Teniae coli guided navigation and registration for virtual colonoscopy

We present a new method for guiding virtual colonoscopic navigation and registration by using teniae coli as anatomical landmarks. As most existing protocols require a patient to be scanned in both supine and prone positions to increase sensitivity in detecting colonic polyps, reference and registration between scans are necessary. However, the conventional centerline approach, generating only the longitudinal distance along the colon, lacks the necessary orientation information to synchronize the virtual navigation cameras in both scanned positions. In this paper we describe a semi-automatic method to detect teniae coli from a colonic surface model reconstructed from CT colonography. Teniae coli are three bands of longitudinal smooth muscle on the surface of the colon. They form a triple helix structure from the appendix to the sigmoid colon and are ideal references for virtual navigation. Our method was applied to 3 patients resulting in 6 data sets (supine and prone scans). The detected teniae coli matched well with our visual inspection. In addition, we demonstrate that polyps visible on both scans can be located and matched more efficiently with the aid of a teniae coli guided navigation implementation.