Real-time anatomically based deformation mapping and correction

1. A method, comprising:

generating a real-time ultrasound image of an anatomy of interest of a subject being scanned, wherein at least a first sub-portion of the anatomy of interest is deformed from an initial location to a different location by pressure applied by an external force and a second sub-portion of the anatomy of interest is not deformed by the pressure applied by the external force;

obtaining, during a scan, a 2-D slice, which corresponds to a same plane as the real-time ultrasound image, from previously acquired 3-D reference image data, wherein corresponding first and second sub-portions are at the initial location in the 2-D slice;

measuring a first distance between a contour of the first sub-portion and a contour of the second sub-portion in the real-time ultrasound image;

measuring a second distance between a contour of the first sub-portion and a contour of the second sub-portion in the 2-D slice;

determining a differential displacement of the first sub-portion from the first distance and the second distance; and

deforming, during the scan, the previously acquired 3-D reference image data based on the differential displacement to create deformed 3-D reference image data;

combining the real-time ultrasound image with the deformed 3-D reference image data at a corresponding plane in the previously acquired 3-D reference image data; and

displaying the combined data, wherein the combined data is used to navigate a probe to a tissue of interest in the anatomy of interest.

2. The method of claim 1 , wherein deforming the 3-D reference image data includes re-positioning the first sub-portion in the 3-D previously acquired reference image data at a location in the 3-D reference image data that corresponds to the different location.

3. The method of claim 1 , further comprising:

identifying the contour of the first sub-portion in the real-time ultrasound image; identifying the contour of the second sub-portion in the real-time ultrasound image;

identifying the contour of the first sub-portion in the 2-D slice; and identifying the contour of the second sub-portion in the 2-D slice.

4. The method of claim 1 , wherein the real-time ultrasound image and the previously acquired 3-D reference image data include an undeformed structure, and further comprising:

determining the differential displacement based on the undeformed structure.

5. The method of claim 1 , wherein the differential displacement represents an indentation along, at least, a finite length of an image plane.

6. The method of claim 1 , wherein the deforming of the previously acquired 3-D reference image data includes mapping anatomical structures within the previously acquired 3-D reference image data based on the differential displacement.

7. The method of claim 1 , wherein the deforming of the previously acquired 3-D reference image data includes employing directional derivatives of the differential displacement relative to a maximum displacement vector of a probe plane.

8. The method of claim 7 , further comprising:

using one of cylindrical symmetry of the directional derivatives and a smooth transition between two differing derivatives orthogonal to a single plane.

9. The method of claim 1 , further comprising:

deriving gradients for intervening directions using gradients in two orthogonal half planes for two planes with differing gradients.

10. A non-transitory computer readable medium encoded with computer executable instructions, which, when executed by a computer processor, causes the processor to:

generate a real-time ultrasound image of an anatomy of interest of a subject being scanned, wherein at least a first sub-portion of the anatomy of interest is deformed from an initial location to a different location by pressure applied by an external force and a second sub-portion of the anatomy of interest is not deformed by the pressure applied by the external force;

obtain, during a scan, a 2-D slice, which corresponds to a same plane as the real-time ultrasound image, from previously acquired 3-D reference image data, wherein corresponding first and second sub-portions are at the initial location in the 2-D slice;

measure a first distance between a contour of the first sub-portion and a contour of the second sub-portion in the real-time ultrasound image;

measure a second distance between a contour of the first sub-portion and a contour of the second sub-portion in the 2-D slice;

determine a differential displacement of the first sub-portion from the first distance and the second distance; and

deform, during the scan, the previously acquired 3-D reference image data based on the differential displacement to create deformed 3-D reference image data;

combine the real-time ultrasound image with the deformed 3-D reference image data at a corresponding plane in the previously acquired 3-D reference image data; and

display the combined data, wherein the combined data is used to navigate a probe to a tissue of interest in the anatomy of interest.

11. The non-transitory computer readable medium of claim 10 , wherein the computer executable instructions further cause the processor to:

determine the differential displacement based on undeformed structures.

12. The non-transitory computer readable medium of claim 10 , wherein the computer executable instructions further cause the processor to:

deform the previously acquired 3-D reference image data using directional derivatives of the differential displacement relative to a maximum displacement vector of a probe plane.

13. The non-transitory computer readable medium of claim 12 , wherein the computer executable instructions further cause the processor to:

derive gradients for intervening directions using gradients in two orthogonal half planes for two planes with differing gradients.

14. An apparatus, comprising:

a beamformer configured to generate a real-time ultrasound image of an anatomy of interest of a subject being scanned, wherein at least a first sub-portion of the anatomy of interest is deformed from an initial location to a different location by pressure applied by an external force and a second sub-portion of the anatomy of interest is not deformed by the pressure applied by the external force;

a 3-D reference image data memory that stores 3-D reference image data of a volume of interest; and

a processor configured to:

obtain, during a scan, a 2-D slice, which corresponds to a same plane as the real-time ultrasound image, from the stored 3-D reference image data, wherein corresponding first and second sub-portions in the stored 3-D reference image data are at the initial location;

measure a first distance between a contour of the first sub-portion and a contour of the second sub-portion in the real-time ultrasound image;

measure a second distance between a contour of the first sub-portion and a contour of the second sub-portion in the 2-D slice;

determine a differential displacement of the first sub-portion from the first distance and the second distance; and

deform, during the scan, the stored 3-D reference image data based on the differential displacement to create deformed 3-D reference image data;

combine the real-time ultrasound image with the deformed 3-D reference image data at a corresponding plane in the previously acquired 3-D reference image data; and

display the combined data, wherein the combined data is used to navigate a probe to a tissue of interest in the anatomy of interest.

15. The apparatus of claim 14 , wherein the processor warps the stored 3-D reference image data to create the deformed 3-D reference image data.

16. The apparatus of claim 14 , wherein the processor deforms the stored 3-D reference image data based on a decay of the displacement.

17. The apparatus of claim 16 , wherein the decay is represented by (∂U → _y/∂z _+, where the “+” sign indicates a positive coordinate axis direction of a coordinate system tied to the center of a hemispherical cap and with a different axis intersecting an image plane.

18. The apparatus of claim 14 , wherein the processor determines the differential displacement based only on the contour of the first sub-portion in the real-time ultrasound image, the contour of the first sub-portion in the 2-D slice, the contour of the second sub-portion in the real-time ultrasound image, and the contour of the second sub-portion in the 2-D slice.