High-definition White-light Colonoscopy Research Articles

Longer Colonoscopy Withdrawal Time Is Associated With the Detection of Visible Dysplasia in Patients With Inflammatory Bowel Disease.

Colonoscopy withdrawal time (CWT) of at least 6-9 minutes is the minimum time needed for adequate adenoma detection in the general population. The ideal CWT in patients with inflammatory bowel disease (IBD) has not been determined. We aimed to identify the optimal CWT associated with the detection of visible dysplasia in patients with IBD. This is a retrospective study from 1/1/2017 to 9/1/2022 of adult patients with IBD in endoscopic healing undergoing surveillance via high-definition white light colonoscopy. The primary outcome was the association of CWT with visible dysplasia detection. A total of 259 patients (mean age 56 ± 14.8 years; 51.3% female, 68% with ulcerative colitis; 8.9% with primary sclerosing cholangitis) underwent 330 colonoscopies. Patients with visible dysplasia were more likely to be older (P < .001) and have a personal history of visible dysplasia (P < .001) and invisible dysplasia (P = .023). The mean CWT was significantly longer in the visible dysplasia group at 26 minutes (interquartile range [IQR] 20-38.5) vs. 21 minutes (IQR 15-28) in procedures without visible dysplasia (P < .001). On multivariable analysis, increased age (P < .001), increased CWT (P = .001), and personal history of visible dysplasia (P = .013) were independently associated with the detection of visible dysplasia. A CWT of ≥15 minutes (odds ratio [OR] 2.71; 95% confidence interval [CI], 1.11-6.6; P = .02] and not ≥9 minutes (OR 2.57; 95% CI, 0.33-20.2; P = .35) is significantly associated with detection of visible dysplasia. For patients with IBD undergoing surveillance via high-definition white light colonoscopy, the mean CWT was independently associated with the detection of visible dysplasia.

A randomized trial evaluating the utility of non-targeted biopsies for colorectal neoplasia detection in adults with inflammatory bowel disease: a pilot study protocol

BackgroundPersons with inflammatory bowel diseases are at increased risk of developing colorectal cancer and require frequent colonoscopy surveillance. Guidelines recommend taking 30 to 40 non-targeted biopsies throughout the colorectum to detect “invisible” neoplasia in this setting, despite a lack of evidence supporting this practice. We sought to assess the utility of this practice through a randomized controlled trial. We first propose an internal pilot study to assess recruitment potential, protocol adherence and data capture to guide the full trial.MethodsWe have designed a multi-centre, parallel-group, non-inferiority randomized controlled trial to test the utility of non-targeted biopsies as an adjunct to colonoscopy surveillance for neoplasia detection in persons with inflammatory bowel disease involving the colorectum in routine clinical practice. Participants are randomized 1:1, stratified by study site, to either standard of care high-definition white-light colonoscopy with 32 to 40 non-targeted biopsies of non-neoplastic-appearing mucosa along with a sampling of abnormal-appearing mucosa (control group) or modified colonoscopy with targeted sampling alone (intervention group). The primary outcome for the full trial will be the proportion of persons with ≥ 1 neoplastic focus detected during colonoscopy. For the pilot phase, we will assess the feasibility of recruiting a minimum of 15% of the estimated sample size within 1 year, under identical conditions as the full trial, while maintaining ≥ 90–95% rate of protocol adherence and data capture. These participants will contribute data to the full trial. The trial is being conducted at 12 centres across Canada, with a total sample size of 1952 persons.DiscussionsThe trial protocol has been approved by the ethics committees of all participating sites, and the pilot study has received funding through the Canadian Institutes of Health Research (PJT 159607). If feasibility metrics are met during the pilot phase, we will complete the full trial. The trial outcomes will contribute to update the practice guidelines in this area.Trial registrationClinicalTrials.gov, NCT04067778.

Endoscopic submucosal dissection for giant colorectal laterally spreading tumor 33 cm in diameter.

A 77-year-old male presented with recurrent diarrhea for more than 2 years, aggravated and a 1-month history of a rectal mass. High-definition white light colonoscopy showed an approximately circumferential elevated lesion from about 12 cm from the anus to the dentate line, with surface nodules of different sizes, some surfaces slightly congested, and internal hemorrhoids. The patient was diagnosed with a giant laterally spreading tumor-granular nodular mixed type (LST-G-M) of the rectum with the possibility of local malignant transformation and treated with single-tunnel assisted endoscopic submucosal dissection (ESD) at the patient's request. Histopathology of the specimen showed villous tubular adenoma with local carcinogenesis, 33*12cm in size, negative margins, no lymphovascular invasion. No bleeding or perforation was observed during or after procedure, and no stenosis was scrutinized at 2 months later.

