Methods and apparatus for processing medical images

• US 7,646,898 B1
• Filed: 11/24/2000
• Issued: 01/12/2010
• Est. Priority Date: 11/24/2000
• Status: Active Grant

• Current Assignee: Kent Ridge Digital Labs
• Original Assignee: Kent Ridge Digital Labs
• Inventors: Thirunavuukarasuu, Arumugam, Nowinski, Wieslaw L.
• Primary Examiner(s): Carter; Aaron W
• Application Number:
  US10/416,520
• Time in Patent Office: 3,336 Days
• Field of Search: 382128-134, 382/170, 382207-209, 382/154, 382/294, 382/285, 707/104.1
• US Class Current: 382/128
• CPC Class Codes: G06T 2207/30016 Brain
• CPC Class Codes: G06T 7/0012 Biomedical image inspection
• CPC Class Codes: G06T 7/33 using feature-based methods
• CPC Class Codes: G06T 7/38 Registration of image sequences

Abstract

A system for analysing a brain image compares the image with a brain atlas, labels the image accordingly, and annotating the regions of interest and/or other structures. This atlas-enhanced data is written to a file (or more than one file) in the Dicom format or any web-enabled format such as SGML or XML format. The image used may be produced by any medical imaging modality. A fast algorithm is proposed for a landmark-based piecewise linear mapping of one volumetric image into another volumetric image. Furthermore, a new set of brain landmarks are proposed, and algorithms for the automatic identification of these landmarks are formulated for three orientations, axial, coronal, and sagittal.

Claims

1. A method of analysing an image of a brain by a computer device, the method comprising:

receiving data defining a three-dimensional image of a brain;

comparing the received data with a brain atlas to generate a three-dimensional mapping between the image and the brain atlas by warping the brain atlas to the received data, thereby generating an individualized brain atlas;

using the mapping to annotate the received data; and

writing said annotated data as one or more data files;

wherein in writing said annotated data, the annotated data is written in Dicom, including one or more Dicom overlays or in a web-enabled format, with the received data and the individualized brain atlas saved separately as two corresponding images; and

wherein the annotated data is provided to compatible workstations for further processing by medical professionals.

2. A method according to claim 1 in which said data is received from a file in Dicom format.

3. A method according to claim 1 in which said comparison is performed by:

(i) identifying a set of first features in said image corresponding to respective second features in said brain atlas;

(ii) defining a first direction in said image, and a plurality of first planes in the image perpendicular to and spaced apart in said first direction, each first plane containing one or more of said first features, and corresponding to a respective second plane in the brain atlas containing the corresponding one or more second features;

(iii) partitioning each first plane into rectangular sections based on said first features;

(iv) for each first plane, applying a linear transformation to each section to transform its dimensions to be equal to those of a respective rectangular section of the corresponding second plane; and

(v) defining a transformation of the spacing between said first plane which makes the spacing of the first planes equal to the spacing of the corresponding second planes.

4. A method according to claim 1 in which said comparison is performed by:

(i) identifying a set of first features in said brain atlas corresponding to respective second features in said image;

(ii) defining a first direction in said brain atlas, and a plurality of first planes in the brain atlas perpendicular to and spaced apart in said first direction, each first plane containing one or more of said first features, and corresponding to a respective second plane in the image containing the corresponding one or more second features;

(iii) partitioning each first plane into rectangular sections based on said first features;

(iv) for each first plane, applying a linear transformation to each section to transform its dimensions to be equal to those of a respective rectangular section of the corresponding second plane; and

(v) defining a transformation of the spacing between said first plane which makes the spacing of the first planes equal to the spacing of the corresponding second planes.

5. A method according to claim 1 in which said annotation is performed by selecting regions of interest on the image, and deriving from the brain atlas information associated with this region of interest.

6. A method according to claim 1 in which said annotation includes placing text on the brain image.

7. A method according to claim 1 in which said annotation includes placing mensuration on the brain image.

8. A method according to claim 1 in which said annotation includes labelling of one or more regions of interest based on labels associated with corresponding portions of the brain atlas.

