Endoscopic measurement of lesion size: improved accuracy with image processing

Usefulness of virtual scale endoscope for early gastrointestinal lesions

Objectives

For early gastrointestinal lesions, size is an important factor in the selection of treatment. Virtual scale endoscope (VSE) is a newly developed endoscope that can measure size more accurately than visual measurement. This study aimed to investigate whether VSE measurement is accurate for early gastrointestinal lesions of various sizes and morphologies.

Methods

This study prospectively enrolled patients with early gastrointestinal lesions ≤20 mm in size visually. Lesion sizes were measured in the gastrointestinal tract visually, on endoscopic resection specimens with VSE, and finally on endoscopic resection specimens using a ruler. The primary endpoint was the normalized difference (ND) of VSE measurement. The secondary endpoints were the ND of visual measurement and the variation between NDs of VSE and visual measurements. ND was calculated as (100 × [measured size - true size] / true size) (%). True size was defined as size measured using a ruler.

Results

This study included 60 lesions from April 2022 to December 2022, with 20 each in the esophagus, stomach, and colon. The lesion size was 14.0 ± 6.3 mm (mean ± standard deviation). Morphologies were protruded, slightly elevated, and flat or slightly depressed type in 8, 24, and 28 lesions, respectively. The primary endpoint was 0.3 ± 8.8%. In the secondary endpoints, the ND of visual measurement was -1.7 ± 29.3%, and the variability was significantly smaller in the ND of VSE measurement than in that of visual measurement (p < 0.001, F-test).

Conclusions

VSE measurement is accurate for early gastrointestinal lesions of various sizes and morphologies.

Exploratory investigation of virtual lesions in gastrointestinal endoscopy using a novel phase-shift method for three-dimensional shape measurement

Accurate measurement of the size of lesions or distances between any two points during endoscopic examination of the gastrointestinal tract is difficult owing to the fisheye lens used in endoscopy. To overcome this issue, we developed a phase-shift method to measure three-dimensional (3D) data on a curved surface, which we present herein. Our system allows the creation of 3D shapes on a curved surface by the phase-shift method using a stripe pattern projected from a small projecting device to an object. For evaluation, 88 measurement points were inserted in porcine stomach tissue, attached to a half-pipe jig, with an inner radius of 21 mm. The accuracy and precision of the measurement data for our shape measurement system were compared with the data obtained using an Olympus STM6 measurement microscope. The accuracy of the path length of a simulated protruded lesion was evaluated using a plaster model of the curved stomach and graph paper. The difference in height measures between the measurement microscope and measurement system data was 0.24 mm for the 88 measurement points on the curved surface of the porcine stomach. The error in the path length measurement for a lesion on an underlying curved surface was <1% for a 10-mm lesion. The software was developed for the automated calculation of the major and minor diameters of each lesion. The accuracy of our measurement system could improve the accuracy of determining the size of lesions, whether protruded or depressed, regardless of the curvature of the underlying surface.

Guidelines for endoscopic submucosal dissection and endoscopic mucosal resection for early gastric cancer (second edition)

In response to the rapid and wide acceptance and use of endoscopic treatments for early gastric cancer, the Japan Gastroenterological Endoscopy Society, in collaboration with the Japanese Gastric Cancer Association, produced "Guidelines for Endoscopic Submucosal Dissection and Endoscopic Mucosal Resection for Early Gastric Cancer" in 2014, as a set of basic guidelines in accordance with the principles of evidence-based medicine. At the time, a number of statements had to be established by consensus (the lowest evidence level), as evidence levels remained low for many specific areas in this field. However, in recent years, the number of well-designed clinical studies has been increasing. Based on new findings, we have issued the revised second edition of the above guidelines that cover the present state of knowledge. These guidelines are divided into the following seven categories: indications, preoperative diagnosis, techniques, evaluation of curability, complications, long-term postoperative surveillance, and histology.

Guidelines for endoscopic diagnosis of early gastric cancer

The Japan Gastroenterological Endoscopy Society developed the Guideline for Endoscopic Diagnosis of Early Gastric Cancer based on scientific methods. Endoscopy for the diagnosis of early gastric cancer has been acknowledged as a useful and highly precise examination, and its use has become increasingly more common in recent years. However, the level of evidence in this field is low, and it is often necessary to determine recommendations based on expert consensus only. This clinical practice guideline consists of the following sections to provide the current guideline: [I] Risk stratification of gastric cancer before endoscopic examination, [II] Detection of early gastric cancer, [III] Qualitative diagnosis of early gastric cancer, [IV] Diagnosis to choose the therapeutic strategy for gastric cancer, [V] Risk stratification after endoscopic examination, and [VI] Surveillance of early gastric cancer.

