Colonoscopic miss rates determined by direct comparison of colonoscopy with colon resection specimens

Gastrointestinal image stitching based on improved unsupervised algorithm

Image stitching is a traditional but challenging computer vision task. The goal is to stitch together multiple images with overlapping areas into a single, natural-looking, high-resolution image without ghosts or seams. This article aims to increase the field of view of gastroenteroscopy and reduce the missed detection rate. To this end, an improved depth framework based on unsupervised panoramic image stitching of the gastrointestinal tract is proposed. In addition, preprocessing for aberration correction of monocular endoscope images is introduced, and a C2f module is added to the image reconstruction network to improve the network's ability to extract features. A comprehensive real image data set, GASE-Dataset, is proposed to establish an evaluation benchmark and training learning framework for unsupervised deep gastrointestinal image splicing. Experimental results show that the MSE, RMSE, PSNR, SSIM and RMSE_SW indicators are improved, while the splicing time remains within an acceptable range. Compared with traditional image stitching methods, the performance of this method is enhanced. In addition, improvements are proposed to address the problems of lack of annotated data, insufficient generalization ability and insufficient comprehensive performance in image stitching schemes based on supervised learning. These improvements provide valuable aids in gastrointestinal examination.

Protocol for a prospective multicenter randomized controlled trial to evaluate the efficacy of texture and color enhancement imaging (TXI) observation in the detection of colorectal lesions (deTXIon study)

Colonoscopy is the gold standard for detecting and resecting adenomas or early stage cancers to reduce the incidence and mortality rates of colorectal cancer. In a recent observational study, texture and color enhancement imaging (TXI) was reported to improve polyp detection during colonoscopy. This randomized controlled trial involving six Japanese institutions aims to confirm the superiority of TXI over standard white-light imaging (WLI) in detecting colorectal lesions during colonoscopy. During the 1-year study period, 960 patients will be enrolled, with 480 patients in the TXI and WLI groups. The primary endpoint is the mean number of adenomas detected per procedure. The secondary endpoints include adenoma detection rate, advanced adenoma detection rate, polyp detection rate, flat polyp detection rate, depressed lesion detection rate, mean polyps detected per procedure, sessile serrated lesion (SSL) detection rate, mean SSLs detected per procedure and adverse events.

Detection of colorectal adenomas with texture and color enhancement imaging: Multicenter observational study

OBJECTIVES

We aimed to evaluate the efficacy of texture and color enhancement imaging (TXI), which allows the acquisition of brighter images with enhanced color and surface structure in colorectal polyp detection compared to white light imaging.

METHODS

Patients who underwent colonoscopy with repeated ascending colon observation using TXI and white light imaging between August 2020 and January 2021 were identified in three institutions. The outcomes included the mean number of adenomas detected per procedure (MAP), adenoma detection rate (ADR), and ascending colonic adenoma miss rate (Ac-AMR). Logistic regression was used to determine the effects of the variables on the outcomes.

RESULTS

We included 1043 lesions from 470 patients in the analysis. The MAP, ADR, flat polyp detection rate, and Ac-AMR in TXI and white light imaging were 1.5% (95% confidence interval 1.3-1.6%) vs. 1.0% (0.9-1.1%), 58.2% (51.7-64.6%) vs. 46.8% (40.2-53.4%), 66.2% (59.8-72.2%) vs. 49.8% (43.2-56.4%), and 17.9% (12.1-25.2%) vs. 28.2% (20.0-37.6%), respectively. TXI, age, withdrawal time, and endoscopy type were identified as significant factors affecting the MAP and the ADR using multivariate regression analysis.

CONCLUSIONS

Our study indicates that TXI improve the detection of colorectal neoplastic lesions. However, prospective randomized trials are required to confirm these findings.

In vivo multi spectral colonoscopy in mice

Multi- and hyperspectral endoscopy are possibilities to improve the endoscopic detection of neoplastic lesions in the colon and rectum during colonoscopy. However, most studies in this context are performed on histological samples/biopsies or ex vivo. This leads to the question if previous results can be transferred to an in vivo setting. Therefore, the current study evaluated the usefulness of multispectral endoscopy in identifying neoplastic lesions in the colon. The data set consists of 25 mice with colonic neoplastic lesions and the data analysis is performed by machine learning. Another question addressed was whether adding additional spatial features based on Gauss-Laguerre polynomials leads to an improved detection rate. As a result, detection of neoplastic lesions was achieved with an MCC of 0.47. Therefore, the classification accuracy of multispectral colonoscopy is comparable with hyperspectral colonoscopy in the same spectral range when additional spatial features are used. Moreover, this paper strongly supports the current path towards the application of multi/hyperspectral endoscopy in clinical settings and shows that the challenges from transferring results from ex vivo to in vivo endoscopy can be solved.

Detection of colorectal lesions during colonoscopy

Owing to its high mortality rate, the prevention of colorectal cancer is of particular importance. The resection of colorectal polyps is reported to drastically reduce colorectal cancer mortality, and examination by endoscopists who had a high adenoma detection rate was found to lower the risk of colorectal cancer, highlighting the importance of identifying lesions. Various devices, imaging techniques, and diagnostic tools aimed at reducing the rate of missed lesions have therefore been developed to improve detection. The distal attachments and devices for improving the endoscopic view angle are intended to help avoid missing blind spots such as folds and flexures in the colon, whereas the imaging techniques represented by image‐enhanced endoscopy contribute to improving lesion visibility. Recent advances in artificial intelligence‐supported detection systems are expected to supplement an endoscopist's eye through the instant diagnosis of the lesions displayed on the monitor. In this review, we provide an outline of each tool and assess its impact on the reduction in the incidence of missed colorectal polyps by summarizing previous clinical research and meta‐analyses. Although useful, the many devices, image‐enhanced endoscopy, and artificial intelligence tools exhibited various limitations. Integrating these tools can improve their shortcomings. Combining artificial intelligence‐based diagnoses with wide‐angle image‐enhanced endoscopy may be particularly useful. Thus, we hope that such tools will be available in the near future.

Equity of colonoscopy provision and quality in Māori and New Zealand Europeans: a comparative retrospective study

BACKGROUND

High-quality colonoscopy is essential for investigating suspected colorectal cancer and relies on endoscopists meeting key performance indicator (KPI) targets. The rising demand for colonoscopy raises concerns that Māori populations could be under-served. This study aimed to compare rates of colonoscopy provision and colonoscopy KPIs between Māori and New Zealand (NZ) European patients.

METHODS

This retrospective comparative study was conducted at Whanganui Hospital (NZ). Consecutive colonoscopies performed between September 2016 and March 2020 were included. Primary outcome was the rate of colonoscopy provision for the population. Secondary outcomes were the colonoscopy completion rate (CCR), colonoscope withdrawal time (CWT), polyp detection rate (PDR) and adenoma detection rate (ADR). Subgroup analysis of ADR in index symptomatic colonoscopies was also performed.

RESULTS

A total of 2962 colonoscopies were analysed (385 Māori; 2577 NZ European). Rates of colonoscopy provision in participants aged ≥40 were significantly lower among Māori (6.1% versus 9.1%; P < 0.0001). The CCR (P = 1.00), CWT (P = 0.28) and PDR (P = 0.24) were similar. Whilst the ADR in the overall cohort was significantly lower in Māori (32.7% versus 40.0%; P = 0.028), this was not observed when stratified by 10-year age cohorts. The ADR was similar on subgroup analysis of index symptomatic colonoscopies (P = 0.42).

CONCLUSIONS

This study found inequities in access to colonoscopy services for Māori compared to NZ European patients. Among those that did receive colonoscopy, there were no differences in colonoscopy quality after age stratification. Improving equity will require the addition of colonoscopy provision rates to other mandatory KPIs and reporting these by ethnicity in all endoscopy units.

Topical application of Chlorin e6-PVP (Ce6-PVP) for improved endoscopic detection of neoplastic lesions in a murine colitis-associated cancer model

Screening colonoscopy is crucial in reducing the mortality of colorectal cancer. However, detecting adenomas against the backdrop of an inflamed mucosa (e.g. in ulcerative colitis) remains exceedingly difficult. Therefore, we aimed to improve neoplastic lesion detection by employing a fluorescence-based endoscopic approach. We used the well-established murine AOM/DSS model to induce inflammation-driven carcinogenesis in the colon. In our diagnostic approach, we evaluated Chlorin e6 polyvinylpyrrolidone (Ce6-PVP)-based fluorescence endoscopy in comparison to standard white-light endoscopy. A specialized pathologist then analyzed the histology of the detected lesions. Complementary in vitro studies were performed using human cell lines and a murine organoid system. Ce6-PVP-based fluorescence endoscopy had an improved detection rate of 100% (8/8) in detecting high-grade dysplasias and carcinomas over white-light detection alone with 75% (6/8). Trade-off for this superior detection rate was an increased rate of false positive lesions with an increase in the false discovery rate from 45% for white-light endoscopy to 81% for fluorescence endoscopy. We demonstrate in a proof-of-concept study that Ce6-PVP-based fluorescence endoscopy is a highly sensitive red flag technology to identify biopsy-worthy lesions in the colon.

