Estimation Of Polyp Size Research Articles

Enhancing endoscopic measurement: validating a quantitative method for polyp size and location estimation in upper gastrointestinal endoscopy

BackgroundAccurate measurement of polyps size is crucial in predicting malignancy, planning relevant intervention strategies and surveillance schedules. Endoscopists’ visual estimations can lack precision. This study builds on our prior research, with the aim to evaluate a recently developed quantitative method to measure the polyp size and location accurately during a simulated endoscopy session.MethodsThe quantitative method merges information about endoscopic positions obtained from an electromagnetic tracking sensor, with corresponding points on the images of the segmented polyp border. This yields real-scale 3D coordinates of the border of the polyp. By utilising the sensor, positions of any anatomical landmarks are attainable, enabling the estimation of a polyp’s location relative to them. To verify the method’s reliability and accuracy, simulated endoscopies were conducted in pig stomachs, where polyps were artificially created and assessed in a test–retest manner. The polyp measurements were subsequently compared against clipper measurements.ResultsThe average size of the fifteen polyps evaluated was approximately 12 ± 4.3 mm, ranging from 5 to 20 mm. The test–retest reliability, measured by the Intraclass Correlation Coefficient (ICC) for polyp size estimation, demonstrated an absolute agreement of 0.991 (95% CI 0.973–0.997, p < 0.05). Bland & Altman analysis revealed a mean estimation difference of − 0.17 mm (− 2.03%) for polyp size and, a mean difference of − 0.4 mm (− 0.21%) for polyp location. Both differences were statistically non-significant (p > 0.05). When comparing the proposed method with calliper measurements, the Bland & Altman plots showed 95% of size estimation differences between − 1.4 and 1.8 mm (− 13 to 17.4%) which was not significant (p > 0.05).ConclusionsThe proposed method of measurements of polyp size and location was found to be highly accurate, offering great potential for clinical implementation to improve polyp assessment. This level of performance represents a notable improvement over visual estimation technique used in clinical practice.

Endoscopic measurement of the size of gastrointestinal polyps using an electromagnetic tracking system and computer vision-based algorithm

PurposePolyp size is an important factor that may influence diagnosis and clinical management decision, but estimation by visual inspection during endoscopy is often difficult and subject to error. The purpose of this study is to develop a quantitative approach that enables an accurate and objective measurement of polyp size and to study the feasibility of the method.MethodsWe attempted to estimate polyp size and location relative to the gastro-oesophageal junction by integrating data from an electromagnetic tracking sensor and endoscopic images. This method is based on estimation of the three-dimensional coordinates of the borders of the polyp by combining the endoscope camera position and the corresponding points along the polyp border in endoscopic images using a computer vision-based algorithm. We evaluated the proposed method using a simulated upper gastrointestinal endoscopy model.ResultsThe difference between the mean of ten measurements of one artificial polyp and its actual size (10 mm in diameter) was 0.86 mm. Similarly, the difference between the mean of ten measurements of the polyp distance from the gastroesophageal junction and its actual distance (~ 22 cm) was 1.28 mm. Our results show that the changes in camera positions in which the images were taken and the quality of the polyp segmentation have the most impact on the accuracy of polyp size estimation.ConclusionThis study demonstrated an innovative approach to endoscopic measurements using motion tracking technologies and computer vision and demonstrated its accuracy in determining the size and location of the polyp. The observed magnitude of error is clinically acceptable, and the measurements are available immediately after the images captured. To enhance accuracy, it is recommended to avoid identical images and instead utilise control wheels on the endoscope for capturing different views. Future work should further evaluate this innovative method during clinical endoscopic procedures.