Adenoma detection rate using narrow-band imaging is inferior to high-definition white light colonoscopy in screening and surveillance colonoscopies in daily clinical care: A randomized controlled trial.

Background:Despite recent advances in endoscopic technology adenoma miss rate still is up to 20% contributing to interval cancers. Improved imaging modalities have been introduced to increase adenoma detection rate (ADR). Recently, narrow-band imaging (NBI) (Exera II series, Olympus Corporation) was not significantly better than high-definition white light colonoscopy (HD-WLC). An improved second generation of NBI (190-NBI) is characterized by better illumination of the bowel lumen and may be associated with a higher ADR.Methods:We performed a prospective randomized study on patients referred to the Jena University Hospital for screening or surveillance colonoscopy between January 2015 and April 2017. Participating endoscopists were divided into 2 subgroups depending on their individual experience. Colonoscopy was performed by use of HD-WLC or 190-NBI upon withdrawal.Results:Five hundred fifty-three patients participated in the study. Eighty patients were excluded (insufficient bowel cleansing [n = 34], anticoagulation precluding polypectomy [n=15], partial colonic resection [n=9], other reasons [n = 22]). Mean age was 66.9 years (standard deviation 10.3 years), and 253 patients were male (53.5%). Bowel preparation and withdrawal time were not different. ADR among all subgroups was 39.4% using HD-WLC, but only 29.1% were using 190-NBI (P = .02). Number of polyps per patient was lower using 190-NBI than with HD-WLC (0.58 vs 0.86; P = .02). Subgroup analysis revealed that 190-NBI was inferior to HD-WLC only in unexperienced endoscopists.Conclusion:In our stud,y ADR was lower by use of 190-NBI. These differences persisted only in unexperienced investigators. 190-NBI seems to be more challenging regarding ADR, requiring more intensive training prior to implementing this technology in daily clinical care.Registration:ClinicalTrials.gov (identifier: NCT03081975).

Advances in Colonoscopy for Colorectal Cancer Screening: A Comparison between Chromocolonoscopy Vs Colonoscopy

Aim: A comparison between chromocolonoscopy versus white light colonoscopy in screening colorectal cancer Methods: Patients were randomly assigned to high-definition white light colonoscopy (HDWLC) and high-definition chromocolonoscopy (HDCH). The patients were divided into two groups, each had 110 individuals Results: An adenoma affected 1.2 to 2.1 patients on average, while polyps affected 1.4 to 1.9 patients on average, with an adenoma affecting 0.5 to 1.0 patient on average. Both the number of patients with at least one adenoma (54.5% vs. 47.2%, absolute difference 7.3%, 95% confidence interval (p value &lt;0.01) and the number of adenomas per patient (1.2 versus 1.0, P &lt;0.01) were slightly higher in the chromocolonoscopy group. Adenomas that had progressed by 10 mm or more differed from those that had progressed by &lt;10 mm (0.16 versus 0.14, P = 0.4), although the differences were not statistically significant. In each group, one invasive malignancy was discovered, and it wasn't a benign tumor or neoplasm. By chromocolonoscopy, non-neoplastic lesions (1.9 per patient versus 1.1 per patient, P = 0.01) were detected significantly more frequently than adenomas larger than 5 mm in diameter (0.9 per patient versus 0.8 per patient, P &lt; 0.01) Conclusion: When compared to high-definition white light colonoscopy, high-definition chromocolonoscopy had a marginally greater rate of adenoma diagnosis and a moderate increase in flat adenomas and small lesions but not in large lesions. When it came to more advanced malignancies, both techniques produced the same results. Keywords: Colorectal cancer, chromocolonoscopy

High-Definition Colonoscopy Compared With Cuff- and Cap-Assisted Colonoscopy: Results From a Multicenter, Prospective, Randomized Controlled Trial

