Optical coherence tomography (OCT) is a novel, non-invasive technology which can provide high and ultrahigh resolution structural and functional endoscopic/bronchoscopic imaging information in biological tissues, in-vivo, in real time, at resolutions as fine as 1um. Movable components such as MEMS micro motors, mirrors and lenses, etc., needed to provide scanning for image generation in 2 or 3 dimensions have limited the utility of OCT endoscopy. We describe a novel approach to development of 3-D OCT probes using fiber-bundles for airway and pleural endoscopy that overcomes the requirement for internal moving parts within the probe.
Using high resolution coherent optical conduits, a fiber bundle comprised of >50,000 individual fiber cores was fabricated. Various lengths were tested, and performance was optimized with GRIN lenses at the proximal and distal ends, angled end polishing to prevent back reflections, and index matching between optical components. The coherence of the bundle preserves spatial identity from proximal to distal ends. This approach enables all moving parts to be located externally, proximal to the probe. Planar images are then scanned and constructed with our OCT system.
This novel system was used to image samples of excised rabbit trachea (Figure 1). The OCT image can delineate the micro morphology of the normal rabbit trachea including mucosa, sub mucosa, glands and cartilage rings. When compared to the OCT image from our bench top OCT system, the current fiber bundle image fidelity, including signal to noise ratio, image depth, and contrast, is good, but slightly degraded.
We describe a novel OCT endoscopic imaging probe approach based on a coherent fiber-optic bundle and demonstrate its feasibility in imaging tracheal tissue at transverse and axial resolution of approximately 12 and 10 um, respectively.
Optimization of this fiber bundle method will enable the production of compact and solid 3-D capable imaging probes without any moving parts, that may be used for high and ultra-high resolution endoscopic diagnostics including airway and pleural applications.
Sari Mahon, Grant monies (from sources other than industry) Department of Defense; Grant monies (from industry related sources) Independent peer reviewed research grant to develop lung cancer diangnositics from Philip Morris (3 year research grant).