New spectrally encoded endoscope images in three dimensions

November 21, 2006, Boston, MA--Massachusetts General Hospital (MGH) researchers have developed a new type of miniature endoscope that produces three-dimensional, high-definition images, which may greatly expand the application of minimally invasive diagnostic and therapeutic procedures. In the October 19 issue of Nature, the team from the Wellman Center for Photomedicine at MGH describes their prototype device and a demonstration of its use in a mouse model.

Standard miniature endoscopic devices--which give physicians access to hard-to-reach internal organs and structures--utilize bundles of optical fibers to supply light to and transmit images from the areas of interest. Larger endoscopes that use image sensors to produce high-quality, two-dimensional images can be a centimeter or more in diameter. Existing miniature endoscopes using smaller fiber bundles may be more flexible but have difficulty producing high-quality images.

The new device developed at MGH-Wellman uses a technology called spectrally encoded endoscopy (SEE). Multicolored light from a single optical fiber--introduced through a probe about the size of a human hair--is broken into its component colors and projected onto tissue, with each color illuminating a different part of the tissue surface. The light reflected back is recorded, and the intensity of the various colors decoded by a spectrometer, which analyzes the wavelengths of light. Another device called an interferometer, which calculates structural information based on the interaction between two waves of light, provides the data required to create three-dimensional images.

"The most important feature of this new endoscope is the ability to obtain three-dimensional images, something we don't believe is offered by any commercially available miniature endoscope system," says Dvir Yelin, PhD, first author of the Nature paper. "While the image resolution we achieved in this demonstration is similar to existing small-diameter endoscopes, with further optimization of the optics it is possible to obtain images with 10 times the number of pixels provided by other miniature endoscopes."

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