Objective evaluation of the visibility of colorectal lesions using eye tracking

BACKGROUND AND AIM

To assess the visibility of colorectal lesions using blue laser imaging (BLI)-bright and linked-color imaging (LCI) with an eye-tracking system.

METHODS

Eleven endoscopists evaluated 90 images of 30 colorectal lesions. The lesions were randomly selected. Three images of each lesion comprised white light imaging (WLI), BLI-bright, and LCI in the same position. Participants gazed at the images, and their eye movements were tracked by the eye tracker. We analyzed whether the participants could detect the lesion and how long they took to detect the lesion. We assessed the miss rate and detection time among the imaging modalities.

RESULTS

One endoscopist was excluded, and 10 endoscopists were assessed. Overall, 12.6% of lesions were missed with WLI, 6.0% with BLI-bright, and 4.3% with LCI; the miss rate of BLI-bright and LCI was significantly lower than that of WLI (P < 0.01), with no significant difference between the former modalities (P = 0.54). Mean (± SD) detection times were 1.58 ± 1.60 s for WLI, 1.01 ± 1.21 s for BLI-bright, and 1.10 ± 1.16 s for LCI. Detection time for BLI-bright and LCI was significantly shorter than that for WLI (P < 0.0001), with no significant difference between the former modalities (P = 0.34). Regarding the miss rate and detection time between the expert and the non-experts, there was a significant difference with WLI but not with BLI-bright and LCI.

CONCLUSION

Blue laser imaging-bright and LCI improved the detection of colorectal lesions compared with WLI using an eye-tracking system.

Magnitude, Risk Factors, and Factors Associated With Adenoma Miss Rate of Tandem Colonoscopy: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

We performed a systematic review and meta-analysis to comprehensively estimate adenoma miss rate (AMR) and advanced AMR (AAMR) and explore associated factors.

METHODS

We searched the PubMed, Web of Science, and Ovid EMBASE databases for studies published through April 2018 on tandem colonoscopies, with AMR and AAMR as the primary outcomes. We performed meta-regression analyses to identify risk factors and factors associated with outcome. Primary outcomes were AMR and AAMR and secondary outcomes were AMR and AAMR for different locations, sizes, pathologies, morphologies, and populations.

RESULTS

In a meta-analysis of 43 publications and more than 15,000 tandem colonoscopies, we calculated miss rates of 26% for adenomas (95% confidence interval [CI] 23%-30%), 9% for advanced adenomas (95% CI 4%-16%), and 27% for serrated polyps (95% CI 16%-40%). Miss rates were high for proximal advanced adenomas (14%; 95% CI 5%-26%), serrated polyps (27%; 95% CI 16%-40%), flat adenomas (34%; 95% CI 24%-45%), and in patients at high risk for colorectal cancer (33%; 95% CI 26%-41%). Miss rates could be decreased by adequate bowel preparation and auxiliary techniques (P = .06; P = .04, and P = .01, respectively). The adenoma detection rate (ADR), adenomas per index colonoscopy, and adenomas per positive index colonoscopy (APPC) were independently associated with AMR (P = .02, P = .01, and P = .008, respectively), whereas APPC was the only factor independently associated with AAMR (P = .006). An APPC value greater than 1.8 was more effective in monitoring AMR (31% vs 15% for AMR P < .0001) than an ADR value of at least 34% (27% vs 17% for AMR; P = .008). The AAMR of colonoscopies with an APPC value below 1.7 was 35%, vs 2% for colonoscopies with an APPC value of at least 1.7 (P = .0005).

CONCLUSIONS

In a systematic review and meta-analysis, we found that adenomas and advanced adenomas are missed (based on AMR and AAMR) more frequently than previously believed. In addition to ADR, APPC deserves consideration as a complementary indicator of colonoscopy quality, if it is validated in additional studies.

Linked color imaging enhances endoscopic detection of sessile serrated adenoma/polyps

BACKGROUND AND STUDY AIMS

 Although new image-enhanced endoscopy (IEE) technologies such as blue laser imaging (BLI), BLI-bright, and linked color imaging (LCI) have been developed, their utility for the detection of sessile serrated adenoma/polyps (SSA/Ps) is still unclear. This study aimed to evaluate the utility of BLI, BLI-bright, and LCI for SSA/P detection in still image examinations and in a prospective randomized controlled trial (RCT).

PATIENTS AND METHODS

 A group of 6 expert and non-expert endoscopists read 200 endoscopic still images containing SSA/P lesions using white light image (WLI), BLI, BLI-bright, and LCI. Color differences were calculated using the color space method. A prospective RCT of tandem colonoscopy with WLI and LCI was performed. Patients with SSA/P and those with a history of SSA/P that had been endoscopically removed were enrolled and randomly allocated to WLI-LCI or LCI-WLI groups. Additional endoscopic detection rates for SSA/P were compared between the 2 groups.

RESULTS

 LCI showed the highest SSA/P detection rate among the 4 modes for both expert and non-expert endoscopists. The detection rate with LCI for the 6 expert endoscopists (mean 98.3 ± standard deviation 2.0 %) was significantly higher than that with WLI (86.7 ± 6.0 %, P  < 0.01). Likewise, the detection rate with LCI for the 6 non-expert endoscopists (92.3 ± 2.9 %) was significantly higher than that with WLI (72.7 ± 11.5 %, P  < 0.01). The color difference of SSA/P with LCI was the highest among the 4 modes, and was significantly higher than with WLI (median 15.9, (interquartile range 13.7 - 20.6) vs. 10.2, (7.6 - 14.2); P  < 0.0001). In the RCT, a total of 44 patients (WLI-LCI 22 vs. LCI-WLI 22) underwent colonoscopy. The additional detection rate for SSA/P in the second inspection in the WLI-LCI group (21.6 %, 8/37) was significantly higher than in the LCI-WLI group (3.2 %, 1/31; P  = 0.02). The small, flat, non-mucus and isochromatic SSA/Ps in the transverse colon were detected more frequently in the second inspection with LCI.

CONCLUSIONS

 LCI was the most sensitive mode for SSA/P detection among WLI, BLI, BLI-bright, and LCI in the still image examinations. Our RCT strongly suggests that LCI is superior to conventional WLI for SSA/P detection during colonoscopy. UMIN000017599.

Detectability of colorectal neoplastic lesions using a novel endoscopic system with blue laser imaging: a multicenter randomized controlled trial

BACKGROUND AND AIMS

Most studies have not reported an improvement in the detection of adenomas with the use of image-enhanced colonoscopy methods, possibly because of the darkness of the images. To overcome this limitation, a new-generation endoscopic system has been developed. This system has 2 blue-laser imaging (BLI) observation modes. The BLI observation was set to BLI-bright mode to detect lesions. We aimed to evaluate the efficacy of BLI in detecting lesions.

METHODS

This study was designed as a randomized controlled trial with participants from 8 institutions. We enrolled patients aged ≥40 years. The participants were randomly assigned to 2 groups: observation by using white-light imaging (WLI) with a conventional xenon light source (WLI group) or observation by using BLI-bright mode with a laser light source (BLI group). All of the detected lesions were resected or had a biopsy taken for histopathologic analysis. The primary outcome was the mean number of adenomas per patient (MAP) that were detected per procedure.

RESULTS

The WLI and BLI groups consisted of 474 and 489 patients, respectively. The MAP was significantly higher in the BLI group than in the WLI group (mean ± standard deviation [SD] WLI 1.01 ± 1.36, BLI 1.27 ± 1.73; P = .008). Adenoma detection rate in the BLI group was not significantly higher than in the WLI group. Observation times differed significantly, with BLI (9.48 minutes) being longer than WLI (8.42; P < .001). The mean (± SD) number of polyps per patient was significantly higher in the BLI group compared with the WLI group (WLI 1.43 ± 1.64, BLI 1.84 ± 2.09; P = .001).

CONCLUSIONS

A newly developed system that uses BLI improves the detection of adenomatous lesions compared with WLI. (Clinical trial registration number: UMIN 000014555.).

Missed adenomas with behind-folds visualizing colonoscopy technologies compared with standard colonoscopy: a pooled analysis of 3 randomized back-to-back tandem colonoscopy studies

BACKGROUND AND AIMS

The Third Eye Retroscope, Full Spectrum Endoscope (FUSE), and EndoRings devices have been shown to reduce overall adenoma miss rates. We evaluated the characteristics of adenomas and patient subgroups for which these behind-folds visualizing technologies mostly reduce adenoma miss rates.

