Zhuoshi Wei PhD, Abstract Co-Author: Nothing to Disclose

Shijun Wang, Abstract Co-Author: Nothing to Disclose

Jianhua Yao PhD, Abstract Co-Author: Royalties, iCAD, Inc

Jiamin Liu PhD, Abstract Co-Author: Nothing to Disclose

Ronald M. Summers MD, PhD, Presenter: Royalties, iCAD, Inc Grant, iCAD, Inc Stockholder, Johnson & Johnson Grant, Viatronix, Inc

To show proof of concept for a marginal artery-based colon coordinate system.

We analyzed 40 polyps (average size 9mm, ranging from 5mm to 30mm) from 40 patients with both supine and prone CTC scans. We manually labeled the marginal artery (MA) near each polyp, then projected the MA to the colon wall as the intersection of colon wall and the line between MA and centroid of the colon cross-section. To simplify the processing, all polyps in this study were located within the ascending and descending colon and the cross-section was approximated as the transverse plane. The geodesic distance from the polyp to the projection point was computed, and its ratio to the length of the perimeter of the colon was recorded. The differences of the fractional distance between supine and prone scans were measured. Several possible MA points were labeled if the MA was not clear, and the best match between supine and prone was selected. Student’s t test (paired, two-tailed) was performed to evaluate the supine/prone differences of the fractional distance.

Identification of the marginal artery was possible in all 40 patients. For polyp localization, the average difference of the fractional distance between supine and prone scans was 2.2%±2.5%. Bias for multiple MA selection was estimated up to ±5%. Pairwise comparison of the fractional differences showed that these differences were not significantly different (p=0.25).

The marginal artery runs parallel to the colon and can serve as the origin of an alternative circumferential colon coordinate system. Thus, the marginal artery is a surrogate marker extrinsic to the colon that can help locate polyps and may be useful for supine to prone CTC registration and polyp localization.

The marginal artery can enable registration of polyps on the supine and prone scans potentially improving the accuracy and efficiency of CTC interpretation.  

Wei, Z, Wang, S, Yao, J, Liu, J, Summers, R, A Novel Circumferential Colon Coordinate System for Supine-Prone Registration of CT Colonography Using the Marginal Artery.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12035020.html