Method and software for improving coronary calcium scoring consistency

• US 7,127,096 B2
• Filed: 04/18/2002
• Issued: 10/24/2006
• Est. Priority Date: 11/20/2001
• Status: Expired due to Fees

• Current Assignee: Merge Healthcare Solutions Incorporated (International Business Machines Corporation)
• Original Assignee: AccuImage Diagnostics Corp. (International Business Machines Corporation)
• Inventors: Kaufman, Leon, Carlson, Joseph W.
• Primary Examiner(s): Mehta, Bhavesh M.
• Assistant Examiner(s): MACKOWEY, ANTHONY M
• Application Number:
  US10/126,463
• Publication Number:
  US 20030095693A1
• Time in Patent Office: 1,650 Days
• Field of Search: 382128-132, 382/263, 382/264, 382/279, 382/280, 382/299, 378/207, 702/85
• US Class Current: 382/131
• CPC Class Codes: A61B 6/027 characterised by the use of a particular data acquisition trajectory, e.g. helical or spiral
• CPC Class Codes: A61B 6/5288 involving retrospective matching to a physiological signal
• CPC Class Codes: A61B 6/541 involving acquisition triggered by a physiological signal
• CPC Class Codes: A61B 6/583 using calibration phantoms
• CPC Class Codes: G06T 2207/10081 Computed x-ray tomography [CT]
• CPC Class Codes: G06T 2207/20008 Globally adaptive
• CPC Class Codes: G06T 2207/20056 Discrete and fast Fourier transform, [DFT, FFT]
• CPC Class Codes: G06T 2207/20192 Edge enhancement; Edge preservation
• CPC Class Codes: G06T 2207/30101 Blood vessel; Artery; Vein; Vascular
• CPC Class Codes: G06T 5/10 using non-spatial domain filtering
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: G06T 5/70 Denoising; Smoothing
• CPC Class Codes: G06T 5/73 Deblurring; Sharpening
• CPC Class Codes: G06V 10/30 Noise filtering
• CPC Class Codes: G16H 30/40 for processing medical images, e.g. editing
• CPC Class Codes: G16H 40/40 for the management of medical equipment or devices, e.g. scheduling maintenance or upgrades
• CPC Class Codes: G16H 40/67 for remote operation

Abstract

Methods and devices for improving the machine-to-machine and temporal (e.g., inter and intra-machine) and database consistency of coronary calcium scoring by applying a filtering algorithm that sharpens and/or smoothes the image so as to return a filtered image having a spatial resolution of a certain reference value.

Claims

1. A method of improving the consistency of coronary calcium scoring, the method comprising:

imaging a phantom with an imaging device to produce an image of the phantom;

measuring a spatial resolution from the image of the phantom;

comparing the measured spatial resolution of the image of the phantom against a reference spatial resolution;

choosing a filter algorithm, wherein when filter is applied to the phantom image a filtered image is produced having a spatial resolution substantially matching the reference spatial resolution;

subsequent to choosing a filter algorithm, obtaining an image of a subject;

applying the filter algorithm to the image of the subject to create a filtered image that has a spatial resolution that substantially matches the reference spatial resolution; and

computing a coronary calcium score from the filtered image.

2. The method of claim 1 wherein the measured spatial resolution of the image of the phantom and reference spatial resolution are a full width half maximum.

3. The method of claim 1 where the coronary calcium score is an Agatston Score.

4. The method of claim 1 where the coronary calcium score is a volume score.

5. The method of claim 1 where the coronary calcium score is an integral score.

6. The method of claim 1 wherein the calcium scores from the filtered images are input into a database for comparison with scores from other images that comprise the reference spatial resolution.

7. The method of claim 1 wherein measuring is carried out periodically.

8. The method of claim 7 wherein periodically comprises once a day.

9. The method of claim 1 wherein the phantom comprises a plurality of aluminum wires comprising different dimensions embedded in a low density matrix.

10. The method of claim 9 wherein the aluminum wires comprise a diameter that is between approximately 0.1 times the full width half maximum of the imaging device and 3.0 times the full width half maximum of the imaging device.

