METHOD AND SYSTEM FOR IMAGE ANALYSIS OF SELECTED TISSUE STRUCTURES

• US 20120232375A1
• Filed: 09/10/2010
• Published: 09/13/2012
• Est. Priority Date: 09/11/2009
• Status: Active Grant

• Current Assignee: Curvebeam AI Ltd.
• Original Assignee: Straxcorp Pty Ltd (Curvebeam AI Ltd.)
• Inventors: Zebaze, Roger, Seeman, Ego, Mbala, Aloys, Ghasemzadeh, Ali, Mackie, Eleanor, Bohte, Anne
• Granted Patent: US 9,064,320 B2
• Time in Patent Office: Days
• US Class Current: 600/407
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/505 for diagnosis of bone
• CPC Class Codes: A61B 6/5205 involving processing of raw data to produce diagnostic data
• CPC Class Codes: G06T 11/003 Reconstruction from projections, e.g. tomography
• CPC Class Codes: G06T 2200/24 involving graphical user interfaces [GUIs]
• CPC Class Codes: G06T 2207/10081 Computed x-ray tomography [CT]
• CPC Class Codes: G06T 2207/10088 Magnetic resonance imaging [MRI]
• CPC Class Codes: G06T 2207/20104 Interactive definition of region of interest [ROI]
• CPC Class Codes: G06T 2207/30008 Bone
• CPC Class Codes: G06T 2207/30096 Tumor; Lesion
• CPC Class Codes: G06T 7/0012 Biomedical image inspection
• CPC Class Codes: G06T 7/12 Edge-based segmentation
• CPC Class Codes: G06T 7/70 Determining position or orientation of objects or cameras camera calibration G06T7/80

Abstract

A method for analysing a sample comprising a first material and a second material of generally different densities and having a junction therebetween, the method comprising defining a region of interest in a cross sectional image of at least a portion of the sample that includes said junction, determining a density profile of the sample within the region of interest and crossing the junction, determining a representative density of said second material, and analysing said sample using said junction used to distinguish said first and second materials.

Claims

1-54. -54. (canceled)

55. A computer-implemented method for analysing a sample comprising a first material and a second material of generally different densities and having a junction therebetween, the method comprising:

defining automatically a plurality of regions of interest within an image of the sample that includes said junction, each of said regions of interest having a width of one or more voxels or pixels;

determining respective density, intensity or attenuation profiles within the regions of interest, each of the respective profiles crossing the junction;

analysing said profiles by automatically defining, for each of said profiles, a series of sections of said respective profile comprising at least one S-like portion of the respective profile; and

determining a location of said junction.

56. A method as claimed in claim 55, comprising (i) determining said sections using reference points created in the respective profiles by successively determining representative densities of said second material from the respective profiles and/or (ii) determining an architecture of the first material.

57. A method as claimed in claim 55, further comprising locating the junction in said respective profiles between said first material and said second material.

58. A method as claimed in claim 57, wherein locating the junction in said respective profiles between said first material and said second material comprises (i) creating suitably selected reference points by identifying representative points within said first and second material;

(ii) locating a point in the respective profile that is closest to at least one reference point having the same position as a representative density of the first material and a density similar or lower than that of the second material;

(iii) finding a minimum in the expression √

{square root over (x_i²+y_i²)} in a reference frame within the respective profile centred on (x_i, y_i)=(0,0);

(iv) finding a maximum in the expression √

{square root over (x_i²+y_i²)} in a reference frame within the respective profile centred on (x_i, y_i)=(0,0);

(v) locating a point of greatest rate of change in one or more of the respective sections of the respective profile;

or (vi) locating a point of smallest rate of change in one or more of the respective sections of the respective profile.

59. A method as claimed in claim 55, wherein the sample comprises bone.

60. A method as claimed in claim 55, comprising detecting decay, porosity, cortical fragility or abnormality in the first material, or identifying fracture-vulnerable bone, or identifying a bone fracture.

61. A method as claimed in claim 55, wherein the region of interest includes at least one further junction that is between said first material and a further portion of said sample that comprises either said second material, a third material or a vacancy, and the method further comprises locating said further junction.

62. A method as claimed in claim 61, comprising further analysing the first material by using only portions of said sample between the junction in said profile and the further junction in said profile.

63. A method as claimed in claim 61, wherein locating the further junction in the profile comprises locating a point in the profile that is closest to a further reference point having the same position as point of maximum density difference and the same density as the representative density of the further portion.

64. A method as claimed in claim 55, comprising optimizing the identification of the junction between said first and second materials by providing position and angular offsets of the sample relative to each of the respective regions of interest, and/or overlapping to a selected degree a selected plurality of adjacent regions of interest.

