Surface visualization at CT colonography simulated colonoscopy: effect of varying field of view and retrograde view

Prompt-based polyp segmentation during endoscopy

Accurate judgment and identification of polyp size is crucial in endoscopic diagnosis. However, the indistinct boundaries of polyps lead to missegmentation and missed cancer diagnoses. In this paper, a prompt-based polyp segmentation method (PPSM) is proposed to assist in early-stage cancer diagnosis during endoscopy. It combines endoscopists' experience and artificial intelligence technology. Firstly, a prompt-based polyp segmentation network (PPSN) is presented, which contains the prompt encoding module (PEM), the feature extraction encoding module (FEEM), and the mask decoding module (MDM). The PEM encodes prompts to guide the FEEM for feature extracting and the MDM for mask generating. So that PPSN can segment polyps efficiently. Secondly, endoscopists' ocular attention data (gazes) are used as prompts, which can enhance PPSN's accuracy for segmenting polyps and obtain prompt data effectively in real-world. To reinforce the PPSN's stability, non-uniform dot matrix prompts are generated to compensate for frame loss during the eye-tracking. Moreover, a data augmentation method based on the segment anything model (SAM) is introduced to enrich the prompt dataset and improve the PPSN's adaptability. Experiments demonstrate the PPSM's accuracy and real-time capability. The results from cross-training and cross-testing on four datasets show the PPSM's generalization. Based on the research results, a disposable electronic endoscope with the real-time auxiliary diagnosis function for early cancer and an image processor have been developed. Part of the code and the method for generating the prompts dataset are available at https://github.com/XinZhenRen/PPSM.

A prospective multicenter randomized controlled trial on artificial intelligence assisted colonoscopy for enhanced polyp detection

Colon polyp detection and removal via colonoscopy are essential for colorectal cancer screening and prevention. This study aimed to develop a colon polyp detection program based on the RetinaNet algorithm and verify its clinical utility. To develop the AI-assisted program, the dataset was fully anonymized and divided into 10 folds for 10-fold cross-validation. Each fold consisted of 9,639 training images and 1,070 validation images. Video data from 56 patients were used for model training, and transfer learning was performed using the developed still image-based model. The final model was developed as a real-time polyp-detection program for endoscopy. To evaluate the model's performance, a prospective randomized controlled trial was conducted at six institutions to compare the polyp detection rates (PDR). A total of 805 patients were included. The group that utilized the AI model showed significantly higher PDR and adenoma detection rate (ADR) than the group that underwent colonoscopy without AI assistance. Multivariate analysis revealed an OR of 1.50 for cases where polyps were detected. The AI-assisted polyp-detection program is clinically beneficial for detecting polyps during colonoscopy. By utilizing this AI-assisted program, clinicians can improve adenoma detection rates, ultimately leading to enhanced cancer prevention.

The role of cap-assisted endoscopy and its future implications

Cap-assisted endoscopy refers to a procedure in which a short tube made of a polymer (mostly transparent) is attached to the distal tip of the endoscope to enhance its diagnostic and therapeutic capabilities. It is reported to be particularly useful in: (1) minimizing blind spots during screening colonoscopy, (2) providing a constant distance from a lesion for clear visualization during magnifying endoscopy, (3) accurately assessing the size of various gastrointestinal lesions, (4) preventing mucosal injury during foreign body removal, (5) securing adequate workspace in the submucosal space during endoscopic submucosal dissection or third space endoscopy, (6) providing an optimal approach angle to a target, and (7) suctioning mucosal and submucosal tissue with negative pressure for resection or approximation. Here, we review various applications of attachable caps in diagnostic and therapeutic endoscopy and their future implications.

The impact of EndoCuff-assisted colonoscopy on the polyp detection rate: A cross-over randomized back-to-back study

BACKGROUND AND STUDY AIMS

Colorectal cancer (CRC) is one of the most common cancers worldwide, and most CRCs develop from polyps with malignant potential. We aimed to study the difference in polyp detection rate between EndoCuff-assisted colonoscopies (EAC) and standard colonoscopy (SC).

PATIENTS AND METHODS

This study was conducted at Cairo University Hospitals on patients referred for screening or diagnostic colonoscopy from July 2018 to August 2020. All included patients underwent back-to-back standard colonoscopy (SC) and ENDOCUFF VISION-assisted colonoscopies (EAC).

RESULTS

214 patients were included in this study. In comparison between EAC and SC, EAC increased the polyp detection rate (69 (32.24 %) vs. 57(26.64 %) (p < 0.05), EAC increased the detection of diminutive polyps ≤ 5 mm (104 vs. 81) (p < 0.05), and small polyps 6-9 mm (12 vs. 10) while there was no difference in large polyps ≥ 10 mm. EAC increased the adenoma detection rate (ADR) (37 (17.2 %) vs. 32(14.9 %) (p < 0.05). The findings detected by EAC shortened the interval of surveillance determined by SC findings. EndoCuff caused six mucosal erosions (2.8 %) in patients.

CONCLUSION

EAC increases the number of detected colonic polyps, primarily small polyps on the left and right sides of the colon.

Preclinical Evaluation of a Microwave-Based Accessory Device for Colonoscopy in an In Vivo Porcine Model with Colorectal Polyps

BACKGROUND AND AIMS

Colonoscopy is currently the most effective way of detecting colorectal cancer and removing polyps, but it has some drawbacks and can miss up to 22% of polyps. Microwave imaging has the potential to provide a 360° view of the colon and addresses some of the limitations of conventional colonoscopy. This study evaluates the feasibility of a microwave-based colonoscopy in an in vivo porcine model.

METHODS

A prototype device with microwave antennas attached to a conventional endoscope was tested on four healthy pigs and three gene-targeted pigs with mutations in the adenomatous polyposis coli gene. The first four animals were used to evaluate safety and maneuverability and compatibility with endoscopic tools. The ability to detect polyps was tested in a series of three gene-targeted pigs.

RESULTS

the microwave-based device did not affect endoscopic vision or cause any adverse events such as deep mural injuries. The microwave system was stable during the procedures, and the detection algorithm showed a maximum detection signal for adenomas compared with healthy mucosa.

CONCLUSIONS

Microwave-based colonoscopy is feasible and safe in a preclinical model, and it has the potential to improve polyp detection. Further investigations are required to assess the device's efficacy in humans.

Benefits and challenges in implementation of artificial intelligence in colonoscopy: World Endoscopy Organization position statement

The number of artificial intelligence (AI) tools for colonoscopy on the market is increasing with supporting clinical evidence. Nevertheless, their implementation is not going smoothly for a variety of reasons, including lack of data on clinical benefits and cost-effectiveness, lack of trustworthy guidelines, uncertain indications, and cost for implementation. To address this issue and better guide practitioners, the World Endoscopy Organization (WEO) has provided its perspective about the status of AI in colonoscopy as the position statement. WEO Position Statement: Statement 1.1: Computer-aided detection (CADe) for colorectal polyps is likely to improve colonoscopy effectiveness by reducing adenoma miss rates and thus increase adenoma detection; Statement 1.2: In the short term, use of CADe is likely to increase health-care costs by detecting more adenomas; Statement 1.3: In the long term, the increased cost by CADe could be balanced by savings in costs related to cancer treatment (surgery, chemotherapy, palliative care) due to CADe-related cancer prevention; Statement 1.4: Health-care delivery systems and authorities should evaluate the cost-effectiveness of CADe to support its use in clinical practice; Statement 2.1: Computer-aided diagnosis (CADx) for diminutive polyps (≤5 mm), when it has sufficient accuracy, is expected to reduce health-care costs by reducing polypectomies, pathological examinations, or both; Statement 2.2: Health-care delivery systems and authorities should evaluate the cost-effectiveness of CADx to support its use in clinical practice; Statement 3: We recommend that a broad range of high-quality cost-effectiveness research should be undertaken to understand whether AI implementation benefits populations and societies in different health-care systems.