11. The method of claim 9 wherein measuring the spatial resolution of the phantom comprises measuring a peak signal for each wire.

12. The method of claim 1 wherein comparing is carried out with software.

13. The method of claim 1 wherein the imaging device is a CT scanner and the image of the phantom data comprises absorption data.

14. The method of claim 13 wherein applying the filter algorithm comprises filtering data from detectors of the CT scanner before a reconstruction yields the image.

15. The method of claim 14 wherein applying the filter algorithm comprises multiplying a signal distribution of the images along the detectors by a set of weights that yield the reference spatial resolution.

16. The method of claim 14 where the reconstruction is a back projection.

17. The method of claim 1 wherein the filter algorithm performs at least one of smoothing and sharpening of the acquired images.

18. The method of claim 1 wherein applying the filter algorithm comprises convolving the image with one of a Gaussian filter, Fourier filter, or a cubic filter so that the spatial resolution of the images are adjusted to the reference spatial resolution.

19. The method of claim 1 wherein applying the filter algorithm comprises:

applying a first Fourier Transform operation to the acquired image;

filtering a frequency space two-dimensional data of the acquired image; and

performing a second Fourier Transform operation to obtain an image comprising the reference spatial resolution.

20. The method of claim 1 wherein applying the filter algorithm comprises:

applying a first Fourier Transform operation to a single line of the acquired image;

filtering a frequency space one-dimensional data of the acquired image; and

performing a second Fourier Transform operation to obtain an image comprising the reference spatial resolution;

repeating the applying, filtering and performing steps on all lines that are parallel and perpendicular to the single line.

21. The method of claim 1 wherein applying the filter algorithm comprises filtering absorption data.

22. The method of claim 21 wherein filtering of the absorption data comprises filtering prior to reconstruction.

23. The method of claim 22 wherein reconstruction is a back projection.

24. The method of claim 1 wherein applying the filtering algorithm comprises applying a two-dimensional operator to the image.

25. The method of claim 1 wherein filtering comprises applying a one-dimensional operator to a line of the image;

repeating the applying step to all lines that are parallel to the line; and

repeating the applying step to all lines that are perpendicular to the line.

26. A system for improving coronary and other vessel calcium scoring consistency, the system comprising:

an imaging unit that measures a spatial resolution of an image of a phantom; and

a computer system coupled to the imaging unit, the computer system comprising;

a memory that stores a reference spatial resolution;

means for creating a resolution-adjusted image of an acquired image in which the spatial resolution of the acquired image is adjusted to match the reference spatial resolution, the adjustment being based on a comparison of the measured spatial resolution of the image of the phantom with the reference spatial resolution stored in the memory; and

means for computing a coronary calcium score from a resolution-adjusted image generated by the means for creating.

27. The system of claim 26 wherein the phantom comprises a plurality of objects having known characteristics.

28. The system of claim 27 wherein the plurality of objects comprises aluminum wires having varied diameters which are between 0.1 and 3.0 times the spatial resolution of the imaging unit.

29. The system of claim 26 wherein the imaging unit is a CT scanner.

30. The system of claim 26 wherein the coronary calcium score is an Agatston Score.

31. The system of claim 26 wherein the coronary calcium score is a volume score.

32. The method of claim 26 where the coronary calcium score is an integral score.

33. A method of improving the consistency of coronary calcium scoring, the method comprising:

comparing a spatial resolution of the imaging scanner against a reference spatial resolution;

choosing a filter algorithm based on the comparison of the spatial resolution of the imaging scanner and the reference spatial resolution;

subsequent to choosing a filter algorithm, performing an imaging operation on the imaging scanner to obtain an image of a subject;

applying the filter algorithm to the obtained image to create a filtered image that has a spatial resolution that substantially matches the reference spatial resolution; and

computing a coronary calcium score from the filtered image.

34. The method of claim 33 wherein the spatial resolution of the imaging scanner and reference spatial resolution are a full width half maximum.

35. The method of claim 33 where the coronary calcium score is an Agatston Score.

36. The method of claim 33 where the coronary calcium score is a volume score.

37. The method of claim 33 where the coronary calcium score is an integral score.

38. The method of claim 33 wherein the calcium scores from the filtered images are input into a database for comparison with scores from other images that comprise the reference spatial resolution.

