Polyp Measurement Research Articles

Comparison of the Size Measurement of Gallbladder Polyps by Three Different Radiologists in Abdominal Ultrasonography.

There is little information regarding the size measurement differences in gallbladder (GB) polyps performed by different radiologists on abdominal ultrasonography (US). To reveal the differences in GB polyp size measurements performed by different radiologists on abdominal US. From June to September 2022, the maximum diameter of 228 GB polyps was measured twice on abdominal US by one of three radiologists (a third-year radiology resident [reader A], a radiologist with 7 years of experience in abdominal US [reader B], and an abdominal radiologist with 8 years of experience in abdominal US [reader C]). Intra-reader agreements for polyp size measurements were assessed by intraclass correlation coefficient (ICC). A Bland-Altman plot was used to visualize the differences between the first and second size measurements in each reader. Reader A, reader B, and reader C evaluated 65, 77, and 86 polyps, respectively. The mean size of measured 228 GB polyps was 5.0 ± 1.9 mm. Except for the case where reader A showed moderate intra-reader agreement (0.726) for polyps with size ≤ 5 mm, all readers showed an overall high intra-reader reliability (reader A, ICC = 0.859; reader B, ICC = 0.947, reader C, ICC = 0.948), indicative of good and excellent intra-reader agreements. The 95% limit of agreement of reader A, B, and C was 1.9 mm of the mean in all three readers. GB polyp size measurement on abdominal US showed good or excellent intra-reader agreements. However, size changes of approximately less than 1.9 mm should be interpreted carefully because these may be within the measurement error.

CT colonography has advantages over colonoscopy for size measurement of colorectal polyps

PurposeThe aim of this study was to compare the accuracy of colonoscopy (CS) and CT colonography (CTC) in the measurement of colorectal polyps using pathological size as a reference.Materials and methodsThe analysis included 61 colorectal polyps in 28 patients who underwent preoperative CTC at our institution. All polyps were endoscopically resected. Polyp sizes were measured by CS and CTC. Endoscopic polyp size was extracted from endoscopy records written by one of two endoscopists (A with 11 and B with 6 years of endoscopic experience, respectively), who estimated the size visually/categorically without any measuring devices. After matching the location, the polyp size was measured on CTC using manual three-dimensional (3D) measurement on a workstation. The sizes of resected polyps were also measured after pathological inspection. Differences of the polyp size between CTC and histology, and between CS and histology were compared using paired t tests. Differences in measurement between the two endoscopists were also analyzed.ResultsThe mean diameters of polyps measured using CS, CTC, and pathology were 10.5 mm, 9.2 mm, and 8.4 mm, respectively. There was a significant correlation between CS and pathology, as well as between CTC and pathology (both P < 0.0001). The correlation coefficient for CS (r = 0.86) was lower than that for CTC (r = 0.96). The correlations between CS and pathology for endoscopists A and B were 0.90 and 0.89, respectively.ConclusionMeasurements of polyp size using CTC were closer to the pathological measurements compared to those by CS, which exhibited greater variability. This suggests that CTC may be more suitable for polyp size measurements in the clinical setting if patients undergo CTC concurrently with colonoscopy.

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.

Artificial Intelligence Applied to Colonoscopy: Is It Time to Take a Step Forward?

Growing evidence indicates that artificial intelligence (AI) applied to medicine is here to stay. In gastroenterology, AI computer vision applications have been stated as a research priority. The two main AI system categories are computer-aided polyp detection (CADe) and computer-assisted diagnosis (CADx). However, other fields of expansion are those related to colonoscopy quality, such as methods to objectively assess colon cleansing during the colonoscopy, as well as devices to automatically predict and improve bowel cleansing before the examination, predict deep submucosal invasion, obtain a reliable measurement of colorectal polyps and accurately locate colorectal lesions in the colon. Although growing evidence indicates that AI systems could improve some of these quality metrics, there are concerns regarding cost-effectiveness, and large and multicentric randomized studies with strong outcomes, such as post-colonoscopy colorectal cancer incidence and mortality, are lacking. The integration of all these tasks into one quality-improvement device could facilitate the incorporation of AI systems in clinical practice. In this manuscript, the current status of the role of AI in colonoscopy is reviewed, as well as its current applications, drawbacks and areas for improvement.