Mucosal exposure devices including distal attachments such as the cuff and cap have shown variable results in improving adenoma detection rate (ADR) compared with high-definition white light colonoscopy (HDWLE). We performed a prospective, multicenter randomized controlled trial in patients undergoing screening or surveillance colonoscopy comparing HDWLE to 2 different types of distal attachments: cuff (CF) (Endocuff Vision) or cap (CP) (Reveal). The primary outcome was ADR. Secondary outcomes included adenomas per colonoscopy, advanced adenoma and sessile serrated lesion detection rate, right-sided ADR, withdrawal time, and adverse events. Continuous variables were compared using Student's t test and categorical variables were compared using chi-square or Fisher's exact test using statistical software Stata version16. A P value <.05 was considered significant. A total of 1203 subjects were randomized to either HDWLE (n= 384; mean 62 years of age; 81.3% males), CF (n= 379; mean 62.7 years of age; 79.9% males) or CP (n= 379; mean age 62.1 years of age; 80.5% males). No significant differences were found among 3 groups for ADR (57.3%, 59.1%, and 55.7%; P= .6), adenomas per colonoscopy (1.4 ± 1.9, 1.6 ± 2.4, and 1.4 ± 2; P= .3), advanced adenoma (7.6%, 9.2%, and 8.2%; P= .7), sessile serrated lesion (6.8%, 6.3%, and 5.5%; P= .8), or right ADR (48.2%, 49.3%, and 46.2%; P= .7). The number of polyps per colonoscopy were significantly higher in the CF group compared with HDWLE and CP group (2.7 ± 3.4, 2.3 ± 2.5, and 2.2 ± 2.3; P= .013). In a multivariable model, after adjusting for age, sex, body mass index, withdrawal time, and Boston Bowel Preparation Scale score, there was no impact of device type on the primary outcome of ADR (P= .77). In screening patients, CF resulted in more neoplasms per colonoscopy (CF: 1.7 ± 2.6, HDWLE: 1.3 ± 1.7, and CP: 1.2 ± 1.8; P= .047) with a shorter withdrawal time. Results from this multicenter randomized controlled trial do not show any significant benefit of using either distal attachment devices (CF or CP) over HDWLE, at least in high-detector endoscopists. The Endocuff may have an advantage in the screening population. (ClinicalTrials.gov, Number: NCT03952611).

Deep Learning Computer-aided Polyp Detection Reduces Adenoma Miss Rate: A United States Multi-center Randomized Tandem Colonoscopy Study (CADeT-CS Trial)

Artificial intelligence-based computer-aided polyp detection (CADe) systems are intended to address the issue of missed polyps during colonoscopy. The effect of CADe during screening and surveillance colonoscopy has not previously been studied in a United States (U.S.) population. We conducted a prospective, multi-center, single-blind randomized tandem colonoscopy study to evaluate a deep-learning based CADe system (EndoScreener, Shanghai Wision AI, China). Patients were enrolled across 4 U.S. academic medical centers from 2019 through 2020. Patients presenting for colorectal cancer screening or surveillance were randomized to CADe colonoscopy first or high-definition white light (HDWL) colonoscopy first, followed immediately by the other procedure in tandem fashion by the same endoscopist. The primary outcome was adenoma miss rate (AMR), and secondary outcomes included sessile serrated lesion (SSL) miss rate and adenomas per colonoscopy (APC). A total of 232 patients entered the study, with 116 patients randomized to undergo CADe colonoscopy first and 116 patients randomized to undergo HDWL colonoscopy first. After the exclusion of 9 patients, the study cohort included 223 patients. AMR was lower in the CADe-first group compared with the HDWL-first group (20.12% [34/169] vs 31.25% [45/144]; odds ratio [OR], 1.8048; 95% confidence interval [CI], 1.0780-3.0217; P= .0247). SSL miss rate was lower in the CADe-first group (7.14% [1/14]) vs the HDWL-first group (42.11% [8/19]; P= .0482). First-pass APC was higher in the CADe-first group (1.19 [standard deviation (SD), 2.03] vs 0.90 [SD, 1.55]; P= .0323). First-pass ADR was 50.44% in the CADe-first group and 43.64 % in the HDWL-first group (P= .3091). In this U.S. multicenter tandem colonoscopy randomized controlled trial, we demonstrate a decrease in AMR and SSL miss rate and an increase in first-pass APC with the use of a CADe-system when compared with HDWL colonoscopy alone.

