A Confocal Endoscope for Medical Use

A new confocal endoscope from MGH (Tearney’s group) published in Biomedical Optics Express (V4 No10, 2013, doi: 10.1364/BOE.4.001925). Over 5 decades after Marcin Minsky, a Harvard scientist, invented confocal microscopy, the imaging technology has been delivered through catheters for minimally invasive interrogation. Confocal endoscope has been applied in gastrointestinal and colonoscopic imaging. A traditional confocal scanning probe can provide fluorescence images through a work channel of a colonoscope, for example, and provide clear imaging with the aid of water and air jets from the scope, such as a Pentax EC-3870CIFK colonoscope.

This work published in Biomedical Optics Express adapted a method termed spectrally encoded confocal microscopy (SECM). The SECM diffracts each wavelength into one-to-one point via a grating, and thus form a 1-D spectrally encoded image. The line image is formed stationally to increase imaging speed and imaging stability without the use of a scanning motion. The result of the image is a reflectance image instead of fluorescence image.

In this publication, it is demonstrated in the application of Barrett’s esophagus, a precursor of esophageal adenocarcinoma, which is a rare but particularly deadly form of cancer.   

A schematic of spectrally encoded confocal microscopy (SECM) probe optics and system (CL = collimation lens, and BS = beamsplitter). SECM is being developed for possible clinical applications. Courtesy of DongKyun Kang et al (2013), ‘Endoscopic probe optics for spectrally encoded confocal microscopy.’