Inverse Monte Carlo in a multilayered tissue model: merging diffuse reflectance spectroscopy and laser Doppler flowmetry

Ingemar Fredriksson; Oleg Burdakov; Marcus Larsson; Tomas Strömberg

doi:10.1117/1.JBO.18.12.127004

18 December 2013 Inverse Monte Carlo in a multilayered tissue model: merging diffuse reflectance spectroscopy and laser Doppler flowmetry

Ingemar Fredriksson, Oleg Burdakov, Marcus Larsson, Tomas Strömberg

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Journal of Biomedical Optics, Vol. 18, Issue 12, 127004 (December 2013). https://doi.org/10.1117/1.JBO.18.12.127004

Abstract

The tissue fraction of red blood cells (RBCs) and their oxygenation and speed-resolved perfusion are estimated in absolute units by combining diffuse reflectance spectroscopy (DRS) and laser Doppler flowmetry (LDF). The DRS spectra (450 to 850 nm) are assessed at two source–detector separations (0.4 and 1.2 mm), allowing for a relative calibration routine, whereas LDF spectra are assessed at 1.2 mm in the same fiber-optic probe. Data are analyzed using nonlinear optimization in an inverse Monte Carlo technique by applying an adaptive multilayered tissue model based on geometrical, scattering, and absorbing properties, as well as RBC flow-speed information. Simulations of 250 tissue-like models including up to 2000 individual blood vessels were used to evaluate the method. The absolute root mean square (RMS) deviation between estimated and true oxygenation was 4.1 percentage units, whereas the relative RMS deviations for the RBC tissue fraction and perfusion were 19% and 23%, respectively. Examples of in vivo measurements on forearm and foot during common provocations are presented. The method offers several advantages such as simultaneous quantification of RBC tissue fraction and oxygenation and perfusion from the same, predictable, sampling volume. The perfusion estimate is speed resolved, absolute (% RBC×mm/s ), and more accurate due to the combination with DRS.

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Ingemar Fredriksson, Oleg Burdakov, Marcus Larsson, and Tomas Strömberg "Inverse Monte Carlo in a multilayered tissue model: merging diffuse reflectance spectroscopy and laser Doppler flowmetry," Journal of Biomedical Optics 18(12), 127004 (18 December 2013). https://doi.org/10.1117/1.JBO.18.12.127004

Published: 18 December 2013

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