65. A method as claimed in claim 55, wherein the first material is bone, and the method comprises defining a plurality of compartments within the sample, the compartments comprising any one or more of:

a compartment bounded by a periosteal boundary and a beginning of the cortex;

a compartment bounded by a beginning of the cortex and a beginning of the compact cortex;

a compact (or hard) cortex compartment;

a trabecularized cortex compartment;

a cortico-trabecular junction compartment; and

a trabecular compartment.

66. A method as claimed in claim 55, comprising either minimizing partial volume effects when analysing bone structure, or determining the dimensions of a structure within an image while minimizing partial volume effects.

67. A method as claimed in claim 55, comprising determining a proportion of the cortex that has a trabecular-like appearance and/or determining an average of the cortical thicknesses of the compact cortex, of the cortical mass, of the trabecularized cortex, of an area of the compact cortex, of an area of the cortical mass or of an area of the trabecularized cortex.

68. A method as claimed in claim 55, wherein the sample comprises a bone sample, and (i) the sample includes one or more of a trabecular portion, a cortical portion and a cortico-trabecular junction;

and (ii) the method comprises determining whether the sample is abnormal based on having one or more of an abnormal cortex, an abnormal trabecular compartment and an abnormal cortico-trabecular junction.

69. A method as claimed in claim 55, comprising (i) automatically identifying bone;

(ii) identifying non-bone tissue;

(iii) identifying cortical bone and one or more cortical bone indices;

(iv) identifying the cortico-trabecular junction and one or more indices of the cortico-trabecular bone;

(v) identifying trabecular bone and determining one or more trabecular indices;

(vi) identifying trabecular bone and determining one or more trabecular indices; and

/or (vii) determining the degree of mineralization of bone using the surrounding muscular tissue as referent.

70. A method as claimed in claim 55, comprising determining any one or more indices from the group consisting of:

the thickness, porosity or relative porosity of the cortex, of the trabecularized cortex or of the transition zone;

the cortical area or of the trabecularized cortex;

the porosity of cortex, of the trabecularized cortex, or of the transition zone;

whether the cortex or the trabecularized cortex is normal regardless of its absolute thickness or area;

whether the cortex or the trabecularized cortex has been subject to resorption; and

trabecular architecture and porosity from the analysis of the profile;

71. A method as claimed in claim 55, wherein analyzing the sample comprises rotating, translating or both rotating and translating one or more of said regions of interest.

76. Executable instructions or software that, when executed by a computer or processor of a computer, cause the computer or processor of the computer to perform the method of claim 55.

77. A computing device provided with executable instructions or software that, when executed by the computing device or by a processor of the computing device, cause the computing device or processor of the computing device to perform the method of claim 55.

79. An output of a computing device, said output comprising an analysis of a sample that comprises first and second materials of generally different densities and having a junction therebetween, the analysis performed according to the method of claim 55.

72. A computer-implemented method for analysing a sample comprising a first material and a second material of generally different densities and having a junction therebetween, the method comprising:

defining a region of interest or arm in a cross sectional image of at least a portion of the sample that includes said junction;

determining an arm width over which said portion of said sample is locally linear; and

analyzing said image including rotating said arm, translating said arm, or both by rotating and translating said arm.

73. A system for analysing a sample comprising a first material and a second material of generally different densities and having a junction therebetween, the system comprising:

a region of interest selector for selecting a region of interest in an image of at least a portion of the sample that includes said junction;

a density profile analyzer for determining a density, intensity or attenuation profile of the sample within the region of interest and crossing the junction, for performing an analysis of said profile by automatically defining a series of sections of said profile comprising at least one S-like portion of the profile, and determining a location of said junction said analysis; and

an output for outputting a result of said analysis.

74. A system as claimed in claim 73, comprising a region of interest position adjuster, adapted to optimize the position of the selected region of interest for use by the density profile analyzer in determining the profile, and/or a region of interest merger, adapted to overlap to a selected degree a plurality of regions of interest.

78. A computer-implemented method for identifying a junction between first and second materials or regions of generally different densities within an image of a sample, the method comprising:

defining automatically a plurality of regions of interest with said image, each including the first and second materials or regions and a junction therebetween;

determining respective density, intensity or attenuation profiles for said regions of interest by calculating an average, median or other indicative value of density, intensity or attenuation of said first and second materials or regions at a series of locations along a path that crosses said junction, based at each of said locations on density, intensity or attenuation sampled across to said path;

analysing said respective profiles using a plurality of reference points;

centred on (x_i, y_i)=(0,0) relative to each of which said respective profile is analysed to identify one or more sections of said profile that has at least one S-like portion; and

analysing said sections once identified for points indicative of a beginning and an end of said junction, by finding a minimum in √

{square root over (x_i²+y_i²)} relative to said respective reference points.

80. An output of a computing device, said output comprising an analysis of a sample that comprises first and second materials of generally different densities and having a junction therebetween, the analysis performed according to the method of claim 78.