Changes in Adenoma Detection Rate From Full-Spectrum Endoscopy to Standard Forward-Viewing Endoscopy

GOALS

The aim was to investigate the adenoma detection rate (ADR) of endoscopists who have used full-spectrum endoscopy (Fuse) for 3 years and revert back to traditional forward-viewing endoscopes (R-TFV) at an ambulatory surgical center.

BACKGROUND

Traditional forward viewing (TFV) endoscopes have 1 camera and provide an angle of view of 140 to 170 degrees, whereas Fuse provides a 330 degrees view through the addition of 2 side cameras. It has previously been reported that Fuse increased the ADR by 5.4% when compared with previous rates using TFV. Fuse is no longer commercially available. The ADR of endoscopists who revert back to TFV is unknown.

STUDY

We conducted a retrospective analysis of data examining the ADR from average risk screening colonoscopies at a 5-room ambulatory surgical center where endoscopists transitioned from TFV to Fuse in April 2014 and then reverted back to TFV in 2016. The primary outcome was ADR. Secondary outcomes were ADR for advanced and right-sided adenomas.

RESULTS

A total of 6110 procedures were reviewed. The ADR was 23.70% for TFV, 29.02% for Fuse and 28.88% for R-TFV. The ADR for advanced adenomas was 3.8% for TFV, 6.0% for Fuse and 7.3% for R-TFV. The ADR for right-sided adenomas was 13.0% for TFV, 16.7% for Fuse and 16.0% for R-TFV. The results for all 3 categories showed a statistical difference between TFV and Fuse as well as between TFV and R-TFV. There were no statistical differences between the ADR of Fuse compared with R-TFV.

CONCLUSIONS

During R-TFV, endoscopists are able to maintain their increased ability to detect adenomas. This would suggest that there was a change in behavior in endoscopists using Fuse that was durable.

Updates in narrow-band imaging for colorectal polyps: Narrow-band imaging generations, detection, diagnosis, and artificial intelligence

Narrow-band imaging (NBI) is an optical digital enhancement method that allows the observation of vascular and surface structures of colorectal lesions. Its usefulness in the detection and diagnosis of colorectal polyps has been demonstrated in several clinical trials and the diagnostic algorithms have been simplified after the establishment of endoscopic classifications such as the Japan NBI Expert Team classification. However, there were issues including lack of brightness in the earlier models, poor visibility under insufficient bowel preparation, and the incompatibility of magnifying endoscopes in certain endoscopic platforms, which had impeded NBI from becoming standardized globally. Nonetheless, NBI continued its evolution and the newest endoscopic platform launched in 2020 offers significantly brighter and detailed images. Enhanced visualization is expected to improve the detection of polyps while universal compatibility across all scopes including magnifying endoscopy will promote the global standardization of magnifying diagnosis. Therefore, knowledge related to magnifying colonoscopy will become essential as magnification becomes standardly equipped in future models, although the advent of computer-aided diagnosis and detection may greatly assist endoscopists to ensure quality of practice. Given that most endoscopic departments will be using both old and new models, it is important to understand how each generation of endoscopic platforms differ from each other. We reviewed the advances in the endoscopic platforms, artificial intelligence, and evidence related to NBI essential for the next generation of endoscopic practice.

Efficacy of combination colonoscopy using modified cap-assisted and water-exchange colonoscopy with prone position for detection of colorectal adenomas

The efficacy of cap-assisted and water-exchange colonoscopy, individually or in combination for adenoma detection is well documented. Moreover, prone positioning colonoscopy may also improve adenoma detection by decreasing loop formation. However, the efficacy of triple-combination colonoscopy using the above methods for adenoma detection is unclear. This study aimed to compare the effectiveness of combining modified cap-assisted and water-exchange colonoscopy with prone position (CWP) and conventional colonoscopy (CC) for adenoma detection. A total of 746 patients who underwent either CWP or CC, performed by 2 board-certified gastroenterologists between December 2019 and March 2020, were investigated retrospectively. Cap-assisted colonoscopy was modified using hooking and dragging maneuver. We evaluated the polyp detection rate (PDR), adenoma detection rate (ADR), and the mean number of adenomas detected per procedure (MAP). There was no significant difference in sex, age, the indication of colonoscopy and quality of bowel preparation between the 2 groups. PDR, ADR, and proximal colon MAP were significantly higher in the CWP group than in the CC group (PDR: 84.9% vs 59.8%, P < .01; ADR: 70.1%, vs 49.2%, P < .01; proximal colon MAP: 1.24 vs 0.55, P < .01). CWP is more effective than CC for PDR, ADR, and proximal colon MAP. Although it may facilitate adenoma detection, further studies assessing the synergistic or complementary effects of combining these methods are needed.

Colorectal Cancer in Inflammatory Bowel Diseases: Epidemiology and Prevention: A Review

Simple Summary

Colorectal cancer (CRC) is one of the most serious potential complications of inflammatory bowel diseases (IBDs). The aging of patients affected by IBDs makes this issue a challenge that will increasingly be faced by clinicians in clinical practice, especially in light of the poorer prognosis for CRC in this group of people when compared with the general population. In this review, we summarize the current epidemiology, risk factors and various prevention strategies proposed for CRC in patients with IBDs.

Abstract

Colorectal cancer (CRC) is currently the third most frequent form of malignancy and the second in terms of mortality. Inflammatory bowel diseases (IBDs) are recognized risk factors for this type of cancer. Despite a worldwide increase in the incidence of CRC, the risk of CRC-related death in IBD patients has declined over time, probably because of successful surveillance strategies, the use of more effective drugs in the management of remission and improved indications to colectomy. This notwithstanding, CRC 5-year survival in patients with IBD is poorer than in the general population. This review provides a summary of the epidemiological features, risk factors and various prevention strategies proposed for CRC in IBD patients. Moreover, there is a special focus on reporting and highlighting the various prevention strategies proposed by the most important international scientific societies, both in terms of chemoprevention and endoscopic surveillance. Indeed, in conducting the analysis, we have given attention to the current primary, secondary and tertiary prevention guidelines, attempting to emphasize unresolved research and clinical problems related to this topic in order to improve diagnostic strategies and management.

MiWEndo: Evaluation of a Microwave Colonoscopy Algorithm for Early Colorectal Cancer Detection in Ex Vivo Human Colon Models

This study assesses the efficacy of detecting colorectal cancer precursors or polyps in an ex vivo human colon model with a microwave colonoscopy algorithm. Nowadays, 22% of polyps go undetected with conventional colonoscopy, and the risk of cancer after a negative colonoscopy can be up to 7.9%. We developed a microwave colonoscopy device that consists of a cylindrical ring-shaped switchable microwave antenna array that can be attached to the tip of a conventional colonoscope as an accessory. The accessory is connected to an external unit that allows successive measurements of the colon and processes the measurements with a microwave imaging algorithm. An acoustic signal is generated when a polyp is detected. Fifteen ex vivo freshly excised human colons with cancer (n = 12) or polyps (n = 3) were examined with the microwave-assisted colonoscopy system simulating a real colonoscopy exploration. After the experiment, the dielectric properties of the specimens were measured with a coaxial probe and the samples underwent a pathology analysis. The results show that all the neoplasms were detected with a sensitivity of 100% and specificity of 87.4%.

Microwave-Based Colonoscopy: Preclinical Evaluation in an Ex Vivo Human Colon Model

Introduction

Microwave imaging can obtain 360° anatomical and functional images of the colon representing the existing contrast in dielectric properties between different tissues. Microwaves are safe (nonionizing) and have the potential of reducing the visualization problems of conventional colonoscopy. This study assessed the efficacy of a microwave-based colonoscopy device to detect neoplastic lesions in an ex vivo human colon model.

Methods

Fresh surgically excised colorectal specimens containing cancer or polyps were fixed to a 3D positioning system, and the accessory device was introduced horizontally inside the ex vivo colon lumen and moved along it simulating a real colonoscopy exploration. Measurements of the colon were taken every 4 mm with the microwave-based colonoscopy device and processed with a microwave imaging algorithm.