Deep Endoscopic Visual Measurements

Robotic endoscopic systems offer a minimally invasive approach to the examination of internal body structures, and their application is rapidly extending to cover the increasing needs for accurate therapeutic interventions. In this context, it is essential for such systems to be able to perform measurements, such as measuring the distance traveled by a wireless capsule endoscope, so as to determine the location of a lesion in the gastrointestinal tract, or to measure the size of lesions for diagnostic purposes. In this paper, we investigate the feasibility of performing contactless measurements using a computer vision approach based on neural networks. The proposed system integrates a deep convolutional image registration approach and a multilayer feed-forward neural network into a novel architecture. The main advantage of this system, with respect to the state-of-the-art ones, is that it is more generic in the sense that it is 1) unconstrained by specific models, 2) more robust to nonrigid deformations, and 3) adaptable to most of the endoscopic systems and environment, while enabling measurements of enhanced accuracy. The performance of this system is evaluated under ex vivo conditions using a phantom experimental model and a robotically assisted test bench. The results obtained promise a wider applicability and impact in endoscopy in the era of big data.

Integrated Multipoint-Laser Endoscopic Airway Measurements by Transoral Approach

Objectives. Optical and technical characteristics usually do not allow objective endoscopic distance measurements. So far no standardized method for endoscopic distance measurement is available. The aim of this study was to evaluate the feasibility and accuracy of transoral airway measurements with a multipoint-laser endoscope. Methods. The semirigid endoscope includes a multipoint laser measurement system that projects 49 laser points (wavelength 639 nm, power < 5 mW) into the optical axis of the endoscopic view. Distances, areas, and depths can be measured in real-time. Transoral endoscopic airway measurements were performed on nine human cadavers, which were correlated with CT measurements. Results. The preliminary experiment showed an optimum distance between the endoscope tip and the object of 5 to 6 cm. There was a mean measurement error of 3.26% ± 2.53%. A Spearman correlation coefficient of 0.95 (p = 0.01) was calculated for the laryngeal measurements and of 0.93 (p < 0.01) for the tracheal measurements compared to the CT. Using the Bland-Altman-Plot, the 95% limits of agreement for the laryngeal measurements were satisfactory: −0.76 and 0.93. Conclusions. Integrated multipoint-laser endoscopic measurement is a promising technical supplement, with potential use in diagnostic endoscopy and transoral endoscopic surgery in daily practice.

Guidelines for endoscopic submucosal dissection and endoscopic mucosal resection for early gastric cancer

In response to the rapid and wide acceptance and use of endoscopic treatments for early gastric cancer, the Japan Gastroenterological Endoscopy Society (JGES), in collaboration with the Japanese Gastric Cancer Association (JGCA), has produced 'Guidelines for ESD and EMR for Early Gastric Cancer', as a set of basic guidelines in accordance with the principles of evidence-based medicine. These Guidelines cover the present state of knowledge and are divided into the following seven categories: Indications, Preoperative diagnosis, Techniques, Evaluation of curability, Complications, Long-term postoperative surveillance, and Histology. Twenty-three statements were finally accepted as guidelines, and the majority of these were obtained from descriptive studies with lower evidence levels. A number of statements had to be created by consensus (the lowest evidence level), as evidence levels remain low for many specific areas in this field.

Endoscopic overestimation of colorectal polyp size

BACKGROUND AND AIMS

Polyp size ≥ 1 cm triggers more frequent colonoscopic surveillance, yet size is typically based on subjective endoscopic estimates. We sought to compare contemporary assessments of polyp size by endoscopic estimation and pathology measurement.

METHODS

Colonoscopy and pathology reports were reviewed from the 2012 medical records at a large institution. Only polyps resected in toto with both endoscopic estimates and pathology measurements were included. Pathology measurements were considered the criterion standard. Factors affecting endoscopic miscall rates were assessed by multivariate analyses.

RESULTS

From 6067 polyps resected, both endoscopic and pathology sizes were available on 1528. Distribution of polyp size appraised by endoscopy but not by pathology revealed modal clustering, particularly around 1 cm. Among 99 polyps endoscopically called 1 cm, 72% were <1 cm on pathology. Of all 222 polyps estimated as ≥ 1 cm on endoscopy, 46% were <1 cm on pathology; of 1306 polyps estimated as <1 cm, 3.9% were ≥ 1 cm on pathology. By histology, 39% of adenomatous, 59% of sessile serrated, and 73% of hyperplastic polyps were overcalled; P = .008. By configuration, 34% of pedunculated, 49% of sessile, and 61% of flat polyps were overcalled; P = .014. Endoscopic overestimation was more common in women (54%) than in men (40%) (P = .03) and with proximal (56%) than distal (40%) sites; P = .02. Miscall rates were unaffected by endoscopist covariates.

CONCLUSIONS

Substantial discordance exists between endoscopic and pathology-based assessments of polyp size. Almost half of polyps called advanced on endoscopic estimates of size ≥ 1 cm fell below this threshold on actual pathology measurements.

Benefits of radial distortion correction in arthroscopic surgery: a first experimental study on a knee model

BACKGROUND

Lens probes used in arthroscopy typically have a small diameter and wide field-of-view. This introduces strong radial distortion (RD) into the image, ultimately affecting the surgeon's hand-eye coordination. This study evaluates potential benefits of using distortion-free images in arthroscopic surgery.

