Image registration apparatus

• US 8,995,777 B2
• Filed: 11/24/2011
• Issued: 03/31/2015
• Est. Priority Date: 12/02/2010
• Status: Active Grant

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Peters, Jochen, Weese, Juergen, Lehmann, Helko
• Primary Examiner(s): Koziol, Stephen R
• Assistant Examiner(s): Saini, Amandeep
• Application Number:
  US13/990,530
• Publication Number:
  US 20130266230A1
• Time in Patent Office: 1,223 Days
• Field of Search: None
• US Class Current: 382/224
• CPC Class Codes: G06T 2207/10072 Tomographic images
• CPC Class Codes: G06T 2207/20016 Hierarchical, coarse-to-fine, multiscale or multiresolution image processing; Pyramid transform
• CPC Class Codes: G06T 2207/30048 Heart; Cardiac
• CPC Class Codes: G06T 7/344 involving models
• CPC Class Codes: G06T 7/75 involving models

Abstract

The invention relates to an image registration apparatus for registering a first image and a second image with respect to each other. A model, which has a fixed topology, is adapted to the first image for generating a first adapted model and to the second image for generating a second adapted model, and corresponding image elements (40, 48, 49; 50, 58, 9) are determined in the first image and in the second image based on spatial positions of first image elements in the first image with respect to the first adapted model and spatial positions of second image elements in the second image with respect to the second adapted model. Since the model has a fixed topology, corresponding image elements can relatively reliably be found based on the adapted models, even if the first and second images show objects having complex properties like a heart, thereby improving the registration quality.

Claims

1. An image registration apparatus for registering a first image and a second image with respect to each other, the image registration apparatus comprising:

an image providing unit for providing a first image of a first object and a second image of a second object, wherein the first object and the second object are of the same type,

a model providing unit for providing a model of the first object and of the second object, wherein a number of model elements of the model and neighboring relations between the model elements are fixed,

an adaptation unit for adapting the model to the first image for generating a first adapted model and to the second image for generating a second adapted model, wherein the adaptation unit is adapted to determine an internal energy by registering a shape model with the provided model and by determining deviations between the shape model and the provided model for adapting the provided model to the first image and to the second image, and

a corresponding image elements determining unit for determining corresponding image elements in the first image and in the second image based on spatial positions of first image elements in the first image with respect to the first adapted model and spatial positions of second image elements in the second image with respect to the second adapted model.

2. The image registration apparatus as defined in claim 1, wherein the model comprises a first structure and a second structure coupled to the first structure.

3. The image registration apparatus as defined in claim 2, wherein the first structure is an outer surface structure and the second structure is an inner structure.

4. The image registration apparatus as defined in claim 3, wherein the outer surface structure is an outer surface mesh.

5. The image registration apparatus as defined in claim 3, wherein the inner structure is a volumetric mesh.

6. The image registration apparatus as defined in claim 2, wherein the adaptation unit is adapted to

generate the first adapted model by adapting the first structure to the first object and by adapting the second structure using the adapted first structure as boundary condition, and

generate the second adapted model by adapting the first structure to the second object and by adapting the second structure using the adapted first structure as boundary condition.

7. The image registration apparatus as defined in claim 6, wherein the adaptation unit is adapted to adapt the second structure such that the internal energy of the second structure is minimized.

8. The image registration apparatus as defined in claim 1, wherein the corresponding image elements determining unit is adapted to determine a transformation which transforms features of the first adapted model to corresponding features of the second adapted model and to determine corresponding image elements in the first image and in the second image based on the determined transformation.

