Bone segmentation and display for 3D extremity imaging
A method acquires a reconstructed tomographic volume image of anatomy of a patient and constructs a primary axis for a bone of interest in the imaged anatomy. The method forms a sectioned image of the bone in the volume image according to a first plane that is defined to extend along the bone and to extend through two or more articular surfaces. A primary axis for the bone is estimated, wherein the primary axis is midway between outer edges of the bone image that intersect the first sectioning plane. The bone is sectioned in the volume image by a second plane that is orthogonal to the first plane and that extends through the estimated primary axis. The method recalculates the position of the constructed primary axis according to the sectioning of the bone by the second plane. The recalculated constructed primary axis for the bone of interest is displayed.
1. A method of segmentation of a bone of interest within a 3D tomographic volume image of anatomy, the method comprising:
a) accessing the volume image of anatomy comprising the bone of interest;
b) identifying the bone of interest for segmentation;
c) constructing a primary axis extending through the bone of interest;
d) characterizing a surface profile of the bone of interest using a repeated process of:
(i) rotating the volume image to an angle about a constructed primary axis;
(ii) incrementally identifying edges of the bone of interest within a plane that includes the primary axis; and
(iii) defining a segmented bone of interest by isolating the bone of interest within the volume image using the identified bone edges; and
e) displaying, storing, or transmitting the defined segmented bone of interest.
2. The method of claim 1 wherein constructing the primary axis comprises:
estimating an orientation and direction of the primary axis;
generating a first sectioning of the volume image along a first plane projected through the bone of interest and parallel to the estimated direction of the primary axis;
using one or more feature points, calculating a center line extending through the sectioned bone of interest generated from the first sectioning;
generating an orthogonal sectioning of the bone of interest along a second plane, orthogonal to the first plane, through the calculated center line; and
refining the estimated orientation and direction of the primary axis.
3. The method of claim 2 wherein estimating the orientation and direction of the primary axis comprises:
identifying a first joint surface of the bone of interest;
identifying a second joint surface of the bone of interest, the second joint surface being spaced from the first joint surface;
defining a first candidate axis disposed parallel to a normal to the first joint surface and extending within the bone of interest from the first joint surface toward the second joint surface;
defining a second candidate axis disposed parallel to a normal to the second joint surface and extending within the bone of interest from the second joint surface toward the first joint surface; and
selecting the first or second candidate axis as the primary axis according to an axis length.
4. The method of claim 2 wherein estimating the orientation and direction of the primary axis comprises:
generating a projection image from the volume image; and
defining a line through at least two points located midway from edges of the bone of interest in the generated projection image.
5. The method of claim 4 wherein generating the projection image projection image is accomplished using a partial portion of the volume image.
6. The method of claim 1 wherein displaying, storing, or transmitting the segmented bone of interest further comprises displaying different views of the reconstructed volume.
7. The method of claim 1 further comprising using an atlas to identify the bone of interest for segmentation.
8. The method of claim 1 further comprising identifying one or more angular measurements related to the segmentation.
9. The method of claim 1 further comprising transmitting or storing image data for the segmented bone of interest.
10. The method of claim 1 further comprising identifying one or more joint spacing measurements according to the segmentation.
11. The method of claim 1 wherein identifying the bone of interest for segmentation comprises analyzing cumulative data values at a predetermined angle.
12. The method of claim 1 further comprising correlating the identified bone edges with bone features within the volume image.
13. A method for segmentation of a bone feature within a volume image of an extremity, the method comprising:
a) accessing a 3D tomographic volume image of the extremity;
b) identifying a bone feature of the extremity for segmentation;
c) generating a projection image using at least a portion of the volume image;
d) generating a first plane projection by sectioning the projection image along a first plane through the projection image along the identified bone feature;
e) calculating a center line through the bone feature according to edges in the first plane projection;
f)) identifying a second plane substantially orthogonal to the first plane through the bone feature and through the center line;
g) calculating the position of a primary axis through the extremity, wherein the primary axis lies in the second plane;
h) rotating the volume image about the primary axis to determine a surface contour of the bone feature;
i) identifying a surface contour of one or more articular surfaces along the primary axis; and
j) displaying the segmented bone feature.
14. The method of claim 13 wherein displaying the segmented bone feature comprises displaying the one or more articular surfaces of the segmented bone.