Simultaneous dual-band line-field confocal optical coherence tomography: application to skin imaging.

Arthur Davis,Arnaud Dubois,Hicham Azimani,David Siret,Olivier Levecq

doi:10.1364/boe.10.000694

Abstract

Line-field confocal optical coherence tomography (LC-OCT) operating in two distinct spectral bands centered at 770 nm and 1250 nm is reported, using a single supercontinuum light source and two different line-scan cameras. B-scans are acquired simultaneously in the two bands at 4 frames per second. Greyscale representation and color fusion of the images are performed to either produce a single image with both high resolution (1.3 µm × 1.2 µm, lateral × axial, measured at the surface) in the superficial part of the image and deep penetration, or to highlight the spectroscopic properties of the sample. In vivo images of fair and dark skin are presented with a penetration depth of ∼700 µm.

Highlights

Optical coherence tomography (OCT) is an optical technique based on low-coherence interferometry for imaging semi-transparent samples with micrometric resolution
The focus is continuously adjusted during the scan of the sample depth, which allows the use of high numerical aperture (NA) microscope objectives to image with high lateral resolution
Line illumination and detection, combined with the use of high NA microscope objectives, produce an efficient confocal gate preventing most scattered light within the sample that does not contribute to the signal from being detected by the camera, which is beneficial for the imaging penetration depth in scattering biological tissues [10]

Summary

Introduction

Optical coherence tomography (OCT) is an optical technique based on low-coherence interferometry for imaging semi-transparent samples with micrometric resolution. Line illumination and detection, combined with the use of high NA microscope objectives, produce an efficient confocal gate preventing most scattered light within the sample that does not contribute to the signal from being detected by the camera, which is beneficial for the imaging penetration depth in scattering biological tissues [10]. The imaging penetration depth was ~400 μm, which allowed to image with a cellular-level spatial resolution in the region of the dermal-epidermal junction, where most tumors appear This imaging system is promising for skin cancer detection [7], especially melanoma that needs to be detected in its early stages of development to be efficiently treated. It can be of interest to extend the penetration depth of LC-OCT to image deeper in the dermis so as to, for example, better evaluate margins during Mohs surgery or investigate the structure of collagen fibers and study the effects of aging on the skin deeper layers

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Conclusion