# US 8,771,188 B2 · Ultrasonic bone motion tracking system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,771,188 B2 - Document ID: US8771188B2 - Status: Granted - Kind: B2 - Application number: 12/143,225 - Filed: 2008-06-20 - Published: 2009-01-15 - Granted: 2014-07-08 - Earliest claimed: 2007-06-20 - Assignees: Perception Raisonnement Action en Medecine - Applicants: Jonathan Schers; Christopher Plaskos; Stephane Lavallee; Jocelyne Troccaz - Inventors: Jonathan Schers; Christopher Plaskos; Stephane Lavallee; Jocelyne Troccaz - Web page: https://patentgrep.com/patent/US8771188B2 ## CPC - A61B 8/0875: {for diagnosis of bone} - A61B 8/4227: {characterised by straps, belts, cuffs or braces} - A61B 8/4245: {involving determining the position of the probe, e.g. with respect to an external reference frame or to the patient} - A61B 8/483: {involving the acquisition of a 3D volume of data} - A61B 8/5207: {involving processing of raw data to produce diagnostic data, e.g. for generating an image} - A61B 8/5223: {for extracting a diagnostic or physiological parameter from medical diagnostic data (for algorithms to analyse biomedical images G06T7/0012)} - A61B 8/5238: {for combining image data of patient, e.g. merging several images from different acquisition modes into one image} - A61B 8/14: Echotomography - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## Abstract A computerized bone motion tracking system according to one exemplary embodiment is configured to: provide a non-invasive means for accurate measurement and tracking of the motion of a bone using a volumetric ultrasound transducer and a three dimensional position measurement system; provide relative measurements of one bone relative to another bone of a joint; decompose relative joint motion into specific components; and measure joint instability and range of motion. ## Claims ### Claim 1 A method for non-invasively tracking a bone of a subject in three-dimensional space, the method comprising: (a) attaching a 3D or 4D volumetric ultrasound imaging transducer to the subject and acquiring a first reference image volume I0 of a bone surface with the 3D or 4D volumetric ultrasound imaging transducer at an initial time t0, wherein the 3D or 4D volumetric ultrasound imaging transducer acquires 3D image pixel volumes; (b) determining an initial position of the bone using the first reference image volume I0; (c) acquiring a second image volume I1 of the bone surface with the 3D or 4D volumetric ultrasound imaging transducer at a second time t1; (d) measuring a three-dimensional position of the 3D or 4D volumetric ultrasound imaging transducer with a three-dimensional position measuring device at the times t0 and t1 and associating each position with the corresponding image volumes I0 and I1; (e) searching for a relative position of I0 and I1 for which overlapping portions of the image volumes of I0 and I1 are closest aligned to one another and defining this position as a best-match position; (f) determining a 3D transformation between the first reference image volume and the second image volume that corresponds to the best-match position; and (g) repeating steps c to f. ### Claim 2 (depends on 1) The method of claim 1, wherein the best-match search is limited to a region of interest that includes pixels representing the bone surface in at least one of the first reference image volume and the second image volume. ### Claim 3 (depends on 2) The method of claim 2, whereon the region of interest includes the bone surface and a finite region of soft-tissues overlying the bone surface. ### Claim 4 (depends on 1) The method of claim 1, wherein the second image volume is a sparse 3D volume. ### Claim 5 (depends on 4) The method of claim 4, wherein the sparse 3D volume is limited to two or three orthogonal image planes. ### Claim 6 (depends on 1) The method of claim 1, wherein the determined 3D transformation is used as an initial guess for a first relative position used in the best-match search of step (e) for a next successive tracking step. ### Claim 7 (depends on 1) The method of claim 1, wherein the first reference image volume is an extended panoramic volume made up of several image volumes acquired adjacent to one another and matched with one another. ### Claim 8 (depends on 1) The method of claim 1, wherein the bone to be tracked is one of a femur, tibia, scapula, humerus, pelvis, scaphoid and vertebra. ### Claim 9 (depends on 1) The method of claim 1, wherein the bone to be tracked is a femur bone of a knee joint, and a marking element is non-invasively attached to a tibia. ### Claim 10 (depends on 9) The method of claim 9, wherein relative motions of the bones of the knee joint