A112 MEASURING COLORECTAL POLYP SIZE USING A NOVEL VIRTUAL SCALE FUNCTION DURING ENDOSCOPIES: A CLINICAL PILOT STUDY

Abstract Background Although accurate polyp size measurement is essential for adequately managing patients, we still rely on the endoscopists' subjective visual estimation of polyp size in routine practice. Purpose We therefore conducted a clinical pilot study to evaluate relative accuracy of measuring colorectal polyp size during live colonoscopies using a novel virtual scale endoscope (VSE) that superimposes a virtual linear or circular ruler onto objects in the endoscopist's field of view. Method We conducted a pilot phase 1 study to evaluate the relative accuracy of VSE for polyp size measurement. We measured polyp size from fresh polypectomy specimens before formalin fixation using a digital vernier caliper. These reference measurements were compared to visual size estimations and VSE measurements obtained during live colonoscopies. The primary outcome was the relative accuracy of visual size estimation versus size estimation using VSE. The secondary outcome was the percentage of measurements that fall within 25% of true polyp size. Result(s) 43 patients (mean age: 63.3 years; 44.2% male) undergoing screening, surveillance, or diagnostic colonoscopies were included in the pilot study. Colonoscopies were performed by two endoscopists, including one trainee and one staff gastroenterologist. Visual, VSE, and reference size measurements was performed for 17 polyps. VSE during live colonoscopies had a higher relative accuracy of polyp size measurements when compared with visual polyp size estimation 84.3% (95% confidence interval (CI) 77.22% to 91.41%) vs 69.3% (95%CI 61.13% to 77.39%) (p=0.005). The percentage of size measurements that were within 25% of sizes as measured by caliper were 41.2% for visual polyp size estimation and 88.2% for VSE (p=0.02). Conclusion(s) We found that a novel endoscope equipped with a virtual scale allowed for significantly higher accuracy in polyp size measurement. A prospective randomized controlled trial is currently underway to validate these results. Please acknowledge all funding agencies by checking the applicable boxes below Other Please indicate your source of funding below: Fujifilm Disclosure of Interest R. Djinbachian: None Declared, M. Zarandi-Nowroozi: None Declared, M. Taghiakbari: None Declared, D. von Renteln Grant / Research support from: Daniel von Renteln is supported by a “Fonds de Recherche du Québec Santé” (FRQS) career development award and has received research funding from ERBE, Ventage, Pendopharm, Fujifilm, and Pentax., Consultant of: Boston Scientific and Pendopharm,

Polyp Size and Shape Estimation by Using an Endoscopic Hood Information

Medical doctors identify benign or malignant colon polyps by their size and shape. Since this identification is related to whether or not resection surgery is necessary, a technology for estimating absolute size and shape from endoscopic images is required. In previous research, the method for recovering the size and shape of polyps using a blood vessel region as a reference object has been proposed. This paper proposes a method to recover the size and shape of polyps by using a cylindrical endoscopic hood as a reference object. The experimental results confirm that the proposed method can estimate reflectance factor without using blood vessel information.

Measuring polyp size using a virtual scale endoscope: a video tutorial with clinical case demonstration.

Accurate real-time endoscopic assessment of colorectal polyp size plays a key role for selecting adequate post-polypectomy surveillance intervals or when choosing appropriate polypectomy techniques [1]. While visual estimation is the most commonly used method of measurement, there is marked interobserver variability. Biopsy forceps and ruler snares can be used as references for polyp size estimation, but are limited by being external devices that lengthen the duration of the endoscopy and increase the procedural cost [2] [3].

Factors influencing endoscopic estimation of colon polyp size in a colon model.

Background/AimsColorectal polyps are removed to prevent progression to colorectal cancer. Polyp size is an important factor for risk stratification of malignant transformation. Endoscopic size estimation correlates poorly with pathological reports and several factors have been suggested to influence size estimation. We aimed to gain insight into the factors influencing endoscopic polyp size estimation.MethodsImages of polyps in an artificial model were obtained at 1, 3, and 5 cm from the colonoscope’s tip. Participants were asked to estimate the diameter and volume of each polyp. ResultsFifteen endoscopists from three large-volume centers participated in this study. With an intraclass correlation coefficient of 0.66 (95% confidence interval [CI], 0.62–0.71) for diameter and 0.56 (95% CI, 0.50–0.62) for volume. Polyp size estimated at 3 cm from the colonoscope’s tip yielded the best results. A lower distance between the tip and the polyp was associated with a larger estimated polyp size. ConclusionsCorrect endoscopic estimation of polyp size remains challenging. This finding can affect size estimation skills and future training programs for endoscopists.

