Articles by Yoshihisa Aizu in JoVE
Agarose-based Tissue Mimicking Optical Phantoms for Diffuse Reflectance Spectroscopy Afrina Mustari*1, Izumi Nishidate*1, Md. Abdul Wares1,6, Takaaki Maeda2, Satoko Kawauchi3, Shunichi Sato3, Manabu Sato4, Yoshihisa Aizu5 1Graduate School of Bio-application & Systems Engineering, Tokyo University of Agriculture & Technology, 2Department of Mechanical Engineering, Kushiro National College of Technology, 3Division of Bioinformation and Therapeutic Systems, National Defense Medical College Research Institute, 4Graduate School of Science and Engineering, Yamagata University, 5College of Design and Manufacturing Technology, Muroran Institute of Technology, 6Department of Livestock Services, Ministry of Fisheries and Livestock, Government of Bangladesh Here, we demonstrate how agarose-based tissue-mimicking optical phantoms are made and how their optical properties are determined using a conventional optical system with an integrating sphere.
Other articles by Yoshihisa Aizu on PubMed
Estimation of Melanin and Hemoglobin in Skin Tissue Using Multiple Regression Analysis Aided by Monte Carlo Simulation Journal of Biomedical Optics. Jul-Aug, 2004 | Pubmed ID: 15250756 To estimate the concentrations of melanin and blood and the oxygen saturation in human skin tissue, we propose a method using a multiple regression analysis aided by a Monte Carlo simulation for diffuse reflectance spectra from the skin tissue. By using the absorbance spectrum as a response variable and the extinction coefficients of melanin, oxygenated hemoglobin, and deoxygenated hemoglobin as predictor variables, the multiple regression analysis gives regression coefficients. The concentrations of melanin and blood are determined from the regression coefficients using conversion vectors that are estimated numerically in advance, while the oxygen saturation is obtained directly from the regression coefficients. Numerical and experimental investigations were performed for layered skin tissue models and phantoms. Measurements of human skin were also carried out to monitor variations in the melanin and blood contents and oxygenation during cuff occlusion. The results confirmed the usefulness of the proposed method.
Estimation of Wavelength Difference Using Scale Adjustment in Two-wavelength Digital Holographic Interferometry Applied Optics. Nov, 2011 | Pubmed ID: 22086028 We propose a method for an estimation of wavelength difference using scale adjustment in two-wavelength digital holographic interferometry. To estimate wavelength difference, two holograms recorded with different wavelengths are reconstructed on the basis of the Fresnel diffraction integral, and pixel sizes in the reconstruction plane, which depend on the wavelength in recording hologram, are analyzed. In the analysis, a zero-padding method and an intensity correlation function are used to adjust pixel sizes in the reconstruction plane and then obtain a wavelength difference given by a difference between the pixel sizes. Theoretical predictions and experimental results are shown to indicate the usefulness of the proposed method in this paper.
Estimation of Melanin and Hemoglobin Using Spectral Reflectance Images Reconstructed from a Digital RGB Image by the Wiener Estimation Method Sensors (Basel, Switzerland). Jun, 2013 | Pubmed ID: 23783740 A multi-spectral diffuse reflectance imaging method based on a single snap shot of Red-Green-Blue images acquired with the exposure time of 65 ms (15 fps) was investigated for estimating melanin concentration, blood concentration, and oxygen saturation in human skin tissue. The technique utilizes the Wiener estimation method to deduce spectral reflectance images instantaneously from an RGB image. Using the resultant absorbance spectrum as a response variable and the extinction coefficients of melanin, oxygenated hemoglobin and deoxygenated hemoglobin as predictor variables, multiple regression analysis provides regression coefficients. Concentrations of melanin and total blood are then determined from the regression coefficients using conversion vectors that are numerically deduced in advance by the Monte Carlo simulations for light transport in skin. Oxygen saturation is obtained directly from the regression coefficients. Experiments with a tissue-like agar gel phantom validated the method. In vivo experiments on fingers during upper limb occlusion demonstrated the ability of the method to evaluate physiological reactions of human skin.