Sieglinde Neerken

Characterization of age-related effects in human skin: A comparative study that applies confocal laser scanning microscopy and optical coherence tomography.

Skin structure and age-related changes in human skin were characterized in vivo by applying confocal laser scanning microscopy (CLSM) and optical coherence tomography (OCT). The overall effect of aging skin, derived from studies of volunteers belonging to two age groups, was found to be a significant decrease in the maximum thickness of the epidermis and flattening of the dermo-epidermal junction. At a certain depth in the dermis, well below the basal layer, a reflecting layer of fibrous structure is observed in CLSM images. The location of this layer strongly depends on age and is situated much deeper below the skin surface in younger than in older skin. In addition, large structural changes were observed with age. The OCT images show two bright reflecting layers. The first one is due to scattering at the skin surface. The second band appears to be caused by a layer of fibrous structure in the dermis. Direct comparison of CLSM and OCT suggests that the same fibrous layer is imaged by the two techniques. This layer might be due to the transition between the papillary and reticular dermis. A comparison of CLSM and OCT enables a better understanding of the images.

In vivo imaging of human skin: a comparison of optical coherence tomography and confocal laser scanning microscopy

Optical coherence tomography (OCT) and confocal laser scanning microscopy (CLSM) were applied to characterize non-invasively and in vivo the upper layers of human skin on the back of the hand. The techniques enable a detailed determination of the thickness and location of various skin layers in the epidermis and superficial dermis. Due to differences in spatial resolution and penetration depth of these methods, OCT and CLSM give complementary information on the composition and structure of skin. OCT signals of the back of the hand show three reflecting layers at different depth in the skin. A direct comparison with CLSM enables the assignment of these layers: the first one is due to the reflection at the skin surface, the second one appears to be caused by the reflection at the basal epidermal layer and the third layer can be ascribed to reflection at fibrous structure in the upper dermis. A comparison of methods reveals a consistent interpretation of the images.

Mean cell size and collagen orientation from 2D Fourier analysis on confocal laser scanning microscopy and two-photon fluorescence microscopy on human skin in vivo

We present results from 2D Fourier analysis on 3D stacks of images obtained by confocal laser scanning reflectance microscopy (CLSM) and two-photon fluorescence microscopy (2PM) on human skin in vivo. CLSM images were obtained with a modified commercial system (Vivascope1000, Lucid Inc, excitation wavelength 830 nm) equipped with a piezo-focusing element (350 μm range) for depth positioning of the objective lens. 2PM was performed with a specially designed set-up with excitation wavelength 730 nm. Mean cell size in the epidermal layer and structural orientation in the dermal layer have been determined as a function of depth by 2D Fourier analysis. Fourier analysis on microscopic images enables automatic non-invasive quantitative structural analysis (mean cell size and orientation) of living human skin.

Confocal video imaging of human skin in vivo

We use confocal video imaging to obtain 3D images of human skin for e.g. skinlayer thickness determination. Combination with fluorescence imaging and Raman spectroscopy gives new opportunities to characterise the human skin in vivo.