Estimating colorectal polyp size with a virtual scale endoscope and visual estimation during colonoscopy: Prospective, preliminary comparison of accuracy.

The virtual scale endoscope (VSE) is a new endoscope that helps estimate the size of neoplasms in the gastrointestinal tract. We compared the accuracy of polyp size estimation by VSE with that of visual estimation. A dual center prospective study was conducted in two Japanese academic endoscopy units. Ten endoscopists (five trainees and five experts) estimated the size of 20 simulated polyps in four colon phantoms during colonoscopy by two methods: conventional visual estimation and estimation by VSE. The primary endpoint was the relative accuracy in relation to true polyp size according to visual estimation and VSE estimation during colonoscopy. The secondary endpoint was the required time (the time needed to measure in each procedure). The mean values of the primary end-point were 62.5% for visual estimation and 84.0% for VSE estimation; hence the result differed significantly (95% confidence interval 18.3-24.7; P < 0.001). The mean of required times was significantly longer for estimation by VSE (6.4 min) than that by visual estimation (2.9 min; P < 0.001). The accuracy of colorectal polyp size estimation was superior with VSE than with visual estimation during colonoscopy. In the future, VSE should be evaluated in actual clinical settings, including the time required for size estimation.

Artificial intelligence-based measurement outperforms current methods for colorectal polyp size measurement.

An accurate polyp size estimation during colonoscopy is crucial to determine the surveillance interval and predict the risk of malignant progression. However, there is a high degree of subjectivity in estimating polyp size among endoscopists in clinical practice. We aimed to assess the efficacy of a novel method that uses artificial intelligence (AI) to measure the size of colon polyps and compare it with current approaches. Using the W-Net model for vessel segmentation and based on retinal image datasets (DRIVE, STARE, CHASE-DB, and HRF) and colonoscopy images, we developed the bifurcation-to-bifurcation (BtoB) distance measuring method and applied it to endoscopic images. Measurements were compared with those obtained by eight endoscopists (four expert and four trainees). Diagnostic ability and reliability were evaluated using Lin's concordance correlation coefficients (CCCs) and Bland-Altman analyses. For both experts and trainees, visually estimated sizes of the same polyp were significantly inconsistent depending on the camera view used (P < 0.001). Bland-Altman analyses showed that there was a trend toward underestimation of the sizes of the polyps in both groups, especially for polyps larger than 10 mm. The new technique was highly accurate and reliable in measuring the size of colon polyp (CCC, 0.961; confidence interval 0.926-0.979), clearly outperforming the visual estimation and open biopsy forceps methods. The new AI measurement method improved the accuracy and reliability of polyp size measurements in colonoscopy images. Incorporating AI might be particularly important to improve the efficiency of trainees at estimating polyp size during colonoscopy.

Uncertainty meets 3D-spatial feature in colonoscopic polyp-size determination

ABSTRACT This paper presents a new 3D-spatial feature extraction from a 2D colonoscopic image for polyp-size estimation. The polyp-size estimation poses potential demands on colonoscopy, since an endoscopist’s subjective estimation is apt to result in uncertain polyp-size determination. This uncertain determination is derived from the lack of 3D-spatial information. Even though a previous work clarified that depth estimation mitigates uncertainty in binary polyp-size classification, precise estimation of 3D structure from a colonoscopic image(s) remains an unsolved challenge in medical image analysis. This work proposes a 3D-spatial feature that expresses a polyp’s precise 3D shape to mitigate uncertainty in polyp-size determination. First, we introduce an accurate depth estimation method to capture the 3D structure of a colon. Next, we integrate depth estimation and polyp localisation to extract a 3D polyp shape as a feature. Finally, we achieve polyp-size estimation by statistical learning of extracted features. The experimental results demonstrated the validity both of our depth estimation and 3D-spatial feature. Compared with deep RGB and RGB-D convolutional neural networks (CNNs), a shallow CNN with the proposed 3D-spatial feature achieved a more accurate polyp-size estimation with a mean absolute error of 1.36 mm, whereas the one of the deep CNN is 3.11 mm.