A123 COMPARING SIZE MEASUREMENT OF SIMULATED COLORECTAL POLYPS WHEN USING A NOVEL VIRTUAL SCALE ENDOSCOPE, ENDOSCOPIC RULER OR FORCEPS: A BLINDED RANDOMIZED TRIAL

Abstract Background Accurate polyp size measurement is important for guideline conforming choice of polypectomy techniques and subsequent surveillance interval assignments. Some endoscopic tools (forceps or endoscopic rulers [ER]) exist to help with visual size estimation. A virtual scale endoscope (VSE) has been developed that allows superimposing a virtual measurement scale during live endoscopies. Purpose Our aim was to evaluate the performance of VSE when compared to ER and forceps-based measurement. Method We conducted a randomized trial to evaluate the relative accuracy of size measurement of simulated colorectal polyps when using: VSE, ER, and forceps. Six endoscopists performed 60 measurements randomized at a 1:1:1 ratio using each method. Primary outcome was relative accuracy in polyp size measurement. Secondary outcomes included misclassification of sizes at the 5, 10, and 20mm thresholds. Result(s) A total of 360 measurements were performed. The relative accuracy of biopsy forceps, ER, and VSE was 78.9% (95%CI=76.2-81.5), 78.4% (95%CI=76.0-80.8), and 82.7% (95%CI=80.8-84.8). VSE had significantly higher accuracy compared to biopsy forceps (p=0.02) and ER (p=0.006). VSE misclassified a lower percentage of polyps &amp;gt;5mm as ≤5mm (9.4%) compared to forceps (15.7%) and ER (20.9%). VSE misclassified a lower percentage of ≥20mm polyps as &amp;lt;20mm (8.3%) compared with forceps (66.7%) and ER (75.0%). 25.6%, 25.5%, and 22.5% of polyps ≥10mm were misclassified as &amp;lt;10mm with ER, forceps, and VSE, respectively. Conclusion(s) VSE had significantly higher relative accuracy in measuring polyps compared to ER or forceps assisted measurement. VSE improves correct classification of polyps at clinically important size thresholds. Please acknowledge all funding agencies by checking the applicable boxes below None Disclosure of Interest R. Djinbachian: None Declared, M. Taghiakbari: None Declared, C. Haumesser: None Declared, M. Zarandi-Nowroozi: None Declared, M. Abou-Khalil: None Declared, S. Sidani: None Declared, J. Liu: None Declared, B. Panzini: 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,

Comparing size measurement of colorectal polyps using a novel virtual scale endoscope, endoscopic ruler or forceps: A preclinical randomized trial.

Background and study aims Accurate polyp size measurement is important for guideline conforming choice of polypectomy techniques and subsequent surveillance interval assignments. Some endoscopic tools (biopsy forceps [BF] or endoscopic rulers [ER]) exist to help with visual size estimation. A virtual scale endoscope (VSE) has been developed that allows superimposing a virtual measurement scale during live endoscopies. Our aim was to evaluate the performance of VSE when compared to ER and BF-based measurement. Methods We conducted a preclinical randomized trial to evaluate the relative accuracy of size measurement of simulated colorectal polyps when using: VSE, ER, and BF. Six endoscopists performed 60 measurements randomized at a 1:1:1 ratio using each method. Primary outcome was relative accuracy in polyp size measurement. Secondary outcomes included misclassification of sizes at the 5-, 10-, and 20-mm thresholds. Results A total of 360 measurements were performed. The relative accuracy of BF, ER, and VSE was 78.9 % (95 %CI = 76.2-81.5), 78.4 % (95 %CI = 76.0-80.8), and 82.7 % (95 %CI = 80.8-84.8). VSE had significantly higher accuracy compared to BF ( P = 0.02) and ER ( P = 0.006). VSE misclassified a lower percentage of polyps > 5 mm as ≤ 5 mm (9.4 %) compared to BF (15.7 %) and ER (20.9 %). VSE misclassified a lower percentage of ≥ 20 mm polyps as < 20 mm (8.3 %) compared with BF (66.7 %) and ER (75.0 %). Of polyps ≥10mm, 25.6 %, 25.5 %, and 22.5 % were misclassified as <10 mm with ER, BF, and VSE, respectively. Conclusions VSE had significantly higher relative accuracy in measuring polyps compared to ER or BF assisted measurement. VSE improves correct classification of polyps at clinically important size thresholds.

