Assessing the sensitivity of human skin hyperspectral responses to increasing anemia severity levels

Abstract

Abstract. Anemia is a prevalent medical condition that seriously affects millions of people all over the world. In many regions, not only its initial detection but also its monitoring are hindered by limited access to laboratory facilities. This situation has motivated the development of a wide range of optical devices and procedures to assist physicians in these tasks. Although noticeable progress has been achieved in this area, the search for reliable, low-cost, and risk-free solutions still continues, and the strengthening of the knowledge base about this disorder and its effects is essential for the success of these initiatives. We contribute to these efforts by closely examining the sensitivity of human skin hyperspectral responses (within and outside the visible region of the light spectrum) to reduced hemoglobin concentrations associated with increasing anemia severity levels. This investigation, which involves skin specimens with distinct biophysical and morphological characteristics, is supported by controlled in silico experiments performed using a predictive light transport model and measured data reported in the biomedical literature. We also propose a noninvasive procedure to be employed in the monitoring of this condition at the point-of-care.

Tanning-Elicited Variations in the Ultraviolet Absorption Spectra of the Cutaneous Tissues: Skin Photobiology and Photomedicine Implications

“…First, the rel-atively tiny amount of these substances found in the human skin (on the order of nanograms per cm 2 [41]). Second, their molar extinction coefficients are several orders of magnitude (10 −6 [35]) smaller than those of other absorbers found in human skin, notably the melanins [29].…”

“…More specifically, we used HyLIoS to compute the directional-hemispherical reflectance and absorptance curves presented in this work. It is worth stressing that its predictive capabilities have been quantitatively and qualitatively evaluated through comparisons of its outcomes with actual measured data [25], and it has been instrumental in a number of biomedical investigations (e.g., [2], [27], [28], [29], [30]). We note that, within the HyLIoS' ray-optics algorithms, a ray interacting with the tissues of skin specimen can be associated with any wavelength (λ) within a spectral region of interest.…”

On the Sensitivity of Skin Spectral Responses to Variations in the Thickness of the Cutaneous Tissues

“…In this work, we used a first-principles model of light and skin interactions, known as HyLIoS (Hyperspectral Light Impingement on Skin) [16], to compute directionalhemispherical reflectance curves for typical specimens, henceforth referred to as lightly pigmented (LP) and darkly pigmented (DP). We note that the radiometric predictions provided by this model have been extensively evaluated through comparisons of its outcomes with actual measured data [16], and effectively employed in a wide range of biomedical investigations (e.g., [17], [18], [19], [20], [21]).…”

“…This analysis involved the computation of a sensitivity index (SI) that provides the ratio of the change in output to the change in a quantity of interest while the other input quantities are kept fixed [26]. A ratio equal to 1.0 indicates complete sensitivity (or maximum impact), while a ratio less than 0.01 indicates that the measured/modeled quantity is insensitive to changes in the selected input quantity [18], [27]. Accordingly, we computed the mean sensitivity index (MSI) for the spectral regions of interest to assess the mean ratio of change in reflectance with respect to the skin thickness variations.…”

Hyperspectral Modeling of Material Appearance: General Framework, Challenges and Prospects

“…Once it can be demonstrated that the predictions of a given model are correct, its scope of applications can be extended beyond the rendering of believable images [46]. For example, predictive models of light interaction with organic layered materials, such as human skin, can be used not only in computer graphics applications involving the generation of realistic images of virtual characters (e.g., [8]), but also in pattern recognition, computer vision and Hyperspectral Modeling of Material Appearance: General Framework, Challenges and Prospects image processing investigations aimed at the screening of medical conditions (e.g., [4,6,27]), the reconstruction of facial features (e.g., [50,92,109]) and the remote detection of human signatures during search and rescue operations (e.g., [3,40,89]), just to name a few.…”