title: Inverse Monte Carlo method in a multilayered tissue model for diffuse reflectance spectroscopy.
abstract: Model based data analysis of diffuse reflectance spectroscopy data enables the estimation of optical and structural tissue parameters. The aim of this study was to present an inverse Monte Carlo method based on spectra from two source-detector distances (0.4 and 1.2 mm), using a multilayered tissue model. The tissue model variables include geometrical properties, light scattering properties, tissue chromophores such as melanin and hemoglobin, oxygen saturation and average vessel diameter. The method utilizes a small set of presimulated Monte Carlo data for combinations of different levels of epidermal thickness and tissue scattering. The path length distributions in the different layers are stored and the effect of the other parameters is added in the post-processing. The accuracy of the method was evaluated using Monte Carlo simulations of tissue-like models containing discrete blood vessels, evaluating blood tissue fraction and oxygenation. It was also compared to a homogeneous model. The multilayer model performed better than the homogeneous model and all tissue parameters significantly improved spectral fitting. Recorded in vivo spectra were fitted well at both distances, which we previously found was not possible with a homogeneous model. No absolute intensity calibration is needed and the algorithm is fast enough for real-time processing.
authors.affiliation: Linköping University, Department of Biomedical Engineering, University Hospital, 581 85 Linköping, Sweden. ingfr@imt.liu.se
authors.forename: Ingemar
authors.initials: I
authors.lastname: Fredriksson
authors.forename: Marcus
authors.initials: M
authors.lastname: Larsson
authors.forename: Tomas
authors.initials: T
authors.lastname: Strömberg
mesh_terms: D000328:Adult; D001808:Blood Vessels / Q000737:chemistry; D003198:Computer Simulation; D004906:Erythrocyte Count; D005336:Fiber Optic Technology / Q000295:instrumentation; D005542:Forearm / Q000502:physiology; D006454:Hemoglobins / Q000737:chemistry; D006801:Humans; D008027:Light; D008297:Male; D008543:Melanins / Q000737:chemistry; D008954:Models, Biological; D009010:Monte Carlo Method; D010100:Oxygen / Q000097:blood; D012031:Refractometry; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012867:Skin / Q000098:blood supply / Q000737:chemistry; D013057:Spectrum Analysis / Q000295:instrumentation / Q000379:methods*
chemical_list: D006454:Hemoglobins; D008543:Melanins; D010100:Oxygen