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Skin Imaging

By: Steve Herman
Posted: March 3, 2010, from the March 2010 issue of GCI Magazine.

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The first step to analyzing an individual’s skin is assigning a skin type. The most common standard is the Fitzpatrick Classification Scale, which categorizes skin from I to VII based on genetic disposition, reaction to sun exposure and tanning habits. This information is critical to correctly assessing the current condition of the skin and for recommending a treatment regimen. Estheticians are trained to do this by visual examination and a standard questionnaire. Alternatively, optical imaging devices can be programmed to assign a category automatically.

Instrumental analysis of the skin depends on the interaction of light with various molecular elements in the upper layers. Entering the skin, light undergoes wavelength-dependent absorption and scattering that provide the raw data for optical imaging. The two most important skin chromophores in the visible range of the spectrum are hemoglobin and melanin.

The skin also contains fluorophores (a component of a molecule that causes a molecule to be fluorescent) that can provide fluorescence contrast that adds an additional dimension to the image. Skin fluorpohores include collagen and elastin. Biological processes modulate the fluorescence signals in predictable ways. Such cases include intrinsic aging (See “A Closer Look at Intrinsic Aging” from the April 2009 issue of GCI magazine, also available online.), photoaging and conditions such as psoriasis, acne and non-melanoma skin cancer.

Skin analysis uses multiple light sources, normal white light, polarized light and a safe wavelength UV light (approximately 100mn), combined with a high resolution digital camera. A decade ago the Japanese microscope manufacture Scalar developed a high resolution camera that magnifies skin 160 times and was attached to an early version of skin analysis software. The result was Skin Xpert, which provided moisture levels, oil reading, elasticity and pore size measurements.

Many companies provide systems for medical and cosmetic applications, such as the Image Pro II from Enhanced Image Technologies and the Reveal Imager and Omnia Imaging System from Canfield Scientific2. The BTBP Clarity Pro from BrighTex Bio-Photonics3 is another widely used unit, and the company kindly provided images of the author to illustrate some of the information that can be teased from high definition digital images coupled with sophisticated software.