The Size Estimation of Small Bowel Lesions in Wireless Capsule Endoscopy: Comparison of PillCam SB and SB2

Abstract

Background/Aims: Wireless capsule endoscopy(WCE) is a useful instrument in small bowel angiodysplasia, polyposis syndrome. However, in contrast to conventional endoscopy, no standard instruments are available to the size estimation of small bowel lesions in WCE. Therefore, reliable methods are required for accurate size estimation, especially as the current WCE technique is expanding to the colon. We evaluated the accuracy of size estimation by recently suggested ‘calibrating methods’ (Gastrointest Endosc 2008;67: 924-931) in comparison of Pillcam SB and SB2. Methods: We prepared nine 20cm-long segments of bovine small bowel. For simulation of angiodysplasia, five round red disks with diameters from 2mm to 10mm glued onto pins and implanted into each bowel segments. After we slowly pushed and pulled Pillcam SB and SB2 through the bowel, video sequences were obtained Rapid 5 software(Given). We presented two sets of nine video sequences to two groups; group 1 (n=12, physicians), group 2 (m=6, gastroenterologists). After presenting the ‘calibrator’ WCE image printed 1mm by 1mm grid, we presented again same video sequences. The participants recorded on a questionnaire in millimeters. Results: In SB set, group 1 overestimated the diameters of the lesions by 11%, group 2 underestimated by 8% in the first presentation. After presenting the calibrator, group 1 and 2 underestimated the diameters by 41% and 28%, respectively. In SB2 set, group 1 overestimated the diameters of the lesions by 17%, group 2 underestimated by 11% in the first presentation. After presenting the calibrator, group 1 and 2 underestimated the diameters by 15% and 17%, respectively. Conclusion: The ‘calibrating methods’ can't improve accuracy of size estimation, on the other hand it can be a help to precision of size estimation. When we compared Pillcam SB and SB2, there was no difference in accuracy, however, SB2 showed higher precision than SB. Recently as colon capsule endoscopy is used, more reliable ‘calibrator methods’ for size estimation is required.