The use of non-invasive imaging techniques in dermatology has been reported to improve the diagnostic accuracy and the practice of biopsies, and at the same time to reduce the need for tissue excision. However, the current clinically-available imaging techniques do not yet entirely meet the need for early and accurate, non-invasive detection of all skin cancers. A handheld line-field confocal optical coherence tomography (LC-OCT) device has been designed for high-resolution non-invasive imaging of human skin, in vivo. LC-OCT delivers tomographic images in real-time (10 frames/s) with a quasi isotropic spatial resolution of ~ 1 μm, revealing a comprehensive morphological mapping of skin tissues at a cellular level, down to a depth of ~500 μm. The device has been applied to the in vivo imaging of various skin lesions. Surgical excisions of the lesions have then been performed followed by tissue processing to realize H&E-stained histopathological images. The spatial resolution, orientation, and imaging contrast mechanism of the LC-OCT images have allowed for a good level of similarity with the conventional histopathological images. LC-OCT was able to show most of the histopathological elements that allow for medical diagnosis. Using handheld LC-OCT as an adjunct tool in dermatology could help improve clinical diagnostic accuracy, allowing for the early detection of malignant skin tumors and a reduction in the number of surgical excisions of benign lesions.
Line-field confocal optical coherence tomography (LC-OCT) is an imaging method based on dynamically-focused line-field time domain OCT to generate cellular resolution images of biological tissues, either in vertical sections (cross-sectional) or in horizontal sections (en face), with field of views of 1.2 × 0.5 mm2 (horizontal) and 1.2 × 0.4 mm2 (vertical). A handheld LC-OCT probe has recently been developed to facilitate the use of this imaging technique in dermatology for non invasive detection of skin cancers. We present here a video mosaicking method to reconstruct LC-OCT images with extended fields of view from a sequence of images obtained by a free displacement by the user of the LC-OCT probe on the skin surface. The lateral field of view is extended in both vertical and horizontal section images to ~ 5 mm, while maintaining an isotropic spatial resolution of ~ 1 μm. LC-OCT imaging with video-mosaicking is demonstrated for following the edges of large skin structure, as a proof-of-principle of in vivo tumor margin delineation, and for extending the lateral field of vertical section images, in order to approach the field of view of histology in this direction.
An improved optical coherence tomography (OCT) technique called line-field confocal OCT (LC-OCT) has been developed for high-resolution skin imaging. Combining the principles of time-domain OCT and confocal microscopy with line illumination and detection, LC-OCT acquires multiple A-scans in parallel with dynamic focusing. With a quasi isotropic resolution of ∼ 1 μm, the LC-OCT images reveal a comprehensive structural mapping of skin, in vivo, at the cellular level down to a depth of ∼ 500 μm. LC-OCT images of various skin lesions, including carcinomas and melanomas, are found to well correlate with histopathological images. LC-OCT could significantly improve clinical diagnostic accuracy, while reducing the number of biopsies of benign lesions.