Computed tomographic colonography for symptomatic patients: the diminutive polyp dilemma.

Computed tomographic colonography (CTC) is sensitive to polyp detection but is considered inaccurate for measuring diminutive polyps (<6 mm), with divergence between CTC and either colonoscopic or histopathological polyp measurements. Reporting diminutive polyps remains debatable. This study aims to compare outcomes of symptomatic patients with diminutive versus borderline polyps on CTC and to thereby examine the potential implication of reporting diminutive polyps. A single-centre retrospective study of symptomatic patients who underwent CTC from October 2016 through September 2018 was performed. After excluding CTC demonstrating cancer, no polyps, or polyps >6 mm, cases were categorized as either 'diminutive' (largest polyp <6 mm), or 'borderline' (largest polyp=6 mm). The outcome measures were progression to endoscopy, surgery, procedure-related morbidity, dysplasia and malignancy. A total of 308 cases (211 diminutive and 97 borderline) were analysed. The groups were similar (P > 0.05) in mean age (73 vs. 74 years), female proportion (57% vs. 49%), endoscopy-related morbidity (6% vs. 7%) and CTC-related morbidity (0 vs. 1%). Most patients (64%) underwent endoscopy, which was more common in the borderline vs. the diminutive group (76% vs. 59%; P=0.003). Dysplasia was more common in the borderline vs. the diminutive group (69% vs. 48%; P=0.003). No malignancies were diagnosed, and no patients proceeded to surgery. Reporting diminutive polyps on CTC for symptomatic patients frequently leads to endoscopy, which often reveals dysplasia but rarely malignancy. This raises the question of how referring clinicians can best counsel and manage symptomatic patients with diminutive polyps on CTC, by considering the balance between utilitarianism and deontology.

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.

Usefulness of a Colonoscopy Cap with an External Grid for the Measurement of Small-Sized Colorectal Polyps: A Prospective Randomized Trial.

Accurate measurement of polyp size during colonoscopy is crucial. The usefulness of cap-assisted colonoscopy and external grid application on monitor (gCAP) was evaluated for polyp size measurement in this 3-year, single-center, single-blind, randomized trial. Using the endoscopic forceps width as reference, the discrepancy percent (DP), error rate (ER), and measurement time were compared between gCAP and visual estimation (VE) after randomization. ER was calculated within a 20% and 33% limit. From the 111 patients, 280 polyps were measured. The mean polyp sizes were 4.0 ± 1.7 mm and 4.2 ± 1.8 mm with gCAP and VE, respectively (p = 0.368). Compared with that by the forceps method, DP was significantly lower in the gCAP group than in the VE group. Moreover, ER was significantly lower in the gCAP group within its preset limit. The measurement time was 4 s longer in the gCAP group than in the VE group (8.2 ± 4.8 s vs. 4.2 ± 1.5 s; p < 0.001). However, the forceps method lasted 28 s longer than the others. On subgroup analysis by size, gCAP was more accurate for polyp size ≥ 5 mm. The gCAP method was more accurate for polyp size measurement than VE, especially for polyps ≥ 5 mm, and was more convenient than the forceps method.

Accurate measurement of colorectal polyps using computer-aided analysis.

As we know, the majority of colorectal cancers are thought to evolve from colorectal adenomas. In this study, we explored the use of Computer-aided diagnosis (CAD) in the detection of colorectal polyps and the estimation of their sizes, which is important for the diagnosis and management of colorectal cancer. As the distance between colonoscopy and lesion increases, magnification tends to decrease. Therefore, the size of colorectal polyps can be calculated by taking into account the captured image and the shooting distance. In this study, the fitting curve of the magnification of electronic colonoscopy was obtained by simulating intestinal tract and polyps in vitro. Then, the distance was artificially controlled in the endoscopic operation, and the image was taken at a preset distance. The CAD system was then trained on the overall shape of colorectal polyps. Image segmentation was employed to accurately identify colorectal polyps. Finally, on the basis of the magnification factor, the real value of polyps was predicted from the shooting distance and the segmentation image size. The CAD system can automatically calculate the range of colorectal polyps and calculate the true size of the colorectal polyps according to the magnification of the corresponding distance. In this study, we developed a method of accurately estimating the size of colorectal polyps. This approach is compatible with many devices, which would expand its range of applications. This method has the potential for application in other areas of clinical diagnosis.

