Clinical Nonlinear Laser Imaging of Human Skin: A Review

Abstract

Nonlinear optical microscopy has the potential of being used in vivo as a noninvasive imaging modality for both epidermal and dermal imaging. This paper reviews the capabilities of nonlinear microscopy as a noninvasive high-resolution tool for clinical skin inspection. In particular, we show that two-photon fluorescence microscopy can be used as a diagnostic tool for characterizing epidermal layers by means of a morphological examination. Additional functional information on the metabolic state of cells can be provided by measuring the fluorescence decay of NADH. This approach allows differentiating epidermal layers having different structural and cytological features and has the potential of diagnosing pathologies in a very early stage. Regarding therapy follow-up, we demonstrate that nonlinear microscopy could be successfully used for monitoring the effect of a treatment. In particular, combined two-photon fluorescence and second-harmonic generation microscopy were used in vivo for monitoring collagen remodeling after microablative fractional laser resurfacing and for quantitatively monitoring psoriasis on the basis of the morphology of epidermal cells and dermal papillae. We believe that the described microscopic modalities could find in the near future a stable place in a clinical dermatological setting for quantitative diagnostic purposes and as a monitoring method for various treatments.

Observation of an improved healing process in superficial skin wounds after irradiation with a blue‐LED haemostatic device

“…Fluorescence signal was collected on the same detector by removing the narrow band‐pass filter and by inserting a fluorescence filter FF01‐510/84‐25 (Semrock, Rochester, NY, US). A detailed description of the experimental setup has been provided in .…”

Two‐photon microscopy for intracutaneous imaging of stem cell activity in mice

“…Two-photon microscopy has successfully been implemented in dermatological clinical research. [20][21][22][23][24][25] Efforts to use the technology as a diagnostic tool by visualizing human skin are certainly exciting but mouse models are still invaluable for studying basic biological mechanisms of skin function and disease, especially when trying to understand processes as dynamic and complex as tissue regeneration. We have recently established a method for visualizing stem cell activity in the intact skin of living mice using two-photon microscopy.…”

Investigating and Assessing the Dermoepidermal Junction with Multiphoton Microscopy and Deep Learning

“…The usefulness of TPEF and SHG to characterize human skin has been demonstrated both ex-vivo (Paoli et al, 2009, Paoli et al, 2008 and in-vivo , Cicchi et al, 2014, Dimitrow et al, 2009, Koehler et al, 2011, Saager et al, 2015, Sun et al, 2017. Subsequently, MPM tomographs capable of providing virtual biopsies in-vivo have become available in many medical centers across the world (König, 2018).…”