Preclinical swine joint imaging using forward-viewing spectrally encoded endoscopy (Conference Presentation)

Utilizing spatial wavelength encoding, spectrally encoded endoscopy (SEE) makes it possible to create miniature, small diameter endoscopic probes that can allow easy access to hard-to-reach locations within the body. Previously described SEE probes have been side-viewing, which limits their use for guiding the navigation of narrow passages. Forward-viewing SEE (FVSEE) probes are advantageous as they provide a look ahead that facilitates navigation and surveillance of a wider field of view (FOV). In this work, we present a novel FVSEE probe. The 500-µm illumination optics are designed in such a way that the shortest wavelength (460 nm) propagates along the optical axis, while an angle of approximately 56° is formed between the longest wavelength (720 nm) and the optical axis. Two-dimensional illumination was accomplished by rotating the illumination optics at a speed of 15 rps using a miniature torque coil. Reflected light from the sample was collected by 8 multimode detection fibers that were arranged into a circular array around the illumination optics. The proximal ends of the detection fibers were polished at a 17° angle, resulting in a total angle of detection of approximately 100°. Light coming out from the distal end of the detection fibers, which were rearranged into a linear array, was detected using a custom spectrometer with a tall-pixel linear CCD camera. The FVSEE probe was used to conduct a preclinical imaging of a swine joint. The results were compared to a commercial chip-on-the-tip mini-endoscope and showed a better spatial resolution and a wider FOV using the FVSEE probe.