Accuracy in optical diagnosis for polyps between 5 and 15mm and its implications on surveillance. A prospective, multicenter study. (POPS study).

Polyps histology and diameter up to 1cm determine whether a patient needs a colonoscopy after 3years or less, or far ahead. Endoscopists' and pathologists' size estimations can be imprecise. Our aim was to assess endoscopist ability to correctly recommend surveillance colonoscopies for patients with polyps around the 10mm threshold, based on its endoscopic sizing and optical diagnosis by NBI. NBI-assisted diagnosis and endoscopist estimation of polyp size were compared with reference standard, considering this as the post resection polyp measurements by the nurse assistant and the pathologic results, in a prospective, multicenter, real life study, that recruited adults undergoing colonoscopy in five hospitals. By comparing the endoscopic and pathologist size estimation, with polyps' measurement after resection, and optical and histological diagnoses in patients with polyps between 5 and 15mm, sensitivity was assessed at the patient level by means of two characteristics: the presence of adenoma, and the surveillance interval. Surveillance intervals were established by the endoscopist, based on optical diagnosis, and by another gastroenterologist, grounded on the pathologic report. Determinants of accuracy were explored at the polyp level. 532 polyps were resected in 451 patients. Size estimation was more precise for the endoscopist. Endoscopist sensitivity for the presence of adenoma or carcinoma was 98.7%. Considering the presence of high-grade dysplasia or cancer, sensitivity was 82.6% for the endoscopic optical diagnosis. Sensitivity for a correct 3-year surveillance interval was 91.5%, specificity 82.3%, with a PPV of 93.2% and NPV of 78.5% for the endoscopist. 6.51% of patients would have had their follow-up colonoscopy delayed, whereas 22 (4.8%) would have it been performed earlier, had endoscopist recommendations been followed. Our study observes that NBI optical diagnosis can be recommended in routine practice to establish surveillance intervals for polyps between 5 and 15mm. NCT04232176.

Virtual scale function of gastrointestinal endoscopy for accurate polyp size estimation in real-time: a preliminary study.

.Significance: Polyp size is important for selecting the surveillance interval or treatment policy. Nevertheless, it is challenging to accurately estimate the polyp size during endoscopy. An easy and cost-effective function to assist in polyp size estimation is required.Aim: To propose a virtual scale function for endoscopy and evaluate its performance and expected accuracy.Approach: An adaptive virtual scale behavior was demonstrated. The measurement error of the virtual scale along the distance between the tip of the endoscope and the object plane was evaluated using graph paper. The accuracy of polyp size estimation by an expert endoscopist was compared with the accuracy of the biopsy forceps method using phantom images.Results: The measurement errors of the virtual scale were when the distance to the graph paper, which faced the tip of the endoscope, varied from 4 to 30 mm. The accuracy with the virtual scale was significantly higher than that obtained with biopsy forceps ( versus , ).Conclusions: The virtual scale function, which operates in real-time without any additional device, can be used to estimate polyp sizes easily and accurately with endoscopy.

Factors associated with inaccurate size estimation of colorectal polyps: A multicenter cross-sectional study.

