Flexible image registration for rotational angiography

Claim 2

A digital subtraction angiography method useful for rotational 2D imaging of a selected volume of a body, comprising the following steps: acquiring first and second volumes of 2D data sets representative of a series of rotationally offset 2D images of substantially the same selected volume in the body, the first and second data sets being acquired at different times corresponding to a pre- and a post, respectively, application of a process to the body to differentially affect imaging characteristics of the selected volume; determining common reference points for spatially corresponding sub-areas in each image of the series of rotationally offset 2D images in the first and second data sets; comparing in a 3D spatial manner data in sub-areas of the second data set with data in corresponding sub-areas in at least two of the rotationally offset 2D images of the first data set in order to determine a new reference point in each of the sub-areas of the first data set which results in a best match of the spatial similarity of the data in a corresponding sub-area of the second data set; spatially interpolating new data for sub-areas of the first data set using the new reference points determined above and the originally acquired data of the first data set, thereby generating a new first data set for the selected volume; and subtracting the new first data set from the second data set, thereby generating a subtraction data set representative of a series of 2D images of the selected volume in which the given portion is accentuated.

Claim 3

The method of claim 1, comprising the further step of applying said subtracted data set to a display device for displaying an image on said display device of said selected volume wherein said given portion is accentuated.

Claim 4

The method of claim 1, wherein said comparing step comprises 3D transformation of the spatial positioning of the data in said first data set before performing said comparing.

Claim 5

The method of claim 1, wherein said acquiring step includes a processing step for developing a gradient function of the data in said first and second data sets, and said comparing step comprises 3D transformation of the spatial positioning of the gradient function of the data in said first data set and comparing with the result of the gradient function applied to the data in said second data set.

Claim 6

The method of claim 3, wherein said 3D transformation step comprises 3D translation, 2D rotation, and 2D scaling in discreet fractional steps of the spatial positioning of the data in said first data set.

Claim 7

The method of claim 5, wherein said spatial interpolating step comprises tri-linear interpolation.

Claim 8

The method of claim 1, wherein said determining and comparing steps are iteratively repeated until a best match criterion is satisfied, and then said new reference point is determined.

Claim 9

The method of claim 7, wherein said best match criterion comprises a maximization of a stochastic-sign-change function.

Claim 10

The method of claim 7, wherein said best match criterion comprises a maximization of a deterministic-sign-change function.

Claim 11

The method of claim 7, wherein said best match criterion comprises a minimization of the sum of squared differences.

Claim 12

The method of claim 7, wherein said best match criterion comprises a minimization of the sum of absolute differences.

Claim 13

The method of claim 9, wherein a checkerboard pattern is added to the result of said comparing step before evaluation of the deterministic-sign-change function.

Claim 14

The method of claim 1, wherein said acquiring step comprises exposing said selected volume to x-ray beams before and after injection of an x-ray contrast agent into blood vessels of said body, and determining respective first and second data sets of intensity values representative of a series of sequential images of said patient through said selected volume.

Claim 15

A digital subtraction angiography apparatus adapted for rotational 2D imaging of a selected volume of a body, comprising: means for acquiring first and second volumes of 2D data sets representative of a series of rotationally offset 2D images of substantially the same selected volume in the body, the first and second data sets being acquired at different times corresponding to a pre- and a post, respectively, application of a process to the body to differentially affect imaging characteristics of the selected volume; means for determining common reference points for spatially corresponding sub-areas in each image of the series of rotationally offset 2D images in the first and second data sets; means for comparing in a 3D spatial manner data in sub-areas of the second data set with data in corresponding sub-areas in at least two of the rotationally offset 2D images of the first data set in order to determine a new reference point in each of the sub-areas of the first data set which results in a best match of the spatial similarity of the data in a corresponding sub-area of the second data set; means for spatially interpolating new data for sub-areas of the first data set using the new reference points determined above and the originally acquired data of the first data set, thereby generating a new first data set for the selected volume; and means for subtracting the new first data set from the second data set, thereby generating a subtraction data set representative of a series of 2D images of the selected volume in which the given portion is accentuated.

Claim 16

A digital subtraction angiography apparatus adapted for rotational 2D imaging of a selected volume of a body, comprising: means for acquiring first and second volumes of 2D data sets representative of a series of rotationally offset 2D images of substantially the same selected volume in the body, the first and second data sets being acquired at different times corresponding to a pre- and a post, respectively, application of a process to the body to differentially affect imaging characteristics of the selected volume; means for determining common reference points for spatially corresponding sub-areas in each image of the series of rotationally offset 2D images in the first and second data sets; means for comparing in a 3D spatial manner data in sub-areas of the second data set with data in corresponding sub-areas in at least two of the rotationally offset 2D images of the first data set in order to determine a new reference point in each of the sub-areas of the first data set which results in a best match of the spatial similarity of the data in a corresponding sub-area of the second data set; means for spatially interpolating new data for sub-areas of the first data set using the new reference points determined above and the originally acquired data of the first data set, thereby generating a new first data set for the selected volume; and means for subtracting the new first data set from the second data set, thereby generating a subtraction data set representative of a series of 2D images of the selected volume in which the given portion is accentuated.

Claim 17

The apparatus of claim 14, further including a display device responsive to said subtracted data set for displaying an image thereon of said selected volume wherein said given portion is accentuated.

Claim 18

The apparatus of claim 14, wherein said means for comparing includes transformation means for determining a 3D transformation of the spatial positioning of the data in said first data set before performing said comparing.

Claim 19

The apparatus of claim 16, wherein said transformation means includes means for 3D translation, 2D rotation, and 2D scaling in discreet fractional steps of the spatial positioning of the data in said first data set.

Claim 20

The apparatus of claim 14, wherein said acquiring means comprises a rotating x-ray source for exposing said selected volume to x-ray beams at a series of rotationally different angular positions before and after injection of an x-ray contrast agent into blood vessels of said body, and detector and measurement means for determining respective first and second data sets of intensity values representative of a series of 2D images at sequentially different angular positions of said selected volume.