AIUM Practice Parameter for the Performance of Sonohysterography and Hysterosalpingo-Contrast Sonography.

AIUM Practice Parameter for the Performance of Sonohysterography and Hysterosalpingo-Contrast Sonography.

Intraobserver and interobserver reliability in sonographic size measurements of gallbladder polyps.

To evaluate the intraobserver and interobserver reliability of gallbladder polyp measurements using transabdominal US and the factors that affect reliability. From November 2017 to February 2018, two radiologists measured the maximum diameter of 91 gallbladder polyps using transabdominal US. Intraobserver and interobserver agreement were determined using 95% Bland-Altman limits of agreement and intraclass correlation coefficients (ICCs). The effects of image settings, polyp location, and polyp size were evaluated by comparing ICCs using z tests. The intraobserver agreement rates were 0.960 (95% confidence interval [CI], 0.939-0.973) for observer 1 and 0.962 (95% CI, 0.943-0.975) for observer 2. The ICCs between the two observers were 0.963 (95% CI, 0.926-0.979) for the first measurement and 0.973 (95% CI, 0.950-0.984) for the second measurement. The 95% limits of agreement on repeated measurements were 22.3-25.2% of the mean, and those between the two observers were 25.5-34.2% of the mean. ICCs for large polyps (≥ 5mm) were significantly higher than those for small polyps (< 5mm). There were no significant differences in the ICCs between image settings and polyp location. Polyp size measurements using transabdominal US are highly repeatable and reproducible. Polyp size significantly affects the reliability of measurement. Diameter changes of approximately less than 25% may fall within the measurement error; this should be considered while interpreting the change in size during follow-up US, especially for small polyps. • Gallbladder polyp size measurement using transabdominal US is highly repeatable and reproducible. • Diameter changes of approximately less than 25% should be interpreted carefully, especially in small polyps.

Domain-Based Analysis of Colon Polyp in CT Colonography Using Image-Processing Techniques

Background:The purpose of the research was to improve the polyp detection accuracy in CT Colonography (CTC) through effective colon segmentation, removal of tagged fecal matter through Electronic Cleansing (EC), and measuring the smaller polyps. Methods:An improved method of boundary-based semi-automatic colon segmentation with the knowledge of colon distension, an adaptive multistep method for the virtual cleansing of segmented colon based on the knowledge of Hounsfield Units, and an automated method of smaller polyp measurement using skeletonization technique have been implemented. Results:The techniques were evaluated on 40 CTC dataset. The segmentation method was able to delineate the colon wall accurately. The submerged colonic structures were preserved without soft tissue erosion, pseudo enhanced voxels were corrected, and the air-contrast layer was removed without losing the adjacent tissues. The smaller polyp of size less than <10mm was detected correctly. The results were statistically validated qualitatively and quantitatively. Segmented colons were validated through volumetric overlap computation, and accuracy of 95.826±0.6854% was achieved. In polyp measurement, the paired t-test method was applied to compare the difference with ground truth and at α=5%, t=0.9937 and p=0.098 was achieved. The statistical values of TPR=90%, TNR=82.3% and accuracy=88.31% were achieved. Conclusion:An automated system of polyp measurement has been developed starting from colon segmentation to improve the existing CTC solutions. The analysis of domain-based approach of polyp has given good results. A prototype software, which can be used as a low-cost polyp diagnosis tool, has been developed.