39. The method of claim 33 wherein measuring is carried out periodically.

40. The method of claim 39 wherein periodically comprises once a day.

41. The method of claim 33 wherein the spatial resolution of the imaging scanner is based on a image of a phantom comprising a plurality of aluminum wires of different dimensions embedded in a low density matrix.

42. The method of claim 41 wherein the aluminum wires comprise a diameter that is between approximately 0.1 times the full width half maximum of the imaging device and 3.0 times the full width half maximum of the imaging device.

43. The method of claim 41 wherein measuring the spatial resolution of the phantom comprises measuring a peak absorption signal for each wire.

44. The method of claim 33 wherein comparing is carried out with software.

45. The method of claim 33 wherein the imaging device is a CT scanner.

46. The method of claim 45 wherein applying the filter algorithm comprises filtering data from detectors of the CT scanner before a reconstruction yields the image.

47. The method of claim 46 wherein applying the filter algorithm comprises multiplying a signal distribution of the images along the detectors by a set of weights that yield the reference spatial resolution.

48. The method of claim 46 where the reconstruction is a back projection.

49. The method of claim 33 wherein the filter algorithm performs at least one of smoothing and sharpening of the acquired images.

50. The method of claim 33 wherein applying the filter algorithm comprises convolving the image with one of a Gaussian filter, Fourier filter, or a cubic filter so that the spatial resolution of the images are adjusted to the reference spatial resolution.

51. The method of claim 33 wherein applying the filter algorithm comprises:

applying a first Fourier Transform to the acquired image;

filtering a frequency space two-dimensional data of the acquired image; and

performing a second Fourier Transform to obtain an image comprising the reference spatial resolution.

52. The method of claim 33 wherein applying the filter algorithm comprises:

applying a first Fourier Transform to a single line of the acquired image;

filtering a frequency space one-dimensional data of the acquired image; and

performing a second Fourier Transform to obtain an image comprising the reference spatial resolution;

repeating the applying, filtering, and performing steps on all lines that are parallel and perpendicular to the single line.

53. The method of claim 33 wherein applying the filter algorithm comprises filtering absorption data.

54. The method of claim 53 wherein filtering of the absorption data comprises filtering prior to reconstruction.

55. The method of claim 54 wherein reconstruction is a back projection.

56. The method of claim 33 wherein applying the filtering algorithm comprises applying a two-dimensional operator to the image.

57. The method of claim 33 wherein filtering comprises applying a one-dimensional operator to a line of the image;

repeating the applying step to all lines that are parallel to the line; and

repeating the applying step to all lines that are perpendicular to the line.

58. A method of improving a comparison of calcium scores, the method comprising:

providing an algorithm;

obtaining at least one image with an imaging device;

applying the algorithm to the obtained image(s) to adjust a spatial resolution of the obtained image(s) to create resolution-adjusted image(s) that have a spatial resolution that substantially matches a reference spatial resolution; and

computing a coronary calcium score by performing a scoring operation on the resolution-adjusted image(s).

59. The method of claim 58 wherein providing comprises periodically measuring the spatial resolution of the imaging device and adjusting the algorithm based on the measuring of the spatial resolution of the imaging device.

60. The method of claim 59 wherein periodically monitoring occurs once a day.

61. The method of claim 59 wherein periodically monitoring comprises:

imaging a phantom;

comparing the spatial resolution of the imaged phantom to a reference spatial resolution; and

generating the algorithm that adjusts the spatial resolution of the imaged phantom to substantially match the reference spatial resolution.

62. The method of claim 61 wherein the phantom comprises a plurality of wires that have a diameter that is between approximately 0.1 times as large as a full width half maximum of the imaging device and 3.0 times as large as the full width half maximum of the imaging device.

63. The method of claim 58 wherein applying the algorithm comprises at least one of smoothing and sharpening the obtained image.

64. The method of claim 58 wherein the coronary calcium score is an Agatston Score.

65. The method of claim 58 wherein the coronary calcium score is a volume score.

66. The method of claim 58 where the coronary calcium score is an integral score.