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The intrinsic optical parameters absorption coefficient a, scattering coefficient s, anisotropy factor g, and effective scattering coefficient s′were determined for human red blood cell (RBC) suspensions of hematocrit 33.2 dependent on the oxygen saturation (SAT O2) in the wavelength range 250 to 2000 nm, including the range above 1100 nm, about which there are no data available in the literature. Integrating sphere measurements of light transmittance and reflectance in combination with inverse Monte Carlo simulation were carried out for SAT O2levels of 100 and 0. In the wavelength range up to 1200 nm, the absorption behavior is determined by the hemoglobin absorption. The spectral range above the cells’ absorption shows no dependence on SAT O2and approximates the absorption of water with values 20 to 30 below the respective values for water. Parameters sand gare significantly influenced by the SAT O2-induced absorption changes. Above 600 nm, sdecreases continuously from values of 85 mm−1to values of 30 mm−1at 2000 nm. The anisotropy factor shows a slight decrease with wavelengths above 600 nm. In the spectral regions of 1450 and 1900 nmwhere water has local absorption maxima, gshows a significant decrease down to 0.85, whereas s′increases. [ABSTRACT FROM AUTHOR]

This research study explores the combined use of more than one parameter derived from optical tomographic images to increase diagnostic accuracy which is measured in terms of sensitivity and specificity. Parameters considered include, for example, smallest or largest absorption or scattering coefficients or the ratios thereof in an image region of interest. These parameters have been used individually in a previous study to determine if a finger joint is affected or not affected by rheumatoid arthritis. To combine these parameters in the analysis we employ here a vector quantization based classification method called Self-Organizing Mapping (SOM). This method allows producing multivariate ROC-curves from which sensitivity and specificities can be determined. We found that some parameter combinations can lead to higher sensitivities whereas others to higher specificities when compared to singleparameter classifications employed in previous studies. The best diagnostic accuracy, in terms of highest Youden index, was achieved by combining three absorption parameters [maximum(μa), minimum(μa), and the ratio of minimum(μa) and maximum(μa)], which result in a sensitivity of 0.78, a specificity of 0.76, a Youden index of 0.54, and an area under the curve (AUC) of 0.72. These values are higher than for previously reported single parameter classifications with a best sensitivity and specificity of 0.71, a Youden index of 0.41, and an AUC of 0.66. [ABSTRACT FROM AUTHOR]