Method for creating a three-dimensional digital subtraction angiography image and a C-arm X-ray device

1. A method for creating a three-dimensional digital subtraction angiography image of a vascular system of a patient, the method comprising:

providing a first reconstructed three-dimensional filling image that was acquired during at least partial contrast agent filling of the vascular system with a first contrast agent;

providing a second reconstructed three-dimensional filling image that was acquired during at least partial contrast agent filling of the vascular system with a second contrast agent; and

subtracting the first reconstructed three-dimensional filling image from the second reconstructed three-dimensional filling image to produce a three-dimensional subtraction angiography image,

wherein the first contrast agent and the second contrast agent differ in that one of the first or second contrast agents causes increased X-ray absorption and the other contrast agent causes reduced X-ray absorption relative to a vascular system without contrast agent.

2. The method of claim 1 , wherein the first or the second reconstructed three-dimensional filling image is corrected by a method for motion compensation in which movement of the vascular system during acquisition of the respective three-dimensional filling image is compensated.

3. The method of claim 1 , wherein one reconstructed three-dimensional filling image of the first or second reconstructed three-dimensional filling images is registered to the other reconstructed three-dimensional filling image basis on orientation points of the vascular system.

4. The method of claim 3 , wherein the orientation points are vessel sections of the vascular system.

5. The method of claim 3 , wherein, as part of the registration, a rotation, a displacement, or a deformation field is first produced which is applied to the corresponding reconstructed three-dimensional filling image.

6. The method of claim 1 , wherein the first contrast agent or the second contrast agent is iodinated and contains carbon dioxide.

7. A method for creating a three-dimensional digital subtraction angiography image of a vascular system of a patient, the method comprising:

providing a first series of projection filling images that were acquired during at least partial contrast agent filling of the vascular system with a first contrast agent;

providing a second series of projection filling images that were acquired during at least partial contrast agent filling of the vascular system with a second contrast agent;

subtracting the first series of projection filling images pairwise from the second series of projection filling images to produce a series of subtraction images; and

reconstructing the series of subtraction images into a three-dimensional reconstructed subtraction angiography image,

wherein the first contrast agent and the second contrast agent differ in that one of the first or second contrast agents causes increased X-ray absorption and the other contrast agent causes reduced X-ray absorption relative to a vascular system without contrast agent.

8. The method of claim 7 , wherein at least one of the reconstructed three-dimensional filling images is corrected by a method for motion compensation in which movement of the vascular system during acquisition of the series of projection filling images is compensated.

9. The method of claim 7 , wherein the projection filling images of one of the first or second series of projection filling images are registered pairwise to the projection filling images of the other series of projection filling images in each case by a two-dimensional/two-dimensional registration technique.

10. The method of claim 9 , wherein the registration is based on orientation points of the vascular system.

11. The method of claim 10 , wherein the orientation points are vessel sections of the vascular system.

12. The method of claim 9 , wherein the registration is carried out based on orientation points of the vascular system which are oppositely opacified.

13. The method of claim 9 , wherein, following the registration, deformation of the projection filling images of one series relative to the projection filling images of the other series is carried out pairwise such that the vessel sections imaged are positioned congruently on the projection filling images after deformation.

14. The method of claim 7 , wherein the series of subtraction images is filtered on a threshold or spatial frequency basis.

15. The method of claim 7 , wherein the first or second contrast agent is iodinated and contains carbon dioxide.

16. A C-arm X-ray device comprising:

an acquisition system comprising:

a C-arm on which an X-ray source and an X-ray detector are mounted, wherein the C-arm is configured to rotate around an object under examination and to acquire a series of projection filling images from a plurality of projection directions during the rotational movement; and

a processing unit having at least one processor and software for processing projection filling images of first and second contrast agents, for subtracting projection filling images, for reconstructing projection filling images into a reconstructed three-dimensional filling image, for two-dimensional/two-dimensional and/or three-dimensional/three-dimensional registration of reconstructed filling images, and for calculating three-dimensional digital subtraction angiography images, wherein the first contrast agent and the second contrast agent differ in that one of the first or second contrast agents causes increased X-ray absorption and the other contrast agent causes reduced X-ray absorption relative to a vascular system without contrast agent; and

a system controller for controlling the C-arm X-ray device; and

a display unit for displaying the subtraction angiography images.