Toward reliable retrieval of functional information of papillary dermis using spatially resolved diffuse reflectance spectroscopy

Abstract

Spatially resolved diffuse reflectance spectroscopy (SRDRS) has been employed to quantify tissue optical properties and its interrogation volume is majorly controlled by the source-to-detector separations (SDSs). To noninvasively quantify properties of dermis, a SRDRS setup that includes SDS shorter than 1 mm is required. It will be demonstrated in this study that Monte Carlo simulations employing the Henyey-Greenstein phase function cannot always precisely predict experimentally measured diffuse reflectance at such short SDSs, and we speculated this could be caused by the non-negligible backward light scattering at short SDSs that cannot be properly modeled by the Henyey-Greenstein phase function. To accurately recover the optical properties and functional information of dermis using SRDRS, we proposed the use of the modified two-layer (MTL) geometry. Monte Carlo simulations and phantom experiment results revealed that the MTL probing geometry was capable of faithfully recovering the optical properties of upper dermis. The capability of the MTL geometry in probing the upper dermis properties was further verified through a swine study, and it was found that the measurement results were reasonably linked to histological findings. Finally, the MTL probe was utilized to study psoriatic lesions. Our results showed that the MTL probe was sensitive to the physiological condition of tissue volumes within the papillary dermis and could be used in studying the physiology of psoriasis.

Investigation of Water Bonding Status of Normal and Psoriatic Skin in Vivo Using Diffuse Reflectance Spectroscopy

“…31 The probing region of our DRS con guration contains epidermis and upper dermis of human skin, and thus our system is sensitive to the chromophore and structural variation in this skin region. 32 We found that, in the wavelength range from 500 to 900 nm, while the oxygenated and deoxygenated hemoglobin concentrations of psoriatic skin were distinct from those of normal sites, other skin functional parameters, such as melanin, collagen, and reduced scattering coe cients, did not show statistically signi cant difference between the psoriatic and normal sites. 15 However, using the skin hemoglobin concentration derived from DRS alone is di cult in achieving effective psoriasis diagnosis or monitoring.…”

Skin collagen can be accurately quantified through noninvasive optical method: Validation on a swine study

“…Nevertheless, compared to the H&E histology, the SHG intensity image from the collagen structure is clearer. To match the interrogation depth of detection by DRS system, we referred to our previous study, in which Monte Carlo simulation was used to determine the average penetration depth of photon packets with common optical properties . According to different μ a and μ s ′ combinations, the average interrogation depth is 400‐1400 μm.…”

“…To match the interrogation depth of detection by DRS system, we referred to our previous study, in which Monte Carlo simulation was used to determine the average penetration depth of photon packets with common optical properties. 23 According to different μ a and μ s ′ combinations, the average interrogation depth is 400-1400 μm. For the SHG intensity integration, we select 6×8 pieces of SHG image (Light Square in Figure 4B tively.…”

Investigation of water bonding status of normal and psoriatic skin in vivo using diffuse reflectance spectroscopy

“…The probing region of our DRS configuration contains epidermis and upper dermis of human skin, and thus our system is sensitive to the chromophore and structural variation in this skin region 32 . We found that, in the wavelength range from 500 to 900 nm, while the oxygenated and deoxygenated hemoglobin concentrations of psoriatic skin were distinct from those of normal sites, other skin functional parameters, such as melanin, collagen, and reduced scattering coefficients, did not show statistically significant difference between the psoriatic and normal sites 15 .…”