METHODS

Distortion-free images were obtained using RDFixer™ software (Perceive3D, SA) to remove RD in the input video stream. Twelve orthopedic residents performed an arthroscopic task (loose body removal) in a dry-knee model using video with and without distortion. Residents were questioned about image quality, and surgical performance was rated using an adapted Global Rating Scale.

RESULTS

A statistically significant improvement of all parameters was observed with distortion-free images. Residents perceived distortion-free images as providing a wider field-of-view and a better notion of relative depth and distance.

CONCLUSION

RD correction improved the surgical performance of residents, potentially decreasing their learning curve. Future work will study whether the benefits are observable in experienced surgeons. Copyright © 2014 John Wiley & Sons, Ltd.

Optical design and evaluation of a 4 mm cost-effective ultra-high-definition arthroscope

High definition and magnification rigid endoscope plays an important role in modern minimally invasive medical surgery and diagnosis. In this paper, we present the design and evaluation methods of a high definition rigid endoscope, specifically an arthroscope, with a large depth of field (DOF). The incident heights and exit angles of the sampled rays on the relay lens are controlled during the optimization process to ensure an effective field view (70°) and a normal ray path within the limited lens diameter of 2.7 mm. The lens is set up as a multi-configuration system with two extreme and one middle object distances to cover a large DOF. As a result, an entrance pupil of 0.3 mm is achieved for the first time, to bring the theoretical resolution to 23.1 lps/mm in the object space at a working distance of 20 mm, with the wavelength of 0.532 um. The modulation transfer function (MTF) curves approach diffraction limit, and the values are all higher than 0.3 at 160 line pairs/mm (lps/mm) in the image space. Meanwhile, stray light caused by total internal reflection on the inner wall of the rod lenses and the objective lens is eliminated. The measured resolution in the object space at a 20 mm working distance is 22.3 lps/mm, and test results show that other performance characteristics also fulfill design requirements. The relay lenses are designed with only one type of the spacer and two types of lenses to greatly reduce the fabrication and assembly cost. The design method has important research and application values for lens systems used in modern minimally invasive medical surgery and industrial non-destructive testing area.

Clinical study using novel endoscopic system for measuring size of gastrointestinal lesion

AIM: To verify the performance of a lesion size measurement system through a clinical study.

METHODS: Our proposed system, which consists of a conventional endoscope, an optical device, an optical probe, and a personal computer, generates a grid scale to measure the lesion size from an endoscopic image. The width of the grid scale is constantly adjusted according to the distance between the tip of the endoscope and lesion because the lesion size on an endoscopic image changes according to the distance. The shape of the grid scale was corrected to match the distortion of the endoscopic image. The distance was calculated using the amount of laser light reflected from the lesion through an optical probe inserted into the instrument channel of the endoscope. The endoscopist can thus measure the lesion size without contact by comparing the lesion with the size of the grid scale on the endoscopic image. (1) A basic test was performed to verify the relationship between the measurement error e_M and the tilt angle of the endoscope; and (2) The sizes of three colon polyps were measured using our system during endoscopy. These sizes were immediately measured by scale after their removal.

RESULTS: There was no error at α = 0°. In addition, the values of e_M (mean ± SD) were 0.24 ± 0.11 mm (α = 10°), 0.90 ± 0.58 mm (α = 20°) and 2.31 ± 1.41 mm (α = 30°). According to these results, our system has been confirmed to measure accurately when the tilt angle is less than 20°. The measurement error was approximately 1 mm in the clinical study. Therefore, it was concluded that our proposed measurement system was also effective in clinical examinations.

CONCLUSION: By combining simple optical equipment with a conventional endoscope, a quick and accurate system for measuring lesion size was established.

Endoscopic estimation of tumor size in early gastric cancer

BACKGROUND

Although the accurate estimation of tumor size is essential for proper patient selection for endoscopic resection in early gastric cancer (EGC), no study has been conducted to date on tumor size estimation. We aimed to evaluate the accuracy of endoscopic visual estimation of tumor size of EGC.

METHODS

In 508 EGC patients that underwent endoscopic resection, endoscopic visual estimations were performed retrospectively by independent two endoscopists using still images. Data were compared with pathologic measurements as gold standard. Inter-observer agreement was determined using the Bland-Altman method and intra-class correlation coefficients (ICC). Measurement discrepancies were presented as differences between measurements.

RESULTS

The ICC between the two endoscopists was 0.915 (95 % CI 0.900-0.928). Mean endoscopic estimates for both endoscopists were significantly lower than mean pathologic measurements (1.50 and 1.67 vs. 1.80 cm, P < 0.001). Absolute differences between average endoscopic estimates and pathologic measurements were found to be acceptable in most cases: an absolute difference of <0.4 cm was found for 80 % (404/508) of cases. Bland-Altman plot showed that 94 % of cases lay within the 95 % limits of agreement. Measurement discrepancy was proportional to tumor size and increased for an undifferentiated histology.

CONCLUSIONS

Endoscopic visual estimations were found to show reliable agreement with pathologic measurement in EGC patients undergoing endoscopic resection, together with good inter-observer agreement. Further prospective study is needed to confirm the validity of this method.