Interobserver Variation of Colonic Polyp Measurement at Computed Tomography Colonography

BackgroundThe concept of “advanced polyps” is well accepted and is defined as polyps ≥10 mm and/or those having a villous component and/or demonstrating areas of dysplasia. Of these parameters, computed tomography colonography (CTC) can only document size. The accepted management of CTC-detected “advanced polyps” is to recommend excision if feasible, whereas the management of “intermediate” (6–9 mm) polyps is more controversial, and interval surveillance may be acceptable. Therefore, distinction between 6-9 mm and ≥10 mm is important. MethodsDatasets containing 26 polyps originally reported as between 8-12 mm in diameter were reviewed independently by 4 CTC-accredited radiologists. Observers tabulated the largest measurement for each polyp on axial, coronal, sagittal, and endoluminal views at lung-window settings. These measurements were also compared to those determined by the computer-aided detection (CAD) software. ResultsThe interobserver reliability intra-class correlation coefficient (ICC) for sagittal projection was 0.80 (“excellent” category of Hosmer and Lemeshow [2004]), 0.71 for axial (“acceptable”), 0.69 for coronal, and 0.41 for endoluminal (“unacceptable”). The largest of sagittal/axial/coronal measurement gave the best reliability with the smallest variance (ICC = 0.80; 95% CI 0.67–0.89). For 8 of 26 polyps, at least one radiologist's measurement placed the polyp in a different category compared to a colleague. For the majority of the polyps, the CAD significantly overestimated the readings compared to the largest of the manual measurements with an average difference of 1.6 mm (P < .0001 for sagittal/axial/coronal). This resulted in 33% of polyps falling into a different category—10% were lower and 23% were higher (P < .034). ConclusionIt is apparent that around the cutoff point of 10 mm between “advanced” and “intermediate” polyps, interobserver performance is variable.

Polyp Sizing Poster Improves Polyp Measurement but not Adenoma Detection Rates by Endoscopists in a Large Community Practice

Accurate sizing of polyps and improving adenoma detection rates (ADR) are important goals for high-quality colonoscopy. Surveillance intervals are based on accurate sizing of polyps. There are no clinical tools or interventions that have demonstrated improvement in both these metrics. We investigated the efficacy of a simple, low-cost intervention, based on use of polyp sizing posters to improve measurements of polyps and increase ADRs during colonoscopy at a large gastroenterology community practice. We collected data on polyp measurements and ADRs by 62 gastrointestinal endoscopists at a large multi-site community practice, from January to November 2015 (baseline). In a prospective study, endoscopy units were given a polyp sizing poster to be hung above the endoscopy video monitor (intervention group, for 33 endoscopists) or for usual care (control group, for 29 endoscopists) in December 2015, and we collected data on polyp measurements and ADRs over the following 6 months (January-June 2016). We compared the endoscopists' assessment of polyp size and their ADRs before and after the intervention using a mixed effects proportional odds model, controlling for provider age and sex and patient and indication for colonoscopy. Our primary aim was to assess the effect of the snare and forcep-based polyp sizing poster on change in polyp size. The secondary aim was to study the effect of the polyp sizing poster on ADR. Our final analysis included 85,657 polyps from 38,307 colonoscopies. The characteristics of patients who underwent colonoscopy were similar between the control and intervention group (median age, 61 years; 48.1% female; 53.9% undergoing screening; 31.4% undergoing surveillance; 14.7% receiving a diagnostic colonoscopy). The endoscopists' median age was 51 years (range, 33-76) years, and 15 were women (24.2%). During the baseline period, male endoscopists were more likely to size polyps larger than measurements made by female endoscopists (odds ratio [OR], 1.78; 95% CI, 1.24-2.55; P= .002). For the intervention group, 78.6% of polyps were assigned to the 1-5 mm category during the baseline period compared to 76.0% after the intervention, whereas the proportions of polyps assigned to the 6-10 mm category increased from 16.9% during the baseline period to 18.3% after the intervention. In the control group, 78.9% of polyps were assigned to the 1-5 mm category during the baseline period and 78.3% were assigned to this group in the prospective study; 16.5% of polyps were assigned to the 6-10 mm during the baseline period and 17.5% were assigned to this group in the prospective study. The interaction between intervention group and timing (baseline vs after the intervention) was statistically significant, with an increase in the odds of larger polyp sizing after the intervention (OR, 1.15; 95% CI, 1.08-1.23; P < .001). The odds of larger polyp measurement during the intervention period, compared to the baseline period, increased for male endoscopists (OR, 1.17; 95% CI, 1.09-1.27; P < .001) and female endoscopists (OR, 1.18; 95% CI, 1.01-1.36; P= .04), as well as for younger physicians (<50 years; OR, 1.32; 95% CI, 1.20-1.46; P< .001) but not for older physicians (>50 years; OR, 0.96; 95% CI, 0.88-1.06; P= .44). The average ADR for male and female endoscopists combined during the baseline period was 42%. The change in ADR from the baseline vs the post-intervention was an increase of 2.6% in the control group compared to 5.7% in the intervention group (P= .39) CONCLUSIONS: Placement of a polyp sizing poster above the endoscopy video monitor increases the odds of polyps being assigned a larger size but does not affect ADRs.