METHODS

Data of 3 multicenter randomized trials (NCT01044732, NCT01549535, NCT01955122) were combined. Patients underwent same-day, back-to-back tandem examinations with standard colonoscopy and Third Eye Retroscope, FUSE, or EndoRings colonoscopy, respectively. Adenoma miss rates were stratified by adenoma characteristics and patient subgroups.

RESULTS

A total of 650 patients (60% male, mean age 57.5 years, standard deviation 9.7 years) were included; 330 patients underwent behind-folds visualizing colonoscopy first, and 320 patients underwent standard colonoscopy first. Regarding adenoma characteristics, adenoma miss rates were significantly (P < .001) lower with behind-folds visualizing technologies compared with standard colonoscopy for proximal (14% vs 38%) and distal (15% vs 35%), ≤5 mm (17% vs 38%), 6 to 9 mm (8% vs 44%), sessile (16% vs 37%), flat (9% vs 52%; P = .014), and tubular (15% vs 38%) adenomas and sessile serrated polyps (7% vs 50%; P = .039) but were not statistically significantly (P > .05) different for ≥10 mm, pedunculated, (tubulo-)villous, and advanced adenomas. Regarding patient subgroups, adenoma miss rates were significantly (P ≤ .020) lower with behind-folds visualizing technologies for patients ≥50 years, both sexes, and all indications.

CONCLUSIONS

Behind-folds visualizing colonoscopy reduces miss rates for 1 to 9 mm adenomas in the entire colon, whereas no advantage was found for ≥10 mm and advanced adenomas. Whether increased detection and removal of <10 mm adenomas also reduces colorectal cancer incidence and mortality remains to be determined. Future research is needed to determine which colonoscopy technology would be most beneficial for which patient or endoscopist.

Multicenter randomised controlled trial comparing the high definition white light endoscopy and the bright narrow band imaging for colon polyps

AIM

To compare high definition white light endoscopy and bright narrow band imaging for colon polyps’ detection rates.

METHODS

Patients were randomised to high definition white light endoscopy (HD-WLE) or the bright narrow band imaging (bNBI) during withdrawal of the colonoscope. Polyps identified in either mode were characterised using bNBI with dual focus (bNBI-DF) according to the Sano’s classification. The primary outcome was to compare adenoma detection rates (ADRs) between the two arms. The secondary outcome was to assess the negative predictive value (NPV) in differentiating adenomas from hyperplastic polyps for diminutive rectosigmoid lesions.

RESULTS

A total of 1006 patients were randomised to HD-WLE (n = 511) or bNBI (n = 495). The mean of adenoma per patient was 1.62 and 1.84, respectively. The ADRs in bNBI and HD-WLE group were 37.4% and 39.3%, respectively. When adjusted for withdrawal time (OR = 1.19, 95%CI: 1.15-1.24, P < 0.001), the use of bNBI was associated with a reduced ADR (OR = 0.69, 95%CI: 0.52-0.92). Nine hundred and thirty three polyps (86%) in both arms were predicted with high confidence. The sensitivity (Sn), specificity (Sp), positive predictive value and NPV in differentiating adenomatous from non-adenomatous polyps of all sizes were 95.9%, 87.2%, 94.0% and 91.1% respectively. The NPV in differentiating an adenoma from hyperplastic polyp using bNBI-DF for diminutive rectal polyps was 91.0%.

CONCLUSION

ADRs did not differ between bNBI and HD-WLE, however HD-WLE had higher ADR after adjustment of withdrawal time. bNBI surpassed the PIVI threshold for diminutive polyps.

CT colonography with computer-aided detection: recognizing the causes of false-positive reader results

Computed tomography (CT) colonography is a screening modality used to detect colonic polyps before they progress to colorectal cancer. Computer-aided detection (CAD) is designed to decrease errors of detection by finding and displaying polyp candidates for evaluation by the reader. CT colonography CAD false-positive results are common and have numerous causes. The relative frequency of CAD false-positive results and their effect on reader performance on the basis of a 19-reader, 100-case trial shows that the vast majority of CAD false-positive results were dismissed by readers. Many CAD false-positive results are easily disregarded, including those that result from coarse mucosa, reconstruction, peristalsis, motion, streak artifacts, diverticulum, rectal tubes, and lipomas. CAD false-positive results caused by haustral folds, extracolonic candidates, diminutive lesions (<6 mm), anal papillae, internal hemorrhoids, varices, extrinsic compression, and flexural pseudotumors are almost always recognized and disregarded. The ileocecal valve and tagged stool are common sources of CAD false-positive results associated with reader false-positive results. Nondismissable CAD soft-tissue polyp candidates larger than 6 mm are another common cause of reader false-positive results that may lead to further evaluation with follow-up CT colonography or optical colonoscopy. Strategies for correctly evaluating CAD polyp candidates are important to avoid pitfalls from common sources of CAD false-positive results.

Annual Fecal Occult Blood Testing can be Safely Suspended for up to 5 Years After a Negative Colonoscopy in Asymptomatic Average-Risk Patients

OBJECTIVES

Annual fecal occult blood testing (FOBT) is often continued in patients who have had a recent negative colonoscopy, despite recommendations to the contrary. This prospective study aimed to determine the proportion of patients with a positive FOBT who had adenomas and cancers on colonoscopy stratified according to the duration of time since the last negative colonoscopy.

METHODS

A total of 1,119 asymptomatic average-risk patients ≥50 years of age referred for a positive FOBT were prospectively identified and stratified by the duration of time since the last colonoscopy (never, >10 years, 5-10 years, or <5 years). The proportion of patients in each category with adenomas of any size, adenomas ≥10 mm, advanced neoplasms, and cancers was assessed.

RESULTS

The mean age (68.9±9.6 years), sex (95.2% male), and race (48.1% white, 32.1% black, 15.6% Hispanic, and 4.2% other) did not differ between the four groups. Overall, adenomas of any size were detected in 42.8% of patients, adenomas ≥10 mm in 14.7%, advanced neoplasms in 20.7%, and cancers in 7.3%. Advanced neoplasms were detected in 30.4% of patients who have never had a colonoscopy, 27% in those who have had one greater than 10 years prior, 10.0% in 5-10 years prior, and 1.1% in less than 5 years prior.

CONCLUSIONS

In asymptomatic average-risk patients with a negative colonoscopy within the last 5 years, the prevalence of adenomas is low, and no patient was diagnosed with cancer. These findings support the CDC recommendations to suspend annual FOBT for up to 5 years after a negative colonoscopy.

Computer vision and augmented reality in gastrointestinal endoscopy

Augmented reality (AR) is an environment-enhancing technology, widely applied in the computer sciences, which has only recently begun to permeate the medical field. Gastrointestinal endoscopy—which relies on the integration of high-definition video data with pathologic correlates—requires endoscopists to assimilate and process a tremendous amount of data in real time. We believe that AR is well positioned to provide computer-guided assistance with a wide variety of endoscopic applications, beginning with polyp detection. In this article, we review the principles of AR, describe its potential integration into an endoscopy set-up, and envisage a series of novel uses. With close collaboration between physicians and computer scientists, AR promises to contribute significant improvements to the field of endoscopy.

Polyp detection rates using magnification with narrow band imaging and white light

AIM: To compare the yield of adenomas between narrow band imaging and white light when using high definition/magnification.

METHODS: This prospective, non-randomized comparative study was performed at the endoscopy unit of veteran affairs medical center in Phoenix, Arizona. Consecutive patients undergoing first average risk colorectal cancer screening colonoscopy were selected. Two experienced gastroenterologists performed all the procedures that were blinded to each other’s findings. Demographic details were recorded. Data are presented as mean ± SEM. Proportional data were compared using the χ² test and means were compared using the Student’s t test. Tandem colonoscopy was performed in a sequential and segmental fashion using one of 3 strategies: white light followed by narrow band imaging [Group A: white light (WL) → narrow band imaging (NBI)]; narrow band imaging followed by white light (Group B: NBI → WL) and, white light followed by white light (Group C: WL → WL). Detection rate of missed polyps and adenomas were evaluated in all three groups.

