Extended depth of focus tethered capsule OCT endomicroscopy for upper gastrointestinal tract imaging (Conference Presentation)

Endoscopy, the current standard of care for the diagnosis of upper gastrointestinal (GI) diseases, is not ideal as a screening tool because it is costly, necessitates a team of medically trained personnel, and typically requires that the patient be sedated. Endoscopy is also a superficial macroscopic imaging modality and therefore is unable to provide detailed information on subsurface microscopic structure that is required to render a precise tissue diagnosis. We have overcome these limitations through the development of an optical coherence tomography tethered capsule endomicroscopy (OCT-TCE) imaging device. The OCT-TCE device has a pill-like form factor with an optically clear wall to allow the contained opto-mechanical components to scan the OCT beam along the circumference of the esophagus. Once swallowed, the OCT-TCE device traverses the esophagus naturally via peristalsis and multiple cross-sectional OCT images are obtained at 30-40 μm lateral resolution by 7 μm axial resolution. While this spatial resolution enables differentiation of squamous vs columnar mucosa, crucial microstructural features such as goblet cells (~10 μm), which signify intestinal metaplasia in BE, and enlarged nuclei that are indicative of dysplasia cannot be resolved with the current OCT-TCE technology. In this work we demonstrate a novel design of a high lateral resolution OCT-TCE device with an extended depth of focus (EDOF). The EDOF is created by use of self-imaging wavefront division multiplexing that produces multiple focused modes at different depths into the sample. The overall size of the EDOF TCE is similar to that of the previous OCT-TCE device (~ 11 mm by 26 mm) but with a lateral resolution of ~ 8 μm over a depth range of ~ 2 mm. Preliminary esophageal and intestinal imaging using these EDOF optics demonstrates an improvement in the ability to resolve tissue morphology including individual glands and cells. These results suggest that the use of EDOF optics may be a promising avenue for increasing the accuracy of OCT-TCE for the diagnosis of upper GI diseases.