TY - JOUR
T1 - Re-evaluation of model-based light-scattering spectroscopy for tissue spectroscopy
AU - Lau, Condon
AU - Šćepanović, Obrad
AU - Mirkovic, Jelena
AU - McGee, Sasha
AU - Yu, Chung Chieh
AU - Fulghum, Stephen
AU - Wallace, Michael
AU - Tunnell, James
AU - Bechtel, Kate
AU - Feld, Michael
N1 - Funding Information:
This research was primarily conducted at the Massachusetts Institute of Technology Laser Biomedical Research Center and is supported by National Institutes of Health grant P41-RR02594. We would like to thank Irene Georgakoudi for helpful comments.
PY - 2009
Y1 - 2009
N2 - Model-based light scattering spectroscopy (LSS) seemed a promising technique for in-vivo diagnosis of dysplasia in multiple organs. In the studies, the residual spectrum, the difference between the observed and modeled diffuse reflectance spectra, was attributed to single elastic light scattering from epithelial nuclei, and diagnostic information due to nuclear changes was extracted from it. We show that this picture is incorrect. The actual single scattering signal arising from epithelial nuclei is much smaller than the previously computed residual spectrum, and does not have the wavelength dependence characteristic of Mie scattering. Rather, the residual spectrum largely arises from assuming a uniform hemoglobin distribution. In fact, hemoglobin is packaged in blood vessels, which alters the reflectance. When we include vessel packaging, which accounts for an inhomogeneous hemoglobin distribution, in the diffuse reflectance model, the reflectance is modeled more accurately, greatly reducing the amplitude of the residual spectrum. These findings are verified via numerical estimates based on light propagation and Mie theory, tissue phantom experiments, and analysis of published data measured from Barrett's esophagus. In future studies, vessel packaging should be included in the model of diffuse reflectance and use of model-based LSS should be discontinued.
AB - Model-based light scattering spectroscopy (LSS) seemed a promising technique for in-vivo diagnosis of dysplasia in multiple organs. In the studies, the residual spectrum, the difference between the observed and modeled diffuse reflectance spectra, was attributed to single elastic light scattering from epithelial nuclei, and diagnostic information due to nuclear changes was extracted from it. We show that this picture is incorrect. The actual single scattering signal arising from epithelial nuclei is much smaller than the previously computed residual spectrum, and does not have the wavelength dependence characteristic of Mie scattering. Rather, the residual spectrum largely arises from assuming a uniform hemoglobin distribution. In fact, hemoglobin is packaged in blood vessels, which alters the reflectance. When we include vessel packaging, which accounts for an inhomogeneous hemoglobin distribution, in the diffuse reflectance model, the reflectance is modeled more accurately, greatly reducing the amplitude of the residual spectrum. These findings are verified via numerical estimates based on light propagation and Mie theory, tissue phantom experiments, and analysis of published data measured from Barrett's esophagus. In future studies, vessel packaging should be included in the model of diffuse reflectance and use of model-based LSS should be discontinued.
KW - biomedical optics
KW - cancer
KW - diffuse reflectance spectroscopy
KW - light scattering spectroscopy
KW - spectroscopy
KW - vessel packaging
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U2 - 10.1117/1.3116708
DO - 10.1117/1.3116708
M3 - Article
C2 - 19405760
AN - SCOPUS:67650320838
SN - 1083-3668
VL - 14
JO - Journal of Biomedical Optics
JF - Journal of Biomedical Optics
IS - 2
M1 - 024031
ER -