Results

14 ex vivo human colorectal specimens with carcinomas (n = 11) or adenomas with high grade dysplasia (n = 3) were examined with a microwave-based device. Using a detection threshold of 2.79 for the dielectric property contrast, all lesions were detected without false positives or false negatives.

Conclusions

This study demonstrates the use of a microwave-based device to be used as an accessory of a standard colonoscope to detect neoplastic lesions in surgically excised colorectal specimens.

Cap-Assisted Chromoendoscopy Using a Mounted Cap Versus Standard Colonoscopy for Adenoma Detection

OBJECTIVES

Some neoplastic lesions remain undetected on colonoscopy. To date, no studies have investigated whether combining cap-assisted colonoscopy with chromoendoscopy increases the adenoma detection rate (ADR). This study aimed to compare cap-assisted chromoendoscopy (CAP/CHROMO) with standard colonoscopy (SC) with respect to their efficacy in detecting adenomas.

METHODS

This prospective, multicenter, randomized controlled trial included asymptomatic subjects aged 45-75 years who underwent colonoscopy for the first time at 14 university hospitals. Subjects were randomized to either the CAP/CHROMO group (with 0.09% indigo carmine spraying using a cap-mounted catheter at the tip of the colonoscope) or the SC group. All polyps were resected, but only histologically confirmed neoplastic lesions were considered for analysis. The primary outcome was ADR, defined as the proportion of subjects with at least 1 adenoma.

RESULTS

A total of 1,905 subjects were randomized to the CAP/CHROMO (n = 948) or SC (n = 957) group at 14 centers. Subjects' demographic characteristics were similar between both groups. The CAP/CHROMO group had significantly higher ADR than the SC group (54.4% vs 44.9%, P < 0.001). Significantly, more subjects with at least 1 proximal colon adenoma were identified by CAP/CHROMO (38.6%) than by SC (31.2%) (P = 0.001). The proximal serrated polyp detection rate by CAP/CHROMO was significantly higher in the female subgroup vs SC. However, advanced ADR was not different between the CAP/CHROMO and SC groups (9.3% vs 7.6%, P = 0.180).

DISCUSSION

CAP/CHROMO markedly improved the ADR and enhanced the detection of proximal adenoma. CAP/CHROMO is feasible for routine application and will allow for a more effective surveillance program.

An overview of deep learning algorithms and water exchange in colonoscopy in improving adenoma detection

Introduction: Among the Gastrointestinal (GI) Endoscopy Editorial Board top 10 topics in advances in endoscopy in 2018, water exchange colonoscopy and artificial intelligence were both considered important advances. Artificial intelligence holds the potential to increase and water exchange significantly increases adenoma detection.Areas covered: The authors searched MEDLINE (1998-2019) using the following medical subject terms: water-aided, water-assisted and water exchange colonoscopy, adenoma, artificial intelligence, deep learning, computer-assisted detection, and neural networks. Additional related studies were manually searched from the reference lists of publications. Only fully published journal articles in English were reviewed. The latest date of the search was Aug10, 2019. Artificial intelligence, machine learning, and deep learning contribute to the promise of real-time computer-aided detection diagnosis. By emphasizing near-complete suction of infused water during insertion, water exchange provides salvage cleaning and decreases cleaning-related multi-tasking distractions during withdrawal, increasing adenoma detection. The review will address how artificial intelligence and water exchange can complement each other in improving adenoma detection during colonoscopy.Expert opinion: In 5 years, research on artificial intelligence will likely achieve real-time application and evaluation of factors contributing to quality colonoscopy. Better understanding and more widespread use of water exchange will be possible.

The Role of Behind Folds Visualizing Techniques and Technologies in Improving Adenoma Detection Rate

PURPOSE OF REVIEW

Colorectal cancer is one of the most common malignancies in the Western world and is thought to develop from premalignant polyps. Over the past decade, several behind folds visualizing techniques (BFTs) have become available to improve polyp detection. This systematic review and meta-analysis aims to compare BFTs with conventional colonoscopy (CC).

RECENT FINDINGS

In the past five years, 14 randomized controlled trials (RCTs) including 8384 patients comparing different BFTs with CC were published. The overall relative risks for adenoma detection rate, polyp detection rate, and adenoma miss rate comparing BFTs with CC were 1.04 (95% confidence interval [CI] 0.98-1.10; P = 0.15), 1.03 (95% CI 0.98-1.09; P = 0.28), and 0.70 (95% CI 0.46-1.05; P = 0.08), respectively. Other quality metrics for colonoscopy were not significantly different between BFT-assisted colonoscopy and CC either. This meta-analysis of RCTs published in the past five years does not show a significant benefit of BFTs on any of the important quality metrics of colonoscopy. The lack of additional effect of BFTs might be due to improved awareness of colonoscopy quality metrics and colonoscopy skills among endoscopists combined with improvements of conventional colonoscope technology.

Immersive Virtual Colonoscopy

Virtual colonoscopy (VC) is a non-invasive screening tool for colorectal polyps which employs volume visualization of a colon model reconstructed from a CT scan of the patient's abdomen. We present an immersive analytics system for VC which enhances and improves the traditional desktop VC through the use of VR technologies. Our system, using a head-mounted display (HMD), includes all of the standard VC features, such as the volume rendered endoluminal fly-through, measurement tool, bookmark modes, electronic biopsy, and slice views. The use of VR immersion, stereo, and wider field of view and field of regard has a positive effect on polyp search and analysis tasks in our immersive VC system, a volumetric-based immersive analytics application. Navigation includes enhanced automatic speed and direction controls, based on the user's head orientation, in conjunction with physical navigation for exploration of local proximity. In order to accommodate the resolution and frame rate requirements for HMDs, new rendering techniques have been developed, including mesh-assisted volume raycasting and a novel lighting paradigm. Feedback and further suggestions from expert radiologists show the promise of our system for immersive analysis for VC and encourage new avenues for exploring the use of VR in visualization systems for medical diagnosis.

Changes in Adenoma Detection Rate With Implementation of Full-spectrum Endoscopy: A Report of 3998 Screening Colonoscopies

GOALS

To investigate the effect of implementing full-spectrum endoscopy (Fuse) on adenoma detection rate (ADR) at an ambulatory surgical center (ASC).

BACKGROUND

Traditional forward viewing (TFV) endoscopes have 1 camera and provide an angle of view of 140 to 170 degrees, whereas Fuse provides a 330 degrees view through the addition of 2 side cameras. Although randomized studies have shown that Fuse decreases adenoma miss rates, its impact on ADR in a screening population is currently unknown.

STUDY

We conducted a retrospective analysis of data from average risk screening colonoscopies at a 5-room ASC. This ASC transitioned from TFV to Fuse in April 2014. The primary outcome was ADR defined as the percentage of patients who underwent screening colonoscopy and were found to have at least 1 adenomatous polyp.

RESULTS

A total of 1696 screening colonoscopies were performed with TFV and 2302 with Fuse. Overall ADR was 23.7% with TFV and 29.0% with Fuse (P<0.01), an absolute increase of 5.3%. ADR for the proximal colon increased from 13.0% with TFV to 16.7% with Fuse (3.8% increase, P<0.01). ADR for advanced adenomas improved from 3.8% with TFV to 6.0% with Fuse (2.2% increase; P<0.01). The mean number of adenomas detected per colonoscopy increased from 0.32 to 0.41 (P<0.01). In multivariate analysis, the adjusted odds ratio for detecting an adenoma with Fuse versus TFV was 1.30 (P<0.01; 95% confidence interval, 1.11-1.51).

CONCLUSIONS

ADR significantly increased after adopting Fuse endoscopes at an ASC. Further studies are warranted to further understand the effects of Fuse on ADR in real-world settings.