Detection and characterization of early gastric cancer for curative endoscopic submucosal dissection

Because endoscopic submucosal dissection (ESD) of gastric cancer can only be curative if the cancer is detected at an early stage and a precise preoperative diagnosis is made, we reviewed the detection and characterization of early gastric cancer (EGC) using both conventional endoscopy with white-light imaging (C-WLI) and image-enhanced endoscopy (chromoendoscopy [CE] and magnifying narrow-band imaging [M-NBI]). Systematic screening of the stomach by C-WLI after ideal preparation of the patient is important for detecting a mucosal lesion, which can then be characterized using CE. However, a limitation of C-WLI with CE is the diagnosis of flat or small gastric cancers. To overcome this, M-NBI together with a comprehensive diagnostic system, termed the 'vessel plus surface classification' system, was developed and has proven very useful. Preoperative assessment for ESD involves determining: (i) histological type; (ii) size; (iii) depth of invasion; (iv) presence or absence of associated ulceration; and (v) horizontal extent of the cancer. A limitation of endoscopic diagnosis using M-NBI is the histologically undifferentiated type of carcinoma, in which case the biopsy specimen is used to make a histopathological diagnosis.

Videoendoscopic measurement of food bolus formation for quantitative evaluation of masticatory function

PURPOSE

In the field of prosthodontics, many methods for evaluating the masticatory function involve ejection of the food bolus from the mouth. In addition, these methods could not evaluate mastication and swallowing function comprehensively. The present study aimed to quantitatively evaluate masticatory functions during a series of masticatory and swallowing movements by using videoendoscopy.

METHODS

Subjects are ten healthy dentulous adults without dysphagia. The test foods used were 2-colored (green and white) molded rice and uirou (rice cake). The test foods were consumed under the restriction on the number of mastication (10, 15, 20, and 30), and under the instruction to "chew normally" or "chew well". The masticatory function was evaluated by observing the food bolus in the oropharynx with a videoendoscope. The bolus formation index (BFI), in terms of the degree of mixing of the green and white parts, was quantitatively determined using an image measurement software.

RESULTS

The BFI of the rice and uirou increased significantly with increase in the number of mastication times (p<0.01). A significantly correlation coefficient was observed between the BFI and the number of mastication (0.84 for rice and 0.89 for uirou). The BFI obtained by "chewing well" was significantly higher than that obtained by "chewing normally" (p<0.01).

CONCLUSIONS

The results of this study confirm that the endoscopic measurement of food bolus formation by mastication in terms of the color tones of 2-colored test foods enables quantitative evaluation of the masticatory function during a series of masticatory and swallowing movements.

Accuracy of the size estimation in wireless capsule endoscopy: calibrating the M2A PillCam (with video)

OBJECTIVE

To describe the accuracy and precision of a size estimation in wireless capsule endoscopy (WCE) and to develop a simple device that facilitates learning of an exact size estimation in WCE.

DESIGN

A prospective study with an animal model. Seventy-five medical students were compared with 21 physicians not performing WCEs and 21 experts actively performing WCEs.

INTERVENTIONS

Video sequences were recorded with a PillCam wireless endoscope in a porcine small-bowel model after implantation of "lesions" of defined sizes. Volunteers estimated the diameter of these "lesions" with and without the use of a calibrator device, which was a picture from a black-and-white grid taken with the PillCam in direct contact with the transparent dome.

RESULTS

The students overestimated the diameters of the lesions by 26%. The physicians and experts underestimated the diameters by 32% and 31%, respectively. With the help of the calibrator device, the students underestimated the diameters by 15%. Physicians underestimated the diameters by 21%, whereas experts still underestimated the diameters by 35%. The interindividual log-scale standard deviation (SD) of the estimated diameters from the true diameter decreased during training in all groups, whereas intraindividual SDs decreased in students and increased in experts.

LIMITATION

An animal model.

CONCLUSIONS

All investigators agree better when a calibrating device was offered. Experts who performed more than 400 WCEs tended to be more precise.

Initial endoscopic description of esophageal squamous cell carcinomas

INTRODUCTION

The aim of this study was to evaluate initial endoscopic practices at diagnosis of esophageal squamous cell carcinoma in comparison with current recommendations. We wanted to develop a standard model for the endoscopy report which could be used in routine practice.

PATIENTS AND METHODS

From January 2000 to December 2002, 122 patients were hospitalized for esophageal squamous cell carcinoma. The initial endoscopic reports were reviewed retrospectively and compared with a model report established on the basis of current recommendations.

RESULTS

One hundred and nineteen reports were re-examined. The principal reason for performing the endoscopic examination was dysphagia in 73.9% of patients. Tumor measurements (height, upper and lower extremities) were recorded in 51.2%, 79% and 41% of reports, respectively. 14.4% of the analyzed reports concerned endoscopic procedures which were performed after a first endoscopic examination because the initial report provided an imprecise tumor description. Tissue samples taken during the initial endoscopy allowed a pathological diagnosis in 94.2% of patients. Lugol staining was performed in 2.5% of procedures.

