Multispot Monitoring for Use in Optical Coherence Tomography

• US 20100113900A1
• Filed: 03/04/2009
• Published: 05/06/2010
• Est. Priority Date: 03/04/2008
• Status: Active Grant

• Current Assignee: Masimo Corporation
• Original Assignee: GlucoLight Corporation
• Inventors: Iceman, Jason T., Apple, Howard P., Wallace, Phillip William, Schurman, Matthew J., Shakespeare, Walter J., Bennett, William Henry
• Granted Patent: US 8,768,423 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. An optical coherence tomography (OCT) system for determining an analyte level in tissue, comprising:

a light source for generating skin-penetrating radiation suitable for OCT measurements;

a detector for receiving at least a portion of reflected light from the skin-penetrating radiation;

a beam scanner for directing a beam of radiation from the source to a plurality of sites to provide a measure of analyte levels in the tissue at each site, each site associated with a different analyte correlating region; and

a controller for selecting sites from the plurality of sites for monitoring.

2. The OCT system of claim 1, wherein the sites have a non-overlapping areas.

3. The OCT system of claim 1, wherein the controller is configured to associate OCT measurements with each of the plurality of sites.

4. The OCT system of claim 3, wherein the controller is configured to associate monitored sites with a corresponding measure of the analyte level.

5. The OCT system of claim 4, wherein the controller is configured to select sites based on whether a site is validated for analyte level measurement.

6. The OCT system of claim 5, wherein the controller is configured to designate whether the site is validated based upon tissue hydration level.

7. The OCT system of claim 5, wherein the controller is configured to provide an aggregated measure of the analyte level using OCT measurements associated with a plurality of validated sites.

8. The OCT system of claim 5, wherein OCT measurements associated with at least one validated site are utilized to calibrate the OCT system.

9. The OCT system of claim 1, wherein the beam scanner is configured to scan the entire area of at least one of the plurality of sites.

10. The OCT system of claim 1, wherein the beam scanner comprises:

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

11. The OCT system of claim 10, wherein the first optical element comprises a moveable mirror.

12. The OCT system of claim 10, 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.

13. The OCT system of claim 12, wherein the second optical element comprises a rotatable prism.

14. The OCT system of claim 1, wherein the analyte level comprises a blood glucose level.

15. A method for performing OCT measurements to determine an analyte level in tissue, comprising:

aligning an OCT system to a subject through an optical coupler;

scanning a beam over a first tissue site using the attached optical coupler to collect a first set of OCT measurements;

scanning the beam over at least a second tissue site using the attached optical coupling to collect a second set of OCT measurements;

selecting at least one site from the scanned sites for monitoring analyte levels; and

processing OCT measurements associated with the selected sites to measure the analyte level in the tissue.

16. The method of claim 15, wherein the first tissue site is spatially distinct from the second tissue site.

17. The method of claim 15, further comprising:

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

18. The method of claim 15, wherein the step of selecting specific sites further comprises designating whether one or more sites is associated with a validated site.

19. The method of claim 18, wherein the step of designating comprises determining validity of the at least one set of OCT measurements based upon tissue hydration level.

20. The method of claim 18, wherein the step of designating comprises validating a plurality of sites, each 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.

21. The method of claim 20, further comprising:

calibrating the OCT system using the aggregated measure of the analyte level in the tissue.

22. The method of claim 15, wherein at least one of the steps of scanning the beam comprises scanning the beam over the entire spatial area of at least one site.

23. The method of claim 15, wherein the analyte level comprises a blood glucose level.

24. The method of claim 15, wherein at least one of the steps of scanning the beam comprises scanning a plurality of tissue depths of a designated tissue site.

25. An apparatus for conducting multiple-scale scanning with an optical coherence tomography (OCT) system, comprising:

a beam scanner configured to be utilized with an OCT apparatus to detect an analyte level in a scanned tissue, the beam scanner configured to adjust movement of a beam on at least two-different length scales, comprising;

(i) a coarse-scale wherein the beam moves over a distance large enough such that the beam scanner probes a plurality of sites, and

(ii) a measurement-scale wherein the beam moves over a distance smaller than the site-scale, OCT measurements taken over the measurement-scale being capable of providing analyte measurement correlation.

26. The apparatus of claim 25, wherein the beam scanner is configured to move the beam over the site-scale such that each of the plurality of sites corresponds with a unique spatial area.

27. The apparatus of claim 25, wherein the beam scanner is configured to move the beam over the measurement-scale such that a measure of the analyte level in the scanned site can be determined.

28. The apparatus of claim 25, wherein the beam scanner is configured to scan the entire area of at least one of the plurality of sites.

29. The apparatus of claim 25, wherein the beam scanner comprises:

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

30. The apparatus of claim 29, wherein the first optical element comprises a moveable mirror.

31. The apparatus of claim 29, wherein the beam scanner further comprises:

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

32. The apparatus of claim 31, wherein the second optical element comprises a rotatable prism.