New-generation full-spectrum endoscopy versus standard forward-viewing colonoscopy: a multicenter, randomized, tandem colonoscopy trial (J-FUSE Study)

BACKGROUND AND AIMS

Although colonoscopy is the criterion standard for detection of colorectal adenomas, some adenomas are missed. Full-spectrum endoscopy (FUSE) allows for observation with a 330-degree angle of view, which is expected to decrease the miss rate. However, no consensus has been reached regarding the superiority of FUSE over standard forward-viewing colonoscopy (SFVC) for detection of adenomas; we therefore compared new-generation FUSE and SFVC regarding colorectal adenoma miss rate (AMR) in this, the first reported randomized control trial using new-generation FUSE.

METHODS

We enrolled individuals aged 40 to 75 years who had been referred for screening, surveillance, fecal occult blood test positivity, or symptoms in a prospective randomized trial of tandem colonoscopy in 8 institutions. Patients were randomly assigned (1:1) via computer-generated stratified randomization. Neither the endoscopists nor patients were blinded to the allocation. The primary endpoint was AMR per patient (AMR-PP).

RESULTS

We enrolled 345 patients and included 319 in the per-protocol analyses. AMR-PP was significantly lower with FUSE (11.7%; 95% confidence interval [CI], 8.0%-15.4%) than with SFVC (22.9%; 95% CI, 17.5%-28.3%; P < .001). AMR-PP for lesions ≤5 mm in size was significantly lower with FUSE (10.4%; 95% CI, 6.5%-14.3%) than with SFVC (20.0%; 95% CI, 14.4%-25.6%; P = .0057). Furthermore, AMR-PP in the ascending colon was significantly lower with FUSE (4.3%; 95% CI, 1.4%-7.2%) than with SFVC (10.6%; 95% CI, 6.1%-15.1%; P = .0212).

CONCLUSIONS

FUSE is superior to SFVC regarding both AMR-PP and AMR; additionally, AMR-PP is both significantly lower with FUSE than SFVC for lesions ≤5 mm in size and in the ascending colon. (Clinical trial registration number: UMIN000020448.).

Impact of Hyoscine Bromide Use on Polyp Detection Rate During Colonoscopy: A Systematic Review and Meta-Analysis

Background

Colorectal cancer (CRC) is a leading cause of death worldwide. Polyp detection rate (PDR) and adenoma detection rate (ADR) are key focus in endoscopic research for CRC screening and prevention. Use of anti-spasmodic agents during colonoscopy to help identify adenomas and polyps has remained a controversial topic. Hyoscine butyl bromide (HBB) is the most commonly used anti-spasmodic agent in patients undergoing colonoscopy. Some randomized controlled trials (RCTs) have questioned the clinical efficacy and safety of routine use of HBB for polyp and adenoma detection rates.

Methods

We conducted a systematic search in PubMed and MEDLINE from inception until February 10, 2018, for studies which compared HBB with placebo. We used RevMan version 5.3 for analysis. Procedural end-points were polyps, adenomas, and advanced adenoma detection rates, mean number of polyps detected and cecal intubation time.

Results

We included seven RCTs with 2,588 patients in our analysis. A total of 1,301 patients were randomized to HBB arm and 1,287 to the placebo arm. There was no significant difference in the primary outcome of polyp detection rate, 654 in HBB group vs. 616 in the placebo group, (odds ratio (OR) = 1.11, confidence interval (CI) = 0.93 - 1.34, P = 0.25). There was no difference in secondary outcomes of adenoma detection rate, 430 in HBB group vs. 396 in the placebo group, (OR = 1.06, CI = 0.89 - 1.26, P = 0.51), advanced adenoma detection rate, 92 in HBB vs. 95 in placebo group (OR = 0.95, CI = 0.70 - 1.30, P = 0.76), mean number of polyps detected (point estimate = 0.12, CI = 0.00 - 0.23, P = 0.05), adenomatous polyps (OR = 0.84, CI = 0.39 - 1.81, P = 0.65) and cecal intubation time (point estimate = 0.73, CI = -1.98 - 0.52, P = 0.25) between the two groups.

Conclusions

The use of HBB in patients undergoing colonoscopy does not appear to improve polyp or adenoma detection rates. It showed a non-significant trend of increased mean number of polyps detected with HBB.

Increase your adenoma detection rate without using fancy adjunct tools

The correlation between a low adenoma detection rate (ADR) and interval cancers (ICs) has made ADR one of the most important quality indicators for colonoscopy. Data from nation-wide colorectal cancer (CRC) screening programs showed that there is room for improvement in ADR in order to reduce ICs in Taiwan. Measures with and without adjunct tools have been shown to have the potential to increase ADR, with the latter being more convenient to apply without additional cost. Optimal withdrawal techniques coupled with sufficient withdrawal time, training endoscopists with emphasis on recognition of subtle characteristics of flat lesions, dynamic position changes during the withdrawal phase, removing small polyps found during insertion, and retroflexion in the right colon have all been associated with increased ADR. In particular, water exchange (WE), which is characterized using water in lieu of air and suction removal of infused water during insertion, appears to meet the needs of colonoscopy patients in Taiwan. Analyses of both primary and secondary outcome variables of recently published studies have consistently shown that WE yields higher ADR than traditional air insufflation, even in propofol-sedated patients. Colonoscopists participating in the nationwide CRC screening program in Taiwan should consider applying one or more of the above measures to improve ADR and hopefully reduce ICs.

Dielectric properties of colon polyps, cancer, and normal mucosa: Ex vivo measurements from 0.5 to 20 GHz

PURPOSE

Colorectal cancer is highly preventable by detecting and removing polyps, which are the precursors. Currently, the most accurate test is colonoscopy, but still misses 22% of polyps due to visualization limitations. In this paper, we preliminary assess the potential of microwave imaging and dielectric properties (e.g., complex permittivity) as a complementary method for detecting polyps and cancer tissue in the colon. The dielectric properties of biological tissues have been used in a wide variety of applications, including safety assessment of wireless technologies and design of medical diagnostic or therapeutic techniques (microwave imaging, hyperthermia, and ablation). The main purpose of this work is to measure the complex permittivity of different types of colon polyps, cancer, and normal mucosa in ex vivo human samples to study if the dielectric properties are appropriate for classification purposes.

METHODS

The complex permittivity of freshly excised healthy colon tissue, cancer, and histological samples of different types of polyps from 23 patients was characterized using an open-ended coaxial probe between 0.5 and 20 GHz. The obtained measurements were classified into five tissue groups before applying a data reduction step with a frequency dispersive single-pole Debye model. The classification was finally compared with pathological analysis of tissue samples, which is the gold standard.

RESULTS

The complex permittivity progressively increases as the tissue degenerates from normal to cancer. When comparing to the gold-standard histological tissue analysis, the sensitivity and specificity of the proposed method is the following: 100% and 95% for cancer diagnosis; 91% and 62% for adenomas with high-grade dysplasia; 100% and 61% for adenomas with low-grade dysplasia; and 100% and 74% for hyperplastic polyps, respectively. In addition, complex permittivity measurements were independent of the lesion shape and size, which is also an interesting property comparing to current colonoscopy techniques.

CONCLUSIONS

The contrast in complex permittivities between normal and abnormal colon tissues presented here for the first time demonstrate the potential of these measurements for tissue classification. It also opens the door to the development of a microwave endoscopic device to complement the outcomes of colonoscopy with functional tissue information.

Advances in CRC Prevention: Screening and Surveillance

Colorectal cancer (CRC) is among the most commonly diagnosed cancers and causes of death from cancer across the world. CRC can, however, be detected in asymptomatic patients at a curable stage, and several studies have shown lower mortality among patients who undergo screening compared with those who do not. Using colonoscopy in CRC screening also results in the detection of precancerous polyps that can be directly removed during the procedure, thereby reducing the incidence of cancer. In the past decade, convincing evidence has appeared that the effectiveness of colonoscopy as CRC prevention tool is associated with the quality of the procedure. This review aims to provide an up-to-date overview of recent efforts to improve colonoscopy effectiveness by enhancing detection and improving the completeness and safety of resection of colorectal lesions.

