利用三倍頻顯微術量化肝斑病人體內黑色素質量密度

Abstract

本研究藉由分析倍頻顯微術影像中三倍頻訊號的放大率，量化肝斑病人體內的黑色素質量密度，並進一步分析黑色素質量密度與肝斑的關聯性。肝斑是一種常見的皮膚疾病，與黑色素沈澱有關。黑色素的數量和分布是決定肝斑治療和癒後的關鍵，因此黑色素量化技術十分重要。倍頻顯微術是一種可作為活體光學虛擬切片的非線性光學顯微術，包括二倍頻訊號與三倍頻訊號。過去的研究顯示，由黑色素造成的三倍頻放大率與黑色素質量密度有明顯的對應關係。因此可藉由分析肝斑病人影像中的三倍頻放大率，量化其體內的黑色素質量密度。 由倍頻顯微術影像中，取得基底細胞三倍頻與膠原蛋白三倍頻訊號強度，以白斑病人影像校正後，可得11位肝斑病人影像的平均黑色素質量密度為 16.7(mg/ml)。在本研究中的理論模型與限制條件之下，顯示肝斑部位 (16.27mg/ml)與對照組 (17.11mg/ml)的黑色素質量密度平均值無顯著差異，但是前者 (6.28%)的三倍頻影像像素飽和比例明顯較後者 (2.85%)高。我們認為像素飽和現象造成了最大值的限制，使得兩組數據皆因此低估，而無法出現顯著差異。此外分析結果亦顯示肝斑部位的表皮層厚度較薄，可能是造成肝斑視覺效果較黑的原因之一；甚至可推論表皮層較薄或變薄，也許是造成肝斑的發生因素或前置警訊。

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.