Accurate polyp size estimation is essential in deciding the therapeutic strategy of colorectal polyps and endoscopic surveillance intervals. However, many endoscopists frequently make incorrect size estimations without being aware of their errors. This cross-sectional study aimed to clarify the characteristics of endoscopists associated with inaccurate estimation. We previously conducted a web trial involving 261 endoscopists in 51 institutions in Japan to assess their ability to estimate polyp size. Participants answered questions about polyp size using visual estimates in a test involving images of 30 polyps. Here, we investigated the relationships between inaccurate size estimation and the backgrounds of participants. The rates of overestimation and underestimation of polyp size were also compared to clarify any trends in the answers of participants with low accuracy (<50%). Multivariable logistic regression analysis revealed that the number of colonoscopic procedures in the past year was the only factor associated with a low accuracy of polyp size estimation (odds ratio 0.750, 95% confidence interval 0.609-0.925; P=0.007). Endoscopists with low accuracy had a greater tendency to overestimate polyp size (42.3% overestimation and 21.2% underestimation, P<0.001) compared with other endoscopists (16.6% overestimation and 17.9% underestimation, P=0.951). Endoscopists with limited experience of colonoscopy in the past year were more likely to make frequent errors in size estimation. Furthermore, endoscopists making inaccurate size estimations had a propensity to overestimate polyp size.

Effect of Screen Distance on Colonic Polyp Detection and Colonic Polyp Size Estimation: A Pilot Study

Background Colorectal cancer is the 3rd most common cancer in the world, with about 1.2 million new cases reported annually. It is one of the three most common causes of cancer related mortality in Europe and North America. Thus, prevention and detection are critical aspects in managing colorectal cancer. Colonoscopy remains the gold standard for screening of colorectal cancer, as it is valuable not only for detection but also prevention with polyp identification. Adenoma detection rate remains a pivotal part of a good endoscopic exam. While various factors have been known to influence it, data regarding ideal screen distance for adenoma detection remains unclear. The aim of this study was to assess the rate of polyp detection and estimate the size of diminutive (&lt;1 cm) polyps with varying screen distance from the proceduralist. Materials and Methods This was a quality improvement project carried at OSF Saint Francis Medical center where post graduate trainees and attending physicians were enrolled. A 26-inch-high resolution screen was used and placed at eye level for the endoscopist. We selected 50 high resolution slides of polyps (&lt;1 cm) intermixed with slides of normal colonic mucosa. These slides were downloaded from Orpheus Medical, a global clinical media platform and video informatics company. These were shown to each endoscopist standing either 3, 6, or 9 feet away (0.91, 1.8, or 2.7 meters) from the screen on three separate days, arranged in 3 different configurations. Both the rate of polyp detection and the sizes of polyps measured at various distances were recorded. The endoscopists were able to move +/- 10 cm (0.5 feet) from their index position to enhance their visualization and for better accommodation. The data was collected for multiple outcomes and statistical analysis was performed using odds ratio and t-test. Results Seven subjects who were either 3rd year Gastroenterology fellows or attendings were included in the study. We included 50 slides, with 33 consisting of polyps (&lt;1 cm) and others containing normal colonic mucosa. Our results showed that the number of polyps detected decreased as the distance from the screen increased. Overall polyp detection rate (PDR) was 92.18% at 3 feet (0.91 m), 87% at 6 feet (1.8m) and 77% at 9 feet (2.7m). An endoscopist positioned at 3 ft had a statistically significant higher polyp detection rate than one positioned at 9 ft with odds ratio (OR) of 3.43 (95% CI: 1.45 – 8.11, p= 0.004). The mean polyp size reported by all subjects was 2.68 mm at 3 feet, 2.57 mm at 6 feet and 2.25 mm at 9 feet. Comparison of mean polyp sizes at different distances from screen did not reveal statistically significant differences. Secondary outcomes included accuracy of polyp detection, miss rate and mean overestimation rate. The participating subjects were surveyed verbally at the end of the study to assess their comfort at various distances. They reported the highest level of comfort at 3 feet (0.91m), followed by 6 feet (1.8m). Conclusions This quality improvement study sheds light on the importance of screen distance for polyp detection, especially in case of smaller polyps &lt;1cm. Our results show that ideal screen distance for polyp detection should be close to 3 feet (0.91m) and ideally no more than 6 feet (1.8m). Similarly, our results also point out that polyp size may be overestimated if the examiner is too close to the screen and underestimated if the examiner is too far from the screen. We advocate standardization of screen distance from the endoscopist, so that the polyp size estimation is uniform across the board.