CT colonography interpretation: how to maximize polyp detection and minimize overcalling

This article outlines how to achieve maximum accuracy in interpreting CT colonography (CTC) regarding colonic findings. Interpreting extracolonic findings seen on CTC is a separate diagnostic task and will not be addressed in this article. While many interpretive pitfalls are in fact related to CTC techniques, this article focuses on issues that are related to interpretive knowledge and skills, avoiding in-depth discussions on CTC techniques. Principal methods and further tips for detecting possible polyp candidates and for confirming true soft-tissue polyps will be discussed. Specific points about optimizing interpretation strategies for difficult flat polyps including sessile serrated polyp will be raised. There are numerous interpretive pitfalls regarding the colonic interpretation of CTC. Knowledge of these pitfalls will shorten the learning curve and help achieve accurate reads.

Can technology increase adenoma detection rate?

Colorectal cancer is the third most common cancer worldwide and the second most common cause of cancer-related death in Europe and North America. Colonoscopy is the gold standard investigation for the colon but is not perfect, and small or flat adenomas can be missed which increases the risk of patients subsequently developing colorectal cancer. Adenoma detection rate is the most widely used marker of quality, and low rates are associated with increased rates of post-colonoscopy colorectal cancer. Standards of colonoscopy and adenoma detection vary widely between different endoscopists. Interventions to improve adenoma detection rate are therefore required. Many devices have been purported to increase adenoma detection rate. This review looks at current available evidence for device technology to improve adenoma detection rate during colonoscopy.

Cap cuff-assisted colonoscopy versus standard colonoscopy for adenoma detection: a randomized back-to-back study

BACKGROUND AND AIMS

EndoCuff is a disposable device applied to standard colonoscopes to improve mucosal visualization. Randomized parallel trials have shown that EndoCuff increases the adenoma detection rate (ADR). The primary aim of this study was to compare the ADR between EndoCuff-assisted colonoscopies (EAC) and standard colonoscopies within a randomized back-to-back trial.

METHODS

This was a single-center randomized crossover study (NCT02374515) involving adult patients undergoing screening, surveillance, or diagnostic colonoscopy. Participants received back-to-back standard colonoscopies and EACs in a random order, performed by the same endoscopist. All polyps were excised, but only those proven at histology to be adenomas were considered for analysis.

RESULTS

From February 2015 to March 2016, a total of 288 patients were enrolled, and 274 were included in the per-protocol analysis. Compared with standard colonoscopies, EACs increased the ADR (29.6% vs 26.3%; P < .01) and the number of diagnosed adenomas (176 vs 129; P < .01), particularly in the left (73 vs 46; P < .01) and right sides of the colon (83 vs 63; P < .01). EAC increased the detection of adenomas <5 mm (129 vs 84; P < .01), but no difference was found with regard to larger lesions. In 7.3% of patients, findings of EndoCuff shortened the surveillance interval determined by standard colonoscopy findings. EndoCuff caused 7 mucosal erosions (2.5% of patients), requiring a mucosal adrenaline injection in 1 case.

CONCLUSIONS

The use of EndoCuff increases the number of identified adenomas, primarily small adenomas in the left and right sides of the colon. This increases the ADR and allows a better definition of the surveillance program. (Clinical trial registration number: NCT02374515.).

Full-spectrum (FUSE) versus standard forward-viewing colonoscopy in an organised colorectal cancer screening programme

OBJECTIVE

Miss rate of polyps has been shown to be substantially lower with full-spectrum endoscopy (FUSE) compared with standard forward-viewing (SFV) colonoscopy in a tandem study at per polyp analysis. However, there is uncertainty on whether FUSE is also associated with a higher detection rate of colorectal neoplasia, especially advanced lesions, in per patient analysis.

METHODS

Consecutive subjects undergoing colonoscopy following a positive faecal immunochemical test (FIT) by experienced endoscopists and performed in the context of a regional colorectal cancer population-screening programme were randomised between colonoscopy with either FUSE or SFV colonoscopy in seven Italian centres. Randomisation was stratified by gender, age group and screening history. Primary outcomes included detection rates of advanced adenomas (A-ADR), adenomas (ADR) and sessile-serrated polyps (SSPDR).

RESULTS

Of 741 eligible subjects, 658 were randomised to either FUSE (n=328) or SFV (n=330) colonoscopy and included in the analysis. Overall, 293/658 and 143/658 subjects had at least one adenoma (ADR 44.5%) and advanced adenoma (A-ADR 21.7%), respectively, while SSP was the most advanced lesion in 18 cases (SSPDR 2.7%). ADR and A-ADR were 43.6% and 19.5% in the FUSE arm, and 45.5% and 23.9% in the SFV arm, with no difference for both ADR (OR for FUSE: 0.96, 95% CI 0.81 to 1.14) and A-ADR (OR for FUSE: 0.82, 95% CI 0.61 to 1.09). No difference in SSPDR or multiplicity was detected between the two arms. In the per polyp analysis, the mean number of adenomas and proximal adenomas per patient was 0.81±1.25 and 0.47±0.93 in the FUSE arm, and 0.85±1.33 and 0.48±0.96 in the SFV colonoscopy arm (p=NS for both comparisons).

CONCLUSIONS

No statistically significant difference in ADR and A-ADR between FUSE and SFV colonoscopy was detected in a per patient analysis in FIT-positive patients.

TRIAL REGISTRATION NUMBER

ISRCTN10357435.

Impact of Full Spectrum Endoscopy® (Fuse®, EndoChoice®) on adenoma detection: a prospective French pilot study

Background

Currently, colonoscopy and polypectomy are the gold standard methods for the prevention of incident cases of colorectal cancer. The use of a new colonoscope (Fuse^®, EndoChoice^®) with a larger view of up to 330° appears to improve the adenoma detection rate (ADR). We performed a prospective observational study concerning this scope. The primary endpoint was potentially omitted adenomas (POA), i.e. adenomas seen on the side screens that will not appear on the central display during colonoscopy withdrawal without oriented movements. Secondary endpoints included our ADR, Fuse^® impact on ADR, time to cecal intubation and withdrawal time.

Methods

We performed a single-center prospective study in one French center. We enrolled patients over 18 years of age between January 2015 and March 2016.

Results

We included 141 patients; 3 were excluded because their colonoscopies were incomplete. Our study included 78 men and 60 women (sex ratio 1.3). The mean age was 60.4 years. A total of 130 polyps were resected. In all, 88/130 were adenomas (68%) and 34/88 adenomas (39%) were POA. The mean time to cecum was 10 min, and the mean withdrawal time was 12 min. ADR was 35% for men and 31% for women. The estimated ADR without POA was 29% for men and 19% for women.

Conclusions

The Fuse^® system appears to be safe and efficient. POA represented 39% of all adenomas. The impact of the panoramic view on the ADR was considered substantial. The main limitations are the lack of randomization and the absence of a control group.

Hyoscine butylbromide for colorectal polyp detection: prospective, randomized, placebo-controlled trial

OBJECTIVES:

The removal of pre-malignant colorectal lesions prevents cancer. Hyoscine has been proposed as a means of improving diagnosis by reducing colonic movements. The aim of this study was to analyze whether this anti-spasmodic enhances the detection of pre-malignant colorectal lesions.

METHODS:

In a randomized, double-blinded fashion patients received hyoscine or a saline solution in all consecutive colonoscopies in which the cecum was reached. Lesions were analysed with respect to number, size, location, histology and capillary pattern.

