Method for data reduction and calibration of an OCT-based blood glucose monitor
First Claim
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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Abstract
The present invention relates to a method for estimating blood glucose levels using a noninvasive optical coherence tomography- (OCT-) based blood glucose monitor. An algorithm correlates OCT-based estimated blood glucose data with actual blood glucose data determined by invasive methods. OCT-based data is fit to the obtained blood glucose measurements to achieve the best correlation. Once the algorithm has generated sets of estimated blood glucose levels, it may refine the number of sets by applying one or more mathematical filters. The OCT-based blood glucose monitor is calibrated using an Intensity Difference plot or the Pearson Product Moment Correlation method.
916 Citations
41 Claims
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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:
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(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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. 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:
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(a) selecting a wavelength of light for which μ
a, an absorption coefficient of 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 averaged data obtained in step (c), wherein the step of calibrating the optical coherence tomography-based sensor comprises; (i) using a Pearson'"'"'s plot to calibrate the optical coherence tomography-based sensor against the at least two invasively obtained blood glucose measurements taken during the time period; and (ii) using Pearson'"'"'s correlation to maximize correlation between data received from an optical coherence tomography-based monitor and the invasively obtained glucose measurements; 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. - View Dependent Claims (27)
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28. A method for calibrating an optical coherence tomography (OCT) sensor by correlating OCT measurements with blood glucose measurements, comprising:
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taking a plurality of blood glucose measurements from a subject over a specified time period; obtaining OCT measurements from biological tissue of the subject such that at least one OCT measurement is associated with each blood glucose measurement, each of the OCT measurements capable of being represented as a plot of intensity against depth of the biological tissue; selecting at least one portion of each of the OCT measurements that includes a selected depth, the selected portion of the OCT measurements correlating with the associated blood glucose measurements, wherein the step of selecting at least one portion of each of the OCT measurements comprises; (a) computing intensity differences between at least two of the obtained OCT measurements at corresponding depths to generate an intensity difference plot; and (b) using the intensity difference plot to obtain the selected portion and the selected depth of the OCT measurements; establishing a calibration relationship for an OCT sensor using the selected portions of the OCT measurements and the associated blood glucose measurements; and using a processor, calibrating the OCT sensor with the calibration relationship. - View Dependent Claims (29, 30, 31, 32, 33, 34)
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35. A method for calibrating an optical coherence tomography (OCT) sensor by correlating OCT measurements with blood glucose measurements, comprising:
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taking a plurality of blood glucose measurements from a subject over a specified time period; obtaining OCT measurements from biological tissue of the subject such that at least one OCT measurement is associated with each blood glucose measurement, each of the OCT measurements capable of being represented as a plot of intensity against depth of the biological tissue; selecting at least one portion of each of the OCT measurements that includes a selected depth, the selected portion of the OCT measurements correlating with the associated blood glucose measurements, wherein the step of selecting at least one portion of each of the OCT measurements comprises; (a) enhancing at least one discontinuity in data associated with an obtained OCT measurement; and (b) using the at least one discontinuity to identify the selected depth; establishing a calibration relationship for an OCT sensor using the selected portions of the OCT measurements and the associated blood glucose measurements; and using a processor, calibrating the OCT sensor with the calibration relationship. - View Dependent Claims (36, 37, 38, 39, 40)
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41. A method for calibrating an optical coherence tomography (OCT) sensor by correlating OCT measurements with blood glucose measurements, comprising:
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taking a plurality of blood glucose measurements from a subject over a specified time period; obtaining OCT measurements from biological tissue of the subject such that at least one OCT measurement is associated with each blood glucose measurement, each of the OCT measurements capable of being represented as a plot of intensity against depth of the biological tissue; selecting at least one portion of each of the OCT measurements that includes a selected depth, the selected portion of the OCT measurements correlating with the associated blood glucose measurements, wherein the step of selecting at least one portion of each of the OCT measurements comprises; (a) creating a Pearson plot to indicate correlations between a plurality of OCT measurements at a plurality of portions and depths of the OCT measurements; and (b) using the Pearson plot to select the at least one portion of the OCT measurements and the selected depth; establishing a calibration relationship for an OCT sensor using the selected portions of the OCT measurements and the associated blood glucose measurements; and using a processor, calibrating the OCT sensor with the calibration relationship.
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Specification