Year-end Sale % OFF 
Abstract
We propose a simple and affordable imaging technique to evaluate transcutaneously multiple physiological parameters by using a digital red-green-blue camera. In this method, the RGB-values were converted into tristimulus values in the CIE (Commission Internationale de l'Eclairage) XYZ color space, which is compatible with the common color spaces. Monte Carlo simulation for light transport in biological tissue was then performed to specify the relationship among the XYZ-values and the concentrations of oxygenated hemoglobin, deoxygenated hemoglobin, bilirubin, and melanin. The concentration of total hemoglobin and tissue oxygen saturation were also calculated from the estimated concentrations of oxygenated and deoxygenated hemoglobin. In vivo experiments with bile duct ligation in rats demonstrated that the estimated bilirubin concentration increased after ligation of the bile duct and reached around 22 mg/dl at 116 h after the onset of ligation, which corresponds to the ground truth value of bilirubin measured by a commercially available transcutaneous bilirubinometer. Experiments with rats while varying the fraction of inspired oxygen demonstrated that oxygenated hemoglobin and deoxygenated hemoglobin decreased and increased, respectively, as the fraction of inspired oxygen decreased. Consequently, tissue oxygen saturation dramatically decreased. We further extended the method to a non-contact imaging photo-plethysmograph and estimation of the percutaneous oxygen saturation. An empirical formula to estimate percutaneous oxygen saturation was derived from the pulse wave amplitudes of oxygenated and deoxygenated hemoglobin. The estimated percutaneous oxygen saturation dropped remarkably when a faction of inspired oxygen was below 19%, indicating the onset of hypoxemia due to hypoxia, whereas the tissue oxygen saturation decreased gradually according to the reduction of the faction of inspired oxygen. The results in this study indicate the potential of this method for imaging of multiple physiological parameters in skin tissue and evaluating an optical biomedical imaging technique that enables cost-effective, easy-to-use, portable, remotely administered, and/or point-of-care solutions.
Highlights
Quantitative evaluation of biological chromophores is useful for detecting various skin diseases including cancers, monitoring health status and tissue metabolism, and assessing clinical and physiological vascular functions
A method for measuring and imaging bilirubin concentration, oxygenated hemoglobin concentration, deoxygenated hemoglobin concentration, and melanin concentration of skin tissues using RGB camera-based diffuse reflectance spectroscopy was demonstrated in the present study
In vivo experiments with rat dorsal skin after bile duct ligation showed good correlation in transcutaneous bilirubin concentrations between the proposed method and a commercially available transcutaneous bilirubinometer, which indicates the ability of the proposed method to evaluate transcutaneous bilirubin concentration
Summary
Quantitative evaluation of biological chromophores is useful for detecting various skin diseases including cancers, monitoring health status and tissue metabolism, and assessing clinical and physiological vascular functions. When the concentration of each chromophore varies, the corresponding change may be observed on diffusely reflected light from the skin tissue in this wavelength range. Delivery of oxygen to peripheral skin tissues can be evaluated from the diffuse reflectance spectrum based on the absorption spectra of oxygenated hemoglobin and deoxygenated hemoglobin. The percentage of oxygenated hemoglobin in a volume of tissue is called tissue oxygen saturation (StO2) or hemoglobin oxygen saturation [3] It is a useful indicator for monitoring peripheral tissue oxygen consumption, hypoperfusion, cyanosis, and tissue viability. Diffuse reflectance and transmittance spectra of peripheral tissue are fluctuated by the periodic temporal variation in blood volume due to the cardiac pulse traveling through the body.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