are measured and decomposed into different directions and axes of rotation. ### Claim 11 (depends on 1) The method of claim 1, wherein the bone to be tracked is a scapula bone of a shoulder joint, and a marking element is non-invasively attached to a humerus. ### Claim 12 (depends on 11) The method of claim 11, wherein relative motions of the bones of the shoulder joint are measured and decomposed in to different directions and axes of rotation. ### Claim 13 (depends on 1) The method of claim 1, wherein multiple 3D or 4D volumetric transducers are positioned at different locations to track the bone. ### Claim 14 (depends on 13) The method of claim 13, wherein the multiple 3D or 4D volumetric transducers are rigidly connected to one another and tracked by a marking element. ### Claim 15 (depends on 1) The method of claim 1, further including the step of displaying the tracked bone on a display and showing movement thereof in approximately real-time. ### Claim 16 (depends on 1) The method of claim 1, further comprising the step of increasing a size of the first reference image volume I0 by acquiring additional located volumes adjacent to one another by moving the 3D or 4D volumetric ultrasound imaging transducer over a skin surface of the bone surface in a plurality of directions. ### Claim 17 A method for non-invasively tracking a bone of a subject in three-dimensional space, the method comprising: attaching a 3D or 4D volumetric ultrasound imaging transducer to the subject and acquiring a first reference image volume I0 of a bone surface with the 3D or 4D volumetric ultrasound imaging transducer at an initial time t0, wherein the 3D or 4D volumetric ultrasound imaging transducer acquires 3D image pixel volumes, and wherein the first reference image volume I0 has a first coordinate system; determining an initial position of the bone using the first reference image volume I0; acquiring a second image volume I1 of the bone surface with the 3D or 4D volumetric ultrasound imaging transducer at a second time t1; measuring a three-dimensional position of the 3D or 4D volumetric ultrasound imaging transducer with a three-dimensional position measuring device at the times t0 and t1 and associating each position with the corresponding image volumes I0 and I1; searching for a relative position of I0 and I1 for which overlapping portions of the image volumes of I0 and I1 are closest aligned to one another and defining this position as a best-match position; and determining a 3D transformation between the first reference image volume and the second image volume that corresponds to the best-match position, wherein the second image volume I1 is displaced from the first coordinate system in the best-match position. ### Claim 18 (depends on 17) The method of claim 17, wherein the best-match search is limited to a region of interest that includes pixels representing the bone surface in at least one of the first reference image volume and the second image volume. ### Claim 19 (depends on 17) The method of claim 17, wherein the second image volume is a sparse 3D volume. ### Claim 20 (depends on 19) The method of claim 19, wherein the sparse 3D volume is limited to two or three orthogonal image planes. ### Claim 21 A method for non-invasively tracking a bone of a subject in three-dimensional space, the method comprising: (a) acquiring a position coordinate system at initial time t0 using a three-dimensional position measuring device; (b) attaching a 3D or 4D volumetric ultrasound imaging transducer to the subject and acquiring a first reference image volume I0 of the bone and tissue adjacent to and attached to the bone with the 3D or 4D volumetric ultrasound imaging transducer at initial time t0 while simultaneously tracking the 3D or 4D volumetric ultrasound imaging transducer; (c) determining an initial position of the bone using the first reference image volume I0 and the position coordinate system; (d) acquiring a second image volume I1 of the bone with the 3D or 4D volumetric ultrasound imaging transducer at a second time t1 while simultaneously tracking the 3D or 4D volumetric ultrasound imaging transducer; (e) selecting a region of interest corresponding to a subset of the first reference image volume I0 and the second image volume I1; (f) searching for a relative position of I0 and I1 for the selected region of interest for which overlapping portions of the image volumes of I0 and I1 are closest aligned to one another and defining this position as a best-match position; (g) determining a 3D transformation between the first reference image volume and the second image volume that corresponds to the best-match position; and (h) repeating steps (d) to (g).