9. A method according to claim 8 in which a user selects said regions of interest successively, and the labels at any instant correspond to the corresponding selection.

10. A method according to claim 1 in which a user points or clicks any structure in the image successively, and, at the pointed location the label of the said structure is being generated, while when clicking and dragging the mouse the line is drawn and the label of the said structure is placed at the end of the said line.

11. A method according to claim 6 comprising generating a lookup table defining a mapping between the portions of the image and respective anatomical indices, said labels being generated using the table.

12. A method according to claim 11 in which the user can select a region of interest using either said image or by selecting one of said indices.

13. A method according to claim 1 in which said comparison is based on a plurality of landmarks in the image.

25. A method according to claim 13 in which the landmarks include the left L and/or right R landmarks on the axial image, which are calculated based on the locations of the right external valley and the left external valley in the vertical (antero-posterior) projection of the image.

26. A method according to claim 13 in which the landmarks include the anterior A and/or posterior P landmarks on the axial image which are calculated based on the locations of the right external valley and the left external valley in the horizontal (left-right) projection of the image.

27. A method according to claim 13 in which the landmarks include the right R and/or left L landmarks on the coronal image which are calculated based on the locations of the left external valley and the right external valley in the vertical (dorso-ventral) projection of the image.

28. A method according to claim 13 in which the landmarks include the superior S landmark on the coronal image which is calculated based on the location of the right external valley in the horizontal (left-right) projection of the image.

29. A method according to claim 13 in which the landmarks include inferior I landmark on the coronal image which is calculated based on the location of the highest peak in the partial vertical (dorso-ventral) projection of the AC image taken ventrally from the AC horizontal line.

31. A method according to claim 13 in which the landmarks include the superior S and inferior I landmarks on the axial image which are calculated based on the scaling of the brain atlas.

32. A method according to claim 13 in which the landmarks include the anterior A and posterior P landmarks on the coronal image which are calculated based on the scaling of the brain atlas.

33. A method according to claim 13 in which the landmarks include the AC landmark on the midsagittal image which is calculated based on the analysis of the bounding box around the corpus collosum and identifying below it in the constraint region the most ventro-anterior white matter structure.

34. A method according to claim 13 in which the landmarks include the PC landmark on the midsagittal image which is calculated by drawing a semi-line from the AC to the bottom of the massa intermedia, and rotating this line clockwise until the first white matter structure is encountered.

35. A method according to claim 13 in which the landmarks include the anterior A and posterior P landmarks on the midsagittal image which are calculated by drawing a line passing through the AC and PC landmarks and identifying the extent of the cortex.

36. A method according to claim 13 in which the landmarks include the superior S landmark on the midsagittal image is calculated by drawing a line perpendicular to the AC-PC line and passing through the PC and identifying the intersection of this line with the cortex.

37. A method according to claim 13 in which the landmarks include the inferior I landmark on the sagittal image which is calculated by scaling the brain atlas.

38. A method according to claim 13 in which the landmarks include the left L and R landmarks in the sagittal three-dimensional brain image which are calculated by scaling the brain atlas.

39. A method as claimed in claim 1 in which an image of the brain is any medical imaging modality image.

40. A computing device having a processor and a memory storing a program which when implemented to performs a method according to claim 1.

41. A computer-readable medium comprising computer program instructions readable by a computer apparatus to cause the computer apparatus to perform a method according to claim 1.

43. A method according to claim 1 further including a step of defining a plurality of landmarks in the image, said landmarks being calculated using peaks and valleys of a graph of the density profile of the image measured along a line and/or peaks and valleys of a projection along a specified direction.

