Comparative Study Of High Definition Colonoscopy And High Definition Colonoscopy Plus I-Scan Imaging System In The Detection Of Colorectal Polyps:A Prospective,Randomized,Controlled Trial

Background:Colorectal cancer(CRC)is one of the most common malignant tumors in the gastrointestinal tract,with its morbidity and mortality rates rank the 3rd and 4th respectively among all malignancies.More than 80% of CRC develop from colorectal adenoma,and colonoscopic removal of adenoma reduces up to 76% to 90% of CRC incidence.So a high adenoma detection rate is vital to prevent CRC.But according to a recent study of colonoscopy,adenoma miss rate could be 22%.Hence improvement of adenoma detection rate,which cannot be achieved without increasing polyp detection rate at the first place,is significant for CRC prevention.bjective: To investigate the usefulness of i-Scan in the detection of colorectal polyps as a routine diagnostic procedure via a prospective randomized controlled trial comparing colorectal polyps detection rates of high definition colonoscopy and high definition colonoscopy plus I-scan imaging system.Methods : Sample size is determined according to calculation formula of quantitative data sampling.Consecutive individuals who had never underwent colonoscopy before and don’t fulfill any exclusion criterion were assigned to i-Scan group or control group with strict randomization concealment.Random numbers were generated by SPSS software version 22.0.Intubation of the cecum was completed with high definition white light for both groups,while withdrawal was performed with additional i-scan SE+4/CE+2 mode for i-Scan group,and merely with high definition white light for control group.Withdrawal procedure were video recorded and withdrawal time was required to be at least 7 min.The location,character and size of all polyps were recorded.A part of patients had their polyps resected or biopsied for histopathological examination.Statistic analysis was performed by SPSS22.0.The Student’s t test was used to compare the continuous variables between two groups,and chi-square test or Fisher exact test for the categorical variables.A p-value <0.05 was considered to be statistically significant.Results: A total of 449 patients who underwent their first colonoscopy at the third people’s hospital of Chengdu from November 2014 to June 2015 were deemed eligible for the study.46 patients were excluded before randomization because of severe colitis(n=13),poor or inadequate bowel preparation(n=12),colorectal cancer(n=9),ischemic enteritis(n=5),failed cecal intubation(n=4)or severe melanosis coli(n=3).403 patients actually entered this study,201 in i-Scan group and 201 in control group.Age,sex,bowel preparation status,indications to colonoscopy and withdrawal time were not significantly different between the two groups.No significant difference was discovered bewteen the two groups in the number of patients with at least one polyps(i-Scan group 103 vs.control group 107;P=0.729).Analysis based on different colonic segments revealed that in all segments but descending colon,patients with at least one polyps in i-scan group outnumbered those in control group,although statistical significance was only detected in cecum and ascending colon(39/201 vs.24/202;P=0.038).A total number of 467 polyps were detected,270 in i-Scan group vs 197 in control group,showing statistical significance in difference(P=0.041).Totally 344 diminutive polyps(polyps with size ≤5mm)were detected,204 in i-Scan group vs 140 in control group,with statistically significant difference(P=0.033).Most polyps were found in sigmoid.No significant differences existed between the two groups in locations of polyps and diminutive polyps.Totally 268 polyps were removed or biopsied for further histopathological evaluation,which revealed 153(57.1%)neoplastic polyps.47.34% of diminutive polyps were neoplastic.16 high-grade intraepithelial neoplasia were detected,3 of them were diminutive polyps.Conclusions: 1.High definition colonscopy with i-Scan can improve polyp detection,especially for diminutive polyps,without prolonged extubation time.2.High definition colonoscopy with i-Scan showed no significantly different polyp detection rate from high definition colonoscopy alone.3.More than 50% of patients undergoing their first colonoscopy could be found to have at least one polyps by high definition image system.4.A small part of diminutive adenomas were high-grade intraepithelial neoplasis.Further studies were needed to evaluate the real time histology predicative value of i-Scan for diminutive adenoma.5.The polyps detect rate is different in statistics bewteen high definition colonoscopy with i-Scan and high definition colonoscopy at ascending colon.Further studies were needed to evaluate the clinical vualue of it.