# US 11,298,103 B2 · Fluid flow analysis > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,298,103 B2 - Document ID: US11298103B2 - Status: Granted - Kind: B2 - Application number: 16/087,442 - Filed: 2017-03-17 - Published: 2019-04-04 - Granted: 2022-04-12 - Earliest claimed: 2016-03-22 - Assignees: Imperial College Innovations Limited - Applicants: Imperial College Innovations Limited - Inventors: Peter David Weinberg - Web page: https://patentgrep.com/patent/US11298103B2 ## CPC - A61B 8/06: Measuring blood flow - A61B 5/026: Measuring blood flow {(A61B3/1233, A61B3/1241 take precedence)} - A61B 5/0285: Measuring or recording phase velocity of blood waves - A61B 5/1075: {for measuring dimensions by non-invasive methods, e.g. for determining thickness of tissue layer (A61B8/0858 takes precedence)} - A61B 8/5223: {for extracting a diagnostic or physiological parameter from medical diagnostic data (for algorithms to analyse biomedical images G06T7/0012)} - G01F 1/66: by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters - G01F 1/667: Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters - G01F 1/7082: using acoustic detecting arrangements - G01F 1/72: Devices for measuring pulsing fluid flows - G01P 5/245: {by measuring transit time of acoustical waves (measuring propagation velocity of acoustical waves per se G01H5/00)} - G16H 50/30: for calculating health indices; for individual health risk assessment - A61B 8/0891: {for diagnosis of blood vessels} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME - G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G}) - G16H: HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA ## Abstract A method of determining a measure of wave speed or intensity in a fluid conduit uses ultrasound measurements to determine the conduit diameter and fluid velocity in a volume element, each as a function of time, and each at a same longitudinal position of the conduit. The ultrasound measurement to determine fluid velocity is effected by tracking objects within the fluid flow in successive frames sampling the volume element, and obtaining displacement vectors for the objects. A wave speed may be determined from a ratio of the change in fluid velocity at the longitudinal position as a function of time and the change in a logarithmic function of the conduit diameter as a function of time. A measure of wave intensity may be determined as a function of change in determined conduit diameter and corresponding change in fluid velocity. ## Claims ### Claim 1 A method of determining a measure of wave speed in a fluid flowing through a fluid conduit, the method comprising: using ultrasound measurements to determine the conduit diameter or conduit cross-sectional area, as a function of time, at a longitudinal position of the conduit; using ultrasound measurements to determine fluid velocity, as a function of time, in a volume element at said longitudinal position of the conduit, the ultrasound measurement to determine fluid velocity being effected by tracking objects within the fluid flow in successive frames sampling the volume element, and obtaining displacement vectors for the objects, in which the objects being tracked comprise red blood cells, white blood cells, or platelets; determining a wave speed from a function of (i) the change in fluid velocity at the longitudinal position as a function of time and (ii) the change in the conduit diameter or conduit cross-sectional area, as a function of time. ### Claim 2 (depends on 1) The method of claim 1 in which the wave speed is determined from a ratio of the change in fluid velocity at the longitudinal position as a function of time and the change in a logarithmic function of the conduit diameter as a function of time. ### Claim 3 (depends on 2) The method of claim 2 in which the wave speed is determined from a ratio of a change in fluid velocity at the longitudinal position within a time interval and a corresponding change in a logarithmic function of the conduit diameter within the same time interval. ### Claim 4 (depends on 1) The method of claim 1 in which the wave speed is determined from the change in fluid velocity at the longitudinal position within a time interval and a corresponding change in the conduit diameter within the same time interval. ### Claim 5 (depends on 1) The method of claim 1 in which the fluid velocity is determined using imaging velocimetry. ### Claim 6 (depends on 1) The method of claim 1 in which the ultrasound measurements for determining fluid velocity comprise a series of B-mode images or B-mode RF data, and obtaining displacement vectors comprises correlating the locations of the tracked objects in successive frames of the B-mode images or B-mode RF data. ### Claim 7 (depends on 1) The method of claim 1 in which the ultrasound measurements for determining conduit diameter and fluid velocity are both derived from a common ultrasound transducer head. ### Claim 8 (depends on 7) The method of claim 7 in which the common transducer head is directed orthogonally to a fluid flow axis of the fluid flow conduit. ### Claim 9 (depends on 7) The method of claim 7 in which the ultrasound measurements for determining conduit diameter or conduit cross-sectional area, and fluid velocity are both derived from common ultrasound excitation and response signals. ### Claim 10 (depends on 1) The method of claim 1 in which the wave speed, c, is determined according to the equation c=0.5(dU/dInD), where dU is a change in the fluid velocity as a function of time and dInD is a change in the natural logarithm of D as a function of time. ### Claim 11 (depends on 1) The method of claim 1 in which the fluid conduit comprises a part of the human or animal circulatory system. ### Claim 12 (depends on 11) The method of claim 11 further including repeating the ultrasound measurements and determining a wave speed at multiple times during a cardiac cycle and correlating the measurement of wave speed with time within the cardiac cycle. ### Claim 13 (depends on 1) The method of claim 1 further including determining a measure of fluid conduit wall elasticity or distensibility at the volume element, from the wave speed. ### Claim 14 (depends on 1) The method of claim 1 in which the wave speed, c, is determined according to the equation c=AdU/dA or c=dU/dInA, where A is the cross-sectional area, dA is the change in cross-sectional area as a function of time, dU is the change in the fluid velocity as a function of time, and dInA is the change in the natural logarithm of A as a function of time. ### Claim 15 A method of determining a measure of wave speed in a fluid flowing through a fluid conduit, the method comprising: using ultrasound measurements to determine the conduit diameter, as a function of time, at a longitudinal position of the conduit; using ultrasound measurements to determine fluid velocity, as a function of time, in a volume element at said longitudinal position of the conduit, the ultrasound measurement to determine fluid velocity being effected by tracking objects within the fluid flow in successive frames sampling the volume element, and obtaining displacement vectors for the objects, in which the objects being tracked comprise red blood cells, white blood cells, or platelets; determining a change in flow rate through the conduit based on the fluid velocity measurements and the conduit diameter measurements; determining a change in cross-sectional area of the conduit based on the conduit diameter measurements; and determining a wave speed from a ratio of the change in flow rate at the longitudinal position as a function of time and the change in conduit cross-sectional area as a function of time. ### Claim 16 (depends on 15) The method of claim 15 in which the fluid velocity is determined using imaging velocimetry. ### Claim 17 (depends on 15) The method of claim 15 in which the ultrasound measurements for determining fluid velocity comprise a series of B-mode images or B-mode RF data, and obtaining displacement vectors comprises correlating the locations of the tracked objects in successive frames of the B-mode images or B-mode RF data. ### Claim 18 (depends on 15) The method of claim 15 in which the ultrasound measurements for determining conduit diameter and fluid velocity are both derived from a common ultrasound transducer head. ### Claim 19 (depends on 18) The method of claim 18 in which the common transducer head is directed orthogonally to the fluid flow axis of the fluid flow conduit. ### Claim 20 (depends on 19) The method of claim 19 in which the ultrasound measurements for determining conduit diameter and fluid velocity are both derived from common ultrasound excitation and response signals. ### Claim 21 (depends on 15) The method of claim 15 in which the wave speed, c, is determined according to the equation c=dQ/dA), where dQ is a change in the fluid flow rate and dA is a change in the cross-sectional area of the conduit. ### Claim 22 (depends on 15) The method of claim 15 in which the fluid conduit comprises a part of the human or animal circulatory system. ### Claim 23 (depends on 22) The method of claim 22 further including repeating the ultrasound measurements and determining a wave speed at multiple times during a cardiac cycle and correlating the measurement of wave speed with time within the cardiac cycle. ### Claim 24 (depends on 15) The method of claim 15 further including determining a measure of fluid conduit wall elasticity or distensibility at the volume element, from the wave speed. ### Claim 25 (depends on 1) An apparatus for determining a measure of wave speed in a fluid conduit, comprising: an analysis module configured to perform the steps of claim 1. ### Claim 26 (depends on 15) An apparatus for determining a measure of wave speed in a fluid conduit, comprising: an analysis module configured to perform the steps of claim 15.