Dysplasia detection is similar between chromoendoscopy and high-definition white-light colonoscopy in inflammatory bowel disease patients: a US-matched case-control study.

Inflammatory bowel disease (IBD) patients are at greater risk of developing colorectal cancer (CRC). Detection of precursor dysplasia is important for cancer prevention. Recent guidelines recommend dye chromoendoscopy (DCE) as the preferred method for dysplasia detection. Universal adoption of DCE is time-consuming and may limit endoscopy access. The benefit of universal application of the guidelines is unclear. We compared high-definition white-light colonoscopy (HD-WLC) with DCE for dysplasia detection in IBD patients. We conducted a retrospective case-control study of adult IBD patients undergoing dysplasia surveillance between September 1, 2015, and February 1, 2020. DCE cases were matched to HD-WLC in a 1:1 ratio for gender, IBD diagnosis, and age. DCE patients were considered high risk for colorectal cancer by the referring provider. A total of 187 subjects were enrolled. Majority were males, were Caucasian, and had longstanding IBD (primarily ulcerative colitis). Baseline characteristics were similar between the two groups, except for history of surgery, duration of IBD, and history of dysplasia. There was no significant difference in dysplasia detection between DCE and HD-WLC (10.2% vs 6.7%, p = 0.39). More polyps were detected in the DCE arm compared with the HD-WLC group (1.35 vs 0.80, p = 0.018), but adenoma detection rate was not statistically different between the two groups (10.2% vs 9.0%, p = 0.31). Mean withdrawal time was longer in the DCE group (24.6 min vs 15.4, p < 0.001). There were no differences in dysplasia detection using DCE compared with HD-WLC, although withdrawal times were longer with DCE.

New artificial intelligence system: first validation study versus experienced endoscopists for colorectal polyp detection

To improve colorectal polyp detection, a new artificial intelligence (AI) system (GI-Genius, Medtronic) was trained and validated on a dataset of white-light endoscopy videos from a high-quality randomised controlled trial...

Mo2042 – Chromoendoscopy Reduces the Subsequent Risk of Advanced Polypoid Dysplasia Compared to High Definition White Light Colonoscopy in a Chronic Ulcerative Colitis Surveillance Program

Mo2042 – Chromoendoscopy Reduces the Subsequent Risk of Advanced Polypoid Dysplasia Compared to High Definition White Light Colonoscopy in a Chronic Ulcerative Colitis Surveillance Program

Effect of I-scan Electronic Chromoendoscopy on Detection of Adenomas During Colonoscopy

I-scan is an electronic chromoendoscopy technology that improves resolution of epithelial and mucosal surfaces and vessels. We performed a randomized controlled trial to compare detection of adenomas by i-scan vs standard high-definition white-light (HDWL) colonoscopy. From February 1 through December 31, 2017, 740 outpatients (50-75 years old) undergoing screening and surveillance for colorectal neoplasia were randomly assigned to groups that received colonoscopies with i-scan 1 (surface and contrast enhancement) or HDWL. When lesions and polyps were detected, endoscopists could switch between i-scan 1 and HDWL imaging to confirm their finding; polyps were collected and analyzed by histology. The primary outcome was adenoma detection rate (ADR, proportion of subjects with at least 1 adenoma of any size); secondary outcomes included detection of sessile serrated polyps and neoplasias, along with location, size, and morphology of polyps. We performed intent to treat and per-protocol analyses (on 357 patients evaluated by i-scan and 358 evaluated by HDWL colonoscopy) to assess the primary and secondary outcomes. There were no differences in baseline characteristics between the groups. In the intent to treat analysis, the ADR was significantly higher in the i-scan 1 group (47.2%) than in the HDWL colonoscopy group (37.7%) (P = .01). In the per-protocol analysis, the ADR in the i-scan 1 group (47.6%) was also significantly higher than in the HDWL group (37.2%) (P = .005), but this effect was not consistent among all endoscopists. There was no difference between groups in detection of sessile serrated polyps. However, the rate of neoplasia detection was significantly higher in the i-scan 1 group (56.4%) than in the than the HDWL group (46.1%) (P=.005). In secondary analyses, the increase in ADR was associated with improved detection of diminutive flat adenomas in the right colon. In a prospective randomized trial, higher proportions of patients with adenomas were identified in a group that underwent colonoscopy with i-scan 1 than in a group evaluated by HDWL colonoscopy. This effect was mainly due to improved detection of diminutive, flat right sided adenomas. I-scan 1 technology may benefit some endoscopists. ClinicalTrials.gov no: NCT02811419.