CONCLUSION

Insufficiently rigorous reporting compromises the reliability of initial upper digestive endoscopic procedures. Application of a standardized model for routine practice would favor more complete reports, starting with the first procedure.

A new method for objective identification and measurement of airway lumen in paediatric flexible videobronchoscopy

BACKGROUND

Accurate measurements of airway and lesion dimensions are important to the developmental progress of paediatric bronchoscopy. The malacia disorders are an important cause of respiratory morbidity in children, but no methods are currently available to measure these lesions or the airway lumen accurately. A new measurement technique is described here.

METHODS

The magnification power of a paediatric videobronchoscope was defined and a simple and user friendly computer based program (Image J) was used to develop an objective technique (colour histogram mode technique, CHMT) for measurement of the airway lumen.

RESULTS

In vivo intra-observer and inter-observer repeatability coefficients for repeated area measurements from 28 images using the Bland-Altman method were 0.9 mm2 and 1.6 mm2, respectively. The average intraclass correlation coefficient for repeated measurements of area was 0.93. In vitro validation measurements using a 2 mm diameter tube resolved radii measurements to within 0.1 mm (coefficient of variability 8%). An "acceptable result" was defined in 92% of 734 images completed with the CHMT alone and 8% with its modification. The success rate for two of three images being within 10% of each other's area was 100%. Measurements of cricoid cross sectional areas from 116 patients compared with expected airway areas for age derived from endotracheal tube sizes were comparable.

CONCLUSIONS

The CHMT method of identifying and measuring airway dimensions is objective, accurate, and versatile and, as such, is important to the future development of flexible videobronchoscopy.

Quantification of the magnification and distortion effects of a pediatric flexible video-bronchoscope

BACKGROUND

Flexible video bronchoscopes, in particular the Olympus BF Type 3C160, are commonly used in pediatric respiratory medicine. There is no data on the magnification and distortion effects of these bronchoscopes yet important clinical decisions are made from the images. The aim of this study was to systematically describe the magnification and distortion of flexible bronchoscope images taken at various distances from the object.

METHODS

Using images of known objects and processing these by digital video and computer programs both magnification and distortion scales were derived.

RESULTS

Magnification changes as a linear function between 100 mm (x1) and 10 mm (x9.55) and then as an exponential function between 10 mm and 3 mm (x40) from the object. Magnification depends on the axis of orientation of the object to the optic axis or geometrical axis of the bronchoscope. Magnification also varies across the field of view with the central magnification being 39% greater than at the periphery of the field of view at 15 mm from the object. However, in the paediatric situation the diameter of the orifices is usually less than 10 mm and thus this limits the exposure to these peripheral limits of magnification reduction. Intraclass correlations for measurements and repeatability studies between instruments are very high, r = 0.96. Distortion occurs as both barrel and geometric types but both types are heterogeneous across the field of view. Distortion of geometric type ranges up to 30% at 3 mm from the object but may be as low as 5% depending on the position of the object in relation to the optic axis.

CONCLUSION

We conclude that the optimal working distance range is between 40 and 10 mm from the object. However the clinician should be cognisant of both variations in magnification and distortion in clinical judgements.

Quantitative Assessment of Tracheal Collapsibility in Infants with Tracheomalacia

Infantile tracheomalacia is a potentially life-threatening disease requiring prolonged artificial respiratory support. Diagnosis and management of this disease may be further improved by establishing a suitable objective and quantitative assessment protocol for tracheal collapsibility. It is our hypothesis that tracheal collapsibility can be represented by the relationship between intraluminal pressure and the cross-sectional area of the trachea. To test this hypothesis, static pressure/area relationships of the trachea were obtained from anesthetized and paralyzed infants, who were diagnosed as having tracheomalacia by endoscopic observation. These relationships were fitted on a linear regression model, followed by calculation of the estimated closing pressure. The tracheal closing pressure ranged from -8 to -27 cm H(2)O, suggesting easy collapsibility of the trachea during crying or coughing and noncollapsibility during the spontaneous respiratory cycle, which coincided with the infants' symptoms. It is our conclusion that tracheal collapsibility of infants with tracheomalacia can be quantitatively assessed by the static pressure/area relationship of the trachea obtained under general anesthesia and paralysis.

Inter- and intra-observer variability in the measurement of length at endoscopy: Implications for the measurement of Barrett's esophagus

BACKGROUND

Endoscopic measurements are frequently used to determine the length of Barrett's epithelium. Decreases in measured length also are used to assess response to pharmacotherapy. The aim of this study was to determine the accuracy of the endoscopic measurement of length under standardized conditions.

METHODS

A life-size model of the esophagus was built by using an opaque polyvinyl tube. Transparent plastic inserts designed to resemble Barrett's epithelium were created. Ten different insert lengths were randomly studied. Trained endoscopists and fellows in training blinded to the lengths of the inserts performed measurements twice in random order.

