Imaging of laser-excited skin autofluorescence bleaching rates. Kristine Rozniece, Ilona Hartmane Clinical Center of Skin and ST Diseases, Riga, Latvia Janis Lesinsh, Janis Spigulis, ASI, LU, Riga, Latvia European Social Fund "Biophotonic research group" Nr.2009/0211/1DP/ /09/APIA/VIAA/077 BADV,Riga,

Autofluorescence of Skin  An optical diagnostic technique in vivo that differentiates skin lesions from healthy tissue, based on measurements of the fluorescence intensity emitted by native fluorophores present in different concentration in skin tissues.  This autofluorescence is due to the absorption of the exciting radiation by fluorophores (tryptophan, collagen, elastin, NADH, flavin, lipofuscin, melanin, hemoglobin) that results in emission of radiation at higher wavelenghts.

Autofluorescence Photobleaching  The process of decreasing the fluoroscence intensity during long-term optical excitation.  Is caused by degradation of the skin endogenous fluorophore molecules.  The florophores that emit under blue- green excitation are NAD, kreatin, as well as the dermal collagen and elastin.

Aim of Research  In this study there are presented some comparative results of using green light (532 nm), low power cw laser as excitation source for cutaneous autofluorescence investigations and evaluation of autofluorescence properties of normal skin and different skin pathalogies in vivo.

Materials and Methods  The round spot of 4 mm in diameter was selected on skin of the inner forearm of healthy volunteer, and the spot was irradiated by 532 nm cw low power laser for 1 min. (n= 30)  Patients with benign different melanocytic, vascular, hyperkeratotic and fibrotic lesions of skin (n=74)  Patients with BCC (n=2)

Junctional NMN

Compound NMN

Angioma

Seborrheic keratosis

Dermatofibroma

BCC

AF in different skin pathologies

Distribution of patients

Statistical Analysis  According the Shapiro –Wilk test min, max, and average intensity of AF was not normally distributed in all patient groups.  Due this reason we used the Mann – Withney test for further analysis of differences.

Conclusions  Taking in consideration that various shapes of autofluorescence in cases of different skin pathologies were clearly different, we have found statistically significant differences in min, max and average only between groups with junctional and compound NMN.  BCC shows the highest AF intensity in comperasion with other pathologies, but more patients should be involved to get statistically significant results in this study.

Thank you for your attention!