Chromoendoscopy for Dysplasia Surveillance in Inflammatory Bowel Disease.

Long-standing ulcerative colitis (UC) and extensive Crohn's colitis confer increased risk for development of colorectal cancer. Screening and surveillance colonoscopy programs aim to identify, resect, or detect dysplasia or colorectal cancer. Dysplastic lesions can be removed by endoscopic resection and patients with unresectable lesions can be referred for colectomy at an earlier stage, with the goal of reducing overall morbidity and mortality from colorectal cancer. Surveillance colonoscopy for patients with inflammatory bowel disease (IBD) is endorsed by multiple specialty societies. High-definition endoscopy systems provide improved image resolution, and application of dilute indigo carmine or methylene blue for chromoendoscopy can provide increased contrast. International specialty society guidelines differ in their recommendations regarding use of chromoendoscopy for dysplasia surveillance, with some guidelines advocating a risk-stratified surveillance strategy. In this review, we discuss chromoendoscopy technique, training, implementation, yield as compared with standard-definition and high-definition white light colonoscopy, and positioning of this technique in clinical practice.

PWE-115 Detection and Characterisation of Colorectal Polyps Using High Definition White Light and I-Scan: Evidence and Delphi Process-Based Consensus Recommendations

Introduction Electronic imaging technologies such as i-Scan, Narrow Band Imaging (NBI) and Fujinon Intelligence Colour Enhancement (FICE) are increasingly used for polyp detection and characterisation, but to date, their use is limited to expert settings. I-scan is a relatively novel technology. Insufficient literature with i-scan and the lack of RCT’s hinder its implementation in clinical practice. Our goal was to review the current literature on the clinical utility of i-scan and develop evidence-based practical recommendations. Methods We conducted a systematic review on the role of high definition white-light (HDWL) and i-Scan colonoscopy for polyp detection and characterisation. A series of evidence-based statements were developed and put through anonymous voting along the lines of a modified Delphi process. A one day consensus meeting was held (June 20, 2015, Milan). Each statement was voted until consensus (i.e >80% agreement) was achieved or rejection agreed. GRADE recommendations were assigned to the agreed statements. Results The Consensus Panel consisted of 11 international experts. In total, 11 statements were proposed, of which 9 achieved consensus: HDWL is recommended rather than standard definition (SD) for the detection and characterisation of colorectal polyps; HDWL + i-Scan improves polyp and adenoma detection rates; HDWL + i-Scan are superior to HDWL alone for the optical diagnosis of colorectal polyps; HDWL + i-Scan in expert hands meet the ASGE PIVI standards for the optical diagnosis of diminutive polyps; HDWL+i-Scan in non-expert hands do not meet the ASGE PIVI standards for the optical diagnosis of diminutive polyps; Optical diagnosis of polyps with i-Scan has a learning curve and needs systematic training; The performance of i-Scan for real time characterisation of colorectal polyps is similar to NBI & FICE. Two statements failed to achieve consensus: HDWL alone can be effective for the in-vivo characterisation of polyps in expert hands; The adenoma detection rate is comparable when using HDWL + i-scan versus chromoendoscopy. Conclusion The Consensus Panel proposes evidence-based recommendations for the detection and characterisation of colorectal polyps using high-definition white light endoscopy and i-scan, to facilitate implementation of this technology in clinical practice. Areas of uncertainty, controversy and future research needs are addressed. Disclosure of Interest None Declared

Su1706 Is High Definition Narrow Band Imaging Better Than High Definition White Light Colonoscopy for Detection of Adenomas?: A Meta-Analysis of Randomized Controlled Trials

Su1706 Is High Definition Narrow Band Imaging Better Than High Definition White Light Colonoscopy for Detection of Adenomas?: A Meta-Analysis of Randomized Controlled Trials

Su1650 Narrow Band Imaging Does Not Increase Adenoma Detection Rate Compared to High Definition White Light Colonoscopy in Screening and Surveillance Colonoscopies

Su1650 Narrow Band Imaging Does Not Increase Adenoma Detection Rate Compared to High Definition White Light Colonoscopy in Screening and Surveillance Colonoscopies

1001 Detection of Colorectal Adenomatous Lesions By Blue Laser Imaging (LASEREO) Versus High-Definition White Light Colonoscopy: A Randomized Controlled Trial

1001 Detection of Colorectal Adenomatous Lesions By Blue Laser Imaging (LASEREO) Versus High-Definition White Light Colonoscopy: A Randomized Controlled Trial

High-definition white-light (HDWL) colonoscopy and higher adenoma detection rate and the potential for paradoxical over surveillance.

