# US 2025/0143593 A1 · Deep tissue flowmetry using diffuse speckle contrast analysis > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2025/0143593 A1 - Document ID: US20250143593A1 - Status: Published application - Kind: A1 - Application number: 18/740,325 - Filed: 2024-06-11 - Published: 2025-05-08 - Earliest claimed: 2013-01-23 - Assignees: Pedra Technology PTE LTD - Applicants: Pedra Technology Pte Ltd - Inventors: Kijoon Lee; Renzhe Bi; Jing Dong - Web page: https://patentgrep.com/patent/US20250143593A1 ## CPC - A61B 5/0261: {using optical means, e.g. infrared light} - A61B 5/7246: {using correlation, e.g. template matching or determination of similarity} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## Abstract Blood flow rates can be calculated using diffuse speckle contrast analysis in spatial and time domains. In the spatial domain analysis, a multi-pixel image sensor can be used to detect a spatial distribution of speckles in a sample caused by diffusion of light from a coherent light source that is blurred due to the movement of scatterers within the sample (e.g., red blood cells moving within a tissue sample). Statistical analysis of the spatial distribution can be used to calculate blood flow. In the time domain analysis, a slow counter can be used to obtain time-series fluctuations in light intensity in a sample caused by diffusion of light in the sample that is smoothened due to the movement of scatterers. Statistical analysis of the time-series data can be used to calculate blood flow. ## Claims ### Claim 1 A method for determining blood flow in a patient, the method comprising: directing coherent light onto a first location of the patient's tissue; imaging a second location of the patient's tissue, wherein a portion of the coherent light is scattered by the blood flow beneath the patient's tissue such that the scattered light is at least partially detectable at the second location; and calculating the blood flow based on the image of the second location. ### Claim 2 (depends on 1) The method of claim 1, wherein the calculating comprises calculating the speckle contrast. ### Claim 3 (depends on 2) The method of claim 2, wherein calculating the speckle contrast comprises dividing the standard deviation of intensity by the average intensity of the image of the second location. ### Claim 4 (depends on 1) The method of claim 1, wherein the blood flow is at least 5 mm below the surface of the patient's skin. ### Claim 5 (depends on 1) The method of claim 1, wherein the first and second locations are on a patient's limb. ### Claim 6 (depends on 1) The method of claim 1, wherein the first and second locations are on a patient's foot. ### Claim 7 (depends on 1) The method of claim 1, wherein imaging the second location comprises capturing an image with a CCD camera. ### Claim 8 (depends on 1) The method of claim 1, wherein the coherent light comprises light from a laser. ### Claim 9 (depends on 1) The method of claim 1, wherein the first and second locations are at least 10 mm apart. ### Claim 10 (depends on 1) The method of claim 1, further comprising signaling the blood flow an operator. ### Claim 11 A method for determining blood flow in a patient, the method comprising: directing coherent light onto a first location of the patient's skin; obtaining time-series measurements of the light intensity at a second location of the patient's skin, wherein a portion of the coherent light is scattered by the blood flow beneath the patient's skin such that the scattered light is at least partially detectable at the second location; and calculating the blood flow based on the time-series measurements. ### Claim 12 (depends on 11) The method of claim 11, wherein the calculating comprises calculating the temporal speckle contrast. ### Claim 13 (depends on 12) The method of claim 12, wherein calculating the temporal speckle contrast comprises dividing the temporal standard deviation of intensity by the temporal average intensity at the second location. ### Claim 14 (depends on 11) The method of claim 11, wherein the blood flow is at least 5 mm below the surface of the patient's skin. ### Claim 15 (depends on 11) The method of claim 11, wherein the first and second locations are on a patient's foot. ### Claim 16 (depends on 11) The method of claim 11, wherein the first and second locations are at least 10 mm apart. ### Claim 17 (depends on 11) The method of claim 11, further comprising signaling the blood flow to an operator. ### Claim 18 (depends on 11) The method of claim 11, wherein the signaling comprises providing audible, visual, or tactile indicia of blood flow. ### Claim 19 A system for assessment of blood flow in tissue, the system comprising: a coherent light source configured to apply light to the tissue; a multi-pixel image sensor configured to capture optical information including at least a quantity of light transmitted through the tissue, wherein the light is scattered, at least in part, by the blood flow; an analyzer configured to analyze the optical information to determine blood flow in the tissue; and a feedback device configured to provide a signal indicative of the blood flow determined by the analyzer. ### Claim 20 (depends on 19) The system of claim 19, wherein the multi-pixel image sensor comprises a CCD camera.