also working on additional computer algorithms that could help to automate the process of identifying polyps and lesions from the topographical information generated by the new system.

Full details of the work appear in the Journal of Biomedical Optics; for more information, please visit http://biomedicaloptics.spiedigitallibrary.org/article.aspx?articleid=1714873.

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