FLOWOMETRY IN OPTICAL COHERENCE TOMOGRAPHY FOR ANALYTE LEVEL ESTIMATION

• US 20140051952A1
• Filed: 10/25/2013
• Published: 02/20/2014
• Est. Priority Date: 03/04/2008
• Status: Active Grant

• Current Assignee: Masimo Corporation
• Original Assignee: GLT Acquisition Corporation
• Inventors: Reichgott, Samuel, Shakespeare, Walter J., Kechter, George, Wallace, Phillip William, Schurman, Matthew J.
• Granted Patent: US 9,060,721 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. A system for determining at least one blood characteristic in a tissue sample, comprising:

an optical coherency tomography (OCT) apparatus configured to obtain intensity data measurements from each of a plurality of regions in the tissue sample; and

a processor configured to analyze the intensity data measurements from the OCT apparatus to determine whether blood flow is present in at least one region.

2. The system of claim 1, wherein the processor is configured to convert the intensity data measurements into blood analyte levels from at least one of the regions determined to have a selected level of blood flow.

3. The system of claim 1, wherein the processor is configured to analyze speckle in the intensity data measurements.

4. The system of claim 1, wherein the processor is configured to compare speckle in different intensity data measurements to determine whether blood flow is present.

5. The system of claim 4, wherein the OCT apparatus is configured to provide the different intensity data measurements over a plurality of moments in time.

6. The system of claim 4, wherein the OCT apparatus comprises a beam scanner.

7. The system of claim 6, wherein the beam scanner is configured to provide the different intensity measurements over at least one of a plurality of regions and a plurality of depths.

8. The system of claim 6, wherein the beam scanner is configured to provide raster scans of a plurality of regions.

9. The system of claim 1, wherein the processor is configured to analyze fringe-modulated data in the intensity data measurements.

10. The system of claim 9, wherein the processor is configured to analyze amplitude modulation in the fringe-modulated data.

11. The system of claim 10, wherein the processor is configured to analyze selected high frequency components of the intensity data.

12. The system of claim 9, wherein the processor comprises a signal filter for converting at least a portion of the intensity data measurements into a reduced intensity signal indicating fringe frequency modulation correlating with blood flow presence.

13. The system of claim 12, wherein the signal filter comprises a narrow band filter.

14. The system of claim 13, wherein the processor further comprises a wide band filter configured to convert at least a portion of the intensity data measurements into an attenuated output, the processor configured to compare the reduced intensity signal and the attenuated output to determine whether blood flow is present.