RESULTS: Three hundred patients were studied (100 in each Group). Although the total time for the colonoscopy was similar in the 3 groups (23.8 ± 0.7, 22.2 ± 0.5 and 24.1 ± 0.7 min for Groups A, B and C, respectively), it reached statistical significance between Groups B and C (P < 0.05). The cecal intubation time in Groups B and C was longer than for Group A (6.5 ± 0.4 min and 6.5 ± 0.4 min vs 4.9 ± 0.3 min; P < 0.05). The withdrawal time for Groups A and C was longer than Group B (18.9 ± 0.7 min and 17.6 ± 0.6 min vs 15.7 ± 0.4 min; P < 0.05). Overall miss rate for polyps and adenomas detected in three groups during the second look was 18% and 17%, respectively (P = NS). Detection rate for polyps and adenomas after first look with white light was similar irrespective of the light used during the second look (WL → WL: 13.7% for polyps, 12.6% for adenomas; WL → NBI: 14.2% for polyps, 11.3% for adenomas). Miss rate of polyps and adenomas however was significantly higher when NBI was used first (29.3% and 30.3%, respectively; P < 0.05). Most missed adenomas were ≤ 5 mm in size. There was only one advanced neoplasia (defined by size only) missed during the first look.

CONCLUSION: Our data suggest that the tandem nature of the procedure rather than the optical techniques was associated with the detection of additional polyps’ and adenomas.

Diagnostic yield of third eye retroscope on adenoma detection during colonoscopy: A systematic review and meta-analysis

AIM: To determine the diagnostic yield of the “third eye retroscope”, on adenoma detection rate during screening colonoscopy.

METHODS: The “third eye retroscope” when used with standard colonoscopy provides an additional retrograde view to visualize lesions on the proximal aspects of folds and flexures. We searched MEDLINE (PubMed and Ovid), SCOPUS (including MEDLINE and EMBASE databases), Cochrane Database of Systemic Reviews, Google Scholar, and CINAHL Plus databases to identify studies that evaluated diagnostic yield of “third eye retroscope” during screening colonoscopy. DerSimonian Laird random effects model was used to generate the overall effect for each outcome. We evaluated statistical heterogeneity among the studies by using the Cochran Q statistic and quantified by I² statistics.

RESULTS: Four distinct studies with a total of 920 patients, mean age 59.83 (95%CI: 56.77-62.83) years, were included in the review. The additional adenoma detection rate (AADR) defined as the number of additional adenomas identified due to “third eye retroscope” device in comparison to standard colonoscopy alone was 19.9% (95%CI: 7.3-43.9). AADR for right and left colon were 13.9% (95%CI: 9.4-20) and 10.7 (95%CI: 1.9-42), respectively. AADR for polyps ≥ 6 mm and ≥ 10 mm were 24.6% (95%CI: 16.6-34.9) and 24.2% (95%CI: 12.9-40.8), respectively. The additional polyp detection rate defined as the number of additional polyps identified due to “third eye retroscope” device in comparison to standard colonoscopy alone was 19.8% (95%CI: 7.9-41.8). There were no complications reported with use of “third eye retroscope” device.

CONCLUSION: The “third eye retroscope” device when used with standard colonoscopy is safe and detects 19.9% additional adenomas, compared to standard colonoscopy alone.

Findings on interval colonoscopies: an auditable performance indicator for colonoscopy quality?

OBJECTIVE

An important marker of colonoscopy quality is detection of pathology and incidence of missed pathology. Back-to-back colonoscopies cannot ethically be performed for quality assurance alone yet may be required for clinical reasons. This study aims to investigate the incidence of new findings in colonoscopies repeated within a 12 month period and considers the role of such an analysis in the assessment of colonoscopy quality.

DESIGN

All colonoscopies performed over a 3-year period at an endoscopy training unit were studied. Colonoscopies repeated within a 12-month period were analysed.

RESULTS

5747 colonoscopies were performed over the study period. 137 repeat colonoscopies were included with median interval from initial colonoscopy of 174 days. 19 (14%) repeat colonoscopies yielded new findings including one cancer, 234 days following a normal colonoscopy. Additional polyps were identified in 13 colonoscopies indicating a missed polyp rate of 9%. In these, a median number of two polyps per colonoscopy with median size 5.5 mm were found. There was no morbidity associated with repeat colonoscopy in this series. New findings on repeat colonoscopy appeared more likely following initial colonoscopy by non-consultant non-training grade endoscopists (23% vs 11%, p=0.09) yet small numbers involved preclude meaningful comparison.

CONCLUSIONS

Analysis of clinically indicated repeat colonoscopies and rate of detection of new pathology may offer utility in colonoscopy quality assurance and would offer a direct assessment of the most important aspect of colonoscopy quality.

Fluorescently labeled chimeric anti-CEA antibody improves detection and resection of human colon cancer in a patient-derived orthotopic xenograft (PDOX) nude mouse model

BACKGROUND AND OBJECTIVES

The aim of this study was to evaluate a new fluorescently labeled chimeric anti-CEA antibody for improved detection and resection of colon cancer.

METHODS

Frozen tumor and normal human tissue samples were stained with chimeric and mouse antibody-fluorophore conjugates for comparison. Mice with patient-derived orthotopic xenografts (PDOX) of colon cancer underwent fluorescence-guided surgery (FGS) or bright-light surgery (BLS) 24 hr after tail vein injection of fluorophore-conjugated chimeric anti-CEA antibody. Resection completeness was assessed using postoperative images. Mice were followed for 6 months for recurrence.

RESULTS

The fluorophore conjugation efficiency (dye/mole ratio) improved from 3-4 to >5.5 with the chimeric CEA antibody compared to mouse anti-CEA antibody. CEA-expressing tumors labeled with chimeric CEA antibody provided a brighter fluorescence signal on frozen human tumor tissues (P = 0.046) and demonstrated consistently lower fluorescence signals in normal human tissues compared to mouse antibody. Chimeric CEA antibody accurately labeled PDOX colon cancer in nude mice, enabling improved detection of tumor margins for more effective FGS. The R0 resection rate increased from 86% to 96% with FGS compared to BLS.

CONCLUSION

Improved conjugating efficiency and labeling with chimeric fluorophore-conjugated antibody resulted in better detection and resection of human colon cancer in an orthotopic mouse model.

Colonoscopy as a tool for evaluating colorectal tumor development in a mouse model

PURPOSE

A sporadic colon cancer mouse model with conditional mutations in adenomatous polyposis coli (Apc) is biologically relevant for human colorectal cancer (CRC). This study aimed to determine the utility and limitations of colonoscopy for evaluating colon tumors in this mouse model.

METHODS

We compared the estimates of location, size, and miss rate of tumors detected during colonoscopy with those determined by necropsy. Sixty-six CPC-Apc mice originating from Apc (F/wt) mice harbor a Cdx2-Cre transgene in which colorectal tumorigenesis was driven by Apc allelic loss. The sensitivity and specificity of colonoscopy for detecting tumors in a mouse CRC model were investigated.

RESULTS

A strong positive correlation was found between tumor location as measured by colonoscopy and the location determined by necropsy (p < 0.001). A total of 120 tumors were graded during colonoscopy (grades 1-5: 0, 8, 20, 27, and 65 lesions, respectively), and a strong positive correlation was found between the tumor grade determined by colonoscopy and size measured by necropsy (grades 2-5: 2.08, 2.98, 4.02, and 5.09 mm, respectively; p < 0.005). Although the miss rate was 47.1 %, most of the missed tumors (96 %) were in close proximity (within 5 mm) of another tumor.

CONCLUSIONS

A colonoscopic method for the reliable measurement of colorectal tumors in vivo has been established. The application of this technique to mouse models of colon carcinogenesis will provide a better understanding of the dynamics of tumor growth.

Colonoscopy: what are we missing?

The purpose of most colonoscopies is to detect and treat colorectal neoplasia, preventing or providing early diagnosis of cancer. Basic to this mission is the recognition and diagnosis of neoplasms. Recent data suggest that detection of neoplasia during colonoscopy is suboptimal, resulting in a failure of screening colonoscopy as an efficient strategy for the prevention of cancer. In this article, the ramifications of these observations are examined and their relevance to the practice of colonoscopy considered.

Image partitioning and illumination in image-based pose detection for teleoperated flexible endoscopes

OBJECTIVE

Colorectal cancer is one of the leading causes of cancer-related deaths in the world, although it can be effectively treated if detected early. Teleoperated flexible endoscopes are an emerging technology to ease patient apprehension about the procedure, and subsequently increase compliance. Essential to teleoperation is robust feedback reflecting the change in pose (i.e., position and orientation) of the tip of the endoscope. The goal of this study is to first describe a novel image-based tracking system for teleoperated flexible endoscopes, and subsequently determine its viability in a clinical setting. The proposed approach leverages artificial neural networks (ANNs) to learn the mapping that links the optical flow between two sequential images to the change in the pose of the camera. Secondly, the study investigates for the first time how narrow band illumination (NBI) - today available in commercial gastrointestinal endoscopes - can be applied to enhance feature extraction, and quantify the effect of NBI and white light illumination (WLI), as well as their color information, on the strength of features extracted from the endoscopic camera stream.

