Virtual Colonoscopy (VC) has become a more prevalent and accepted method of colorectal cancer diagnosis. An essential element for detecting cancerous polyps using VC, in conjunction with computer-aided detection, is the accurate segmentation of the colon wall. While the inner boundary of the colon wall, the lumen-mucosal boundary, has often been the focus of previous segmentation work, detection of the outer wall, the serosal tissue boundary, allows for the segmentation of the colon wall, which is useful in determining potential polyps, muscular hypertrophy, and diverticulitis of the colon. Unfortunately, automatic determination of the outer colon wall position often is difficult due to the low contrast between CT attenuation values of the colon wall and the surrounding fat tissue. This invention is a level set based method to determine, from a CT colonography (CTC) scan, the location of the colon serosal tissue boundary. After determining this location, the algorithm segments the entire colon wall at subvoxel accurate precision.

In this algorithm, the loops in the colon caused by over-distention are detected and removed when the centerline calculation is performed. Also, a newly developed method for the detection and segmentation of the outer wall of the colon is used to connect collapsed portions where the lumen segmentation failed to produce a connected centerline. These two methods allow for a complete and accurate centerline to be calculated in uniformly distended colons as well as colons containing segments which are over and/or under-distended.

Applications:

Diagnostics

Publications:

1. R Van Uitert, I Bitter. Subvoxel precise skeletons of volumetric data based on fast marching methods. Med Phys. 2007 Feb;34(2):627-638.
2. RL Van Uitert, RM Summers. Automatic correction of level set based subvoxel precise centerlines for virtual colonoscopy using the colon outer wall.  IEEE Trans Med Imaging. 2007 Aug;26(8):1069-1078.
3. RM Summers, J Yao, PJ Pickhardt, M Franaszek, I Bitter, D Brickman, V Krishna, JR Choi. Computed tomographic virtual colonoscopy computer-aided polyp detection in a screening population. Gastroenterology. 2005 Dec;129(6):1832-1844.
4. R Van Uitert, I Bitter, RM Summers, JR Choi, PJ Pickhardt. Quantitative assessment of colon distention for polyp detection in CT virtual colonoscopy. Proc SPIE Int Soc Opt Eng. (2006) 6143,61431B:451-457; published online 13 Mar 2006, doi 10.1117/12.653205.
5. R Van Uitert, I Bitter, RM Summers. Detection of colon wall outer boundary and segmentation of the colon wall based on level set methods. Conf Proc IEEE Eng Med Biol Soc. 2006;1:3017-3020.
6. G Iordanescu, RM Summers. Benefits of centerline analysis for CT colonography computer-aided polyp detection. Proc SPIE Int Soc Opt Eng. (2003) 5031:388-397; published online 02 May 2003, doi:10.1117/12.485797.
7. G Iordanescu, RM Summers.  Automated centerline for computed tomography colonography. Acad Radiol. 2003 Nov;10(11):1291-1301.

Inventors:

Robert L. Van Uitert, Ronald M. Summers, Ingmar Bitter (CC)

Licensees sought.