MULTISPOT MONITORING FOR USE IN OPTICAL COHERENCE TOMOGRAPHY

• US 20140336481A1
• Filed: 05/16/2014
• Published: 11/13/2014
• Est. Priority Date: 03/04/2008
• Status: Active Grant

• Current Assignee: Masimo Corporation
• Original Assignee: GLT Acquisition Corporation
• Inventors: Shakespeare, Walter J., Bennett, William Henry, Iceman, Jason T., Apple, Howard P., Wallace, Phillip William, Schurman, Matthew J.
• Granted Patent: US 9,833,180 B2
• Time in Patent Office: Days
• US Class Current: 600/316
• CPC Class Codes: A61B 2576/00 Medical imaging apparatus involving image processing or analysis A61B1/00009, A61B6/52 and A61B8/52 take precedence; image processing per se G06T; details of algorithms for analysing medical images G06T7/0012
• CPC Class Codes: A61B 5/0066 Optical coherence imaging
• CPC Class Codes: A61B 5/0073 by tomography, i.e. reconstruction of 3D images from 2D projections A61B5/0066 takes precedence
• CPC Class Codes: A61B 5/026 Measuring blood flow A61B3/1233, A61B3/1241 take precedence
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/4875 Hydration status, fluid retention of the body
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/725 using specific filters therefor, e.g. Kalman or adaptive filters A61B5/316 take precedence
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence

Abstract

Optical coherence tomography (herein “OCT”) based analyte monitoring systems are disclosed. In one aspect, techniques are disclosed that can identify fluid flow in vivo (e.g., blood flow), which can act as a metric for gauging the extent of blood perfusion in tissue. For instance, if OCT is to be used to estimate the level of an analyte (e.g., glucose) in tissue, a measure of the extent of blood flow can potentially indicate the presence of an analyte correlating region, which would be suitable for analyte level estimation with OCT. Another aspect is related to systems and methods for scanning multiple regions. An optical beam is moved across the surface of the tissue in two distinct manners. The first can be a coarse scan, moving the beam to provide distinct scanning positions on the skin. The second can be a fine scan where the beam is applied for more detailed analysis.

Claims

1. (canceled)

2. A method for performing optical coherence tomography measurements to determine an analyte level in tissue, comprising:

aligning an optical coherence tomography system to a subject through an optical coupler;

scanning a beam over a first tissue site of the subject using the optical coupler to collect a first set of optical coherence tomography measurements;

scanning the beam over at least a second tissue site of the subject using the optical coupler to collect a second set of optical coherence tomography measurements;

selecting at least one tissue site from the first tissue site and the at least second tissue site for monitoring analyte levels, wherein the selected at least one tissue site comprises a tissue site that is valid for measuring an analyte level;

processing optical coherence tomography measurements associated with the selected at least one tissue site to measure the analyte level in the tissue; and

not processing optical coherence tomography measurements associated with at least one other tissue site not selected to for monitoring analyte levels.

3. The method of claim 2, wherein the first tissue site is spatially distinct from the second tissue site.

4. The method of claim 2 further comprising:

scanning the beam over at least one additional tissue site using the optical coupler to collect optical coherence tomography measurements corresponding with each additional tissue site.

5. The method of claim 2, wherein the step of selecting the at least one tissue site further comprises determining whether each of the first tissue site and the at least second tissue site is associated with a region that is valid for measuring an analyte level.

6. The method of claim 5 further comprising:

designating whether the region is valid for measuring an analyte level based upon tissue hydration level.

7. The method of claim 6, wherein the step of designating comprises validating a plurality of tissue sites, each tissue site associated with a corresponding measure of the analyte level in the tissue, the method further comprising:

aggregating a plurality of validated measures of the analyte level in the tissue to provide an aggregated measure of the analyte level in the tissue.

8. The method of claim 7 further comprising:

calibrating the optical coherence tomography system using the aggregated measure of the analyte level in the tissue.

9. The method of claim 2, wherein at least one of the steps of scanning the beam comprises scanning the beam over an entire spatial area of at least one region of skin of the subject.

10. The method of claim 2, wherein the analyte level comprises a blood glucose level.

11. The method of claim 2, wherein at least one of the steps of scanning the beam comprises scanning a plurality of tissue depths of a designated tissue site.

12. The method of claim 2, wherein areas associated with the first tissue site and the at least second tissue site do not overlap.

13. A method comprising:

directing a beam of radiation suitable for optical coherence tomography measurements from a beam scanner to a plurality of different locations on a region of a skin surface to scan a plurality of different tissue sites associated with each different location;

determining a subset of tissue sites that each include an analyte correlating region, wherein an analyte correlating region comprises a tissue site that is valid for measuring an analyte level; and

monitoring, using the beam scanner, each of the subset of tissue sites determined to include analyte correlating regions and not monitoring at least a portion of tissue sites determined not to include analyte correlating regions.

14. The method of claim 13, wherein each of the plurality of tissue sites comprises an area that does not overlap with an area of any of the other tissue sites.

15. The method of claim 14, wherein determining a subset of tissue sites that each include an analyte correlating region is based upon tissue hydration level.

16. The method of claim 14, wherein t determining a subset of tissue sites that each include an analyte correlating region is based upon blood perfusion.

17. The method of claim 13, wherein the analyte level comprises a blood glucose level.

18. The method of claim 13, wherein the beam scanner is configured to adjust direction of the beam on at least two-different length scales comprising:

a coarse-scale wherein the beam is directed over a distance large enough such that the beam scanner probes a plurality of sites, and

a measurement-scale wherein the beam is directed over a distance smaller than the site-scale, optical coherence tomography measurements taken over the measurement-scale being capable of providing analyte measurement correlation.

19. The method of claim 18, wherein the beam scanner is configured to direct the beam over the site-scale such that each of the plurality of sites corresponds with a unique spatial area.

20. The method of claim 18, wherein the beam scanner is configured to direct the beam over the measurement-scale such that a measure of an analyte level in the scanned site can be determined.

21. The method of claim 18, wherein the beam scanner comprises:

a first optical element configured to direct the beam on at least one of the site-scale and the measurement-scale.

22. The method of claim 21, wherein the first optical element comprises a moveable mirror.

23. The method of claim 21, wherein the beam scanner further comprises:

a second optical element configured to direct the beam on the site-scale, wherein the first optical element is configured to direct the beam on the measurement-scale.

24. The method of claim 23, wherein the second optical element comprises a rotatable prism.

25. The method of claim 13, wherein the beam scanner comprises:

a first optical element configured to move the beam of radiation.

26. The method of claim 25, wherein the first optical element comprises a moveable mirror.

27. The method of claim 25, wherein the beam scanner further comprises:

a second optical element configured to move the beam of radiation to the plurality of sites, wherein the first optical element is configured to scan the beam of radiation within a site.

28. The method of claim 27, wherein the second optical element comprises a rotatable prism.