METHODS AND MATERIALS

In order to provide the best features for the neural networks to learn the change in pose based on the image stream, we investigated two different imaging modalities - WLI and NBI - and we applied two different spatial partitions - lumen-centered and grid-based - to create descriptors used as input to the ANNs. An experiment was performed to compare the error of these four variations, measured in root mean square error (RMSE) from ground truth given by a robotic arm, to that of a commercial state-of-the-art magnetic tracker. The viability of this technique for a clinical setting was then tested using the four ANN variations, a magnetic tracker, and a commercial colonoscope. The trial was performed by an expert endoscopist (>2000 lifetime procedures) on a colonoscopy training model with porcine blood, and the RMSE of the ANN output was calculated with respect to the magnetic tracker readings. Using the image stream obtained from the commercial endoscope, the strength of features extracted was evaluated.

RESULTS

In the first experiment, the best ANNs resulted from grid-based partitioning under WLI (2.42mm RMSE) for position, and from lumen-centered partitioning under NBI (1.69° RMSE) for rotation. By comparison, the performance of the tracker was 2.49mm RMSE in position and 0.89° RMSE in rotation. The trial with the commercial endoscope indicated that lumen-centered partitioning was the best overall, while NBI outperformed WLI in terms of illumination modality. The performance of lumen-centered partitioning with NBI was 1.03±0.8mm RMSE in positional degrees of freedom (DOF), and 1.26±0.98° RMSE in rotational DOF, while with WLI, the performance was 1.56±1.15mm RMSE in positional DOF and 2.45±1.90° RMSE in rotational DOF. Finally, the features extracted under NBI were found to be twice as strong as those extracted under WLI, but no significance in feature strengths was observed between a grayscale version of the image, and the red, blue, and green color channels.

CONCLUSIONS

This work demonstrates that both WLI and NBI, combined with feature partitioning based on the anatomy of the colon, provide valid mechanisms for endoscopic camera pose estimation via image stream. Illumination provided by WLI and NBI produce ANNs with similar performance which are comparable to that of a state-of-the-art magnetic tracker. However, NBI produces features that are stronger than WLI, which enables more robust feature tracking, and better performance of the ANN in terms of accuracy. Thus, NBI with lumen-centered partitioning resulted the best approach among the different variations tested for vision-based pose estimation. The proposed approach takes advantage of components already available in commercial gastrointestinal endoscopes to provide accurate feedback about the motion of the tip of the endoscope. This solution may serve as an enabling technology for closed-loop control of teleoperated flexible endoscopes.

The new view of colon cancer screening: forwards and backwards

Many different techniques for colon cancer screening are available. The fecal immunochemical test is best for fecal-based screening, although the DNA investigation may be more specific when further developed. Computed tomographic colonography is as good as colonoscopy for detecting colon cancer and is almost as good as colonoscopy for detecting advanced adenomas, but has limitations. The flexible sigmoidoscopic examination markedly decreases the incidence of cancer in the visualized segments, but colonoscopy is currently the best procedure for evaluating the large bowel. Techniques for retroflexion or backward view of the colon have been investigated, with all showing increased polyp detection.

High-definition with i-Scan gives comparable accuracy for detecting colonic lesions by non-expert and expert endoscopists

BACKGROUND

Lesion detection rate during colonoscopy may be influenced by the endoscopist's experience. EPK-i system colonoscopy (i-Scan) can improve mucosal and vascular visualization for detecting lesions.

AIM

To compare mucosal lesions detection rate and the withdrawal time of the instrument among non-expert and expert endoscopists.

METHODS

Colonoscopy records of all consecutive patients undergoing first HD+ with i-Scan- or SWL-equipped colonoscopy for colorectal cancer screening over a twelve-month period were evaluated, in a "post hoc" analysis.

RESULTS

542 colonoscopies (389 HD+ with i-Scan; 153 SWL): expert and non-expert endoscopists did respectively 272 and 117 HD+ with i-Scan and 83 and 70 SWL colonoscopies. Expert endoscopists did more i-Scan colonoscopies than non-experts (p=0.006). In the SWL procedures, the experts detected mucosal lesions in more colonoscopies than non-experts (61/22 vs. 23/47, p=0.0001) and found a significantly higher mean number of lesions (1.34 vs. 0.47; p=0.0001). Experts detected more or less the same mean number of lesions with both imaging techniques, while among non-experts detection with HD+ with i-Scan was significantly better than with SWL imaging (1.39 vs. 0.47; p=0.0001).

CONCLUSIONS

HD+ with i-Scan imaging enables less skilled endoscopists to achieve results comparable to those of experienced ones in detecting mucosal lesions.

Clinical significance of jejunoileal involvement of non-Hodgkin's lymphoma detected by double-balloon enteroscopy

Jejunoileal involvement of non-Hodgkin's lymphoma (NHL) is an important diagnostic factor in determining optimal treatment strategies. Here, we used double-balloon enteroscopy (DBE) to detect jejunoileal involvement of NHL and studied its clinical significance in a series of patients with NHL. Adults aged between 18 and 85 years with infiltration of the stomach, duodenum, or colon confirmed by gastrointestinal endoscopy or colonoscopy, suspected jejunoileal involvement determined by CT or FDG-PET, or any other gastrointestinal symptoms, were eligible for inclusion in the study. Among 428 patients with histologically confirmed NHL between 2004 and 2011, 83 were eligible for DBE, but 20 patients were excluded due to rejection or poor clinical status. Thus, 63 underwent DBE. The 3-year overall survival rate was significantly lower in patients with (n = 33), than without (n = 30) jejunoileal involvement of NHL confirmed by DBE (49 vs. 92 %, p < 0.005). Four participants developed aspiration pneumonia, but recovered after treatment with antibiotics.

Image-enhanced endoscopy for diagnosis of colorectal tumors in view of endoscopic treatment

Recently, image-enhanced endoscopy (IEE) has been used to diagnose gastrointestinal tumors. This method is a change from conventional white-light (WL) endoscopy without dyeing solution, requiring only the push of a button. In IEE, there are many advantages in diagnosis of neoplastic tumors, evaluation of invasion depth for cancerous lesions, and detection of neoplastic lesions. In narrow band imaging (NBI) systems (Olympus Medical Co., Tokyo, Japan), optical filters that allow narrow-band light to pass at wavelengths of 415 and 540 nm are used. Mucosal surface blood vessels are seen most clearly at 415 nm, which is the wavelength that corresponds to the hemoglobin absorption band, while vessels in the deep layer of the mucosa can be detected at 540 nm. Thus, NBI also can detect pit-like structures named surface pattern. The flexible spectral imaging color enhancement (FICE) system (Fujifilm Medical Co., Tokyo, Japan) is also an IEE but different to NBI. FICE depends on the use of spectral-estimation technology to reconstruct images at different wavelengths based on WL images. FICE can enhance vascular and surface patterns. The autofluorescence imaging (AFI) video endoscope system (Olympus Medical Co., Tokyo, Japan) is a new illumination method that uses the difference in intensity of autofluorescence between the normal area and neoplastic lesions. AFI light comprises a blue light for emitting and a green light for hemoglobin absorption. The aim of this review is to highlight the efficacy of IEE for diagnosis of colorectal tumors for endoscopic treatment.

High-definition colonoscopy with i-Scan: Better diagnosis for small polyps and flat adenomas

AIM: To investigate if high-definition (HD) colonoscope with i-Scan gave a higher detection rate of mucosal lesions vs standard white-light instruments.

METHODS: Data were collected from the computerized database of the endoscopy unit of our tertiary referral center. We retrospectively analyzed 1101 consecutive colonoscopies that were performed over 1 year with standard white-light (n = 849) or HD+ with i-Scan (n = 252) instruments by four endoscopists, in an outpatient setting. Colonoscopy records included patients’ main details and family history for colorectal cancer, indication for colonoscopy (screening, diagnostic or surveillance), type of instrument used (standard white-light or HD+ plus i-Scan), name of endoscopist and bowel preparation. Records for each procedure included whether the cecum was reached or not and the reason for failure, complications during or immediately after the procedure, and number, size, location and characteristics of the lesions. Polyps or protruding lesions were defined as sessile or pedunculated, and nonprotruding lesions were defined according to Paris classification. For each lesion, histological diagnosis was recorded.

