Point-probe spectroscopy: A real-time technique to identify gastrointestinal dysplasia

Screening and surveillance can prevent gastrointestinal cancer by detecting precursor lesions of cancer, but in many cases dysplasia is invisible to the eye of the endoscopist. Therefore, surveillance in these situations requires extensive random biopsies and histologic examination of the excised tissue for dysplasia. This biopsy strategy may overlook areas of dysplasia and is limited by sampling errors. Spectroscopic methods have the potential to overcome these limitations by rapidly and safely evaluating wide regions of tissue for dysplasia without required excision of the tissue. Spectroscopy can objectively quantify the color and brightness of light and uses this information to detect changes within the mucosa that are too subtle to be appreciated by the naked eye. Most spectroscopic techniques are initially developed and tested with optical fiber probes. These probes have several advantages including ease of passage through the accessory channel of standard diagnostic endoscopes and highly predictable geometry between fibers that provide the source of light and those that deliver collected light to the detector. These factors make point probes highly suitable for research and technology development; however, they are limited by the small surface area they examine at the tip of the probe.