RESULTS

A total of 240 measurements were made by 12 endoscopists. The mean difference (1 standard deviation) between the measured and correct length was 1.10 (1.7) cm. Overestimation of the length occurred in 47% and underestimation in 37%. The kappa statistic for the first and second measurement (within 0.5 cm) performed by the same individual (intra-observer) was 0.40, suggesting only fair agreement. There was considerable variability between endoscopists.

CONCLUSIONS

Accurate measurement of length at endoscopy is difficult even under ideal conditions. Intra-observer agreement is fair, but results obtained by different endoscopists are widely divergent. Small improvements in the length of Barrett's epithelium observed in some clinical trials could be because of chance instead of therapeutic effect.

Validation of virtual colonoscopy in the detection of colorectal polyps and masses: rationale for proper study design

BACKGROUND

Colorectal cancer, the second-leading cause of cancer-related mortality, is a preventable malignancy in many cases. Despite the availability of several screening modalities, compliance with screening recommendations remains unacceptably low. Virtual colonoscopy is a novel, minimally-invasive technique with the potential to increase colorectal cancer screening rates, but its effectiveness must first be validated. Published studies comparing virtual colonoscopy to conventional colonoscopy have reported varying results. These discrepancies may be attributed to differences in bowel preparation and scanning techniques, as well as errors in endoscopic lesion measurement, endoscopic colonic segmental localization, and the ability of conventional colonoscopy to actually detect lesions. These methodological issues can affect scientific results and ultimately affect the public's perception of this emerging technique.

AIM

The goal of this report is to expose existing methodological shortcomings and propose solutions incorporated in this study design. This article describes the rationale, study design, and outcome definitions of a single-center, blinded, direct comparative trial aiming at assessing the ability of virtual colonoscopy to detect colorectal polyps and masses relative to the criterion standard, conventional colonoscopy. DESIGN FEATURES: Bowel preparation was standardized using oral sodium phosphate lavage, orally administered iodinated contrast, and controlled colonic insufflation. Segmental unblinding allowed a second-look when results were discrepant and polyp matching was performed using an algorithm based on segmental localization and lesion size determination.

CONCLUSIONS

This methodology could be applied to other studies assessing the accuracy of virtual colonoscopy in order to have uniformity of results.

A new stereoscopic endoscopy system: accurate 3-dimensional measurement in vitro and in vivo with distortion-correction function

BACKGROUND

The purpose of this study was to evaluate the accuracy and reproducibility of measurements obtained with a new 3-dimensional stereoscopic endoscopy system in vitro and in vivo.

METHODS

The system includes an electronic stereoscopic endoscope and a personal computer. After correction of barrel distortion by an image-processing technique, 3-dimensional data are computed with triangulation. Initially, graph paper and models of gastric lesions, both elevated and depressed, were used as objects. For evaluating accuracy and reproducibility, the absolute error (/E/) and the coefficient of variation (CV) were calculated: /E/ = average value of absolute value (measured value minus sign true value)/true value. Then, the sizes of 50 gastric lesions were measured by 2 endoscopists, one experienced and the other inexperienced, and the findings were compared with measurements made radiographically.

RESULTS

The maximum for /E/ and for the CV for the distance on the graph paper were, respectively, 5.6% and 7.0%. The /E/ and CV for the diameter and for the height of the elevated model were, respectively, 5.9% and 5.7% for the former and, respectively, 16.8% and 16.5% for the latter. The /E/ and CV for the area of the depressed model were, respectively, 9.0% and 1.6%. The correlation coefficients between the sizes of lesions measured by stereoscopic endoscopy and radiographically were 0.91: 99% CI [0.81, 1.00], and 0.98: 99% CI [0.85, 1.00], respectively, for the experienced and inexperienced endoscopists.

CONCLUSIONS

The new stereoscopic endoscopy system is useful for measuring gastric lesion size in clinical practice.

Quantitative analysis of the velopharyngeal sphincter function during speech

OBJECTIVE

This study reports a new concept for quantitative analysis of velopharyngeal function using electromagnetic articulography and simultaneous transoral video endoscopy.

PARTICIPANTS

The velopharyngeal closure mechanism was studied in 16 healthy German subjects during production of the vowel-consonant-vowel sequences /afa/ and /apa/.

DESIGN

Velar movements in the sagittal and vertical direction were measured by electromagnetic articulography (EMA) while video endoscopy was used for recording in the sagittal and transverse directions.

MAIN OUTCOME MEASURE

A transverse sagittal quotient (TSQ) was defined after the measurement of sagittal and transverse diameters of the velopharyngeal port (VPP) in the video-endoscopic pictures on the basis of a frame-by-frame analysis.

RESULTS

The sphincter morphology was objectively determined with the TSQ base value. A terminal sphincter deformation (TSD) for closure phases of articulatory movement was revealed by a qualitative shape analysis of the TSQ curves.

CONCLUSIONS

The assessment of the TSQ of velopharyngeal port diameters and the TSD in the terminal closure period lead to a new dynamic interpretation of velopharyngeal closure patterns.

