Automatic editing of electroanatomical maps
A method for mapping includes computing an initial three-dimensional (3D) form representing an inner surface of a cavity within a body of a living subject and receiving physiological data measured at multiple points distributed over the inner surface of the cavity. For each area among a plurality of areas of the initial 3D form, a respective distance is computed from the area to a nearest one of the multiple points, and one or more of the areas for which the respective distance is greater than a specified threshold distance are identified. The initial 3D form is modified so as to bring each of the identified areas to within the specified threshold distance of at least one of the multiple points. A 3D map of the cavity is rendered to a display a based on the modified 3D form and the measured physiological data.
1 . A method for mapping, comprising:
computing an initial three-dimensional (3D) form representing an inner surface of a cavity within a body of a living subject;
measuring electrophysiological data at multiple points distributed over the inner surface of the cavity using a probe within the cavity;
for each area among a plurality of areas of the initial 3D form, computing a respective distance from the area to a nearest one of the multiple points;
identifying one or more of the areas for which the respective distance is greater than a specified threshold distance;
shaving the initial 3D form so as to bring each of the identified areas to within the specified threshold distance of at least one of the multiple points; and
displaying a 3D map of the cavity based on the shaved 3D form and the measured electrophysiological data.
2 . The method according to claim 1 , wherein computing the initial 3D form comprises receiving a point cloud comprising multiple location coordinates of the probe acquired while the probe moved within the cavity, and modeling an outer surface of the point cloud to find the initial 3D form of the inner surface of the cavity.
3 . The method according to claim 1 , wherein computing the initial 3D form comprises constructing a polygonal mesh representing the inner surface of the cavity, and wherein computing the respective distance comprises finding the respective distance from each polygon within the mesh to the nearest one of the multiple points.
4 . The method according to claim 3 , wherein identifying one or more of the areas comprises identifying a polygon for which the respective distance to the respective one of the multiple points is greater than the specified threshold, and
wherein shaving the initial 3D form comprises removing a volume of the initial 3D form that is contained within a specified depth beneath the identified polygon, and reconstructing the polygonal mesh in a vicinity of the removed volume.
5 . The method according to claim 4 , and comprising, after reconstructing the polygonal mesh, recomputing the respective distance from the polygon to the nearest one of the multiple points and, when the recomputed distance is still greater than the specified threshold, iteratively removing one or more further volumes beneath the reconstructed polygonal mesh until the recomputed distance is no greater than the specified threshold.
6 . The method according to claim 3 , wherein constructing the polygonal mesh comprises constructing a triangular mesh, and wherein finding the respective distance comprises measuring a geodesic distance from each vertex of each triangle in the mesh to a respective one of the multiple points that is nearest to the vertex.
7 . The method according to claim 1 , wherein measuring the electrophysiological data comprises measuring electrical signals using a catheter within a chamber of a heart of the living subject, and
wherein displaying the 3D map comprises displaying an electroanatomical map of the chamber.
8 . The method according to claim 1 , wherein displaying the 3D map comprises coloring the areas of the shaved 3D form according to values of the electrophysiological data measured at the points that are nearest to the areas.
9 . A system for mapping, comprising:
a probe that measures electrophysiological data at multiple points distributed over an inner surface of a cavity within a body of a living subject;
an interface configured to receive the electrophysiological data measured at the multiple points distributed over the inner surface of the cavity; and
a processor configured to:
compute an initial three-dimensional (3D) form representing the inner surface of the cavity;
compute, for each area among a plurality of areas of the initial 3D form, a respective distance from the area to a nearest one of the multiple points;
identify one or more of the areas for which the respective distance is greater than a specified threshold distance;
shave the initial 3D form so as to bring each of the identified areas to within the specified threshold distance of at least one of the multiple points; and
display a 3D map of the cavity based on the shaved 3D form and the measured electrophysiological data.
10 . The system according to claim 9 , wherein the processor is configured to receive a point cloud comprising multiple location coordinates of the probe acquired while the probe moved within the cavity, and to model an outer surface of the point cloud to find the initial 3D form of the inner surface of the cavity.
