System and method for local deformable registration of a catheter navigation system to image data or a model
A method for registering a catheter navigation system to a three-dimensional image generally includes obtaining a three-dimensional image including position information for a plurality of surface points on a part of a patient's body, using a catheter navigation system to place a tool at a location on the surface of the patient's body, measuring position information for the surface location, identifying a corresponding location on the image, associating position information for the surface location and the location identified on the image as a fiducial pair, and using at least one fiducial pair to generate a mapping function. The mapping function transforms points within the coordinate system of the catheter navigation to the coordinate system of the three-dimensional image such that, for each fiducial pair, the mapping error is about zero. Suitable warping algorithms include thin plate splines, mean value coordinates, and radial basis function networks.
1. A method of registering a catheter navigation system to a three-dimensional image, comprising:
a) obtaining a three-dimensional image of at least a portion of a heart, the three-dimensional image including position information for a plurality of location points on a surface of the heart measured relative to a coordinate frame Y;
b) placing a tool on a surface location X i of the heart;
c) measuring position information for the surface location X i relative to a coordinate frame X;
d) identifying a corresponding location Y i on the three-dimensional image;
e) associating the position information for the surface location X i as measured by the catheter navigation system relative to the coordinate frame X with position information for the corresponding location Y i on the three-dimensional image relative to the coordinate frame Y as a fiducial pair (X i , Y i ); and
f) using at least two fiducial pairs (X i , Y i ) to generate a mapping function ƒ that transforms points within the coordinate frame X the to coordinate frame Y such that, for each fiducial pair (X i , Y i ), an error function ƒ(X i )−Y i ≈0, wherein the step of using the at least two fiducial pairs to generate a mapping function comprises:
using a thin plate splines algorithm to generate the mapping function,
wherein the thin plate splines algorithm comprises summing a fixed number of weighted basis functions,
wherein the fixed number of weighted basis functions is the same as a number of fiducial pairs that were associated, and
wherein the mapping function compensates for inhomogeneities in the catheter navigation system such that, for each fiducial pair (X i , Y i ), the error function ƒ(X i )−Y i ≈0.
2. The method of claim 1 , further comprising smoothing the mapping function with a regularization parameter.
3. The method of claim 2 , wherein the regularization parameter is about zero.
4. A method of registering a catheter navigation system to a three-dimensional image, comprising:
a) obtaining a three-dimensional image of at least a portion of a heart, the three-dimensional image including position information for a plurality of location points on a surface of the heart measured relative to a coordinate frame Y;
b) placing a tool on a surface location X i of the heart;
c) measuring position information for the surface location X i relative to a coordinate frame X;
d) identifying a corresponding location Y i on the three-dimensional image;
e) associating the position information for the surface location X i as measured by the catheter navigation system relative to the coordinate frame X with position information for the corresponding location Y i on the three-dimensional image relative to the coordinate frame Y as a fiducial pair (X i , Y i ); and
f) using at least two fiducial pairs (X i , Y i ) to generate a mapping function ƒ that transforms points within the coordinate frame X to the coordinate frame Y such that, for each fiducial pair (X i , Y i ), an error function ƒ(X i )−Y i ≈0, wherein the step of using the at least two fiducial pairs to generate a mapping function comprises using a mean value coordinate algorithm to generate the mapping function, wherein the mean value coordinate algorithm compensates for inhomogeneities in the catheter navigation system such that, for each fiducial pair (X i , Y i ), the error function ƒ(X i )−Y i ≈0.
5. The method of claim 4 , further comprising:
repeating steps b) through e) until at least four fiducial pairs are associated; and
generating a closed triangulated surface model of at least a portion of the heart, wherein the vertices of the closed triangulated surfaces comprise the at least four fiducial pairs.
6. A method of registering a catheter navigation system to a three-dimensional image, comprising:
a) obtaining a three-dimensional image of at least a portion of a heart, the three-dimensional image including position information for a plurality of location points on a surface of the heart measured relative to a coordinate frame Y;
b) placing a tool on a surface location X i of the heart;
c) measuring position information for the surface location X i relative to a coordinate frame X;
d) identifying a corresponding location Y i on the three-dimensional image;
e) associating the position information for the surface location X i as measured by the catheter navigation system relative to the coordinate frame X with position information for the corresponding location Y i on the three-dimensional image relative to the coordinate frame Y as a fiducial pair (X i , Y i ); and
f) using at least two fiducial pairs (X i , Y i ) to generate a mapping function ƒ that transforms points within the coordinate frame X to the coordinate frame Y such that, for each fiducial pair (X i , Y i ), an error function ƒ(X i )−Y i ≈0, wherein the step of using the at least two fiducial pairs to generate a mapping function comprises using at least three fiducial pairs and a mean value coordinate algorithm to generate the mapping function, wherein the mean value coordinate algorithm compensates for inhomogeneities in the catheter navigation system such that, for each fiducial pair (X i , Y i ), the error function ƒ(X i )−Y i ≈0.
7. A method of registering a catheter navigation system to a three-dimensional image, comprising:
a) obtaining a three-dimensional image of at least a portion of a heart, the three-dimensional image including position information for a plurality of location points on a surface of the heart measured relative to a coordinate frame Y;
b) placing a tool on a surface location X i of the heart;
c) measuring position information for the surface location X i relative to a coordinate frame X;
d) identifying a corresponding location Y i on the three-dimensional image;
e) associating the position information for the surface location X i as measured by the catheter navigation system relative to the coordinate frame X with position information for the corresponding location Y i on the three-dimensional image relative to the coordinate frame Y as a fiducial pair (X i , Y i ); and
f) using at least two fiducial pairs (X i , Y i ) to generate a mapping function ƒ that transforms points within the coordinate frame X to the coordinate frame Y such that, for each fiducial pair (X i , Y i ), an error function ƒ(X i )−Y i ≈0, wherein the step of using the at least two fiducial pairs to generate a mapping function comprises using a radial basis function networks algorithm to generate the mapping function, wherein the radial basis function networks algorithm compensates for inhomogeneities in the catheter navigation system such that, for each fiducial pair (X i , Y i ), the error function ƒ(X i )−Y i ≈0.
8. The method according to claim 1 , wherein the tool comprises a catheter including at least one localization element that can be localized by the catheter navigation system.
9. The method according to claim 8 , further comprising:
g) localizing the at least one localization element within the coordinate frame X using the catheter navigation system;
h) transforming the localization of the at least one localization element into the coordinate frame Y using the mapping function ƒ, and i) depicting a graphical representation of the tool in the three-dimensional image of at least a portion of a heart.