S0296 Effect of Trainee Participation on Accurate Sizing of Polyps Detected During Screening Colonoscopy

INTRODUCTION: Accurate estimation of polyp size during screening colonoscopy is an important factor in determining future surveillance intervals for colorectal cancer screening. However, the determination of polyp size is based on a subjective assessment by the endoscopist during the procedure. Studies have reported substantial discordance between endoscopic and pathology-based estimates of polyp size. Trainee participation in screening colonoscopy may lead to improvement in some quality metrics such as adenoma detection rate. It remains unclear whether the participation of GI fellows affects other procedural factors. We aim to investigate whether the participation of GI fellows at different stages of training affect accurate sizing of polyps compared to screening colonoscopies performed by attendings without fellows. METHODS: We performed a retrospective review of all patients who underwent a screening colonoscopy at our institution between January 2018 and June 2019. We included polyps resected in total and having both endoscopic estimation and pathology measurements documented. Polyps reported as fragmented on pathology review were excluded. Categorical variables were compared using Chi-Square test with a 95% confidence interval. RESULTS: A total of 895 colonoscopies were reviewed. From 950 polyps resected during the study period, 514 met the inclusion criteria and were included in the analysis, of which 43% were performed with a GI fellow. Polyp size was accurately estimated in 38.2% of diminutive polyps as compared to 18.3% of polyps ≥ 1 cm (P < 0.001). Polyp size accuracy was comparable with and without participation of a GI fellow (P = 0.56). The polyp was overestimated in 28.1% of cases with a GI fellow compared to 22.1% without a GI fellow (P = 0.127). 58% of polyps estimated ≥1 cm on endoscopy were <1 cm on pathology and this was not affected by fellow participation. In addition, there was no significant difference in polyp size accuracy between fellows at different levels of training. CONCLUSION: Inaccuracy in the appraisal of polyps is high, especially for polyps ≥1 cm and is unaffected by fellow participation regardless of training stage. While technical colonoscopy skills are emphasized and continue to improve during fellowship training, GI fellows could benefit from additional training in polyp size estimation. Using of biopsy forceps or snare to estimate polyp size may be helpful tools when learning this important aspect of polyp assessment.

S0145 Closer the Better? Impact of Screen Distance on Adenoma Detection

INTRODUCTION: Colorectal cancer is one of the most common cancers all over the world. Colonoscopy remains the gold standard for screening of colorectal cancer. Adenoma detection rate remains a pivotal part of a high quality endoscopic exam. While various factors have been known to influence it, data regarding ideal screen distance for adenoma detection remains unclear. The aim of this study was to assess the rate of polyp detection and estimating size of diminutive (<1 cm) polyps at 3, 6, and 9 feet. METHODS: This was a quality improvement project carried out at OSF Saint Francis Medical center where post graduate trainees and attending physicians were enrolled. A 26-inch-high resolution screen was used and placed at eye level for the endoscopist. Fifty high resolution slides from our digital imaging storage software (Orpheus) of polyps (<1 cm) intermixed with slides of normal colonic mucosa were included. These were shown to each endoscopist standing at 3, 6, and 9 feet on three separate days arranged in 3 different configurations. Polyp detection and sizes of polyps measured at various distances were recorded. RESULTS: Seven subjects that included 3rd year Gastroenterology fellows and attendings were included in the study. 50 slides were included, 33 slides with polyps intermixed with slides of normal colonic mucosa. Results demonstrated that the number of polyps detected decreased as the distance from the screen increased. Mean number of polyps observed at 3 feet was 33.28, at 6 feet was 30.28, while at 9 feet mean polyp detection decreased to 26.14. Similarly, we noticed the estimate of polyp size to also decrease as the distance from the screen increased. Mean polyp size reported by all subjects at 3 feet was 1.94 mm, while at 6 feet it was 1.74 mm, and at 9 feet mean estimated polyp size was 1.55 mm. The participating subjects were surveyed verbally at the end of the study. They reported the highest level of comfort at 3 feet followed by 6 feet. CONCLUSION: Our study shed light on the importance of screen distance for polyp detection especially in case of smaller polyps. Our results suggest that the ideal screen distance for polyp detection should be close to 3 feet and ideally no more than 6 feet. Similarly, polyp size estimation is influenced inversely by screen distance with increasing distance from screen equating to smaller polyp size approximation. Larger studies are needed to draw further conclusions as more concrete guidelines may lead to uniformity in outcomes.

