Historical comparison of breast tissue by image processing

• US 6,909,792 B1
• Filed: 06/23/2000
• Issued: 06/21/2005
• Est. Priority Date: 06/23/2000
• Status: Expired due to Fees

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Litton Systems Incorporated
• Inventors: Burke, Thomas M., Carrott, David T.
• Primary Examiner(s): Johns, Andrew W.
• Assistant Examiner(s): Akhavannik, Hussein
• Application Number:
  US09/602,251
• Time in Patent Office: 1,824 Days
• Field of Search: 382128-132, 382/294
• US Class Current: 382/128
• CPC Class Codes: A61B 5/4848 Monitoring or testing the effects of treatment, e.g. of medication
• CPC Class Codes: A61B 6/502 for diagnosis of breast, i.e. mammography
• CPC Class Codes: G06T 2207/30068 Mammography; Breast
• CPC Class Codes: G06T 7/0012 Biomedical image inspection
• CPC Class Codes: G06T 7/32 using correlation-based methods

Abstract

An image processing system and method visually documents and displays changes between historical and later mammographic images, preferably in three dimensions. A composite image is created which visually emphasizes temporal differences between the historical and later images. Preferably three-dimensional, digitized images, displayable in various projections, are stored for archival purposes on computer readable media. An image processor preferably exploits an optical correlator to register the historical and later images accurately and provide correlation values as temporal scalars of the differences. The registered images are then compared, voxel-by-voxel, to detect temporal differences. The composite image is displayed with synthetic colors or other visual clues to emphasize apparent changes (for example, tumor growth or shrinkage).

Claims

1. A method of visually documenting historical changes in biological tissue, comprising the steps of:

(a) obtaining a first image of a region of tissue;

(b) obtaining pathological feature data for said region of tissue;

(c) obtaining a second image of said region of tissue using a first level of resolution;

(d) digitally storing said first and second images as digitized first and second images;

(e) spatially adjusting at least one of said first and second digitized images to spatially register said images so that corresponding features in both images are mapped to corresponding positions, said spatially adjusting comprising;

determining a coordinate transformation which produces at least a pre-determined degree of correlation between said first and second digitized images, and

applying said coordinate transformation to at least one of said first and second digitized images, to align said images;

said coordinate transformation determined by;

applying coordinate transformations of scale, position and rotation to one of said first and second digitized images, to obtain a plurality of corresponding adjusted images,

cross-correlating said adjusted images with one of said first and second digitized images, to produce a correlation output, and

selecting a coordinate transformation which produces at least a defined correlation output from its corresponding adjusted image;

said cross-correlating comprising;

inputting said first and second images to an optical correlator, and

reading said correlation output from an output of said optical correlator;

(f) correlating said pathological feature data with said second image to define a historical region-of-interest (ROI) in said second image;

(g) rescanning the defined ROI using a second level of resolution higher than said first level of resolution to obtain a third image;

(h) spatially adjusting at least one of said historical and rescanned ROI images to spatially register said ROI images so that corresponding features in both images are mapped to corresponding positions; and

(i) creating from said historical and rescanned ROI images a composite image which visually emphasizes temporal differences between said ROI images, thereby visually emphasizing historical changes between said historical and rescanned ROI images.

2. The method of claim 1, further comprising the step of recording said composite image for archiving.

3. The method of claim 2, wherein said step of recording comprises storing said composite image on a computer readable medium.

4. The method of claim 2, wherein said step of recording comprises printing an image based upon said composite image.

5. The method of claim 1, wherein at least one of said historical and rescanned ROI images is a three-dimensional image.

6. The method of claim 1, wherein said step of creating a composite image comprises:

comparing an image intensity at a location in said historical ROI image with a respective intensity at a corresponding location in said rescanned ROI image, and

determining a temporal difference image value based upon the temporal difference between said image intensity at said location in said historical ROI image and the respective intensity at said corresponding location in said rescanned ROI image.

7. The method of claim 1, wherein said composite image visually emphasizes temporal image differences by representing various regions of said composite image in synthetic colors, based upon temporal image differences between the historical and rescanned ROI images.

8. The method of claim 1, wherein said pathological feature data corresponds to predetermined image shapes or characteristics retrieved from a pathological image library.

9. The method of claim 1, wherein said pathological feature data is obtained by automated analysis of said first image.

10. The method of claim 1, wherein said second image is obtained using ultrasonic imaging.

11. The method of claim 1, wherein both of said historical and rescanned ROIs are three-dimensional volume regions which are aligned by registration in three dimensions.

12. A system for enhancing imagery of bodily tissues by relating earlier and later images, comprising:

an image processor, programmed to;

(a) receive a first image of a region of tissue;

(b) obtain pathological feature data for said region of tissue;

(c) obtain a second image of said region of tissue using a first level of resolution;

(d) register the first and second images by controlling an optical correlator to find a position of correlation between said first and second images, said registering of said first and second images comprising;

determining a coordinate transformation which produces a pre-determined degree of correlation between said first and second images, said coordinate transformation determined by;

applying coordinate transformations of scale, position and rotation to one of said first and second images to obtain a plurality of corresponding adjusted images,

cross-correlating said adjusted images with one of said first and second images to produce a correlation output, said cross-correlating comprising inputting said first and second images to said optical correlator and reading said correlation output from an output of said optical correlator;

selecting a coordinate transformation which produces a defined correlation output from its corresponding adjusted image, and

applying said coordinate transformation to at least one of said first and second images, to align said images;

(e) correlate said pathological feature data with said second image to define a historical region-of-interest (ROI) in said second image;

(f) rescan the defined ROI using a second level of resolution higher than said first level of resolution to obtain a third image;

(g) register said historical and rescanned ROI images by controlling an optical correlator to find a position of correlation between said historical and rescanned ROI images;

(h) derive a composite image from the historical and rescanned ROI images;

(i) compute temporal differences between said historical and rescanned ROI images; and

(j) emphasize said temporal differences in said composite image; and

an optical correlator coupled to said image processor and arranged to perform said correlations.

13. The system of claim 12, further comprising a visual display, coupled to said image processor and receiving from said image processor said composite image, to permit a user to view said composite image.

14. The system of claim 12, further comprising an ultrasonographic imaging system, arranged to communicate ultrasonographic image data to said image processor to provide at least one of said first and second images.