4522 Is high resolution magnifying colonoscope combined with indigo carmine dye scattering useful for diagnosis of the depth of invasion in colorectal tumors

Background: High resolution magnifying colonoscopy(HRM) has recently been paid attention as a clinically useful diagnostic tool for diagnosis of the depth of invasion in colorectal tumors. However, there were no studies available whether magnified observation combined with indigo carmine dye scattering(ICD) provides better ability for diagnosis of the depth of invasion of the tumor than ordinary observation.We carried out this study to validate a usefulness of magnified observation by comparing accuracy of its prediction of depth of invasion with that of ordinary observation. Methods:20 lesions(10: adenoma & m or sm1 cancer,10: sm cancer deeper than sm2) were recorded using HRM(Fujinon EC400(410)CM or 410CW) without ICD and with ICD by video(S-VHS).We studied interobserver ability and superiority of magnified observation(Mo) combined with ICD to predict the depth of invasion in these lesions when compared to ordinary observation(Oo) without ICD. 6 colonoscopists(3 beginners(Group A) & 3 experienced(Group B)) reviewed an edited video tape composed of short segments of randomly arranged 20 lesions without and with ICD in succession. They were instructed to predict each lesion's depth of invasion (m,sm1 or deeper than sm2) based on the findings of its ordinary observation and also its magnified observation(including pit pattern). Results: Diagnostic accuracy rate of the depth of invasion is significantly higher by magnified observation combined with ICD than by ordinary observation without ICD especially in colorectal tumors deeper than sm2. Diagnostic accuracy rate of the depth of invasion colonoscopist m,sm1 deeper than sm2 Oo Group A 47% a 63% c ICD(-) GroupB 87% 67% d Mo GroupA 77% b 90% e ICD(+) GroupB 87% 97% f Significant difference(p