RESULTS:

A total of 440 colonoscopies were randomized. The overall polyp detection rate (PDR) and the adenoma detection rate (ADR) were 65.2% and 49.3%, respectively. In the hyoscine group, non-polypoid lesions were detected significantly more often (p=0.01). In the placebo group 281 lesions were diagnosed (202 adenomas) and in the hyoscine group 282 lesions were detected (189 adenomas) (p=0.23). The PDR and ADR were similar between the placebo and hyoscine groups (64% vs 66% and 50% vs 47%, respectively). No differences were observed between the two groups in the advanced-ADR or advanced neoplasia detection rate, as well the mean numbers of polyps, adenomas, advanced adenomas and advanced neoplasias detected per patient. The administration of hyoscine also did not improve the diagnostic accuracy of digital chromoendoscopy. The presence of adenomatous polyps in the right colon was detected significantly more frequently in the hyoscine group (OR 5.41 95% CI 2.7 - 11; p<0.01 vs OR 2.3 95% CI 1.1 - 4.6; p=0.02).

CONCLUSION:

The use of hyoscine before beginning the withdrawal of the colonoscope does not seem to enhance the PDR and the ADR.

Surveillance strategies for colitis-associated cancer: state of the art and future perspectives

Colitis-associated cancer (CAC) represents a concrete risk of morbidity and mortality in patients with long lasting inflammatory bowel diseases. Surveillance colonoscopy is a rapidly evolving research field with profound changes from the traditional approach based on scheduled controls and random biopsy protocols. Areas covered: A literature search was performed using PubMed/Embase to review the latest evidence supporting the need for surveillance colonoscopy. By focusing on the most promising recent advances in this field, we provide a state-of-the-art overview of the current gold standards for the diagnosis and management of colitis-associated dysplasia. Expert commentary: Evidence-based and emerging data have questioned the efficacy and effectiveness of both standard surveillance colonoscopy and random biopsy protocols. The latest guidelines endorse early initiation of surveillance programs, risk-profiling assessment of colonoscopy intervals and standardized use of advanced imaging modalities to detect early dysplasia. Current trends clearly reveal increased attention to direct visualization and endoscopic management of visible dysplastic lesions, even in patients with longstanding colitis. Emerging technological advances in gastrointestinal endoscopy are expected to change the endoscopic surveillance protocols in the near future.

Increasing Navigation Speed at Endoluminal CT Colonography Reduces Colonic Visualization and Polyp Identification

As navigation speed increases, gaze of the reader becomes more central and polyp identification rates fall.

Purpose

To investigate the effect of increasing navigation speed on the visual search and decision making during polyp identification for computed tomography (CT) colonography

Materials and Methods

Institutional review board permission was obtained to use deidentified CT colonography data for this prospective reader study. After obtaining informed consent from the readers, 12 CT colonography fly-through examinations that depicted eight polyps were presented at four different fixed navigation speeds to 23 radiologists. Speeds ranged from 1 cm/sec to 4.5 cm/sec. Gaze position was tracked by using an infrared eye tracker, and readers indicated that they saw a polyp by clicking a mouse. Patterns of searching and decision making by speed were investigated graphically and by multilevel modeling.

Results

Readers identified polyps correctly in 56 of 77 (72.7%) of viewings at the slowest speed but in only 137 of 225 (60.9%) of viewings at the fastest speed (P = .004). They also identified fewer false-positive features at faster speeds (42 of 115; 36.5%) of videos at slowest speed, 89 of 345 (25.8%) at fastest, P = .02). Gaze location was highly concentrated toward the central quarter of the screen area at faster speeds (mean gaze points at slowest speed vs fastest speed, 86% vs 97%, respectively).

Conclusion

Faster navigation speed at endoluminal CT colonography led to progressive restriction of visual search patterns. Greater speed also reduced both true-positive and false-positive colorectal polyp identification.

^© RSNA, 2017

Online supplemental material is available for this article.

[Additional polyp detection rate using colonoscopic retroflexion in right colon]

BACKGROUND/AIMS

There have been several studies showing that retroflexion (RF) in the right colon (RC) could reduce the polyp miss rate of proximal colon during colonoscopy. This study was conducted to evaluate the additional benefit of RF technique in the RC.

METHODS

Patients who underwent colonoscopy from May 2008 to April 2011 were enrolled in the study. Data were obtained by retrospectively reviewing the medical records. RF was attempted in every patients undergoing colonoscopy since May 2008 except in cases of small RC vault, co-morbidity, severe diverticulosis, failed RF despite two trials, complaints of severe abdominal pain, or time burden. At first, RC was examined under direct vision. It was then examined by RF to detect missed polyps during the initial observation. Finally, the RC was re-examined with direct view.

RESULTS

The cumulative RF success rate in the RC was 78.84% (1,805 of 2,319). The RF success rate increased with the number of cases (50% at 160 cases, 70% at 400 cases, and reached near 90% over 1,000 cases). Few polyps (4.88%) were detected only with RF and the additional adenoma detection rate was 3.32%. The additional polyp/adenoma detection rates were higher in the old age group (p<0.01). There were no RF associated perforation or severe complication.

CONCLUSIONS

Using RF examination, additional 4.88% of polyps could be detected in the RC. This technique could be a useful and safe method to detect hidden polyp during colonoscopy.

Advances in endoscopic imaging in ulcerative colitis

Modern strategies for the treatment of ulcerative colitis require more accurate tools for gastrointestinal imaging to better assess mucosal disease activity and long-term prognostic clinical outcomes. Recent advances in gastrointestinal luminal endoscopy are radically changing the role of endoscopy in every-day clinical practice and research trials. Advanced endoscopic imaging techniques including high-definition endoscopes, optical magnification endoscopy, and various chromoendoscopy techniques have remarkably improved endoscopic assessment of ulcerative colitis. More recently, optical biopsy techniques with either endocytoscopy or confocal laser endomicroscopy have shown great potential in predicting several histological changes in real time during ongoing endoscopy. Here, we review current applications of advanced endoscopic imaging techniques in ulcerative colitis and present the most promising upcoming headways in this field.

Feasibility of full-spectrum endoscopy: Korea’s first full-spectrum endoscopy colonoscopic trial

AIM: To evaluate the full-spectrum endoscopy (FUSE) colonoscopy system as the first report on the utility thereof in a Korean population.

METHODS: We explored the efficacy of the FUSE colonoscopy in a retrospective, single-center feasibility study performed between February 1 and July 20, 2015. A total of 262 subjects (age range: 22-80) underwent the FUSE colonoscopy for colorectal cancer screening, polyp surveillance, or diagnostic evaluation. The cecal intubation success rate, the polyp detection rate (PDR), the adenoma detection rate (ADR), and the diverticulum detection rate (DDR), were calculated. Also, the success rates of therapeutic interventions were evaluated with biopsy confirmation.

RESULTS: All patients completed the study and the success rates of cecal and terminal ileal intubation were 100% with the FUSE colonoscope; we found 313 polyps in 142 patients and 173 adenomas in 95. The overall PDR, ADR and DDR were 54.2%, 36.3%, and 25.2%, respectively, and were higher in males, and increased with age. The endoscopists and nurses involved considered that the full-spectrum colonoscope improved navigation and orientation within the colon. No colonoscopy was aborted because of colonoscope malfunction.

CONCLUSION: The FUSE colonoscopy yielded a higher PDR, ADR, DDR than did traditional colonoscopy, without therapeutic failure or complications, showing feasible, effective, and safe in this first Korean trial.

Mechanisms of hyoscine butylbromide to improve adenoma detection: A case-control study of surface visualization at simulated colonoscope withdrawal

BACKGROUND AND STUDY AIMS

Antispasmodics may improve mucosal visualization during colonoscope withdrawal, potentially improving polyp and adenoma detection. Meta-analysis and case-control studies suggest a 9 % to 13 % relative increase in adenoma and polyp detection. We aimed to assess the impact of hyoscine butylbromide on the expected visualization during colonoscope withdrawal using a CT colonography (CTC) simulation.

PATIENTS AND METHODS

Datasets from a previous CTC study examining the effect of antispasmodic were re-analyzed with customised CTC software, adjusted to simulate a standard colonoscopic view. Eighty-six patients received intravenous (IV) hyoscine butylbromide 20 mg, 40 mg or no antispasmodic. Main outcome measurements at unidirectional flythrough, simulating colonoscope withdrawal, were percentage colonic surface visualization, numbers and sizes of unseen areas, and colonic length.

