DIFFUSION WEIGHTED IMAGE PROCESSING APPARATUS AND RECORDING MEDIUM FOR RECORDING IMAGE ANALYSIS PROGRAM

Abstract

It is an object to provide a diffusion weighted image processing apparatus or the like which can correct a distortion of a diffusion weighted image requiring smaller endurance on a patient in a diffusion weighted image processing method for correcting distortion of a diffusion weighted image. The diffusion weighted image processing apparatus has a correcting device which relatively corrects, with mutual reference among two or more diffusion weighted images having different directions of gradient field pulses during imaging, distortions occurring in the directions of the gradient field pulses during the imaging of the diffusion weighted images, the distortion being caused by the gradient field pulse of the diffusion weighted image.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the configuration of a diffusion weighted image processing apparatus of the present invention;

FIG. 2 is a flowchart showing image processing according to Embodiment 1 of image processing;

FIG. 3 is explanatory drawing showing a feature point determining approach;

FIG. 4 is a flowchart showing image processing according to Embodiment 2 of image processing;

FIG. 5 is a flowchart showing acquisition of distortion amount Warp[i];

FIG. 6 is an explanatory drawing showing calculation of feature quantity CV[p,q] of local region ROI[p,q];

FIG. 7A is a flowchart showing calculation of feature quantity CV[p,q][i] of local region ROI[p,q];

FIGS. 7B to 7D are explanatory drawings showing calculation of feature quantities of various local regions ROI;

FIGS. 8A to 8E are explanatory drawings showing features of distortions of diffusion weighted images;

FIGS. 9A and 9B are explanatory drawings showing feature points;

FIG. 10 is a flowchart showing acquisition of distortion amounts Warp[z][i] on feature points Z1 and Z2 relative to each image;

FIGS. 11A to 11C are explanatory drawings showing acquisition of distortion amounts Warp [z][i] on the feature points Z1 and Z2 relative to each image;

FIG. 12 is an explanatory drawing showing acquisition of distortion amounts Warp[z][i] on the feature points Z1 and Z2 relative to each image;

FIGS. 13A to 13C are diagrams schematically showing an array of distortion amounts Warp[z][i] on each feature point Z;

FIGS. 14A and 14B are explanatory drawings showing interpolation of distortion amounts Warp[p,q][i];

FIG. 15 is a flowchart showing superimposition of n images;

FIG. 16 is an explanatory drawing showing mutual correction of four images; and

FIG. 17 is a flowchart showing acquisition of distortion amount Warp according to Embodiment 3 of image processing.

Claims

1. A diffusion weighted image processing apparatus, comprising a correcting device which relatively corrects, with mutual reference among two or more diffusion weighted images having different directions of gradient field pulses during imaging, distortions occurring in the directions of the gradient field pulses during the imaging of the diffusion weighted images, the distortion being caused by the gradient field pulse of the diffusion weighted image.

2. The diffusion weighted image processing apparatus according to claim 1, further comprising: a first dividing device for dividing the diffusion weighted image into two or more band like regions along the direction of the gradient field pulse obtained during the imaging of the diffusion weighted image, and further dividing the band like region into two or more divided regions, anda searching device for searching for, by pattern matching, at least two or more divided regions in each of the band like regions and regions corresponding to the divided regions on an other diffusion weighted image,wherein the correcting device refers to the corresponding regions and corrects the divided regions of the diffusion weighted image based on the directions of the gradient field pulses of the diffusion weighted image and the other diffusion weighted image.

3. The diffusion weighted image processing apparatus according to claim 1, further comprising: a second dividing device for dividing the diffusion weighted image into two or more band like regions along the direction of the gradient field pulse obtained during the imaging of the diffusion weighted image,a feature point determining device for determining at least two feature points representing the features of the image in each of the band like regions of the diffusion weighted image, anda corresponding point obtaining device for searching for, by pattern matching on the other diffusion weighted image, a region corresponding to a local region around the feature point, and obtaining a point on the found corresponding region as a corresponding point of the feature point,wherein the correcting device corrects the feature points based on a position coordinate of the corresponding point and the directions of the gradient field pulses of the diffusion weighted image and the other diffusion weighted image, and corrects regions other than the band like region including the feature points of the diffusion weighted image by using the corrected feature points.

