System and method for fused PET-CT visualization for heart unfolding

• US 20060235294A1
• Filed: 04/11/2006
• Published: 10/19/2006
• Est. Priority Date: 04/19/2005
• Status: Active Grant

• Current Assignee: Siemens Medical Solutions USA Incorporated (Siemens AG)
• Original Assignee: Siemens Medical Solutions USA Incorporated (Siemens AG)
• Inventors: Moreau-Gobard, Romain, Florin, Charles
• Granted Patent: US 7,813,535 B2
• Time in Patent Office: Days
• US Class Current: 600/425
• CPC Class Codes: A61B 5/05 Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves impedance plethysmography A61B5/0295; measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24

Abstract

A method for fusing two digitized image datasets for 2-dimensional visualization of the heart, includes providing a first digitized image and a second digitized image, each image acquired from a different imaging modality and each comprising a plurality of intensities corresponding to a domain of points on a 3-dimensional grid, and wherein the first and second images have been registered, segmenting the heart in one of said digitized images, forming a 2-dimensional maximum intensity projection of a surface of said heart from each of said digitized images, and fusing said images by overlaying one 2-dimensional projection of said surface over the other 2-dimensional projection of said surface.

Claims

1. A method of fusing two digitized image datasets for 2-dimensional visualization of the heart, comprising the steps of:

providing a first digitized image and a second digitized image, each image acquired from a different imaging modality and each comprising a plurality of intensities corresponding to a domain of points on a 3-dimensional grid, and wherein the first and second images have been registered;

segmenting the heart in one of said digitized images;

forming a 2-dimensional maximum intensity projection of a surface of said heart from each of said digitized images; and

fusing said images by overlaying one 2-dimensional projection of said surface over the other 2-dimensional projection of said surface.

2. The method of claim 1, wherein one of said images is acquired from a positron emission tomography (PET) scan, and the other of said two images is acquired from a computed tomography (CT) scan.

3. The method of claim 2, wherein the heart is segmented in the CT image.

4. The method of claim 1, wherein the heart segmentation identifies the surface of the heart.

5. The method of claim 4, further comprising forming a distance map that associates with each point in said heart a distance from said point to the surface of the heart.

6. The method of claim 5, further comprising using said distance map to model the heart surface by a 3-dimensional ellipsoid.

7. The method of claim 6, wherein said 3-dimensional ellipsoid is a bi-axial ellipsoid wherein a center is computed as a center of gravity G of all points located on a distance map isosurface of distance 0, a major axis Z is a vector {right arrow over (G)}_M, where M is a point on said isosurface maximizing the length |{right arrow over (G)}_M|, a minor axis X is a vector {right arrow over (G)}_N, where N is a point on said isosurface minimizing the length |{right arrow over (G)}_N|, and a third axis Y orthogonal to said axes Z and X.

8. The method of claim 6, wherein forming said 2-dimensional maximum intensity projection comprises casting rays from said ellipsoidal surface into said heart to form said 2-dimensional projection, wherein an intensity of a point I(X)=I(u,v) on said 2D projection is a normalized sum of each intensity, I_n along the ray

9. The method of claim 6, comprising using a transverse Mercator projection for forming said 2-dimensional maximum intensity projection of said heart surface from said ellipsoid.

10. The method of claim 3, wherein forming said 2-dimensional maximum intensity projection of said heart surface using said PET image comprises computing corresponding points on said heart surface in said PET image from said CT image using said registration, selecting points on the surface in said PET image, along with points slightly inside the heart and slightly outside the heart, and summing and averaging intensity values along rays cast through said selected points.

11. A method of fusing two digitized image datasets for 2-dimensional visualization of the heart, comprising the steps of:

providing a digitized computed tomography (CT) image and a digitized positron emission tomography (PET) image, each image comprising a plurality of intensities corresponding to a domain of points on a 3-dimensional grid;

segmenting the heart surface in said CT image;

modeling the heart surface with a 3-dimensional ellipsoid and forming a 2-dimensional projection of said heart surface from each of said digitized images; and

overlaying a 2-dimensional projection from said CT image over a 2-dimensional projection from said PET image.

12. The method of claim 11, further comprising registering said segmented heart surface from the CT image onto the PET image wherein correspondence formulae from the CT image to the PET image are obtained.

13. The method of claim 12, wherein forming a 2-dimensional projection of said heart surface from said CT image comprises casting rays from said ellipsoid into said heart to form a maximum intensity projection of said heart surface, wherein coordinates of the rays are saved.

14. The method of claim 13, wherein forming a 2-dimensional projection of said heart surface from said PET image comprises applying said correspondence formulae to said saved ray coordinates from said CT image to said PET image.

15. A program storage device readable by a computer, tangibly embodying a program of instructions executable by the computer to perform the method steps for fusing two digitized image datasets for 2-dimensional visualization of the heart, comprising the steps of:

providing a first digitized image and a second digitized image, each image acquired from a different imaging modality and each comprising a plurality of intensities corresponding to a domain of points on a 3-dimensional grid, and wherein the first and second images have been registered;

segmenting the heart in one of said digitized images;

forming a 2-dimensional maximum intensity projection of a surface of said heart from each of said digitized images; and

fusing said images by overlaying one 2-dimensional projection of said surface over the other 2-dimensional projection of said surface.

18. The computer readable program storage device of claim 15, wherein the heart segmentation identifies the surface of the heart.

19. The computer readable program storage device of claim 18, the method further comprising forming a distance map that associates with each point in said heart a distance from said point to the surface of the heart.

20. The computer readable program storage device of claim 19, the method further comprising using said distance map to model the heart surface by a 3-dimensional ellipsoid.

21. The computer readable program storage device of claim 20, wherein said 3-dimensional ellipsoid is a bi-axial ellipsoid wherein a center is computed as a center of gravity G of all points located on a distance map isosurface of distance 0, a major axis Z is a vector {right arrow over (G)}_M, where M is a point on said isosurface maximizing the length |{right arrow over (G)}_M|, a minor axis X is a vector {right arrow over (G)}_N, where N is a point on said isosurface minimizing the length |{right arrow over (G)}_N|, and a third axis Y orthogonal to said axes Z and X.

22. The computer readable program storage device of claim 20, wherein forming said 2-dimensional maximum intensity projection comprises casting rays from said ellipsoidal surface into said heart to form said 2-dimensional projection, wherein an intensity of a point I(X)=I(u,v) on said 2D projection is a normalized sum of each intensity, I_n along the ray

23. The computer readable program storage device of claim 20, the method further comprising using a transverse Mercator projection for forming said 2-dimensional maximum intensity projection of said heart surface from said ellipsoid.

16. The computer readable program storage device of claim 16, wherein one of said images is acquired from a positron emission tomography (PET) scan, and the other of said two images is acquired from a computed tomography (CT) scan.

17. The computer readable program storage device of claim 16, wherein the heart is segmented in the CT image.

24. The computer readable program storage device of claim 17, wherein forming said 2-dimensional maximum intensity projection of said heart surface using said PET image comprises computing corresponding points on said heart surface in said PET image from said CT image using said registration, selecting points on the surface in said PET image, along with points slightly inside the heart and slightly outside the heart, and summing and averaging intensity values along rays cast through said selected points.