CT colonography: size reduction of submerged colorectal polyps due to electronic cleansing and CT-window settings

ObjectivesTo assess whether electronic cleansing (EC) of tagged residue and different computed tomography (CT) windows influence the size of colorectal polyps in CT colonography (CTC).MethodsA database of 894 colonoscopy-validated CTC datasets of a low-prevalence cohort was retrospectively reviewed to identify patients with polyps ≥6 mm that were entirely submerged in tagged residue. Ten radiologists independently measured the largest diameter of each polyp, two-dimensionally, before and after EC in colon, bone, and soft-tissue-windows, in randomised order. Differences in size and polyp count before and after EC were calculated for size categories ≥6 mm and ≥10 mm. Statistical testing involved 95% confidence interval, intraclass correlation and mixed-model ANOVA.ResultsThirty-seven patients with 48 polyps were included. Mean polyp size before EC was 9.8 mm in colon, 9.9 mm in bone and 8.2 mm in soft-tissue windows. After EC, the mean polyp size decreased significantly to 9.4 mm in colon, 9.1 mm in bone and 7.1 mm in soft-tissue windows. Compared to unsubtracted colon windows, EC, performed in colon, bone and soft-tissue windows, led to a shift of 6 (12,5%), 10 (20.8%) and 25 (52.1%) polyps ≥6 mm into the next smaller size category, thus affecting patient risk stratification.ConclusionsEC and narrow CT windows significantly reduce the size of polyps submerged in tagged residue. Polyp measurements should be performed in unsubtracted colon windows.Key Points• EC significantly reduces the size of polyps submerged in tagged residue.• Abdominal CT-window settings significantly underestimate 2D sizes of submerged polyps.• Size reduction in EC is significantly greater in narrow than wide windows.• Underestimation of polyp size due to EC may lead to inadequate treatment.• Polyp measurements should be performed in unsubtracted images using a colon window.

A structured light laser probe for gastrointestinal polyp size measurement: a preliminary comparative study.

Background and study aims Polyp size measurement is an important diagnostic step during gastrointestinal endoscopy, and is mainly performed by visual inspection. However, lack of depth perception and objective reference points are acknowledged factors contributing to measurement errors in polyp size. In this paper, we describe the proof-of-concept of a polyp measurement device based on structured light technology for future endoscopes. Patients and methods Measurement accuracy, time, user confidence, and satisfaction were evaluated for polyp size assessment by (a) visual inspection, (b) open biopsy forceps of known size, (c) ruled snare, and (d) structured light probe, for a total of 392 independent polyp measurements in ex vivo porcine stomachs. Results Visual assessment resulted in a median estimation error of 2.2 mm, IQR = 2.6 mm. The proposed probe can reduce the error to 1.5 mm, IQR = 1.67 mm ( P = 0.002, 95 %CI) and its performance was found to be statistically similar to using forceps for reference ( P = 0.81, 95 %CI) or ruled snare ( P = 0.99, 95 %CI), while not occluding the tool channel. Timing performance with the probe was measured to be on average 54.75 seconds per polyp. This was significantly slower than visual assessment (20.7 seconds per polyp, P = 0.005, 95 %CI) but not significantly different from using a snare (68.5 seconds per polyp, P = 0.73, 95 %CI). However, the probe’s timing performance was partly due to lens cleaning problems in our preliminary design. Reported average satisfaction on a 0 – 10 range was highest for the proposed probe (7.92), visual assessment (7.01), and reference forceps (7.82), while significantly lower for snare users with a score of 4.42 ( P = 0.035, 95 %CI). Conclusions The common practice of visual assessment of polyp size was found to be significantly less accurate than tool-based assessment, but easy to carry out. The proposed technology offers an accuracy on par with using a reference tool or ruled snare with the same satisfaction levels of visual assessment and without occluding the tool channel. Further study will improve the design to reduce the operating time by integrating the probe within the scope tip.

