Improved method for predicting polyp location from CT colonography for optical colonoscopy

The ability to accurately locate a polyp found on computed tomographic colonography (CTC) at subsequent optical colonoscopy (OC) is an important part of CTC for colorectal cancer screening. A previous study has shown that a polyp´s normalized distance along the colon centerline (NDACC) derived from CTC data can be utilized to predict its location at OC. We present a novel and automated method using a high degree uniform B-Spline curve fitting of the colon centerline on CTC to simulate OC colonoscope paths in order to more accurately predict polyp position. This evaluation is to determine whether the B-Spline method produces statistically significant improvement over the NDACC method in terms of prediction errors within 5 and 10 cm (± 1 colonoscope mark). Two-tailed Fisher´s Exact Tests indicate the B-Spline method is superior to the NDACC method, especially for locating polyps in the central portion of the colon. The ability to predict polyp locations within 5 and 10 cm increased 31.5 % and 10.2 % respectively using the B-Spline method.