11 . The system according to claim 9 , wherein the initial 3D form comprises a polygonal mesh representing the inner surface of the cavity, and wherein the processor is configured to compute the respective distance from each polygon within the mesh to the nearest one of the multiple points.
12 . The system according to claim 11 , wherein the processor is configured to identify a polygon for which the respective distance to the respective one of the multiple points is greater than the specified threshold, and to shave the initial 3D form by removing a volume of the initial 3D form that is contained within a specified depth beneath the identified polygon, and reconstructing the polygonal mesh in a vicinity of the removed volume.
13 . The system according to claim 12 , wherein the processor is configured, after reconstructing the polygonal mesh, to recompute the respective distance from the polygon to the nearest one of the multiple points and, when the recomputed distance is still greater than the specified threshold, to remove iteratively one or more further volumes beneath the reconstructed polygonal mesh until the recomputed distance is no greater than the specified threshold.
14 . The system according to claim 11 , wherein the polygonal mesh comprises a triangular mesh, and wherein the processor is configured to compute respective distances by measuring a geodesic distance from each vertex of each triangle in the mesh to a respective one of the multiple points that is nearest to the vertex.
15 . The system according to claim 9 , and comprising a catheter, which is configured to provide the electrophysiological data by measuring electrical signals within a chamber of a heart of the living subject, and wherein the 3D map comprises an electroanatomical map of the chamber.
16 . The system according to claim 9 , wherein the display of the 3D map of the cavity comprises coloring the areas of the shaved 3D form according to values of the electrophysiological data measured at the points that are nearest to the areas.
17 . A computer software product, comprising a tangible, non-transitory computer-readable medium in which program instructions are stored, which instructions, when read by a computer, cause the computer to:
measure electrophysiological data at multiple points distributed over an inner surface of a cavity within a body of a living subject using a probe within the cavity;
compute an initial three-dimensional (3D) form representing an inner surface of the cavity;
compute, for each area among a plurality of areas of the initial 3D form, a respective distance from the area to a nearest one of the multiple points;
identify one or more of the areas for which the respective distance is greater than a specified threshold distance;
shave the initial 3D form so as to bring each of the identified areas to within the specified threshold distance of at least one of the multiple points; and
display a 3D map of the cavity based on the shaved 3D form and the measured electrophysiological data.
18 . The product according to claim 17 , wherein the instructions cause the computer to receive a point cloud comprising multiple location coordinates of the probe acquired while the probe moved within the cavity, and to model an outer surface of the point cloud to find the initial 3D form of the inner surface of the cavity.
19 . The product according to claim 17 , wherein the initial 3D form comprises a polygonal mesh representing the inner surface of the cavity, and wherein the instructions cause the computer to compute the respective distance from each polygon within the mesh to the nearest one of the multiple points.
20 . The product according to claim 19 , wherein the instructions cause the computer to identify a polygon for which the respective distance to the respective one of the multiple points is greater than the specified threshold, and to shave the initial 3D form by removing a volume of the initial 3D form that is contained within a specified depth beneath the identified polygon, and reconstructing the polygonal mesh in a vicinity of the removed volume.
21 . The product according to claim 20 , wherein the instructions cause the computer, after reconstructing the polygonal mesh, to recompute the respective distance from the polygon to the nearest one of the multiple points and, when the recomputed distance is still greater than the specified threshold, to remove iteratively one or more further volumes beneath the reconstructed polygonal mesh until the recomputed distance is no greater than the specified threshold.
22 . The product according to claim 19 , wherein the polygonal mesh comprises a triangular mesh, and wherein the instructions cause the computer to compute respective distances by measuring a geodesic distance from each vertex of each triangle in the mesh to a respective one of the multiple points that is nearest to the vertex.
23 . The product according to claim 17 , wherein the instructions cause the computer to:
acquire the electrophysiological data from electrical signals measured using a catheter within a chamber of a heart of the living subject; and
display an electroanatomical map of the chamber using the electrophysiological data.
24 . The product according to claim 17 , wherein the display of the 3D map of the cavity comprises coloring the areas of the shaved 3D form according to values of the electrophysiological data measured at the points that are nearest to the areas.