Registration method with three-dimensional representation of a vascular tree as a function of blood flow
A three-dimensional volume data record contains a vascular tree. A two-dimensional projection image is an image of an actual fill state, to which the vascular tree is filled with a contrast agent at an acquisition time. The volume data record and the projection image are registered in relation to one another by means of the set of imaging parameters. A computation facility determines an expected target fill state, which describes which parts of the vascular tree should be filled with contrast agent at acquisition time in the three-dimensional volume data record. The computation facility determines the set of imaging parameters based on the target fill state and the projection image.
1. A method for determining an imaging parameter for registering a three-dimensional volume data record of an object comprising a vascular tree with a two-dimensional projection image of the object comprising the vascular tree being filled with a contrast agent at an acquisition time, comprising:
determining a target fill state time describing which parts of the vascular tree are filled with the contrast agent in the three-dimensional volume data record at the acquisition time; and
determining the imaging parameter based on the target fill state and the two-dimensional projection image for registering the volume data record with the projection image,
wherein:
the volume data record comprises voxels being assigned to the vascular tree,
the target fill state indicates whether the voxels are filled with the contrast agent at the acquisition time,
the projection image comprises pixels being filled with the contrast agent,
the voxels filled with the contrast agent at the acquisition time are mapped into the projection image,
a number of the voxels that are filled with the contrast agent in the volume data record and mapped into the projection image is determined, and
the imaging parameter is determined to maximize the number of the voxels.
2. The method as claimed in claim 1 , wherein a further two-dimensional projection image comprising the vascular tree being filled with the contrast agent is recorded at a further acquisition time.
3. The method as claimed in claim 2 , wherein the target fill state is determined based on the further two-dimensional projection image and a further imaging parameter for the further projection image.
4. The method as claimed in claim 2 , wherein the projection image and the further projection image are recoded with an identical recording imaging parameter.
5. The method as claimed in claim 2 , wherein projection image and the further projection image are recorded with different recording imaging parameters.
6. The method as claimed in claim 2 , wherein the acquisition time and the further acquisition time are identical.
7. The method as claimed in claim 2 , wherein the acquisition time and the further acquisition time are different.
8. The method as claimed in claim 7 , wherein:
an initial fill state is determined based on the further projection image and the further imaging parameter for the further projection image,
the initial fill state describes which parts of the vascular tree are filled with the contrast agent in the three-dimensional volume data record at the further acquisition time, and
the target fill state is determined by a temporal extrapolation of the initial fill state.
9. The method as claimed in claim 8 , wherein the imaging parameter is iteratively determined based on a last-determined imaging parameter and a temporally subsequent recorded projection image.
10. The method as claimed in claim 9 , wherein the imaging parameter is limited in a parameter space.
11. The method as claimed in claim 1 , wherein:
a number of the pixels being filled with the contrast agent in the projection image is determined, and
a ratio of the number of the voxels filled with the contrast agent in the volume data record and mapped into the projection image to the number of the pixels filled with the contrast agent in the projection image is calculated, and
whether a further iteration is carried out is determined based on the ratio so that an optimum imaging parameter is determined.
12. The method as claimed in claim 1 , wherein the imaging parameter is determined using an elastic registration method.
13. The method as claimed in claim 1 , wherein the projection image is a digital subtraction angiography image.
14. A memory device for storing a computer program in a machine readable form for determining an imaging parameter for registering a three-dimensional volume data record of an object comprising a vascular tree with a two-dimensional projection image of the object comprising the vascular tree being filled with a contrast agent at an acquisition time, comprising:
a computer program that:
determines a target fill state time describing which parts of the vascular tree are filled with the contrast agent in the three-dimensional volume data record at the acquisition time; and
determines the imaging parameter based on the target fill state and the two-dimensional projection image for registering the volume data record with the projection image,
wherein:
the volume data record comprises voxels being assigned to the vascular tree,
the target fill state indicates whether the voxels are filled with the contrast agent at the acquisition time,
the projection image comprises pixels being filled with the contrast agent,
the voxels filled with the contrast agent at the acquisition time are mapped into the projection image,
a number of the voxels that are filled with the contrast agent in the volume data record and mapped into the projection image is determined, and
the imaging parameter is determined to maximize the number of the voxels.
15. A computer for determining an imaging parameter for registering a three-dimensional volume data record of an object comprising a vascular tree with a two-dimensional projection image of the object comprising the vascular tree being filled with a contrast agent at an acquisition time, comprising:
a processing unit that:
determines a target fill state time describing which parts of the vascular tree are filled with the contrast agent in the three-dimensional volume data record at the acquisition time; and
determines the imaging parameter based on the target fill state and the two-dimensional projection image for registering the volume data record with the projection image,
wherein:
the volume data record comprises voxels being assigned to the vascular tree,
the target fill state indicates whether the voxels are filled with the contrast agent at the acquisition time,
the projection image comprises pixels being filled with the contrast agent,
the voxels filled with the contrast agent at the acquisition time are mapped into the projection image,
a number of the voxels that are filled with the contrast agent in the volume data record and mapped into the projection image is determined, and
the imaging parameter is determined to maximize the number of the voxels.