Line-field confocal optical coherence tomography (LC-OCT) for ex-vivo skin imaging with extended field-of-view

Abstract

Line-field confocal optical coherence tomography (LC-OCT) is an optical technique based on a combination of reflectance confocal microscopy and optical coherence tomography to generate cellular-resolution images, in either vertical (x×z) or horizontal (x×y) sections, or in three-dimensions (3D), with a field of view of 1.2×0.5×0.4 mm³ (x×y×z). LC-OCT was originally designed for in vivo skin imaging. Here, we present a novel implementation of LC-OCT that enables ex vivo biological tissue imaging with an extended field of view. In this implementation, a specific sample holder is used so that the head of the LC-OCT device is not in contact with the sample to be imaged. The sample can thus be displaced independently of the LC-OCT head in a controlled manner using multi-axes motorized translations, while acquiring LCOCT images. A stitching algorithm is used to extend the field of view of vertical section images, horizontal section images, and also 3D images. In addition, as the device can also acquires color images of the sample surface (dermoscopic images) in parallel with the tomographic LC-OCT images, a similar mosaicking approach can be applied to the surface images. The method allows the reconstruction of a wide-field surface image of the sample, precisely collocated to the LC-OCT mosaic. This approach allows full characterization of entire skin punch biopsies of several millimeters with ~ 1 micron resolution, in 3D, and over a depth of 0.4 mm, with an associated dermoscopy-like image of the entire tissue surface.