RESULTS: Eight hundred and forty-nine colonoscopies were carried with the standard white-light video colonoscope and 252 with the HD+ plus i-Scan video colonoscope. The four endoscopists did 264, 300, 276 and 261 procedures, respectively; 21.6%, 24.0%, 21.7% and 24.1% of them with the HD+ plus i-Scan technique. There were no significant differences between the four endoscopists in either the number of procedures done or the proportions of each imaging technique used. Both techniques detected one or more mucosal lesions in 522/1101 procedures (47.4%). The overall number of lesions recognized was 1266; 645 in the right colon and 621 in the left. A significantly higher number of colonoscopies recognized lesions in the HD+ plus i-Scan mode (171/252 = 67.9%) than with the standard white-light technique (408/849 = 48.1%) (P < 0.0001). HD+ with i-Scan colonoscopies identified more lesions than standard white-light imaging (459/252 and 807/849, P < 0.0001), in the right or left colon (mean ± SD, 1.62 ± 1.36 vs 1.33 ± 0.73, P < 0.003 and 1.55 ± 0.98 vs 1.17 ± 0.93, P = 0.033), more lesions < 10 mm (P < 0.0001) or nonprotruding (P < 0.022), and flat polyps (P = 0.04). The cumulative mean number of lesions per procedure detected by the four endoscopists was significantly higher with HD+ with i-Scan than with standard white-light imaging (1.82 ± 2.89 vs 0.95 ± 1.35, P < 0.0001).

CONCLUSION: HD imaging with i-Scan during the withdrawal phase of colonoscopy significantly increased the detection of colonic mucosal lesions, particularly small and nonprotruding polyps.

The impact of narrow band imaging for colon polyp detection: a multicenter randomized controlled trial by tandem colonoscopy

BACKGROUND

Previous studies have yielded conflicting results on the adenoma detection rate with narrow band imaging (NBI) compared with white light imaging (WLI). To overcome the confounding factors of these studies, we aimed to evaluate the colonic adenoma detection rate with primary NBI versus that with primary WLI by using consistent NBI system, endoscope, and imaging settings, and experienced colonoscopists.

METHODS

In this multicenter prospective trial, 813 patients were randomized to undergo high-definition, tandem colonoscopy in the right colon with either NBI followed by WLI (NBI-WLI group) or WLI followed by NBI (WLI-NBI group). The NBI settings were fixed at surface structure enhancement level A-5 and adaptive index of hemoglobin color enhancement level 3. All detected polyps were resected or biopsied for histopathological analysis. The primary and secondary outcome measures were the adenoma detection rates and miss rates, respectively, with primary imaging.

RESULTS

The NBI-WLI and WLI-NBI groups comprised 389 and 393 patients, respectively, who met the inclusion criteria. The groups did not differ significantly in age, gender, institution, indication for colonoscopy, bowel preparation, or observation time. The adenoma detection rates of primary NBI and WLI were 42.3 and 42.5 %, respectively [difference not significant (NS)]. The adenoma miss rate was significantly less with primary NBI than with primary WLI (21.3 vs. 27.8 %; p = 0.03).

CONCLUSIONS

NBI does not improve the adenoma detection rate during primary colonoscopy; however, it has a lower miss rate for adenoma lesions in the proximal colon than WLI.

Retrograde-viewing device improves adenoma detection rate in colonoscopies for surveillance and diagnostic workup

AIM: To determine which patients might benefit most from retrograde viewing during colonoscopy through subset analysis of randomized, controlled trial data.

METHODS: The Third Eye^® Retroscope^® Randomized Clinical Evaluation (TERRACE) was a randomized, controlled, multicenter trial designed to evaluate the efficacy of a retrograde-viewing auxiliary imaging device that is used during colonoscopy to provide a second video image which allows viewing of areas on the proximal aspect of haustral folds and flexures that are difficult to see with the colonoscope’s forward view. We performed a post-hoc analysis of the TERRACE data to determine whether certain subsets of the patient population would gain more benefit than others from use of the device. Subjects were patients scheduled for colonoscopy for screening, surveillance or diagnostic workup, and each underwent same-day tandem examinations with standard colonoscopy (SC) and Third Eye colonoscopy (TEC), randomized to SC followed by TEC or vice versa.

RESULTS: Indication for colonoscopy was screening in 176/345 subjects (51.0%), surveillance after previous polypectomy in 87 (25.2%) and diagnostic workup in 82 (23.8%). In 4 subjects no indication was specified. Previously reported overall results had shown a net additional adenoma detection rate (ADR) with TEC of 23.2% compared to SC. Relative risk (RR) of missing adenomas with SC vs TEC as the initial procedure was 1.92 (P = 0.029). Post-hoc subset analysis shows additional ADRs for TEC compared to SC were 4.4% for screening, 35.7% for surveillance, 55.4% for diagnostic and 40.7% for surveillance and diagnostic combined. The RR of missing adenomas with SC vs TEC was 1.11 (P = 0.815) for screening, 3.15 (P = 0.014) for surveillance, 8.64 (P = 0.039) for diagnostic and 3.34 (P = 0.003) for surveillance and diagnostic combined. Although a multivariate Poisson regression suggested gender as a possibly significant factor, subset analysis showed that the difference between genders was not statistically significant. Age, bowel prep quality and withdrawal time did not significantly affect the RR of missing adenomas with SC vs TEC. Mean sizes of adenomas detected with TEC and SC were similar at 0.59 cm and 0.56 cm, respectively (P = NS).

CONCLUSION: TEC allows detection of significantly more adenomas compared to SC in patients undergoing surveillance or diagnostic workup, but not in screening patients (ClinicalTrials.gov Identifier: NCT01044732).

A randomized controlled trial of sodium phosphate tablets and polyethylene glycol solution for polyp detection

OBJECTIVE

The study was aimed to assess the efficacy of sodium phosphate (NaP) tablets and polyethylene glycol (PEG) on colon cleansing.

METHODS

A prospective, randomized trial was conducted at the Graduate School of Medicine, University of Tokyo. Participants who were scheduled for colonoscopy were included and randomized into either the NaP or PEG group. An interim analysis was programmed into the study design when approximately 50% of the enrolments were completed. The primary outcome was the detection rate of polyps with a diameter ≤5 mm.

RESULTS

A total of 92 patients were included in the analysis, of whom 44 were in the NaP group and 48 in the PEG group. The quality of colonic preparation was similar in both groups. The NaP group showed a higher detection rate of polyps with a diameter ≤5 mm than the PEG group (38.6% vs 18.8%, P = 0.004). A multivariate analysis showed that NaP and the withdrawal time of the colonoscope were independent factors associated with the detection of polyps with a diameter ≤5 mm.

CONCLUSIONS

NaP is certainly not inferior to PEG. In fact, the results suggest that diminutive polyp detection using NaP might be superior to that using PEG.

Advanced technologies for gastrointestinal endoscopy

The gastrointestinal tract is home to some of the most deadly human diseases. Exacerbating the problem is the difficulty of accessing it for diagnosis or intervention and the concomitant patient discomfort. Flexible endoscopy has established itself as the method of choice and its diagnostic accuracy is high, but there remain technical limitations in modern scopes, and the procedure is poorly tolerated by patients, leading to low rates of compliance with screening guidelines. Although advancement in clinical endoscope design has been slow in recent years, a critical mass of enabling technologies is now paving the way for the next generation of gastrointestinal endoscopes. This review describes current endoscopes and provides an overview of innovative flexible scopes and wireless capsules that can enable painless endoscopy and/or enhanced diagnostic and therapeutic capabilities. We provide a perspective on the potential of these new technologies to address the limitations of current endoscopes in mass cancer screening and other contexts and thus to save many lives.

Adenoma detection rates vary minimally with time of day and case rank: a prospective study of 2139 first screening colonoscopies

BACKGROUND

Adenoma detection rate is an important measure of colonoscopy quality; however, factors including procedure order that contribute to adenoma detection are incompletely understood.

OBJECTIVE

The aim of this study was to prospectively evaluate factors associated with adenoma detection rate.

DESIGN

Prospective cohort study. Data were collected on patient and physician characteristics, trainee participation, time of day, and case rank.

SETTING

Outpatient tertiary-care center.

PATIENTS

This study involved consecutive patients presenting for first screening colonoscopies.

MAIN OUTCOME MEASUREMENTS

Adenoma and polyp detection rates (proportion of cases with one or more lesion detected) and ratios (mean number of lesions detected per case).

RESULTS

A total of 2139 colonoscopies were performed by 32 gastroenterologists. Detection rates were 42.7% for all polyps, 25.4% for adenomas, and 5.0% for advanced adenomas. Adenoma detection was associated with male sex and increasing age on multivariate analysis. In the overall study cohort, time of day and case rank were not significantly associated with detection rates. In post hoc analysis, polyp and adenoma detection rates appeared lower after the fifth case of the day for endoscopists with low volumes of cases and after the tenth case of the day for endoscopists with high volumes of cases.

LIMITATION

Single center.