Quantitative endoscopy: initial accuracy measurements

The geometric optics of an endoscope can be used to determine the absolute size of an object in an endoscopic field without knowing the actual distance from the object. This study explores the accuracy of a technique that estimates absolute object size from endoscopic images. Quantitative endoscopy involves calibrating a rigid endoscope to produce size estimates from 2 images taken with a known traveled distance between the images. The heights of 12 samples, ranging in size from 0.78 to 11.80 mm, were estimated with this calibrated endoscope. Backup distances of 5 mm and 10 mm were used for comparison. The mean percent error for all estimated measurements when compared with the actual object sizes was 1.12%. The mean errors for 5-mm and 10-mm backup distances were 0.76% and 1.65%, respectively. The mean errors for objects <2 mm and > or =2 mm were 0.94% and 1.18%, respectively. Quantitative endoscopy estimates endoscopic image size to within 5% of the actual object size. This method remains promising for quantitatively evaluating object size from endoscopic images. It does not require knowledge of the absolute distance of the endoscope from the object, rather, only the distance traveled by the endoscope between images.

Induction and maintenance of gastric ulceration in horses in simulated race training

Gastric ulceration is a prevalent condition of racehorses. A number of models of gastric ulceration have been described, but none mimic the conditions of a horse in training. The objectives of this study were to determine whether gastric ulcers could be induced and maintained in a group of horses in simulated race training. In addition, serum cortisol was measured on a weekly basis to investigate the possibility that stress may be important in the pathogenesis of gastric ulceration. Thirty horses used in the trial were fed Bermuda grass hay and 6 kg of a concentrate diet, and exercised 6 days/week at speed over a distance of 1.6-2.4 km. Serum was collected and gastroendoscopic examinations performed on a weekly basis for the duration of the trial. All horses developed moderate to severe ulceration, and ulcers were maintained for the 56 day period of the trial. Only one horse had signs of abdominal discomfort, which resolved with minimal symptomatic treatment and without the use of anti-ulcer medications. Serum cortisol remained within reference ranges for the duration of the trial. Although there was some variation between the weekly examinations, serum cortisol concentrations were decreased from values obtained at the start of the trial. In this study ulcers developed without the administration of nonsteroidal anti-inflammatory agents or withholding of feed. This model provides a method to study the condition, and to investigate the effects of medications on the healing of ulcers in racehorses.

Mathematical model of fluorescence endoscopic image formation

We present a mathematical model that describes the spatial distribution of photons in fluorescence endoscopic images, resulting in expressions for image signal-to-noise ratio and resolution. This model was applied to quantitative analysis of fluorescence images collected from human colonic mucosa with a fiber-optic and an electronic endoscope. It provides a tool for the design of fluorescence endoscopic imaging systems and for extraction of quantitative information about image features. The results apply generally to endoscopic imaging of remote structures in biological and industrial settings, in which light of weak intensity such as fluorescence as well as reflected white light is used.

Quantitative bronchoscopic assessment of airway collapsibility in newborn lamb tracheae

To date, quantitative studies of the inherent characteristics of the developing airway wall have required excision of an airway segment or surgical creation of an isolated segment. We hypothesized that airway wall characteristics, at various collapsing pressures, and attendant changes in stiffness after smooth muscle stimulation could be quantitated bronchoscopically from airway pressure-area relationships. Neonatal lamb tracheal segments (n = 12) were suspended over hollow mounts, in a buffer-filled chamber, and subjected to a range (0 to -4.0 kPa) of pressures to determine wall stiffness under collapsing forces before and after stimulation of the trachealis with methacholine. Luminal images were recorded through a 3.6-mm flexible bronchoscope under the same conditions, subsequently corrected for distortion, and a cross-sectional area was quantitated. Both pressure-volume and pressure-area relationships detected significant changes in airway wall stiffness after methacholine administration (p < 0.002), and the magnitude of change was similar between methods. These data suggest that quantitative flexible bronchoscopy can be used clinically in the intact airway to assess wall stiffness.

The pathologic measurement of polyp size is preferable to the endoscopic estimate

BACKGROUND

There is no standardized technique to measure polyp size. Estimation of polyp size at endoscopy is difficult. Polyp size measurement by pathologists would seem to be an accurate alternative, but tissue fixation may alter polyp size. To evaluate methods of determining polyp size, we compared endoscopists' estimates and pathologists' measurements with measurements made by an independent examiner.

METHODS

Polyps were measured by an independent investigator before and after formalin fixation. The investigator's measurement before fixation (the "gold standard") was compared with the endoscopists' estimates and the pathologists' measurements.

RESULTS

Ten endoscopists removed 61 polyps with a snare in 33 patients: 82% were adenomatous and 72% were pedunculated. Mean size was 0.85 +/- 0.6 cm (SD) (range: 0.3 to 3.6 cm, 26% > or = 1 cm). Polyps remained in formalin for a mean of 239 minutes (46 to 1164 minutes). Polyps neither consistently shrank nor enlarged in formalin (maximum change +/- 0.2 cm, r = 0.99 [p < 0.001]). Interobserver agreement between pathologists' and the investigator's post-formalin measurements showed that 55 of 57 polyps (97%) were within +/- 0.3 cm. Endoscopists inaccurately estimated 11 of 56 polyps (20%) (> 0.3 cm difference from the independent examiner). Polyp size was underestimated in three instances (range 0.5 to 0.9 cm) and overestimated in eight (range 0.4 to 0.8 cm). In 5 of 11 instances (46%), this inaccuracy altered polyp size classification across the 1 cm threshold. Results were not dependent on endoscopist, histology, or polyp location.