Accuracy of estimation of polyp size at colonoscopy.

The Cancer Council posits that the size of adenomas is a more robust marker of risk than histological characteristics. The purpose of our study is to assess the accuracy of estimation of polyp size at colonoscopy amongst different levels of endoscopists and compare this with histopathological size. A retrospective review of prospectively collected data was performed. Specimens were included if they were (i) from patients aged 18 years or older, (ii) polyp obtained at colonoscopy, (iii) measured in quantitative units and (iv) the largest eligible polyp per patient. A total of 92 patients were included. Our results demonstrate that the relationship between the histological size of a polyp and an endoscopist's estimate depended upon seniority level (P = 0.001). Senior consultants tended to overestimate lesion size (P < 0.001), fellows/junior consultants tended to underestimate size (P = 0.010), whilst registrars' estimates demonstrated no systematic difference from histological size (P = 0.518). The ratio of a senior consultant's estimate of polyp size to histological size was on average 74% with their estimates ranging from 31% to 173%. The corresponding estimates are 123% (32-470%) for fellows/junior consultants and 107% (35-334%) for registrars. Our study demonstrates that senior consultants are more precise with more junior endoscopists having a great degree of variability in their practice. It is evident that there is a relationship between proceduralist experience and polyp size estimation. It is, therefore, important to consider the ways in which we can mitigate this learning curve and continue to develop technology to improve our accuracy.

Short educational video to improve the accuracy of colorectal polyp size estimation: Multicenter prospective study.

Accurate polyp size estimation is necessary for appropriate management of colorectal polyps. Polyp size is often determined by subjective visual estimation in clinical situations; however, it is inaccurate, especially for beginner endoscopists. We aimed to clarify the usefulness of our short training video, available on the Internet, for accurate polyp size estimation. We conducted a multicenter prospective controlled study in Japan. After completing a pretest composed of near and far images of 30 polyps, participants received the educational video lecture (<10min long). The educational content included the knowledge of strategies based on polyp size and criteria for size estimation including the endoscopic equipment size and videos of polyps in vivo. After onemonth, the participants undertook a posttest. The primary outcome was a change in the accuracy of polyp size visual estimation between the pretest and posttest in beginners. Participants including 111 beginners, 52 intermediates, and 97 experts from 51 institutions completed both tests. Accuracy of polyp size estimation in the beginners showed a significant increase after the video lecture [54.1% (51.3-57.0%) to 59.0% (56.5-61.5%), P=0.003]. Multivariable logistic regression analysis showed that the category of beginners and a low score on pretest (P=0.020 and <0.001, respectively) were the factors that contributed to an increase of ≥10% in the accuracy. Our educational video led to an improvement in polyp size estimation in beginners. Furthermore, this video may be useful for non-beginners with insufficient polyp size estimation accuracy.

Sizing of Polyp Illustrations Differs by Endoscopists’ Gender and Improves With a Measurement Reference