RESULTS

Use of antispasmodic was associated with a significant relative increase in percentage surface visualization of 2.6 % to 3.9 %, compared with no antispasmodic, P < 0.006. Total numbers of missed areas and intermediate sized (300 - 1000 mm(2)) missed areas were significantly decreased, by approximately 20 %. There were no differences between the 20-mg and 40-mg doses. Mean colonic length (161 - 169 cm) was unchanged by antispasmodic.

CONCLUSIONS

IV hyoscine butylbromide at simulated colonoscope withdrawal was associated with significant increases in surface visualization, which might explain up to half the improvement in adenoma detection seen in clinical studies.

New technologies and techniques to improve adenoma detection in colonoscopy

Adenoma detection rate (ADR) is a key component of colonoscopy quality assessment, with a direct link between itself and future mortality from colorectal cancer. There are a number of potential factors, both modifiable and non-modifiable that can impact upon ADR. As methods, understanding and technologies advance, so should our ability to improve ADRs, and thus, reduce colorectal cancer mortality. This article will review new technologies and techniques that improve ADR, both in terms of the endoscopes themselves and adjuncts to current systems. In particular it focuses on effective techniques and behaviours, developments in image enhancement, advancement in endoscope design and developments in accessories that may improve ADR. It also highlights the key role that continued medical education plays in improving the quality of colonoscopy and thus ADR. The review aims to present a balanced summary of the evidence currently available and does not propose to serve as a guideline.

Novel endocuff-assisted colonoscopy significantly increases the polyp detection rate: a randomized controlled trial

GOALS AND BACKGROUND

Screening colonoscopy for colorectal cancer has proven to reduce mortality rates. Recently the Endocuff (EC), an attachment to the distal tip of the colonoscope, was introduced. The aim of our study was to compare EC-assisted colonoscopies with standard colonoscopies for the detection of colonic polyps.

STUDY

This study is a randomized prospective 2-center trial. The study was conducted at 2 tertiary care centers.

PARTICIPANTS

A total of 498 patients [249 males; median age 67 y; interquartile range (IQR), 56-75 y] for colon adenoma screening purposes were included. All patients underwent standard colonoscopy with or without the use of EC. Overall polyp detection rate, the number of colonic polyps, and the polyp distribution in the colon were measured. Difference in recognition of polyps with or without the use of EC was assessed. Statistical analysis was applied.

RESULTS

In the EC group, the number of polyps detected per patient was 63% higher [2.00 (IQR, 1.00-4.00) vs. 1.00 (IQR, 1.00-2.25), P<0.0001]. The polyp detection rate in patients increased by 14% with the use of EC (56% vs. 42%, P=0.001). For polyp detection, superiority by use of EC could be observed in the sigmoid (P=0.001) and cecum (P=0.002) for polyps <1 cm in diameter. In the EC group, the number of adenomas detected per patient significantly increased by 86% (P=0.002). No major complications occurred in both groups.

CONCLUSIONS

The use of the EC is feasible and safe with significantly higher polyp detection rates, especially for those located in the sigmoid region. The cuff system has the potential to improve the accuracy of screening colonoscopies.

Advanced technology for the improvement of adenoma and polyp detection during colonoscopy

Early detection and removal of adenomatous polyps reduces colorectal cancer death. However, many studies have reported that up to 20% of adenomas can be missed during colonoscopy. To improve visualization and reduce the blind spot of the colonic mucosa for an increase in the adenoma detection rate, many endoscopic techniques and technologies have been developed. The benefit of the high-definition endoscope for improving adenoma and polyp detection is marginal. Wide-angle colonoscope has failed to improve adenoma detection compared to standard colonoscopy. Although the cap-assisted colonoscope can reduce cecal intubation times, it does not seem to improve adenoma and polyp detection. The diagnostic accuracy of the colon capsule endoscope is low compared to the conventional colonoscope. Third Eye(®) retroscope(®) , which provides additional retrograde viewing, has revealed significant improvement in adenoma and polyp detection compared to standard colonoscopy. However, this device increases procedural times. Recently developed full-spectrum endoscopy colonoscope and extra-wide-angle-view colonoscope have demonstrated a significantly lower miss rate of polyps. However, clinical trials are mandatory to determine the efficacy of these novel technologies for cancer screening. In addition, education and training for these novel techniques and technologies should seriously be considered to improve adenoma and polyp detection.

Electronic imaging to enhance lesion detection at colonoscopy

Adenoma removal prevents colorectal cancer (CRC) development. Lower adenoma detection rates correlate with increased postcolonoscopy CRC. Chromoendoscopy it is not practical for routine use. It was hoped that electronic imaging techniques would offer effective alternatives to improve detection; however, meta-analyses in average-risk patients indicate no benefit. Narrow band imaging may be of benefit for high-risk surveillance. Combining electronic imaging techniques with molecular imaging probes may highlight dysplasia at a molecular level. In future colonoscopy is likely to rely on sensitive and specific, labeled molecular probes detected by electronic endoscopic imaging to enhance detection and reduce miss rates for premalignant lesions.

The endoscopy evolution: 'the superscope era'

Developments to the design of the flexible endoscope are transforming the field of gastroenterology. There is a drive to improve colonic adenoma detection rates leading to advancements in the design of the colonoscope. Novel endoscopes now allow increased visualisation of colonic mucosa, including behind colonic folds, and aim to reduce pain associated with the procedure. In addition, a shift in surgical paradigm towards minimally invasive endoluminal surgery has meant innovations in flexible platforms are being sought. There are a number of limitations of the basic endoscope. These include a lack of stability and triangulation of instruments. Modifications to the flexible endoscope design form the basis of a number of newly developed and research platforms, some of which are discussed in this review.

How can screening colonoscopy be optimized?

Since the implementation of screening programmes, both the incidence and mortality of colorectal cancer have been decreasing. The choice of the preferred screening tool, however, is divergent and the adherence to screening programmes in most countries is still low. Cancer detection tests such as the guaiac faecal occult blood test (gFOBT) and the immunohistochemical FOBT (iFOBT) achieve higher acceptance than endoscopy. The sensitivity and specificity of iFOBT are higher than those of gFOBT, but gFOBT is cheaper and easier to perform. Endoscopic screening, which represents cancer prevention tests, has higher sensitivity for premalignant lesions than gFOBT and iFOBT and enables diagnosis and therapy in one single procedure. Since screening colonoscopy and sigmoidoscopy are invasive procedures with potentially severe adverse events, the highest possible quality must be provided. High-tech equipment, experience, training, quality control programmes, excellent bowel preparation and low adverse event rates are pivotal. Alternative screening tools such as CT colonography, barium enema CT and multitarget stool DNA tests have not been established as routine screening tools to date.

Endoscopic innovations to increase the adenoma detection rate during colonoscopy

Up to a quarter of polyps and adenomas are missed during colonoscopy due to poor visualization behind folds and the inner curves of flexures, and the presence of flat lesions that are difficult to detect. These numbers may however be conservative because they mainly come from back-to-back studies performed with standard colonoscopes, which are unable to visualize the entire mucosal surface. In the past several years, new endoscopic techniques have been introduced to improve the detection of polyps and adenomas. The introduction of high definition colonoscopes and visual image enhancement technologies have been suggested to lead to better recognition of flat and small lesions, but the absolute increase in diagnostic yield seems limited. Cap assisted colonoscopy and water-exchange colonoscopy are methods to facilitate cecal intubation and increase patients comfort, but show only a marginal or no benefit on polyp and adenoma detection. Retroflexion is routinely used in the rectum for the inspection of the dentate line, but withdrawal in retroflexion in the colon is in general not recommended due to the risk of perforation. In contrast, colonoscopy with the Third-Eye Retroscope^® may result in considerable lower miss rates compared to standard colonoscopy, but this technique is not practical in case of polypectomy and is more time consuming. The recently introduced Full Spectrum Endoscopy™ colonoscopes maintains the technical capabilities of standard colonoscopes and provides a much wider view of 330 degrees compared to the 170 degrees with standard colonoscopes. Remarkable lower adenoma miss rates with this new technique were recently demonstrated in the first randomized study. Nonetheless, more studies are required to determine the exact additional diagnostic yield in clinical practice. Optimizing the efficacy of colorectal cancer screening and surveillance requires high definition colonoscopes with improved virtual chromoendoscopy technology that visualize the whole colon mucosa while maintaining optimal washing, suction and therapeutic capabilities, and keeping the procedural time as low and patient discomfort as optimal as possible.

