Noninvasive Monitoring of Dynamical Processes in Bruised Human Skin Using Diffuse Reflectance Spectroscopy and Pulsed Photothermal Radiometry

Abstract

We have augmented a recently introduced method for noninvasive analysis of skin structure and composition and applied it to monitoring of dynamical processes in traumatic bruises. The approach combines diffuse reflectance spectroscopy in visible spectral range and pulsed photothermal radiometry. Data from both techniques are analyzed simultaneously using a numerical model of light and heat transport in a four-layer model of human skin. Compared to the earlier presented approach, the newly introduced elements include two additional chromophores (β-carotene and bilirubin), individually adjusted thickness of the papillary dermal layer, and analysis of the bruised site using baseline values assessed from intact skin in its vicinity. Analyses of traumatic bruises in three volunteers over a period of 16 days clearly indicate a gradual, yet substantial increase of the dermal blood content and reduction of its oxygenation level in the first days after injury. This is followed by the emergence of bilirubin and relaxation of all model parameters towards the values characteristic for healthy skin approximately two weeks after the injury. The assessed parameter values and time dependences are consistent with existing literature. Thus, the presented methodology offers a viable approach for objective characterization of the bruise healing process.

Integrated Optical Coherence Tomography and Deep Learning for Evaluating of the Injectable Hydrogel on Skin Wound Healing

“…Marin, Ana et al combined diffuse reflectance spectroscopy and pulsed photothermal radiometry (PPTR) in the visible spectral range to examine the dynamic process of traumatic bruising recovery, while using a numerical model of light and heat transport in a four-layer model of human skin from data for both techniques. Figure 6d and f shows both DRS spectra and PPTR signals obtained from the bruised site display large differences with respect to the nearby intact site.We can see a significant reduction in diffuse reflectance can be seen throughout the presented spectral range, mainly due to the higher blood content in the dermis [59]. These tasks show that DRS should also be able to quantitatively evaluate the wound healing during the treatment of wounding gel, including the scar condition after wound healing, whether the wound ulcers occurs.…”

“…It can be seen that in the range of 500-600 nm, the absorption rate of keloids is higher than that of normal scars and uninjured skin, and the magnitude of the reduced scattering spectrum of keloids is the lowest (Figure 6b and c) [53]. The results of this study demonstrate that the DRS system can not only quantify collagen concentration, water content, [53,59].…”

Pulsed Photothermal Radiometric Depth Profiling of Bruises by 532 nm and 1064 nm Lasers

“…However, an increase in the papillary dermis blood volume or edema—due to the increased refractive index mismatch and hydration [ 38 ]—would have increased the scattering, resulting in more backscattered photons. The observed behavior was thus a combination of two opposing effects, with each dominating at a different time in the bruise development [ 22 ].…”

“…The feasibility of the PPTR technique for the bruise evolution research has already been assessed within our group [ 22 , 29 , 30 , 31 , 46 ]; however, only the 532 nm light has been used until now. Models of bruise evolution dynamics were developed with the goal to provide bruise age estimation.…”

“…An attractive alternative is pulsed photothermal radiometry (PPTR), which has sufficient penetration depth and the ability to determine the depth distribution of chromophores [ 17 , 18 , 19 , 20 , 21 ]. In PPTR, we specifically measure transient changes in mid-infrared emissions from the sample surface after exposure to a short-light pulse; these signals are then used to noninvasively assess irradiation-induced temperature–depth profiles to reveal the depths of absorbing structures [ 22 , 23 ]. This technique enables the localization of selected chromophores within biological tissue and has been successfully applied in tissue phantoms [ 24 , 25 ], healthy skin [ 26 ], and port wine stains [ 27 , 28 ].…”