Components of the confocal laser endoscope

The distal tip of this newly developed colonoscope contains the components of the confocal laser microscope, an air and water jet nozzle, two light guides, an auxiliary water-jet channel (used for topical application of the contrast agent) and a 2.8-mm working channel, allowing endomicroscopically guided biopsies (figure).

 

 

The confocal laser endoscope has a short protrusion at the distal tip, which contains the confocal microscope. Gentle contact with the mucosal surface is necessary to obtain microscopic images.  Actuation of the imaging plane depth is controlled by two additional buttons on the endoscope’s control.

 

The diameters of the distal tip and the insertion tube are 13.4 mm and 12.8 mm, respectively. During laser endoscopy, solid state ion laser delivers an excitation wavelength of 488 nm, and the maximum laser power output is < 1 mW at the surface of the tissue. The confocal image data are collected at scanning rates of 1.6 frames/s (1024 x 512 pixels) or 0.8 frames/s (1024 x 1024 pixels). The optical slice thickness is 7 µm, with a lateral resolution of 0.7 µm (field of view 475 x 475 µm). The range of the z-axis is 0-250 µm below the surface layer.

 

The confocal endoscope can be handled in the same way as a standard endoscope. The distal tip of the endoscope is placed in gentle contact with the mucosa, allowing targeted endomicroscopic imaging, and the position of the focal plane within the specimen is adjusted by using two additional buttons on the endoscope control. Images from the surface to the deeper parts of mucosal layer can be obtained, and images of interest can be stored digitally on the hard drive using a foot switch.