Multispot monitoring for use in optical coherence tomography

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.

1 . (canceled) 
     
     
         2 . A system comprising:
 a beam scanner for use in optical coherence tomography; and   one or more processors configured to:
 cause the beam scanner to direct a beam of radiation suitable for optical coherence tomography measurements from the 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; 
 determine 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 
 monitor, using the beam scanner, each of the subset of tissue sites determined to include analyte correlating regions and not monitor at least a portion of tissue sites determined not to include analyte correlating regions. 
   
     
     
         3 . The system of  claim 2 , 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. 
     
     
         4 . The system of  claim 3 , wherein determining a subset of tissue sites that each include an analyte correlating region is based upon tissue hydration level. 
     
     
         5 . The system of  claim 3 , wherein determining a subset of tissue sites that each include an analyte correlating region is based upon blood perfusion. 
     
     
         6 . The system of  claim 2 , wherein the analyte level comprises a blood glucose level. 
     
     
         7 . The system of  claim 2 , 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 coarse-scale, optical coherence tomography measurements taken over the measurement-scale being capable of providing analyte measurement correlation.   
     
     
         8 . The system of  claim 7 , 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. 
     
     
         9 . The system of  claim 7 , 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. 
     
     
         10 . The system of  claim 7 , 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.   
     
     
         11 . The system of  claim 10 , wherein the first optical element comprises a moveable mirror. 
     
     
         12 . The system of  claim 10 , 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.   
     
     
         13 . The system of  claim 12 , wherein the second optical element comprises a rotatable prism. 
     
     
         14 . The system of  claim 2 , wherein the beam scanner comprises:
 a first optical element configured to move the beam of radiation.   
     
     
         15 . The system of  claim 14 , wherein the first optical element comprises a moveable mirror. 
     
     
         16 . The system of  claim 14 , 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.   
     
     
         17 . The system of  claim 16 , wherein the second optical element comprises a rotatable prism. 
     
     
         18 . 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.   
     
     
         19 . The method of  claim 18 , 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. 
     
     
         20 . The method of  claim 19 , wherein determining a subset of tissue sites that each include an analyte correlating region is based upon tissue hydration level. 
     
     
         21 . The method of  claim 19 , wherein t determining a subset of tissue sites that each include an analyte correlating region is based upon blood perfusion. 
     
     
         22 . The method of  claim 18 , wherein the analyte level comprises a blood glucose level.