Hani A F M, Baba R, Shamsuddin N, Nugroho H
Centre for Intelligent Signal and Imaging Research, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750, Tronoh, Perak Darul Ridzuan, Malaysia.
Int J Cosmet Sci. 2014 Oct;36(5):451-8. doi: 10.1111/ics.12147. Epub 2014 Aug 4.
Melanin is a major skin colour pigment that is made up of eumelanin (the dark brown-black colour) and pheomelanin (the light red-yellow colour) pigments. Skin-whitening products typically contain depigmentation agents that reduce the level of pigmentation by changing the pheomelanin-eumelanin production. Similarly, in skin pigment treatment of skin disorders, the melanin production is managed accordingly. To assess and improve treatment efficacy, it is important to have a measurement tool that is capable of determining the melanin types objectively. So far, the efficacy assessment is subjective. In this study, an inverse skin reflectance pigmentation analysis system that determines eumelanin and pheomelanin content is developed and evaluated in an observational study involving 36 participants with skin photo type IV.
The reflectance spectra of the left forearms of participants were analysed by the pigmentation analysis system to determine their skin parameters--pheomelanin and eumelanin concentrations, melanosome volume fraction, and epidermal thickness. The determined skin parameters are then inputted into the realistic skin model (RSM) of the Advanced Systems Analyses Program (asap®) to generate the ground truth reflectance spectra for the given skin parameters to validate the system.
The developed pigmentation analysis system is found to be accurate with a spectral error of 0.0163 ± 0.009 between measured reflectance and the reflectance output of the analysis system and RSM. The regression analysis shows a strong linear relationship (R(2) = 0.994) indicating good precision. The relative concentrations of pheomelanin (38.23 ± 15.04) and eumelanin (1.68 ± 0.91) analysed by the system gives a ratio of pheomelanin to eumelanin of 0.048 ± 0.029; this value is consistent with previously reported figure of 0.049.
The proposed pigmentation analysis system is able to determine melanin types and their relative concentrations. It has the potential to assess the efficacy of the skin-whitening and pigmentation treatments objectively in a non-invasive manner.
黑色素是一种主要的皮肤色素，由真黑素（深棕黑色）和褐黑素（浅红黄色）组成。美白产品通常含有色素沉着抑制剂，通过改变褐黑素 - 真黑素的生成来降低色素沉着水平。同样，在治疗皮肤疾病的皮肤色素沉着时，也会相应地控制黑色素的生成。为了评估和提高治疗效果，拥有一种能够客观测定黑色素类型的测量工具非常重要。到目前为止，疗效评估是主观的。在本研究中，开发了一种能测定真黑素和褐黑素含量的皮肤反射色素沉着分析系统，并在一项涉及36名皮肤光类型为IV型的参与者的观察性研究中进行了评估。
用色素沉着分析系统分析参与者左前臂的反射光谱，以确定他们的皮肤参数——褐黑素和真黑素浓度、黑素小体体积分数以及表皮厚度。然后将测定的皮肤参数输入高级系统分析程序（asap®）的真实皮肤模型（RSM）中，以生成给定皮肤参数的真实反射光谱，从而验证该系统。
发现所开发的色素沉着分析系统准确无误，测量反射率与分析系统和RSM的反射率输出之间的光谱误差为0.0163±0.009。回归分析显示出很强的线性关系（R² = 0.994），表明精度良好。该系统分析的褐黑素（38.23±15.04）和真黑素（1.68±0.91）的相对浓度得出褐黑素与真黑素的比例为0.048±0.029；该值与先前报道的0.049一致。
所提出的色素沉着分析系统能够确定黑色素类型及其相对浓度。它有潜力以非侵入性方式客观评估美白和色素沉着治疗的效果。