4. The diffusion weighted image processing apparatus according to claim 1, further comprising: a second dividing device for dividing the diffusion weighted image into two or more band like regions along the direction of the gradient field pulse obtained during the imaging of the diffusion weighted image,a feature point determining device for determining at least two feature points representing the features of the image in each of the band like regions of the diffusion weighted image,a corresponding point obtaining device for searching for, by pattern matching on the other diffusion weighted image, a region corresponding to a local region around the feature point, and obtaining a point on the found corresponding region as a corresponding point of the feature point, anda feature point distortion amount obtaining device for obtaining a distortion amount for each of the feature points based on a position coordinate of the corresponding point and the directions of the gradient field pulses of the diffusion weighted image and the other diffusion weighted image,wherein the correcting device corrects the diffusion weighted image for each of the band like regions by using the distortion amount of the feature point belonging to the band like region.

5. The diffusion weighted image processing apparatus according to claim 1, further comprising: a superimposing device for generating a composite image by superimposing the diffusion weighted images having been corrected by the correcting device.

6. The diffusion weighted image processing apparatus according to claim 1, wherein the apparatus has a feature resulted from the gradient field pulse and the feature is image enhancement based on anisotropy of dispersion of a water molecule depending upon the direction of the gradient field pulse during the imaging of the diffusion weighted image.

7. A recording medium for recording an image processing program readable by a computer, the program causing the computer to act as a correcting device which relatively corrects, with mutual reference among two or more diffusion weighted images having different directions of gradient field pulses during imaging, distortions occurring in the directions of the gradient field pulses during the imaging of the diffusion weighted images, the distortion being caused by the gradient field pulse of the diffusion weighted image.

8. The recording medium for recording an image processing program according to claim 7, wherein the image processing program causes the computer to act as: a first dividing device for dividing the diffusion weighted image into two or more band like regions along the direction of the gradient field pulse obtained during the imaging of the diffusion weighted image, and further dividing the band like region into two or more divided regions, anda searching device for searching for, by pattern matching, at least two or more divided regions in each of the band like regions and regions corresponding to the divided regions on an other diffusion weighted image,wherein the image processing program causes the correcting device to refer to the corresponding regions and correct the divided regions of the diffusion weighted image based on the directions of the gradient field pulses of the diffusion weighted image and the other diffusion weighted image, and causes the correcting device to correct regions other than the band like region including the feature points of the diffusion weighted image by using the corrected feature points.

9. The recording medium for recording an image processing program according to claim 7, wherein the image processing program causes the computer to act as: a second dividing device for dividing the diffusion weighted image into two or more band like regions along the direction of the gradient field pulse obtained during the imaging of the diffusion weighted image,a feature point determining device for determining at least two feature points representing the features of the image in each of the band like regions of the diffusion weighted image, anda corresponding point obtaining device for searching for, by pattern matching on the other diffusion weighted image, a region corresponding to a local region around the feature point, and obtaining a point on the found corresponding region as a corresponding point of the feature point,wherein the image processing program causes the correcting device to correct the feature points based on a position coordinate of the corresponding point and the directions of the gradient field pulses of the diffusion weighted image and the other diffusion weighted image.

10. The recording medium for recording an image processing program according to claim 7, wherein the image processing program causes the computer to act as: a second dividing device for dividing the diffusion weighted image into two or more band like regions along the direction of the gradient field pulse obtained during the imaging of the diffusion weighted image,a feature point determining device for determining at least two feature points representing the features of the image in each of the band like regions of the diffusion weighted image,a corresponding point obtaining device for searching for, by pattern matching on the other diffusion weighted image, a region corresponding to a local region around the feature point, and obtaining a point on the found corresponding region as a corresponding point of the feature point, anda feature point distortion amount obtaining device for obtaining a distortion amount for each of the feature points based on a position coordinate of the corresponding point and the directions of the gradient field pulses of the diffusion weighted image and the other diffusion weighted image,wherein the image processing program causes the correcting device to correct each of the band like regions by using the distortion amount of the feature point belonging to the band like region.

11. The recording medium for recording an image processing program according to claim 7, wherein the image processing program causes the computer to act as a superimposing device for generating a composite image by superimposing the diffusion weighted images having been corrected by the correcting device.

12. The recording medium for recording an image processing program according to claim 7, wherein the recording medium has a feature resulted from the gradient field pulse and the feature is image enhancement based on anisotropy of dispersion of a water molecule depending upon the direction of the gradient field pulse during the imaging of the diffusion weighted image.