Vessel segmentation with nodule detection
View Patent ↗A region-growing method for identifying nodules in an anatomical volume segments a 3-D image volume by controlled voxel growth from seed points. The process is based on creation and use of a distance map for tracking the distance of vessel voxels from a predetermined location. A volume map is created that identifies the largest sphere that can pass between a voxel and a predetermined location without touching a non-vessel voxel. The ratio between the distance map and the volume map is analyzed to find regions more likely to contain nodules, the features of which can be extracted or otherwise highlighted.
1. A method for detecting a candidate nodule from anatomical images comprising the steps of:
selecting a seed voxel from a volume created from the anatomical images;
growing a region from the seed voxel, said region defined by a volume made up of voxels contiguous to the seed voxel and satisfying growth criteria;
creating a first array having first array values that relate each voxel of the region to a first voxel distance;
creating a second array having second array values that relate each voxel of the region to a second voxel distance; and
processing a ratio of a first array value to a corresponding second array value to determine a candidate nodule location.
2. The method of claim 1 wherein the seed voxel is part of a blood vessel.
3. The method of claim 1 wherein the seed voxel is part of a blood vessel and at least one voxel face is associated with a heart or heart region.
4. The method of claim 1 wherein the seed voxel exceeds a threshold intensity level.
5. The method of claim 1 wherein the seed voxel is selected within a geometric volume containing roots of blood vessel trees.
6. The method of claim 5 wherein the geometric volume is an ellipsoid.
7. The method of claim 1 wherein the growth criteria for adding voxels to the region is whether a voxel has an intensity level greater than a threshold.
8. The method of claim 1 wherein the growing of a region stops once a predetermined number of voxels is added to the region.
9. The method of claim 1 wherein the growth criteria for adding voxels to the region is whether a voxel has an intensity level greater than a threshold in a Laplacian-of-Gaussian volume.
10. The method of claim 1 further including the step of performing noise reduction on the volume created from the anatomical images.
11. The method of claim 1 further including the step of creating a distance map which tracks the distance of each voxel in the region from a predetermined location.
12. The method of claim 11 wherein the predetermined location is the seed voxel.
13. The method of claim 11 wherein the predetermined location is a heart.
14. The method of claim 11 wherein the predetermined location is a kidney, liver, spleen or brain.
15. The method of claim 1 further including the step of detecting variations in a width of the region.
16. The method of claim 1 wherein the region corresponds to a vessel volume.
17. The method of claim 1 wherein the region is a blood vessel.
18. The method of claim 1 wherein the first voxel distances are distances of the voxels in the region to the seed voxel.
19. The method of claim 1 wherein the first voxel distance is a distance of a voxel in the region to a heart or heart region.
20. The method of claim 1 wherein the second voxel distances are distances of a voxel in the region to nearest voxels outside the region.
21. The method of claim 1 wherein the step of processing a ratio further includes identifying as candidate nodules voxels resulting in ratio greater than ‘1’.
22. A computer system including software for identifying candidate nodules in a series of digital images of the lung:
logic code for selecting a seed voxel from a volume created from the digital images;
logic code for growing a region from the seed voxel, said region defined by a volume made up of voxels contiguous to the seed voxel and satisfying growth criteria;
logic code for creating a first array having first array values that relate each voxel of the region to a first voxel distance;
logic code for creating a second array having second array values that relate each voxel of the region to a second voxel distance; and
logic code for processing a ratio of first array values to a corresponding second array values to determine one or more candidate nodule locations.
23. The computer system of claim 22 wherein the region is a blood vessel tree.
24. A method for detecting from anatomical images a candidate location of a blockage in a vessel comprising the steps of:
selecting one or more seed voxels from a volume created from the anatomical images;
growing a first region from s seed voxel, said region defined by a volume made up of voxels contiguous to the seed voxel and satisfying a first set of growth criteria;
growing within the first region a second region, said second region defined by a volume made up of voxels contiguous with the seed voxels and satisfying a second set of growth criteria; and
analyzing one or more portions of the first region that are not included in the second region based on the voxel intensities for voxels in the one or more portions.