CONCLUSIONS

(1) Polyp size is not significantly affected by formalin fixation; 2) Endoscopists' estimates of polyp size are often unreliable; and, when possible, (3) Pathologists' measurements of polyp size should be used in clinical trials and in clinical practice.

Cold snare excision is a safe method for diminutive colorectal polyps

Cold snare excision (CSE) has proved to be an effective method for the destruction of diminutive polyps of the colon and rectum. We investigated the correlation between polyp size and bleeding time at the resected end after CSE, and also an appropriate measuring method using CSE. Eighty patients with single polyps were examined. Each polyp was identified as being 5 mm in diameter or smaller using the open-biopsy forceps technique (OBFT). The size of the polyp was calculated using our measuring system (SMS). Of the polyps identified as being 5 mm in diameter or less using OBFT, 15% were 6 mm or more using the SMS. CSE was performed for each polyp, and the time taken for the hemostasis (bleeding time of the CSE; BTCSE) was determined. In seventy-seven polyps that were 6 mm or smaller in SMS, a correlation was noted between SMS and BTCSE. In three polyps that were 7 mm or more by SMS, hemostasis took 10 min or more after CSE, and required electrocoagulation. These results suggest that CSE is a safe method for the removal of polyps determined to be 6 mm in diameter or smaller using the SMS.

New 3-dimensional mapping device for cystoscopy

PURPOSE

The crucial shortcoming of cystoscopy is that it does not measure the size of observed objects, and so we developed a new device that adds measurement capability to the cystoscope.

MATERIALS AND METHODS

The device consists of 5 arms linked to each other by freely bending joints. Before use 1 end of the arm is fixed to the examination table and the other end is linked to the eyepiece of the cystoscope. While linked to the arms, the cystoscope can move freely in any direction. Each joint carries an accurate sensor to measure its angle. The angle measurements are calculated collectively to obtain the 3-dimensional coordinates at the tip of the cystoscope. The tip of the cystoscope can be moved to the other side of the objects to be measured, which provides a pair of 3-dimensional coordinates, because the distance between them can be calculated.

RESULTS

We could calculate the distance between the bladder neck and each ureteral orifice, and the angle of the bladder neck formed with the left and right orifices in clinical cases. By continuous measurement of the location of the bladder neck and the ureteral orifice, it was clearly demonstrated that the distance between them increased as the bladder filled.

CONCLUSIONS

Our computer assisted, 3-dimensional mapping device can replace unreliable cystoscopic assessment with more reliable numerical values. New diagnostic criteria based on the exact numerical values can be established with the use of this device.

The difference in colon polyp size before and after removal

BACKGROUND

Accurate knowledge of polyp size is important in assessing cancer risk in both clinical studies and individual patients. We sought to determine if a difference exists between the endoscopic estimation of colon polyp size and the actual measurement after removal.

METHODS

We measured polyps in a systematic fashion. Using open biopsy forceps as a guide, the largest diameter of 31 pedunculated polyps was estimated endoscopically. The polyp was then removed by snare polypectomy and directly measured by a technician who was blinded to the endoscopic estimate. Each polyp was also measured after formalin fixation by a pathologist who was blinded to previous measurements.

RESULTS

There was a significant difference between the endoscopic estimates and the postpolypectomy measurements. Endoscopic estimates on average were 1.6 mm greater than the postpolypectomy measurements (p< 0.05), representing an 18% difference. Twenty-three of the 31 (74%) endoscopic estimates were larger than the postpolypectomy measurements. There was not a significant difference between the postpolypectomy and postfixation measurements.

CONCLUSIONS

The size of polyps measured endoscopically is significantly larger on average than postpolypectomy measurements. This is most likely due to factors involved in the removal of the in vivo polyp.

Endoscopic estimation of size: improved accuracy by directed teaching

Previous studies have demonstrated the inaccuracy of endoscopic estimation of size. Although several devices have been developed to help improve estimation of size, none are convenient for clinical use. We have designed and evaluated a clinical teaching protocol to aid endoscopists in better estimating size. Thirteen "endoscopists" with varying levels of experience (none, less than 1 year, more than 1 year) estimated the size of six steel ball bearings placed into a model colon and viewed with a videoendoscope. They were then taught to compensate for optic distortion and retested immediately after teaching and again 1 month later. The mean error of estimation decreased from 28% before teaching to 8% after teaching (p < .05) and rose to 12% 1 month later (p < .05). Although the indices of mean error decreased immediately after teaching in all groups, only those individuals with less than 1 year of endoscopic experience retained the improvement 1 month after teaching. We conclude that endoscopists can be taught how to compensate for the optic distortion encountered during endoscopy. This teaching is most effective if performed early in the training program.