Colorectal cancer surveillance intervals by colonoscopy are based on the size and number of polyps removed. Evidence suggests endoscopists' estimation of polyp size is often inaccurate, but the differences by endoscopists' characteristics have not been reported. This study assesses endoscopists' accuracy of measuring polyp illustrations, the effect of endoscopists' characteristics, and the impact of having a measurement reference. Endoscopists in a community-based, gastroenterology practice estimated the size of several illustrations in a booklet. One month later, they estimated the size of illustrations with a provided measurement reference. Accuracy was defined as no difference between estimated and actual value. Endoscopists were accurate in sizing only 15% of the time, with a tendency toward undersizing. Female endoscopists, those with less than 10 years in practice and those with lower adenoma detection rates, were more likely to undersize polyps. Accuracy of measuring the polyp illustrations increased to 50% (p < .01) with the measurement reference. The improvement in accuracy was seen across endoscopists' demographic groups. Endoscopists had poor accuracy of measuring polyp illustrations. Almost universally, endoscopists tended to undersize the polyp illustrations. Accuracy improved significantly with the use of a polyp-measuring guide, particularly when considering important surveillance thresholds of 5 and 10 mm.

Reproducibility and accuracy of visual estimation of polyp size in large colorectal polyps

Background: Previous studies indicate that visual size estimation (in situ) of polyp size tends to differ from postfixation measurements, which effects allocation to surveillance intervals. Little is known about interobserver variation of in-situ measurements of large polyps. The primary objective was to assess interobserver variation of in situ measurements of large colorectal polyps. Secondary objectives were the agreement of in situ measurements with postfixation measurements, and the agreement on detection of ≥20 mm polyps between these measurements.Material and methods: Interobserver variability of in situ polyp size measurements was assessed between a diagnostic colonoscopy and the secondary therapeutic colonoscopy by dedicated endoscopists, in patients that were referred for an advanced polypectomy. After excision pre- and postfixation polyp sizes were measured with a ruler in three dimensions.Results: A total of 40 patients, with 45 polyps, were included in the study. The average difference between the two in situ measurements was 2.4 mm (95% confidence interval (CI): −0.4–5.2). The differences between the first in situ, second in situ and pre-fixation measurement in comparison to postfixation measurements were 1.8 mm (95% CI: −1.2–4.9), 0.1 mm (95% CI: −1.5–1.8) and 1.0 mm (95% CI: −0.2–2.2). Cohen’s Kappa on detection of ≥20 mm polyps in agreement with postfixation measurements was 0.65 in the primary and 0.88 in the secondary in situ measurements.Conclusion: This study shows a variation between in situ size measurements of large polyps. Improvements in daily clinical routines can be made by using an instrument to compare polyp size with and refraining from rounding sizes up or down. A randomized controlled trial assessing which instruments should be used for in-situ measurements of large polyps is warranted, in order to optimize size measurements of large colorectal polyps.

Capsule endoscopy vs. colonoscopy vs. histopathology in colorectal cancer screening: matched analyses of polyp size, morphology, and location estimates.

Colon capsule endoscopy (CCE) is considered a potential alternative to optical colonoscopy (OC) for colorectal cancer screening. However, the accuracy of CCE in polyp size and morphology estimation is unknown. A fully paired study was performed (2015-2016), where 255 participants from the Danish national screening program had CCE, OC, and histopathology (HP) of all detected polyps. We developed a new algorithm to match CCE and OC polyps, based on objective measures of similarity between polyps. We performed paired comparisons of size, morphology and location of CCE, and OC- and HP-matched polyps. We used cross-validation to develop a model able to predict HP polyp size, based on CCE. CCE overestimated size assessed by HP (by 4.3mm; 95%CI 3.3-5.2mm) and OC (by 2.7mm; 95%CI 1.4-3.9mm). Polyps were more likely to being assessed as "pedunculated" and less likely to being assessed as "flat" in CCE, compared to OC (p < 0.0001). Our model could predict HP polyp size ≥ 6mm, solely using CCE-assessed size, location, and morphology as model inputs, with a sensitivity = 0.93 (95%CI 0.66-1.00) and specificity = 0.50 (95%CI 0.32-0.68). If CCE is to be used as a screening test, it is essential: (1) to translate CCE polyp estimations into histopathologic polyp sizes and (2) to consider that, compared to OC, CCE has a higher tendency to assess polyps as pedunculated and a lower tendency to assess them as flat. Clinicaltrials.gov No. NCT02303756.