In Vivo Quantification of Melanin Mass Density in Human by Using Third Harmonic Generation Microscopy
Date Issued
2015
Date
2015
Author(s)
Wei, Ming-Liang
Abstract
Melasma is a common skin disease of hyperpigmentation disorder of melanin. Since the quantity and distribution of melanin are the main factors of the therapeutic decision and outcome of melasma, the quantification method of melanin is very important. Harmonic generation microscopy (HGM), including second harmonic generation (SHG) microscopy and third harmonic generation (THG) microscopy, is a nonlinear optical microscopy for in vivo optical virtual biopsy of human skin. In previous studies, the THG enhancement ratio by melanin is obviously related to the melanin mass density, so in this study, we can quantify the melanin mass density in human by the analysis of THG enhancement ratio in third harmonic generation microscopy. By analyzing the images of HGM, we can get the THG signal intensity of basal cell and collagen. Then we can get the average melanin mass density (16.7mg/ml) of all HGM images from patients with melasma by calibrating with the HGM images from patients with vitiligo. Under the boundary conditions in this study, the difference between the melanin mass density of the melasma group (16.27mg/ml) and control group (17.11mg/ml) is not statistically significant, but the saturated ratio of the THG image in melasma group (6.28%) is obvious higher than the control one (2.85%). The results also show that the epidermis in the melasma group is thinner than the control one, and it may result in the darker visual appeal. It also implies that the thinner skin is one of the cause of melasma.
Subjects
melasma
melanin
quantification
harmonic generation microscopy
THG enhancement ratio
melanin mass density
SDGs
Type
thesis
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