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

• US 10,791,971 B2
• Filed: 10/04/2018
• Issued: 10/06/2020
• Est. Priority Date: 08/11/2004
• Status: Active Grant

• Current Assignee: Masimo Corporation
• Original Assignee: Masimo Corporation
• Inventors: Schurman, Matthew J., Shakespeare, Walter J., Bennett, William Henry
• Primary Examiner(s): Winakur, Eric F
• Application Number:
  US16/151,917
• Publication Number:
  US 20190029574A1
• Time in Patent Office: 733 Days
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 5/0066 Optical coherence imaging
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/1545 comprising means for indicating vein or arterial entry
• CPC Class Codes: A61B 5/441 Skin evaluation, e.g. for skin disorder diagnosis
• CPC Class Codes: A61B 5/72 Signal processing specially adapted for physiological signals or for diagnostic purposes character recognition, recognising digital ink, document-oriented image-based pattern recognition G06V30/00; recognition or understanding of postal images G06V30/424
• CPC Class Codes: A61B 5/7246 using correlation, e.g. template matching or determination of similarity
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence

Abstract

The present invention relates to a method and system for estimating blood analyte levels using a noninvasive optical coherence tomography (OCT) based physiological monitor. An algorithm correlates OCT-based estimated blood analyte data with actual blood analyte data determined by other methods, such as invasively. OCT-based data is fit to the obtained blood analyte measurements to achieve the best correlation. Once the algorithm has generated sets of estimated blood analyte levels, it may refine the number of sets by applying one or more mathematical filters. The OCT-based physiological monitor can be calibrated using an Intensity Difference plot or the Pearson Product Moment Correlation method.

Claims

1. A method of estimating a blood analyte level using an optical coherence tomography (OCT) device, the method comprising:

receiving, from an OCT device, at least two OCT scans of an area of biological tissue along a depth dimension, the at least two OCT scans obtained at different times;

computing intensity differences between the at least two OCT scans to generate an intensity difference plot;

determining a portion of the intensity difference plot associated with at least a zero crossing and corresponding localized extrema;

selecting, based on the determined portion of the intensity difference plot, one or more portions of the at least two OCT scans; and

estimating a blood analyte level based on a comparison of the one or more portions of the at least two OCT scans with OCT calibration data.

2. The method of claim 1, wherein the portion of the intensity difference plot correlates with blood vessels.

3. The method of claim 1, wherein the portion of the intensity difference plot correlates with blood analyte level changes.

4. The method of claim 1, wherein the OCT calibration data is generated based on correlations among previous OCT scans and blood analyte measurements obtained independently from the previous OCT scans.

5. The method of claim 1, wherein blood analyte level comprises a glucose level.

6. Non-transitory computer-readable storage having stored thereon instructions that, when executed, direct a computing system to perform operations comprising:

receiving, from an OCT device, at least two OCT scans of an area of biological tissue along a depth dimension, the at least two OCT scans obtained at different times;

computing intensity differences between the at least two OCT scans to generate an intensity difference plot;

determining a portion of the intensity difference plot associated with at least a zero crossing and corresponding localized extrema;

selecting, based on the determined portion of the intensity difference plot, one or more portions of the at least two OCT scans; and

estimating a blood analyte level based on a comparison of the one or more portions of the at least two OCT scans with OCT calibration data.

7. The non-transitory computer-readable storage of claim 6, wherein the portion of the intensity difference plot correlates with blood vessels.

8. The non-transitory computer-readable storage of claim 6, wherein the portion of the intensity difference plot correlates with blood analyte level changes.

9. The non-transitory computer-readable storage of claim 6, wherein the OCT calibration data is generated based on correlations among previous OCT scans and blood analyte measurements obtained independently from the previous OCT scans.

10. The non-transitory computer-readable storage of claim 6, wherein the blood analyte level comprises a glucose level.

11. A system for estimating a blood analyte level using an optical coherence tomography (OCT) device, the system comprising:

a processor configured to;

receive, from an OCT device, at least two OCT scans of an area of biological tissue along a depth dimension, the at least two OCT scans obtained at different times;

compute intensity differences between the at least two OCT scans to generate an intensity difference plot;

select, based on one or more portions of the intensity difference plot having large changes in intensity, corresponding one or more portions of the at least two OCT scans having large changes in intensity; and

estimate a blood analyte level based on a comparison of the one or more portions of the at least two OCT scans with OCT calibration data.

12. The system of claim 11, wherein selecting the corresponding one or more portions of the at least two OCT scans comprises identifying regions of the intensity difference plot where the large changes in intensity correlate with blood vessels.

13. The system of claim 11, wherein selecting the corresponding one or more portions of the at least two OCT scans comprises identifying regions of the intensity difference plot where the large changes in intensity correlate with blood analyte level changes.

14. The system of claim 11, wherein the OCT calibration data is generated based on correlations among previous OCT scans and blood analyte measurements obtained independently from the previous OCT scans.

15. The system of claim 11, wherein the blood analyte level comprises a glucose level.

16. Non-transitory computer-readable storage having stored thereon instructions that, when executed, direct a computing system to perform operations comprising:

receiving, from an OCT device, at least two OCT scans of an area of biological tissue along a depth dimension, the at least two OCT scans obtained at different times;

computing intensity differences between the at least two OCT scans to generate an intensity difference plot;

selecting, based on one or more portions of the intensity difference plot having large changes in intensity, corresponding one or more portions of the at least two OCT scans having large changes in intensity; and

estimating a blood analyte level based on a comparison of the one or more portions of the at least two OCT scans with OCT calibration data.

17. The non-transitory computer-readable storage of claim 16, wherein selecting the corresponding one or more portions of the at least two OCT scans comprises identifying regions of the intensity difference plot where the large changes in intensity correlate with blood vessels.

18. The non-transitory computer-readable storage of claim 16, wherein selecting the corresponding one or more portions of the at least two OCT scans comprises identifying regions of the intensity difference plot where the large changes in intensity correlate with blood analyte level changes.

19. The non-transitory computer-readable storage of claim 16, wherein the OCT calibration data is generated based on correlations among previous OCT scans and blood analyte measurements obtained independently from the previous OCT scans.

20. The non-transitory computer-readable storage of claim 16, wherein the blood analyte level comprises a glucose level.