Patients undergoing high-definition white-light colonoscopy by a high adenoma detector may have a lower risk of interval adenoma detection on follow-up colonoscopy and may require less frequent follow-up but may paradoxically be assigned to more frequent surveillance when more adenomas are detected. To evaluate whether high-definition white-light colonoscopy (vs. standard-definition white-light colonoscopy) and endoscopist adenoma detection rate (ADR) at index colonoscopy are associated with increased likelihood of adenomas at follow-up. Longitudinal follow-up of prior cross-section cohort study of patients who underwent colonoscopy at baseline with at least one detected adenoma was included. Associations of type of white-light at index colonoscopy and the ADR of the endoscopist at index colonoscopy (high vs. low adenoma detector) were evaluated with various adenoma and polyp detection endpoints. Eighteen endoscopists were classified as high and low adenoma detectors based on the median ADR of 0.255. There were no significant differences in subsequent interval adenoma or polyp detection endpoints with regard to whether baseline exam was performed with high-definition white-light or standard-definition white-light colonoscopy nor between high and low ADR after adjusting for multiple testing (P≤0.0029 considered significant). Prior to multiple testing adjustment, there was a significantly lower detection rate of hyperplastic polyps in the left colon (24 vs. 35%, OR: 0.56, P=0.033) at follow-up colonoscopy when baseline exam was performed with high-definition white-light index colonoscopy. The results of this study do not support adjusting colonoscopy surveillance guidelines based on type of colonoscopy performed or the endoscopist's ADR.

Narrow band imaging vs. high definition colonoscopy for detection of colorectal adenomas in patients with positive faecal occult blood test: a randomised trial.

The impact of narrow band imaging in improving the adenoma detection rate in a screening scenario is still unclear. To evaluate whether narrow band imaging compared with high definition white light colonoscopy can enhance the adenoma detection rate during screening colonoscopy. Consecutive patients presenting for screening colonoscopy were included into this study and were randomly assigned to the narrow band imaging group (Group 1) or standard colonoscopy group (Group 2). Primary end point was the adenoma detection rate and secondary aim was the detection rate of advanced adenomas. Overall, 117 patients were allocated to Group 1 and 120 to Group 2. Both the adenoma detection rate and the detection rate of advanced adenomas were not significantly different between the two groups (respectively, 52.1% vs. 55%, RR=0.95, 95% CI 0.75-1.20; 32.5% vs. 44.2%, RR=0.74, 95% CI 0.53-1.02). No significant difference between the proportions of polypoid and flat adenomas was found. Male gender, no prior history of screening, and endoscopist's adenoma detection rate were independent predictive factors of higher advanced adenoma detection rate. In a screening scenario, narrow band imaging did not improve the adenoma nor advanced adenoma detection rates compared to high definition white light colonoscopy.

Mo1665 High- Definition Colonoscopy Detects More Polyps in the Right Colon Than Standard White- Light Colonoscopy

In recent times, one of the important advances in endoscopy has been the introduction of high definition endoscopy. As this technology provides better quality of images, one would expect an increase in the polyp detection rate with high- definition white-light colonoscopy (HDC) as compared to standard -definition white-light colonoscopy (SDC). Few studies have been done comparing these two modalities for polyp detection rate and adenoma detection rate in the past with conflicting results. We performed a study at our institution to compare the polyp detection rate and adenoma detection rate with HDC Vs SDC for screening colonoscopies.

A Randomized Controlled Trial Comparing High-Definition White Light Colonoscopy to I-Scan Enhanced Colonoscopy for Adenoma Detection in a Population at Increased Risk of Colorectal Cancer: A Pilot Study

A Randomized Controlled Trial Comparing High-Definition White Light Colonoscopy to I-Scan Enhanced Colonoscopy for Adenoma Detection in a Population at Increased Risk of Colorectal Cancer: A Pilot Study