Method for data reduction and calibration of an OCT-based blood glucose monitor

  • US 7,822,452 B2
  • Filed: 04/13/2006
  • Issued: 10/26/2010
  • Est. Priority Date: 08/11/2004
  • Status: Active Grant
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First Claim
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1. A noninvasive method of determining estimated blood glucose levels in a biological tissue of a subject using an optical coherence tomography-based monitor comprising a sensor and at least one algorithm, the method comprising the steps of:

  • (a) selecting a wavelength of light for which μ

    a, an absorption coefficient of the biological tissue, is small relative to μ

    s, a scattering coefficient of the tissue for the selected wavelength of light;

    (b) repeatedly scanning a two-dimensional surface area of the biological tissue and interferometrically scanning in a depth dimension with the light during a time period;

    (c) averaging data obtained during scanning to generate a plurality of optical coherence tomography scan data lines, wherein an x-axis of each optical coherence tomography scan data line is depth and a y-axis of each optical coherence tomography scan data line is intensity;

    (d) calibrating an optical coherence tomography-based sensor against at least two invasively obtained blood glucose measurements taken during the time period using the averaged data obtained in step (c), wherein the step of calibrating the optical coherence tomography-based sensor comprises;

    (i) generating a calibration set of estimated blood glucose values by;

    a. selecting the at least first and second invasively obtained blood glucose measurements obtained over the time period, wherein the at least two measurements are spaced apart by a concentration value of at least about 40 mg/dL;

    b. selecting first and second optical coherence tomography scan data lines, corresponding with the first and second invasively obtained blood glucose measurements;

    c. computing intensity differences between the two selected optical coherence tomography scan data lines by subtracting a first baseline scan data line (n) from a second, subsequent optical coherence tomography scan data line (n+1) at every point along the two selected optical coherence tomography scan data lines to generate an intensity difference plot; and

    d. using the intensity difference plot to determine a multitude of offsets and a multitude of intervals to construct a glucose vector grid comprising a multitude of offset, interval pairs; and

    (ii) applying the calibration set to calibrate an optical coherence tomography-based monitor; and

    (e) allowing the calibrated optical coherence tomography-based sensor and at least one algorithm to determine an estimated blood glucose level in the biological tissue.

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