CONCLUSION

Overall, time of day and case rank did not influence adenoma detection rate. We observed a small but significant decrease in detection rates in later procedures, which was dependent on physician typical procedure volume. These findings imply that colonoscopy quality in general is stable throughout the day; however, there may be a novel "stamina effect" for some endoscopists, and interventions aimed at improving colonoscopy quality need to take individual physician practice styles into consideration.

Narrow-band imaging does not improve detection of colorectal polyps when compared to conventional colonoscopy: a randomized controlled trial and meta-analysis of published studies

BACKGROUND

A colonoscopy may frequently miss polyps and cancers. A number of techniques have emerged to improve visualization and to reduce the rate of adenoma miss.

METHODS

We conducted a randomized controlled trial (RCT) in two clinics of the Gastrointestinal Department of the Sanitas University Foundation in Bogota, Colombia. Eligible adult patients presenting for screening or diagnostic elective colonoscopy were randomly allocated to undergo conventional colonoscopy or narrow-band imaging (NBI) during instrument withdrawal by three experienced endoscopists. For the systematic review, studies were identified from the Cochrane Library, PUBMED and LILACS and assessed using the Cochrane risk of bias tool.

RESULTS

We enrolled a total of 482 patients (62.5% female), with a mean age of 58.33 years (SD 12.91); 241 into the intervention (NBI) colonoscopy and 241 into the conventional colonoscopy group. Most patients presented for diagnostic colonoscopy (75.3%). The overall rate of polyp detection was significantly higher in the conventional group compared to the NBI group (RR 0.75, 95%CI 0.60 to 0.96). However, no significant differences were found in the mean number of polyps (MD -0.1; 95%CI -0.25 to 0.05), and the mean number of adenomas (MD 0.04 95%CI -0.09 to 0.17). Meta-analysis of studies (regardless of indication) did not find any significant differences in the mean number of polyps (5 RCT, 2479 participants; WMD -0.07 95% CI -0.21 to 0.07; I2 68%), the mean number of adenomas (8 RCT, 3517 participants; WMD -0.08 95% CI -0.17; 0.01 to I2 62%) and the rate of patients with at least one adenoma (8 RCT, 3512 participants, RR 0.96 95% CI 0.88 to 1,04;I2 0%).

CONCLUSION

NBI does not improve detection of colorectal polyps when compared to conventional colonoscopy (Australian New Zealand Clinical Trials Registry ACTRN12610000456055).

Spectral classifier design with ensemble classifiers and misclassification-rejection: application to elastic-scattering spectroscopy for detection of colonic neoplasia

Optical spectroscopy has shown potential as a real-time, in vivo, diagnostic tool for identifying neoplasia during endoscopy. We present the development of a diagnostic algorithm to classify elastic-scattering spectroscopy (ESS) spectra as either neoplastic or non-neoplastic. The algorithm is based on pattern recognition methods, including ensemble classifiers, in which members of the ensemble are trained on different regions of the ESS spectrum, and misclassification-rejection, where the algorithm identifies and refrains from classifying samples that are at higher risk of being misclassified. These "rejected" samples can be reexamined by simply repositioning the probe to obtain additional optical readings or ultimately by sending the polyp for histopathological assessment, as per standard practice. Prospective validation using separate training and testing sets result in a baseline performance of sensitivity = .83, specificity = .79, using the standard framework of feature extraction (principal component analysis) followed by classification (with linear support vector machines). With the developed algorithm, performance improves to Se ∼ 0.90, Sp ∼ 0.90, at a cost of rejecting 20-33% of the samples. These results are on par with a panel of expert pathologists. For colonoscopic prevention of colorectal cancer, our system could reduce biopsy risk and cost, obviate retrieval of non-neoplastic polyps, decrease procedure time, and improve assessment of cancer risk.

Effect of a retrograde-viewing device on adenoma detection rate during colonoscopy: the TERRACE study

BACKGROUND

Although colonoscopy is currently the optimal method for detecting colorectal polyps, some are missed. The Third Eye Retroscope provides an additional retrograde view that may detect polyps behind folds.

OBJECTIVE

To determine whether the addition of the Third Eye Retroscope to colonoscopy improves the adenoma detection rate.

DESIGN

Prospective, multicenter, randomized, controlled trial.

SETTING

Nine European and U.S. centers.

PATIENTS

Of 448 enrolled subjects, 395 had data for 2 procedures.

INTERVENTIONS

Subjects underwent same-day tandem examinations with standard colonoscopy (SC) and Third Eye colonoscopy (TEC). Subjects were randomized to SC followed by TEC or TEC followed by SC.

MAIN OUTCOME MEASUREMENTS

Detection rates for all polyps and adenomas with each method.

RESULTS

In the per-protocol population, 173 subjects underwent SC and then TEC, and TEC yielded 78 additional polyps (48.8%), including 49 adenomas (45.8%). In 176 subjects undergoing TEC and then SC, SC yielded 31 additional polyps (19.0%), including 26 adenomas (22.6%). Net additional detection rates with TEC were 29.8% for polyps and 23.2% for adenomas. The relative risk of missing with SC compared with TEC was 2.56 for polyps (P < .001) and 1.92 for adenomas (P = .029). Mean withdrawal times for SC and TEC were 7.58 and 9.52 minutes, respectively (P < .001). The median difference in withdrawal times was 1 minute (P < .001). The mean total procedure times for SC and TEC were 16.97 and 20.87 minutes, respectively (P < .001).

LIMITATIONS

Despite randomization and a large cohort, there was disparity in polyp prevalence between the 2 groups of subjects.

CONCLUSION

The Third Eye Retroscope increases adenoma detection rate by visualizing areas behind folds. (

CLINICAL TRIAL REGISTRATION NUMBER

NCT01044732.).

A comparison of high-definition versus conventional colonoscopes for polyp detection

BACKGROUND

High-resolution, high-definition colonoscopes (HD) with 170 degrees angle of view providing brighter images, sharper resolution, and a 30 degrees wider field of view than conventional colonoscopes (CC) are available. The impact of these innovations on enhancing the detection of clinically important colonic lesions or over detection of clinically insignificant colonic lesions is not well established.

OBJECTIVES

To compare the difference in the detection of individuals with polyps, adenomas, or high-risk adenoma features between HD and CC. We also compared the difference in detection of individuals with clinically insignificant colonic lesions, >or=2, <6-mm hyperplastic polyps between HD and CC.

METHODS

Endoscopic findings from 426 individuals who underwent HD were compared to a cohort of 426 individuals who underwent CC after matching by gender, age (+/-5 years), and indication for colonoscopy based on propensity score. Conditional logistic regression was used to assess for differences in polyp detection rates and risk classification between the two groups.

RESULTS

HD affords no increase over CC in the detection of individuals with polyps, 39.9 vs. 36.9% (P = 0.34) or adenomas, 24.7 vs. 21.9% (P = 0.36). The proportion of subjects classified as high risk did not differ between the groups, 5.7% in the HD group and 4.5% in the CC group (P = 0.43) and 5.6% of each cohort was found to have >or=2, <6-mm hyperplastic polyps (P = 0.99).

CONCLUSIONS

HD colonoscopy does not increase the detection of individuals with polyps, adenomas, or high-risk adenoma features. HD does not increase the detection of individuals with clinically insignificant colonic lesions.

Finding polyps at colonoscopy previously noted on CT colonography

Colon screening examinations have been shown to discover neoplastic lesions at an early stage. Even the most careful studies by colonoscopy and by computed tomographic colonography (CTC) can overlook tumors with a diameter greater than 5 mm. Advances in technology have continually improved the ability to find polyps, which will lead to a real decrease in colorectal cancer incidence.

Narrow Band Imaging and Autofluorescence Imaging for the Detection and Optical Diagnosis of Colorectal Polyps

Colorectal cancer is the most common cancer in Singapore and polyps which are detected during screening colonoscopy are routinely removed. Conventional white light colonoscopy has a substantial miss-rate for polyps and limited accuracy in differentiating neoplastic from non-neoplastic polyps. Dye-based chromoendoscopy and more recent equipment-based image enhanced endoscopic techniques such as narrow-band imaging (NBI) and autofluorescence imaging (AFI) are promising tools to improve polyp detection and optical diagnosis. Current evidence suggests that NBI may not be superior compared to high definition white-light for polyp detection, but it achieves excellent accuracy in polyp characterisation, approaching that of histopathology. AFI is a wide area scanning modality which functions as a red-flag technique to improve polyp detection, although the evidence is still evolving. The ability to accurately characterise polyps with NBI and AFI will guide the management of polyps and in some cases, avoid unnecessary polypectomy and routine histopathology. This has potential to reduce associated costs and risks of polypectomy, and improves on overall efficiency of screening colonoscopy. The review will discuss the technology, current evidence and the issues relevant to the role of NBI and AFI for the detection and optical diagnosis of polyps in colorectal cancer screening.

