In vivo characterization of healthy human skin with a novel, non‐invasive imaging technique: line‐field confocal optical coherence tomography

Background Line‐field confocal optical coherence tomography (LC‐OCT) is a non‐invasive optical technique recently developed for skin examination in vivo. It provides real‐time, high‐resolution vertical images with an isotropic resolution of ~1 µm and a penetration depth of ~500 µm. Objectives Study goals were to qualitatively/quantitatively characterize healthy skin at different body sites using LC‐OCT. Methods The skin of young healthy volunteers was imaged with a handheld LC‐OCT imaging device. Seven body sites (back of the hand, forehead, cheek, nose, chest, forearm and back) were investigated. An independent qualitative [cutaneous structures' description; visibility of keratinocytes' nuclei and dermal–epidermal junction (DEJ)] and quantitative [stratum corneum (SC)/epidermal thicknesses; height of dermal papillae] assessment of the LC‐OCT images was performed. Results A total of 88 LC‐OCT images were collected from 29 participants (20 females; nine males; mean age 25.9 years). Keratinocytes' nuclei and DEJ were visible in the totality of images. The different layers of the epidermis and the remaining cutaneous structures/findings were visualized. Body sites‐related variability was detected for SC/epidermal thicknesses and height of dermal papillae. Inter‐observer agreement was excellent (SC thickness), good‐to‐excellent (epidermal thickness) and moderate‐to‐good (papillae). Conclusions Line‐field confocal‐OCT provides non‐invasive, real‐time imaging of the skin in vivo with deep penetration and high resolution, enabling the visualization of single cells. The histology‐like vertical view provides an easy way to recognize/measure different cutaneous structures/findings. LC‐OCT appears as a promising technique for the examination of physiological/pathological skin.