How long does protection last? - In vivo fluorescence confocal laser scanning imaging for the evaluation of the kinetics of a topically applied lotion in an everyday setting

Fluorescent fibre-optic confocal characterization of in vivo epidermal changes in atopic eczema

BACKGROUND/AIMS

Fibre-optic confocal imaging (FOCI) allows non-invasive visualization of live skin in vivo. A contrast agent, a fluorophore, is injected into the dermis. FOCI images are horizontal optical sections with cellular resolution. The aim was to study in vivo epidermal changes and the cellular structure of keratinocytes in moderate to severe atopic eczema (AE).

METHODS

Eight patients with AE with active lesions on the forearms were studied and compared to a control group of six healthy individuals, and two cases of AE without activity. Fluorescein sodium was used as fluorophore. A hand-held fibre-optic laser scanner (Stratum^® ) was used. The study included morphometric analyses.

RESULTS

The confocal in vivo images identified characteristic features of epidermis and keratinocytes in active AE vs healthy skin controls. FOCI could non-invasively image acanthosis, spongiosis, and parakeratosis in AE. Epidermal oedema and micro-vesicles were visualized. Morphometry based on FOCI demonstrated 14% increased width of keratinocytes of atopic skin vs healthy controls. The epidermal structures and organization in distinctive cell layers were deviant as a result of the disease.

CONCLUSIONS

Fibre-optic confocal imaging can visualize essential epidermal structures of atopic eczema directly in vivo, in real-time, and with cellular resolution thus without disturbing the natural state of the skin. FOCI is primarily a research tool, but with a potential to become used in the clinic for non-invasive microscopic diagnosis of AE and monitoring of effect of therapies.

Potential of contrast agents to enhance in vivo confocal microscopy and optical coherence tomography in dermatology: A review

Distinction between normal skin and pathology can be a diagnostic challenge. This systematic review summarizes how various contrast agents, either topically delivered or injected into the skin, affect distinction between skin disease and normal skin when imaged by optical coherence tomography (OCT) and confocal microscopy (CM). A systematic review of in vivo OCT and CM studies using exogenous contrast agents on healthy human skin or skin disease was performed. In total, nine CM studies and one OCT study were eligible. Four contrast agents aluminum chloride (AlCl) n = 2, indocyanine green (ICG) n = 3, sodium fluorescein n = 3 and acetic acid n = 1 applied to CM in variety of skin diseases. ICG, acetic acid and AlCl showed promise to increase contrast of tumor nests in keratinocyte carcinomas. Fluorescein and ICG enhanced contrast of keratinocytes and adnexal structures. In OCT of healthy skin gold nanoshells, increased contrast of natural skin openings. Contrast agents may improve delineation and diagnosis of skin cancers; ICG, acetic acid and AlCl have potential in CM and gold nanoshells facilitate visualization of adnexal skin structures in OCT. However, as utility of bedside optical imaging increases, further studies with robust methodological quality are necessary to implement contrast agents into routine dermatological practice.

Fluorescence (Multiwave) Confocal Microscopy

In addition to reflectance confocal microscopy, multiwave confocal microscopes with different laser wavelengths in combination with exogenous fluorophores allow fluorescence mode confocal microscopy in vivo and ex vivo. Fluorescence mode confocal microscopy improves the contrast between the epithelium and the surrounding soft tissue and allows the depiction of certain structures, like epithelial tumors, nerves, and glands.