Impact of experience with a retrograde-viewing device on adenoma detection rates and withdrawal times during colonoscopy: the Third Eye Retroscope study group

BACKGROUND

Colonoscopy has been adopted as the preferred method to screen for colorectal neoplasia in the United States. However, lesions can be missed because of numerous factors, including location on the proximal aspect of folds or flexures, where they may be difficult to detect with the forward-viewing colonoscope. The Third Eye Retroscope (TER) is a disposable device that is passed through the instrument channel of a standard colonoscope to provide a retrograde view that complements the forward view of the colonoscope during withdrawal.

OBJECTIVE

To evaluate whether experience with the TER affects polyp detection rates and procedure times in experienced endoscopists who had not previously used the equipment.

DESIGN, SETTING, PATIENTS

This was an open-label, prospective, multicenter study at 9 U.S. sites, involving 298 patients presenting for colonoscopy, evaluating the use of the TER in combination with a standard colonoscope.

INTERVENTIONS

After cecal intubation, the TER was inserted through the instrument channel of the colonoscope. During withdrawal, the forward and retrograde video images were observed simultaneously on a wide-screen monitor.

MAIN OUTCOME MEASUREMENTS

Primary outcome measures were the number and size of adenomas and all polyps detected with the standard colonoscope and with the colonoscope combined with the TER. Secondary outcome measures were withdrawal phase time and total procedure time. Each endoscopist examined 20 subjects, divided into quartiles according to the order of their procedures, and results were compared among quartiles.

RESULTS

Overall, 182 polyps were detected with the colonoscope and 27 additional polyps with the TER, a 14.8% increase (P < .001). A total of 100 adenomas were detected with the colonoscope and 16 more with the TER, a 16.0% increase (P < .001). For procedures performed after each endoscopist had completed 15 procedures while using the TER, the mean additional detection rates with the TER were 17.0% for all polyps (P < .001) and 25.0% for adenomas (P < .001). For lesions 6 mm or larger, the overall additional detection rates with the TER for all polyps and for adenomas were 23.2% and 24.3%, respectively. For lesions 10 mm or larger, the overall additional detection rates with the TER for all polyps and for adenomas were 22.6% and 19.0%, respectively. The mean withdrawal times in the first and fourth quartiles were 10.6 and 9.2 minutes, respectively (P = .044).

LIMITATIONS

There was no randomization or separate control group. The endoscopists judged whether each lesion could have been detected with the colonscope alone by using their standard technique.

CONCLUSIONS

Polyp detection rates improved significantly with the TER, especially after 15 procedures, when the mean additional detection rate for adenomas was 25.0%. Additional detection rates with the TER for medium-size and large adenomas were greater than for smaller lesions. These results suggest that, compared with a colonoscope alone, a retrograde-viewing device can increase detection rates for clinically significant adenomas without detriment to procedure time or procedure complications. (

CLINICAL TRIAL REGISTRATION NUMBER

NCT00969124.).

Variation in colonoscopic technique and adenoma detection rates at an academic gastroenterology unit

The purpose of this research is to evaluate the quality of colonoscopy at an academic institution with a focus on factors influencing withdrawal times and adenoma detection rates. Procedural data and pathologic results of 550 consecutive screening colonoscopies in average risks patients (mean [+/-SD] age, 57 +/- 7.6, 44% male) completed by ten academic gastroenterologists were reviewed. Per individual gastroenterologist, the adenoma detection rates ranged widely from 0.09 to 0.82 adenomas per patient with a mean of 0.46 for the group. The mean withdrawal time was 7.0 min for the group and ranged from 3.4 to 9.6 min. There was a significant positive relationship between the number of adenomas detected and the withdrawal time (P = 0.006). Endoscopists with cecal intubation time to withdrawal time ratios of less than 1 detected significantly more adenomas compared to endoscopists with ratios greater than 1 (P = 0.001). (1) Significant variation in academic gastroenterologists' abilities to detect adenomas during screening colonoscopies exists. (2) Colonoscopic withdrawal time and the cecal intubation to withdrawal time ratio are important factors associated with increased adenoma detection rates.

Diagnostic accuracy of CT colonography and optical colonoscopy evaluated using surgically resected specimens

OBJECTIVE

The aim of this study was to clarify the diagnostic ability of CT colonography (CTC) using surgically resected specimens to avoid inaccuracy associated with optical colonoscopy (OC).

SUBJECTS AND METHODS

CTC and OC were performed in 152 consecutive patients with colorectal cancer. Forty patients had simultaneous lesions other than the ones for which the surgery was intended, and these lesions were used as the gold standard. In 24 patients without stenosis, the sensitivity and positive predictive values (PPV) of CTC and OC were evaluated. In 16 patients with stenosis, the diagnostic ability of CTC for lesions located proximal to the stenosis was assessed.

RESULTS

Sensitivity of CTC and OC was 81% and 66% (P = 0.16), and PPV was 90% and 100% (P = 0.13), respectively. For 22 lesions larger than 5 mm, the sensitivity of CTC and OCS was 96% and 91% (P > 0.50), and PPV was 100% and 100%, respectively. In patients with stenosis, sensitivity and PPV were 89% and 80%, respectively. These results were not significantly different from those in patients without stenosis.

CONCLUSIONS

CTC is a reliable modality for the diagnosis of colorectal polyps. It is also useful to evaluate the colon proximal to severe stenosis which could not be observed by OC.

Does trainee participation during colonoscopy affect adenoma detection rates?

INTRODUCTION

Training future endoscopists is essential to meeting the increasing demands for colonoscopy. It remains unknown whether adenoma detection rates are adversely affected by trainee participation.

METHODS

This is a single-center, prospective study. The primary aim of this study was to investigate whether adenoma detection rates differed between procedures with or without trainee involvement. A total of 368 consecutive patients entered the analysis (181 with trainee participation and 187 without).

RESULTS

Adenomas were detected in 19.3% of experienced physician-only procedures and in 14.9% of procedures with trainee participation. Advanced adenomas were detected in 8.6% of experienced physicians' procedures vs. 4.9% of trainee procedures. Polyp detection was nearly identical in both groups (32% for experienced physicians; 33% for trainees). Trainee participation delayed the procedure by a mean of seven minutes.

CONCLUSION

Adenoma detection rates did not differ significantly, whether there was trainee involvement or not. A trend toward finding more adenomas or advanced adenomas in the absence of a trainee was observed, but it was lower than previously reported interobserver variability among experienced physicians. The small difference in adenoma detection was not observed for polyp detection, which may be explained by the more frequent removal of hyperplastic polyps by trainees.

Are many colorectal cancers due to missed adenomas?

BACKGROUND

An unknown number of colorectal cancers could be due to missed adenomas during previous endoscopy. Data in the literature are sparse. A large cross-sectional study was done in a prospective database of all patients diagnosed with colorectal cancer.

METHODS

All consecutive endoscopies over a period of 15 years, in which colorectal cancer was diagnosed were included. All patients who underwent more than one endoscopy and in whom ultimately cancer was diagnosed were studied separately.

RESULTS

Colorectal cancer was diagnosed in 835 patients. Twenty-five patients underwent a previous endoscopy without a cancer diagnosis. These 25 patients were divided into three groups according to the time between the endoscopy in which the cancer was detected and the previous endoscopy. Five out of these 25 patients underwent regular surveillance. Only 11 patients had no argument for regular follow-up. Assuming that these cancers developed from an adenoma than only 11 out of 835 (1.3%) cancers were missed in the adenoma phase. There was no difference in the size of the tumour between the three groups of patients.

CONCLUSION

In normal daily practice, only a small number of clinically important adenomas are missed. The problem of missed adenomas probably is being exaggerated.

Future expectations in digestive endoscopy: competition with other novel imaging techniques

Digestive endoscopy has been evolving from primary diagnostic to extensive therapeutic modalities in the management of gastrointestinal diseases. The present endoscopic imaging includes (A) standard endoscopy alone and /or with adjunct technologies such as point enhancement, e.g. confocal endomicroscopy and field enhancement technologies such as chromoendoscopy, NBI and FICE and (B) endoscopic ultrasound. Other novel imaging technologies including virtual colonoscopy or CT/MR colonography, CT or MRI enterography and capsule endoscopy have also been developed. This article reviews the diagnostic and therapeutic role of digestive endoscopy and future directions of digestive endoscopy are discussed. Digestive endoscopy is also compared with emerging novel imaging techniques in gastrointestinal diseases such as capsule endoscopy and CT colonography. The fact that digestive endoscopy has become a multidisciplinary specialty combining advances in all fields (radiology, bioengineering, surgery and gastroenterology) is highlighted.