Measurement Bias of Polyp Size at Colonoscopy: What Is the Big Deal?

International post-polypectomy surveillance guidelines and optical diagnoses depend on accurate determination of polyp size at colonoscopy. Study 1 was a retrospective, population-based study of all colonoscopies performed within the state-funded health system in Brisbane over a 12-month-period: 12,597 electronic colonoscopy reports were individually analyzed to obtain the frequencies of polyp measurements. Study 2 introduced a novel, proof-of-concept measurement device to reduce measurement bias. Fifty endoscopists used 3 measurement strategies (M1: no visual cues; M2: a snare tip; M3: a novel 1x1 mm grid) to evaluate 120 endoscopic images of 40 simulated polyps (1 to 10 mm) presented in random order. In study 1, 65 endoscopists individually sized 8,591 from 18,276 detected polyps (47%). Most polyps were 5 mm in size, and endoscopists were likely biased toward measurements in 5-mm increments. In study 2, the exact accuracy of polyp measurement was significantly different between methods: 20%, 33%, and 90% (p < 0.001). Endoscopists had limited insight to their accuracy because >70% of measurements were made with high confidence. Using M3, endoscopists were 99.8% accurate for high-confidence classifications of polyps into clinically relevant size categories. Endoscopists are inaccurate in measuring polyps at colonoscopy. Improvements in measurement accuracy are urgently needed.

Measurement Bias of Polyp Size at Colonoscopy.

The success of current and proposed strategies to reduce colorectal cancer (CRC) incidence and mortality rates are fundamentally based on measurement accuracy. The aim of this study was to evaluate the densities of colorectal polyps individually measured at colonoscopy and whether measurement bias is a systemic phenomenon among colonoscopists. A population-wide, observational study. All hospitals of the government-funded health system in Brisbane, Australia. Our study investigated measurement bias at colonoscopy through systematic analysis of 8,591 individual polyp measurements recorded from 12,597 colonoscopies. All colonoscopies performed over a 12-month period between December 1, 2014, and November 30, 2015, were included. A total of 12,597 electronic colonoscopy reports were individually reviewed, hospital-by-hospital, and 8,591 individual size measurements from 18,276 detected polyps (47%) were obtained. Our study is limited because the true size of unresected polyps was unknown. We chose not to compare pathologic and histologic sizes as resection specimens sent to pathologists are morphologically different and are measured differently to the pre-resection polyp images seen by endoscopists. Colonoscopists may be inaccurate in the measurement of polyp size and appear biased towards and against certain size measurements. These findings cast doubt over the validity of international post-polypectomy surveillance guidelines and the safety of optical diagnosis as a potential management paradigm for diminutive colorectal polyps. They also question the historical accuracy of polyp size data and risk estimates upon which these strategies were based.

Measurement of smaller colon polyp in CT colonography images using morphological image processing.

Automated measurement of the size and shape of colon polyps is one of the challenges in Computed tomography colonography (CTC). The objective of this retrospective study was to improve the sensitivity and specificity of smaller polyp measurement in CTC using image processing techniques. A domain knowledge-based method has been implemented with hybrid method of colon segmentation, morphological image processing operators for detecting the colonic structures, and the decision-making system for delineating the smaller polyp-based on a priori knowledge. The method was applied on 45 CTC dataset. The key finding was that the smaller polyps were accurately measured. In addition to 6-9mm range, polyps of even <5mm were also detected. The results were validated qualitatively and quantitatively using both 2D MPR and 3D view. Implementation was done on a high-performance computer with parallel processing. It takes [Formula: see text]min for measuring the smaller polyp in a dataset of 500 CTC images. With this method, [Formula: see text] and [Formula: see text] were achieved. The domain-based approach with morphological image processing has given good results. The smaller polyps were measured accurately which helps in making right clinical decisions. Qualitatively and quantitatively the results were acceptable when compared to the ground truth at [Formula: see text].