Estimation of optical pathlength through tissue from direct time of flight measurement

Department of Medical Physics, University College London, UK.
Physics in Medicine and Biology (Impact Factor: 2.92). 01/1989; 33(12):1433-42. DOI: 10.1088/0031-9155/33/12/008
Source: PubMed

ABSTRACT Quantitation of near infrared spectroscopic data in a scattering medium such as tissue requires knowledge of the optical pathlength in the medium. This can now be estimated directly from the time of flight of picosecond length light pulses. Monte Carlo modelling of light pulses in tissue has shown that the mean value of the time dispersed light pulse correlates with the pathlength used in quantitative spectroscopic calculations. This result has been verified in a phantom material. Time of flight measurements of pathlength across the rat head give a pathlength of 5.3 +/- 0.3 times the head diameter.

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Available from: John Stephen Wyatt, Jan 04, 2014
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    • "Each participant's hemodynamic response was baseline-corrected by subtracting the mean intensity of the optical signal recorded during the 15 s from the overall hemodynamic activity. The modified Beer-Lambert equation (mBL; Delpy et al. 1988) was used to convert wavelength data to oxy-and deoxy-hemoglobin concentrations (designated as HbO and Hb, respectively, see Huppert et al. 2009, for details). Following the conversion, the time course data (all channels, all conditions) for each participant were plotted in Matlab and visually inspected for motion artifacts and signal quality; blocks containing signal changes that occurred too rapidly to be physiological (3 s or less) were removed across all channels from further analyses. "
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