Virtual endoscopy

• US 8,009,167 B2
• Filed: 10/14/2010
• Issued: 08/30/2011
• Est. Priority Date: 06/23/2004
• Status: Expired due to Fees

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Dekel, Doron, Durgan, Jacob S., Fleiter, Thorsten R.
• Primary Examiner(s): Nguyen; Kimbinh T
• Application Number:
  US12/904,483
• Publication Number:
  US 20110116692A1
• Time in Patent Office: 320 Days
• Field of Search: 345/419, 345/420, 345/424, 345/620, 345/421, 382/128, 382/154, 600/443, 600/103, 600/407, 600/431
• US Class Current: 345/420
• CPC Class Codes: G06T 15/08 Volume rendering
• CPC Class Codes: G06T 19/00 Manipulating 3D models or images for computer graphics
• CPC Class Codes: G06T 2210/41 Medical
• CPC Class Codes: G06T 2215/06 Curved planar reformation of 3D line structures

Abstract

In a virtual endoscopy method, an unfolding axis substantially along an elongated lumen is divided into axis segments. Ray casting directions are selected extending generally radially from the axis segments. At least some of the ray casting directions are tilted away from a camera position. Ray casting is performed along the tilted ray casting directions to define pixel values that are arranged into an unfolded view. The ray casting employs at least one of (i) volume rendering and (ii) computing a statistical characteristic of voxels over a preselected distance (d_interval) along the ray casting direction into the lumen-defining structure.

Claims

1. A virtual endoscopy method for performing virtual endoscopy on a volumetric image of a lumen, the method comprising:

selecting, via a processor, a plurality of different ray casting directions that are concurrently extending from a plurality of different viewpoint axis segments toward a lumen-defining surface of the lumen, wherein at least one of the selected ray casting directions extends orthogonally from a viewpoint axis segment to the lumen-defining surface and at least a different one of the selected ray casting directions extends non-orthogonally from a different one of the viewpoint axis segments to the lumen-defining surface;

computing, via the processor, a statistical characteristic of voxels over a preselected distance along each ray casting direction into the lumen-defining structure;

defining, via the processor, a pixel value for each ray casting direction based at least on the computed statistical characteristic; and

arranging, via the processor, the pixel values into an endoscopic view of the lumen-defining structure,

wherein a pixel value defined by the ray casting direction extending non-orthogonally from the viewpoint axis segment to the lumen-defining surface captures information about the lumen that is not captured by a pixel value defined by a ray casting direction extending orthogonally from the same viewpoint axis segment to the lumen-defining surface, wherein the information includes a feature in a fold in the lumen.

2. The virtual endoscopy method as set forth in claim 1, wherein the statistical characteristic is one of a maximum intensity projection and a minimum intensity projection over the preselected distance along the ray casting direction into the lumen-defining structure.

3. The virtual endoscopy method as set forth in claim 1, wherein the statistical characteristic is an average value of the voxels over the preselected distance along the ray casting direction into the lumen-defining structure.

4. The virtual endoscopy method as set forth in claim 1, wherein the defining of the pixel value based at least on the computed statistical characteristic includes:

performing volume rendering for each ray casting direction to produce a rendered voxel value representative of the intersected lumen-defining surface; and

adjusting the rendered voxel value based on the computed statistical characteristic.

5. The virtual endoscopy method as set forth in claim 4, wherein the adjusting of the rendered voxel value includes adjusting a color of the rendered voxel value based on the computed statistical characteristic.

6. The virtual endoscopy method as set forth in claim 1, wherein the lumen-defining structure is an anatomical organ, the virtual endoscopy method further including:

prior to acquiring the volumetric image of the anatomical organ, administering an intravenous contrast agent providing enhanced vascular contrast in the volumetric image.

7. The virtual endoscopy method as set forth in claim 1, wherein (i) the ray casting directions are selected to extend generally radially from an unfolding axis generally positioned at a camera position, and (ii) the pixel values are arranged into an unfolded endoscopic view.

8. The virtual endoscopy method as set forth in claim 7, wherein the unfolding axis is divided into a plurality of axis segments, ray casting directions are radially symmetrically arranged around each axis segment, and the virtual endoscopy method further includes:

tilting the ray casting directions away from the camera position based on distance between the corresponding axis segment and the camera position, the tilting generally increasing with increasing distance of the axis segment from the camera position.

9. The virtual endoscopy method as set forth in claim 1, wherein (i) the ray casting directions are selected to extend from a camera position, and (ii) the pixel values are arranged into a perspective endoscopic view.

10. A method, comprising:

reconstructing, via a processor, projection data and generating, via the processor, an image of a flattened perspective view of an internal wall of a lumen having a longitudinal axis, wherein pixel values for the image are determined from voxel values of reconstructed volumetric image data representing the lumen that are located along both orthogonal and non-orthogonal paths from predetermined axis segments on the longitudinal axis to the internal wall, wherein a pixel value defined by a tilted ray from a same particular axis segment captures information about the lumen that is not captured by a pixel value defined by a non-tilted ray from the same particular axis segment, wherein the tilted ray extends non-orthogonally from the same particular axis segment to the lumen and the non-tilted ray extends orthogonally from the same particular axis segment to the lumen.

11. The method of claim 10, further comprising:

determining an unfolding axis substantially within the lumen and generally positioned at a camera position, the unfolding axis being divided into the axis segments.

12. The method of claim 11, further comprising:

selecting ray casting directions extending generally radially from the axis segments of the unfolding axis, wherein the non-tilted ray extends along one of the selected ray casting directions extending generally radially from the axis segments of the unfolding axis.

13. The method of claim 12, further comprising:

tilting at least some of the ray casting directions away from the camera position based on distance between the corresponding axis segment and the camera position, wherein the tilted ray extends along one of the tilted ray casting directions.

14. The method of claim 13, further comprising:

performing ray casting along the tilted ray casting directions to define pixel values, wherein the tilted ray extends along one of the tilted ray casting directions, thereby producing the tilted ray; and

arranging the pixel values into the unfolded view.

15. The method of claim 14, wherein the information includes a feature in a fold in the lumen.

16. A method, comprising:

reconstructing, via a processor, projection data and generating, via a processor, an image of a flattened perspective view of an internal wall of a lumen so as to show information located in folded regions of the internal wall, wherein a pixel value defined by a tilted ray from a same particular axis segment captures information about the lumen that is not captured by a pixel value defined by a non-tilted ray from the same particular axis segment, wherein the information includes a feature in a fold in the lumen wherein the tilted ray extends non-orthogonally from the same particular axis segment to the lumen and the non-tilted ray extends orthogonally from the same particular axis segment to the lumen.

17. The method of claim 16, further comprising:

determining an unfolding axis substantially within the lumen and generally positioned at a camera position, the unfolding axis being divided into the axis segments.

18. The method of claim 17, further comprising:

selecting ray casting directions extending generally radially from the axis segments of the unfolding axis, wherein the non-tilted ray extends along one of the selected ray casting directions extending generally radially from the axis segments of the unfolding axis.

19. The method of claim 18, further comprising:

tilting at least some of the ray casting directions away from the camera position based on distance between the corresponding axis segment and the camera position, wherein the tilted ray extends along one of the tilted ray casting directions.

20. The method of claim 19, further comprising:

performing ray casting along the tilted ray casting directions to define pixel values, wherein the tilted ray extends along one of the tilted ray casting directions, thereby producing the tilted ray; and

arranging the pixel values into the unfolded view.