46. A method according to claim 1 in which said web-enabled format is XML format.

14. A method of mapping an image of a brain to an existing brain atlas by a computer device, the method comprising:

(i) identifying a set of first features in said image corresponding to respective second features in said brain atlas;

(ii) defining a first direction in said image, and a plurality of first planes in the image perpendicular to and spaced apart in said first direction, each first plane containing one or more of said first features, and corresponding to a respective second plane in the brain atlas containing the corresponding one or more second features;

(iii) partitioning each first plane into rectangular sections based on said first features;

(iv) for each first plane, applying a linear transformation to each section to transform its dimensions to be equal to those of a corresponding rectangular section of the corresponding second plane; and

(v) defining a transformation of the spacing between said first plane which makes the spacing of the first planes equal to the spacing of the corresponding second planes;

wherein the brain image is annotated using said mapping method and said annotated image is written in Dicom including one or more Dicom overlays, or in a web-enabled format, with the brain image and the brain atlas saved separately as two corresponding images; and

wherein the annotated data is provided to compatible workstations for further processing by medical professionals.

16. A method according to claim 14 in which said features of the image are a plurality of landmarks.

44. A method according to claim 14 wherein identifying the set of first features in said image comprises defining a plurality of landmarks in the image, said landmarks being calculated using peaks and valleys of a graph of the density profile of the image measured along a line and/or peaks and valleys of a projection along a specified direction.

15. A method of mapping an existing brain atlas to an image of the brain by a computer device, the method comprising the steps of:

(i) identifying a set of first features in said brain atlas corresponding to respective second features in said image;

(ii) defining a first direction in said brain atlas, and a plurality of first planes in the brain atlas perpendicular to and spaced apart in said first direction, each first plane containing one or more of said first features, and corresponding to a respective second plane in the image containing the corresponding one or more second features;

(iii) partitioning each first plane into rectangular sections based on said first features;

(iv) for each first plane, applying a linear transformation to each section to transform its dimensions to be equal to those of a corresponding rectangular section of the corresponding second plane; and

(v) defining a transformation of the spacing between said first plane which makes the spacing of the first planes equal to the spacing of the corresponding second planes;

wherein the brain image is annotated and an individualized brain atlas is generated using said mapping method and said annotated image is written in Dicom, including one or more Dicom overlays or in a web-enabled format, with the brain image and the individualized brain atlas saved separately as two corresponding images; and

wherein the annotated data is provided to compatible workstations for further processing by medical professionals.

45. A method according to claim 15 further including identifying the second features in said image by defining a plurality of landmarks in the image, said landmarks being calculated using peaks and valleys of a graph of the density profile of the image measured along a line and/or peaks and valleys of a projection along a specified direction.

17. A method of forming a mapping between a brain image and a brain atlas by a computer device, the method including:

defining a plurality of landmarks in the image, said landmarks being calculated using peaks and valleys of a graph of the density profile of the image measured along a line and/or peaks and valleys of a projection along a specified direction; and

forming said mapping based on the correspondence of the positions of said landmarks in the brain image with corresponding landmarks in the brain atlas.

18. A method according to claim 17 in which the line is the AC-PC line.

19. A method according to claim 18 further including identifying the position of the AC-PC line from an antero-posterior projection of the image.

20. A method according to claim 19 in which the position of the AC-PC line is defined using the location of the central valley of the antero-posterior projection of the image.

21. A method according to claim 17 in which the line is the AC line or the PC line.

22. A method according to claim 17 in which the orientation of the image is determined by obtaining a projection of the image at each of a plurality of angles, and orientation (the rotation angle) is derived from the projection for which the central depression is deepest.

23. A method according to claim 22 in which the orientation determined is the axial orientation, the plurality of projections of the image are at each a plurality of angles, and the rotation angle is derived from the projection for which the central depression is deepest.

24. A method according to claim 22 in which the orientation determined is the coronal orientation, and the plurality of projections of the image are at each of a plurality of angles.

30. A method as claimed in claim 17 in which each reference to a “

peak”

is replaced by a reference to a “

valley”

, and each reference to a valley is replaced by a reference to a peak.

42. A method according to claim 17 in which the brain image is annotated using said method of forming the mapping between the brain image and the brain atlas and said annotated image is written in one or more Dicom overlays or in a web-enabled format, with the brain image and the brain atlas saved separately as two corresponding images.