# US 10,117,640 B2 · Quantitative elastography with tracked 2D ultrasound transducers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,117,640 B2 - Document ID: US10117640B2 - Status: Granted - Kind: B2 - Application number: 15/798,186 - Filed: 2017-10-30 - Published: 2018-05-10 - Granted: 2018-11-06 - Earliest claimed: 2012-09-28 - Assignees: The University of British Columbia - Applicants: The University of British Columbia - Inventors: Septimiu Edmund Salcudean; Caitlin Marie Schneider; Robert N. Rohling; Ali Baghani; Mohammad Honarvar - Web page: https://patentgrep.com/patent/US10117640B2 ## CPC - A61B 8/485: {involving measuring strain or elastic properties} - A61B 8/0891: {for diagnosis of blood vessels} - A61B 8/12: in body cavities or body tracts, e.g. by using catheters - A61B 8/4209: {by using holders, e.g. positioning frames} - A61B 8/4218: {characterised by articulated arms} - A61B 8/4263: {using sensors not mounted on the probe, e.g. mounted on an external reference frame} - A61B 8/483: {involving the acquisition of a 3D volume of data} - A61B 8/4281: {characterised by sound-transmitting media or devices for coupling the transducer to the tissue} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## Abstract A method is described for acquiring 3D quantitative ultrasound elastography volumes. A 2D ultrasound transducer scans a volume of tissue through which shear waves are created using an external vibration source, the synchronized measurement of tissue motion within the plane of the ultrasound transducer with the measurement of the transducer location in space, the reconstruction of tissue displacements and/or tissue velocities in time and space over a volume from this synchronized measurement, and the computation of one or several mechanical properties of tissue from this volumetric measurement of displacements. The tissue motion in the plane of the transducer may be measured at a high effective frame rate in the axial direction of the transducer, or in the axial and lateral directions of the transducer. The tissue displacements and/or tissue velocities over the measured volume may be interpolated over a regular grid in order to facilitate computation of mechanical properties. ## Claims ### Claim 1 A method for measuring the mechanical properties in a volume of tissue, the method comprising the steps of: applying an excitation to said volume of tissue with a vibration source; scanning said volume of tissue with a tracked ultrasound transducer; measuring said tracked ultrasound transducer locations relative to a base coordinate system; computing a tissue response relative to said tracked ultrasound transducer from echo data measured by said tracked ultrasound transducer, wherein said tissue response comprises one or more of tissue displacements and tissue velocities; converting said tissue response from said tracked ultrasound transducer coordinate system to said base coordinate system using said tracked ultrasound transducer locations; and calculating said mechanical properties in said volume of tissue from said tissue response in said base coordinate systems; wherein said changing of the coordinate system of said tissue response to said base coordinate system comprises a phase compensation for time delays for one or both of (i) time of flight of ultrasound pulses, and (ii) time delays between subsequent ultrasound pulses. ### Claim 2 (depends on 1) A method according to claim 1, wherein calculating said mechanical properties comprises interpolating said tissue response in said base coordinate system onto a uniform grid. ### Claim 3 (depends on 1) A method according to claim 1, wherein said excitation is steady-state. ### Claim 4 (depends on 1) A method according to claim 1, wherein a location of said tracked ultrasound transducer is determined using one or more of: (a) electromagnetic sensing, (b) passive or active optical sensing, (c) robot sensing; (d) sensing by an inertial measurement unit; and (e) a mechanical linkage between the tracked ultrasound transducer and a tracking base. ### Claim 5 (depends on 4) A method according to claim 4 wherein said location of the tracked ultrasound transducer is constrained by a constraining fixture or linkage. ### Claim 6 (depends on 4) A method according to claim 4 wherein one or more degrees of freedom of the tracked ultrasound transducer is constrained by a constraining fixture or linkage. ### Claim 7 (depends on 4) A method according to claim 4, wherein said location of said tracked ultrasound transducer is determined based on ultrasound transducer image-based motion estimation. ### Claim 8 (depends on 7) A method according to claim 7, wherein the ultrasound transducer image-based motion estimation comprises applying a correlation-based algorithm to determine the transducer motion within each imaging plane or within and outside each imaging plane, from ultrasound echo data. ### Claim 9 (depends on 7) A method according to claim 7, wherein the ultrasound transducer image-based motion estimation comprises applying a machine learning-based algorithm to determine the transducer motion within each imaging plane or within and outside each imaging plane, from ultrasound echo data. ### Claim 10 (depends on 1) A method according to claim 1, wherein said vibration source is placed on the skin of a patient. ### Claim 11 (depends on 1) A method according to claim 1, wherein said tracked ultrasound transducer is placed on the skin of a patient. ### Claim 12 (depends on 1) A method according to claim 1, wherein said tracked ultrasound transducer is placed inside a patient and directly adjacent to an area or organ of interest. ### Claim 13 (depends on 1) A method according to claim 1, wherein the calculation of said mechanical properties of tissue comprises calculation of coherence between said tissue displacements and a reference displacement to distinguish soft tissue from a fluid. ### Claim 14 (depends on 1) A method according to claim 1, wherein said tracked ultrasound transducer is moved in a discrete stepwise fashion over said volume of tissue wherein each step comprises holding said tracked ultrasound transducer stationary while measuring said echo data, and then moving said tracked ultrasound transducer to a different location. ### Claim 15 (depends on 1) A method according to claim 1, wherein said tracked ultrasound transducer is moved in a continuous fashion over said volume of tissue. ### Claim 16 (depends on 1) A method according to claim 1, wherein said mechanical properties comprise a quantitative measure of the shear modulus of tissue. ### Claim 17 (depends on 1) A method according to claim 1, wherein said mechanical properties comprise a quantitative measure of the elasticity of the tissue. ### Claim 18 (depends on 1) A method according to claim 1, wherein mechanical properties comprise a quantitative measure of the shear wave speed of the tissue. ### Claim 19 (depends on 1) A method according to claim 1, wherein said mechanical properties comprise a quantitative measure of the shear viscosity of the tissue. ### Claim 20 (depends on 1) A method according to claim 1, wherein said mechanical properties are calculated as a function of frequency. ### Claim 21 (depends on 1) A method according to claim 1, wherein said tracked ultrasound transducer is a matrix transducer array that is capable of both 2D cross-sectional imaging and 3D volumetric imaging. ### Claim 22 (depends on 1) A method according to claim 1, wherein said tissue response comprises tissue velocities, and computing said tissue response comprises computing said tissue velocities from a plurality of scans of a sector comprising one or more transducer lines.