In vivo determination of local skin optical properties and photon path length by use of spatially resolved diffuse reflectance with applications in laser Doppler flowmetry
Marcus Larsson, Henrik Nilsson, and Tomas Strömberg
Marcus Larsson, Henrik Nilsson, and Tomas Strömberg, "In vivo determination of local skin optical properties and photon path length by use of spatially resolved diffuse reflectance with applications in laser Doppler flowmetry," Appl. Opt. 42, 124-134 (2003)
Methods for local photon path length and optical properties estimation, based on measured and simulated diffuse reflectance within 2 mm from the light source, are proposed and evaluated in vivo on Caucasian human skin. The accuracy of the methods was good (2%–7%) for path length and reduced scattering but poor for absorption estimation. Reduced scattering and absorption were systematically lower in the fingertip than in the forearm skin (633 nm). A maximum intrasite and interindividual variation of ∼35% in an average photon path length was found. The methodology was applied in laser Doppler flowmetry, where path-length normalization of the estimated perfusion removed the optical property dependency.
Frédéric Bevilacqua, Dominique Piguet, Pierre Marquet, Jeffrey D. Gross, Bruce J. Tromberg, and Christian Depeursinge Appl. Opt. 38(22) 4939-4950 (1999)
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Sets 1–4 correspond to main reference, main validation, subreference, and subvalidation sets, respectively. Set 5 corresponds to tissue phantom A, and set 6 to tissue phantom B. Within each set all possible combinations of μa, μs′, and 〈cos θ〉 were simulated, resulting in a total of 239 simulations.
For path-length-normalized and linearized perfusion (PerfNLi) and linearized perfusion (PerfLi) expressed as CV (standard deviation/mean) and range (min-max). All fibers refers to the five fiber separations ρi = 0.23, 0.46, …, 1.15 mm.
Obtained by use of the third degree MPR estimation algorithm, applied to the validation simulations of either the main reference and the subreference sets, with and without 5% (rms) noise. and refer to path-length estimates for fiber separations of 0.23 and 1.15 mm, respectively.
Calculated as the average CV (standard deviation/mean) for each site over all individuals. Measurement series with less than three acceptable estimations (data points that fell inside the convex hull of the reference simulations) were excluded.
For different skin sites (λ = 632.8 nm). The brackets 〈〉 refer to an individual average of all the measurements within each site. Terms and refer to path-length estimates for fiber separations of 0.23 and 1.15 mm, respectively.
Calculated as the mean of the individual ratios 〈fingerA〉/〈armB〉. The brackets 〈〉 refer to an individual average of all the measurements within each site.
Sets 1–4 correspond to main reference, main validation, subreference, and subvalidation sets, respectively. Set 5 corresponds to tissue phantom A, and set 6 to tissue phantom B. Within each set all possible combinations of μa, μs′, and 〈cos θ〉 were simulated, resulting in a total of 239 simulations.
For path-length-normalized and linearized perfusion (PerfNLi) and linearized perfusion (PerfLi) expressed as CV (standard deviation/mean) and range (min-max). All fibers refers to the five fiber separations ρi = 0.23, 0.46, …, 1.15 mm.
Obtained by use of the third degree MPR estimation algorithm, applied to the validation simulations of either the main reference and the subreference sets, with and without 5% (rms) noise. and refer to path-length estimates for fiber separations of 0.23 and 1.15 mm, respectively.
Calculated as the average CV (standard deviation/mean) for each site over all individuals. Measurement series with less than three acceptable estimations (data points that fell inside the convex hull of the reference simulations) were excluded.
For different skin sites (λ = 632.8 nm). The brackets 〈〉 refer to an individual average of all the measurements within each site. Terms and refer to path-length estimates for fiber separations of 0.23 and 1.15 mm, respectively.
Calculated as the mean of the individual ratios 〈fingerA〉/〈armB〉. The brackets 〈〉 refer to an individual average of all the measurements within each site.