What is the most reliable imaging modality for small colonic polyp characterization? Study of white-light, autofluorescence, and narrow-band imaging.

BACKGROUND AND STUDY AIMS: In vivo optical diagnosis of small colorectal polyps has potential clinical and cost advantages, but requires accuracy and high interobserver agreement for clinically acceptability. We aimed to assess interobserver variability and diagnostic performance of endoscopic imaging modalities in characterizing small colonic polyps. METHODS: High quality still images of 80 polyps < 1 cm were recorded using white-light endoscopy (WLE), autofluorescence imaging (AFI) and narrow-band imaging with and without magnification (NBI and NBImag). All images were assessed for quality, prediction of polyp histology, and vascular pattern intensity (with NBI) by nine experienced colonoscopists (four experts in advanced imaging) from five UK centers. Interobserver agreement (kappa statistic), sensitivity, specificity, and accuracy were calculated compared with histopathological findings. RESULTS: Interobserver agreement for predicting polyp histology using NBImag was significantly better for experts (κ = 0.63, substantial) compared with nonexperts (κ = 0.30, fair; P < 0.001), and was moderate for all colonoscopists with WLE, AFI and NBI. Interobserver agreement for vascular pattern intensity using NBI was 0.69 (substantial) for experts and 0.57 (good) for nonexperts. NBImag had higher sensitivity than WLE (experts, 0.93 vs. 0.68, P < 0.001; nonexperts, 0.90 vs. 0.52, P < 0.001) and higher overall accuracy (experts, 0.76 vs. 0.64, P = 0.003; nonexperts 0.61 vs. 0.40, P < 0.001). AFI had worse accuracy than WLE for both expert colonoscopists (0.53 vs. 0.64, P = 0.02) and nonexperts (0.32 vs. 0.40, P = 0.04). CONCLUSIONS: Of the imaging modalities tested, NBImag appeared to have the best overall accuracy and interobserver agreement, although not adequate for in vivo diagnosis. NBI and AFI did not have better sensitivity, specificity, or accuracy compared with WLE.

Recall of informed consent information by healthy volunteers in clinical trials.

BACKGROUND: Information sheets for clinical research are becoming increasingly complex but the extent to which they are understood is uncertain. AIMS: To assess, as our primary outcome, recall by healthy volunteers of key facts in a patient information sheet in a phase 3 clinical trial. As secondary outcomes, we examined whether there was a difference between medical student and non-medically trained volunteers. DESIGN: Questionnaire to determine recall by healthy volunteers of informed consent information. METHODS: Eighty-two healthy volunteers participating in a capsule endoscopy study were given a 13 page written information sheet and allowed to asked questions. After indicating they were ready to give consent they were asked to complete a 6-item questionnaire covering the identity and adverse effects of trial treatments and of the procedure, the duration of the trial and value of the inconvenience allowance. RESULTS: All 82 healthy volunteers were questioned. Of the volunteers, 74 (90%) had university level education and 49 (60%) were clinical medical students. However, only 10 subjects (12%) could name the three trial drugs. The maximum number of risks remembered was 6 (n = 2) of 23. Only 14 (17%) could name three or more potential risks of the medication they might be exposed to, whilst 17 (20%) could identify none. Most subjects (77/82, 90%) identified capsule endoscopy as the trial procedure and impaction/obstruction as its main risk (52/82, 64%). All but one subject (98.8%) could recall the exact value of the inconvenience payment. CONCLUSION: A comprehensive information sheet resulted in limited recall of trial risks. Shorter information sheets with a test and feedback session should be trialled so that informed consent becomes valid informed consent.

Narrow-band imaging with magnification in Barrett's esophagus: validation of a simplified grading system of mucosal morphology patterns against histology.