Retroview colonoscopy

A retroview in the colon permits an 11-25% increase in the adenoma detection rate when compared with a standard straight forward view during colonoscopy. This can often be accomplished in the rectum or the proximal colon by using dial controls and shaft manipulation to turn the tip of a standard colonoscope 180°. A special slim caliber instrument, the "Third Eye Retroscope" (a backward viewing device) has been developed which is inserted through the working channel of a colonoscope. New colonoscopes are being developed that have the capability of side vision with accompanying light illumination which, with wide angle lenses, provide an almost complete retroview of the colon.

A novel extra-wide-angle-view colonoscope: a simulated pilot study using anatomic colorectal models

BACKGROUND

A major factor that may contribute to a higher adenoma miss rate during colonoscopy is undetected lesions located behind haustral folds, flexures, or rectal valves.

OBJECTIVE

To assess the efficacy of a prototype, novel, extra-wide-angle-view colonoscope that provides a simultaneous lateral-backward view that complements the forward view lens.

DESIGN

A simulated pilot study of two anatomic colorectal models, each prepared with 8 polyps positioned in obvious locations and 8 polyps placed behind folds. Thirty-two endoscopists with different levels of experience performed examinations on models in a random order by using the extra-wide-angle-view colonoscope and a standard colonoscope.

MAIN OUTCOME MEASUREMENTS

The detection rates of simulated polyps.

RESULTS

The mean detection rate for all simulated polyps with the extra-wide-angle-view colonoscope was significantly higher than that with the standard colonoscope (68% vs 51%; P < .0001). The detection rate for polyps behind folds was significantly higher in the extra-wide-angle-view colonoscope than in the standard colonoscope (61.7% vs 46.9%; P = .0009).

LIMITATIONS

Not a clinical study.

CONCLUSION

The novel, extra-wide-angle-view colonoscope may represent an advancement in colorectal polyp detection. The value of the colonoscope for clinical use awaits further study.

A feasibility study of unidirectional 240°-angle 3D CT colonography

In three-dimensional (3D) CT colonography (CTC), a wider viewing angle provides a larger field of view. The purpose of this study was to investigate the polyp detection rate and time efficiency of unidirectional 240°-angle 3D CTC compared with bidirectional 120°-angle CTC. CTC data sets of 40 patients were reviewed by two readers using the two methods. The unidirectional 240°-angle CTC showed a performance in polyp detection similar to the bidirectional 120°-angle CTC with improved time efficiency.

Colonoscopic Cancer Surveillance in Inflammatory Bowel Disease: What's New Beyond Random Biopsy?

Colonoscopy based colitis surveillance is widely accepted to try to prevent development of and ensure early detection of colitis-associated colorectal cancer. Traditionally this has been performed with quadrantic random biopsies throughout the colon. Chromoendoscopy "dye-spray" with targeted biopsies only has been shown to increase dysplasia detection 4 to 5 fold on a per lesion basis. It has therefore been suggested that random biopsies should be abandoned as they do not increase dysplasia detection nor change patient clinical course. Recent British guidelines for colitis surveillance have strongly endorsed chromoendoscopy. This short review summarizes current international guidelines and looks at how to optimize white light colonoscopy in colitis considering: bowel preparation, withdrawal time, high definition, and structure enhancement. Data for advanced imaging techniques are reviewed including positive evidence in favor of chromoendoscopy, and limited data suggesting autofluoresence imaging may be promising. Narrow band imaging does not increase dysplasia detection in colitis. Confocal endomicroscopy might potentially reduce biopsies beyond that of chromoendoscopy but does not offer a clear detection advantage. Pan-colonic chromoendoscopy with targeted biopsies increases dysplasia detection and is the standard of care in the United Kingdom. It is likely that the use of chromoendoscopy for colitis surveillance will become widely accepted internationally.

Narrow band imaging for detection of dysplasia in colitis: a randomized controlled trial

OBJECTIVES

In ulcerative colitis surveillance, chromoendoscopy improves dysplasia detection 3 – 5-fold compared with white light endoscopy (WLE). The aim of this study was to investigate whether narrow band imaging (NBI) can improve dysplasia detection compared with WLE.

METHODS

This was a randomized, parallel-group trial. A total of 220 patients were needed to be recruited to detect a threefold increase in dysplasia detection. In all, 112 patients with long-standing ulcerative colitis were randomized to colonoscopic extubation with NBI (56) or WLE (56) (1:1 ratio) at two tertiary endoscopy units in the United Kingdom. Targeted biopsies of suspicious areas and quadrantic random biopsies every 10 cm were taken in both groups. The primary outcome measure was the proportion of patients with at least one area of dysplasia detected. In a prespecified mid-point analysis, the criteria for trial discontinuation were met and the trial was stopped and analyzed at this point.

RESULTS

There was no difference in the primary outcome between the two groups, with 5 patients having at least one dysplastic lesion in each group (odds ratio (OR) 1.00, 95 % confidence interval (95 % CI) 0.27 – 3.67, P = 1.00). This remained unchanged when adjusted for other variables (OR 0.69, 95 % CI 0.16 – 2.96, P = 0.62). Overall, dysplasia detection was 9 % in each arm. Yield of dysplasia from random nontargeted biopsies was 1 / 2,707 (0.04 % ).

CONCLUSIONS

Overall, in this multicenter parallel-group trial, there was no difference in dysplasia detection when using NBI compared with high-definition WLE colonoscopy. Random background biopsies were ineffective in detecting dysplasia.

Transparent cap-assisted colonoscopy versus standard adult colonoscopy: a systematic review and meta-analysis

BACKGROUND

Cap-assisted colonoscopy uses a transparent plastic hood attached to the tip of the colonoscope to flatten the semilunar folds and improve mucosal exposure. Several studies have examined the effect of cap-assisted colonoscopy on polyp detection, but the data are inconsistent.

OBJECTIVE

This study aimed to evaluate whether cap-assisted colonoscopy improves the yield of colorectal neoplasia detected compared with standard colonoscopy.

DATA SOURCES

A systematic search of the PubMed, MEDLINE, Embase, and Cochrane databases identified 12 studies that met the inclusion criteria for data extraction.

STUDY SELECTION

Publications that compared cap-assisted colonoscopy vs standard colonoscopy in adults in a prospective randomized controlled study were selected for review.

MAIN OUTCOME MEASURES

The primary outcomes used for meta-analysis were cecal intubation rate, cecal intubation time, and polyp detection rate. The analysis was performed using a fixed-effect model. Outcomes were calculated as odds ratios or standardized mean differences with 95% confidence intervals. The average polyp miss rate determined by tandem colonoscopy was also calculated.

RESULTS

The outcomes of 6185 patients were studied. Cap-assisted colonoscopy detected significantly more patients with polyps (OR 1.13; p = 0.030) and had a lower average polyp miss rate (12.2% vs 28.6%) than standard colonoscopy. Cap-assisted colonoscopy had a significantly higher cecal intubation rate than standard colonoscopy (OR 1.36; p = 0.020), whereas the time to cecal intubation (standard mean difference, 0.04 min; p = 0.280) was similar for the 2 colonoscope types.

CONCLUSIONS

Cap-assisted colonoscopy is associated with improved detection of colorectal neoplasia and higher cecal intubation rates than standard adult colonoscopy.