9. The image registration apparatus as defined in claim 1, wherein the first adapted model and the second adapted model are each comprised of model elements, wherein the corresponding image elements determining unit is adapted to determine a second image element of the second image, which corresponds to a provided first image element of the first image, by performing following steps:

determining a first model element comprising the first image element of the first image, wherein the first model element is a model element of the first adapted model,

determining a second model element being a model element of the second adapted model, wherein the second model element is determined such that it corresponds to the determined first model element,

defining a first local coordinate system in the first model element and a second local coordinate system in the second model element with respect to features which are common to the first model element and the second model element,

determining a transformation between the first local coordinate system and the second local coordinate system based on positions of the common features in the first image and in the second image,

determining the position of the first image element in the first local coordinate system,

determining the position of a second image element of the second image, which corresponds to the first image element, in the second local coordinate system depending on the determined position of the first image element in the first local coordinate system and the determined transformation.

10. The image registration apparatus as defined in claim 1, wherein a location is indicated in the provided model and wherein the corresponding image elements determining unit is adapted to determine corresponding image elements in the first image and in the second image, which correspond to the location indicated in the provided model, based on the first adapted model and the second adapted model.

11. The image registration apparatus as defined in claim 10, wherein a value is assigned to the location indicated in the provided model and wherein the image registration apparatus further comprises an assigning unit for assigning the value to the image elements of the first image and the second image, which correspond to the location.

12. The image registration apparatus as defined in claim 1, wherein the image registration apparatus further comprises an image value processing unit for processing the image values of the corresponding image elements.

13. The image registration apparatus as defined in claim 12, wherein

the image value processing unit is adapted to generate a processed value depending on the image values of the corresponding image elements,

the corresponding image elements determining unit is adapted to determine a location within the provided model, which corresponds to the corresponding image elements, depending on the spatial position of at least one of the first image element with respect to the first adapted model and of the second image element with respect to the second adapted model,

the image registration apparatus further comprises an assigning unit for assigning the processed value to the determined location within the provided model.

14. An image registration method for registering a first image and a second image with respect to each other, the image registration method comprising:

providing a first image of a first object and a second image of a second object, wherein the first object and the second object are of the same type,

providing a model of the first object and of the second object, wherein a number of model elements of the model and neighboring relations between the model elements are fixed,

adapting the model to the first image for generating a first adapted model and to the second image for generating a second adapted model, wherein an internal energy is determined by registering a shape model with the provided model and by determining deviations between the shape model and the provided model for adapting the provided model to the first image and to the second image, and

determining corresponding image elements in the first image and in the second image based on spatial positions of first image elements in the first image with respect to the first adapted model and spatial positions of second image elements in the second image with respect to the second adapted model.

15. A non-transitory computer readable medium encoded with computer executable instruction of an image registration computer program, which, when executed by a computer, causes the computer to:

provide a first image of a first object and a second image of a second object, wherein the first object and the second object are of the same type,

provide a model of the first object and of the second object, wherein a number of model elements of the model and neighboring relations between the model elements are fixed,

adapt the model to the first image for generating a first adapted model and to the second image for generating a second adapted model, wherein the adaptation unit is adapted to determine an internal energy by registering a shape model with the provided model and determining deviations between the shape model and the provided model for adapting the provided model to the first image and to the second image, and

determine corresponding image elements in the first image and in the second image based on spatial positions of first image elements in the first image with respect to the first adapted model and spatial positions of second image elements in the second image with respect to the second adapted model.

16. The non-transitory computer readable medium of claim 15, wherein the model comprises a first structure and a second structure coupled to the first structure.

17. The non-transitory computer readable medium of claim 16, wherein the first structure is an outer surface structure and the second structure is an inner structure.

18. The non-transitory computer readable medium of claim 17, wherein the outer surface structure is an outer surface mesh.

19. The non-transitory computer readable medium of claim 17, wherein the inner structure is a volumetric mesh.

20. The non-transitory computer readable medium of claim 16, wherein executing the computer executable instruction causes the computer further to:

generate the first adapted model by adapting the first structure to the first object and by adapting the second structure using the adapted first structure as boundary condition, and

generate the second adapted model by adapting the first structure to the second object and by adapting the second structure using the adapted first structure as boundary condition.