title: Reduction of shading-derived artifacts in skin chromophore imaging without measurements or assumptions about the shape of the subject.
abstract: To quantitatively evaluate skin chromophores over a wide region of curved skin surface, we propose an approach that suppresses the effect of the shading-derived error in the reflectance on the estimation of chromophore concentrations, without sacrificing the accuracy of that estimation. In our method, we use multiple regression analysis, assuming the absorbance spectrum as the response variable and the extinction coefficients of melanin, oxygenated hemoglobin, and deoxygenated hemoglobin as the predictor variables. The concentrations of melanin and total hemoglobin are determined from the multiple regression coefficients using compensation formulae (CF) based on the diffuse reflectance spectra derived from a Monte Carlo simulation. To suppress the shading-derived error, we investigated three different combinations of multiple regression coefficients for the CF. In vivo measurements with the forearm skin demonstrated that the proposed approach can reduce the estimation errors that are due to shading-derived errors in the reflectance. With the best combination of multiple regression coefficients, we estimated that the ratio of the error to the chromophore concentrations is about 10%. The proposed method does not require any measurements or assumptions about the shape of the subjects; this is an advantage over other studies related to the reduction of shading-derived errors.
authors.affiliation: Kao Corporation, Beauty Research Center, 2-1-3 Bunka, Sumida-ku, Tokyo 131-8501, Japan.
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Yoshida
authors.affiliation: Tokyo University of Agriculture & Technology, Graduate School of Bio-applications & Systems Engineering, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan.
authors.forename: Izumi
authors.initials: I
authors.lastname: Nishidate
authors.affiliation: Kao Corporation, Beauty Research Center, 2-1-3 Bunka, Sumida-ku, Tokyo 131-8501, Japan.
authors.forename: Nobutoshi
authors.initials: N
authors.lastname: Ojima
authors.affiliation: Kao Corporation, Beauty Research Center, 2-1-3 Bunka, Sumida-ku, Tokyo 131-8501, Japan.
authors.forename: Kayoko
authors.initials: K
authors.lastname: Iwata
mesh_terms: D000328:Adult; D016477:Artifacts; D003952:Diagnostic Imaging / Q000379:methods*; D004867:Equipment Design; D006454:Hemoglobins / Q000737:chemistry; D006801:Humans; D008027:Light; D008543:Melanins / Q000737:chemistry; D008875:Middle Aged; D008954:Models, Biological; D009010:Monte Carlo Method; D010100:Oxygen / Q000737:chemistry; D012044:Regression Analysis; D015203:Reproducibility of Results; D012867:Skin / Q000473:pathology*; D055815:Young Adult
chemical_list: D006454:Hemoglobins; D008543:Melanins; D010100:Oxygen