BACKGROUND AND STUDY AIMS: Validation of a simplified classification of mucosal morphology in prediction of histology in Barrett's esophagus using narrow-band imaging with magnification (NBI-Z) and assessing its reproducibility by endoscopists experienced in the use of NBI (NBI-experts) and by endoscopists who were new to NBI (non-NBI-experts). PATIENTS AND METHODS: In a prospective cohort study of 109 patients with Barrett's esophagus at a single tertiary referral center, mucosal patterns visualized in Barrett's esophagus on NBI-Z were classified into four easily distinguishable types: A, round pits with regular microvasculature; B, villous/ridge pits with regular microvasculature; C, absent pits with regular microvasculature; D, distorted pits with irregular microvasculature. The NBI-Z grading was compared with the final histopathological diagnosis, and positive (PPV) and negative predictive values (NPV) were calculated. The reproducibility of the grading was then assessed by NBI-expert and non-NBI-expert endoscopists, and interobserver and intraobserver agreement were calculated using kappa statistics. RESULTS: Per-biopsy analysis: In 903 out of 1021 distinct areas (87.9%) the NBI-Z grading corresponded to the histological diagnosis. Per-patient analysis: The PPV and NPV for type A pattern (columnar mucosa without intestinal metaplasia) were 100% and 97% respectively; for types B and C (intestinal metaplasia) they were 88% and 91% respectively, and for type D (high-grade dysplasia) 81% and 99% respectively. Inter- and intraobserver agreement: The mean kappa values in assessing the various patterns were 0.71 and 0.87 in the non-expert group; 0.78 and 0.91 in the expert group. CONCLUSIONS: This study has validated a simplified classification of the various morphologic patterns visualized in Barrett's esophagus and confirmed its reproducibility when used by NBI-expert and non-NBI-expert endoscopists.

High-resolution magnification endoscopy can reliably identify normal gastric mucosa, Helicobacter pylori-associated gastritis, and gastric atrophy.

BACKGROUND AND STUDY AIMS: The aims of the study were to describe the magnified endoscopic findings in the gastric body, correlate these with histology, and evaluate their reproducibility in the assessment of the magnified endoscopic patterns seen. PATIENTS AND METHODS: A total of 95 consecutive dyspeptic patients underwent upper gastrointestinal endoscopy with a magnifying endoscope. The endoscopists classified the magnified endoscopic patterns and correlated them with the histological findings. In the second part of the study, 200 images were shown to five endoscopists in order to examine inter- and intraobserver variability in image assessment. RESULTS: The magnified endoscopic findings in the gastric body were categorized into four types: type 1, honeycomb-type subepithelial capillary network (SECN) with regular arrangement of collecting venules and regular, round pits; type 2, honeycomb-type SECN with regular, round pits, but loss of collecting venules; type 3, loss of normal SECN and collecting venules, with enlarged white pits surrounded by erythema; and type 4, loss of normal SECN and round pits, with irregular arrangement of collecting venules. The sensitivity, specificity, and positive and negative predictive values of the type 1 pattern for predicting normal gastric mucosa were 92.7% (95% confidence interval [CI] 93.2-97.3%), 100% (95% CI 83.9-100%), 100% (95% CI 92.9-100%), and 83.8% (95% CI 65.5-93.9%). The sensitivity, specificity, and positive and negative predictive values of types 2 and 3 patterns for predicting a Helicobacter pylori-infected stomach were 100% (95% CI 83.9-100%), 92.7% (95% CI 93.2-97.3%), 83.8% (95% CI 65.5-93.9%), and 100% (95% CI 92.9-100%). The sensitivity, specificity, and positive and negative predictive values of a type 4 pattern for predicting gastric atrophy were 90% (95% CI 66.8-98.2%), 96% (95% CI 87.9-98.9%), 85.7% (95% CI 62.6-96.2%), and 97.3% (95% CI 89.6-99.5%. The kappa values for inter- and intraobserver agreement in predicting normal gastric mucosa, H. pylori gastritis, and gastric atrophy were 0.864 and 0.913 respectively. CONCLUSION: High-resolution magnification endoscopy can reliably identify the normal gastric mucosa, H. pylori-associated gastritis, and gastric atrophy in a Western population.

Acetic acid-enhanced magnification endoscopy in the diagnosis of specialized intestinal metaplasia, dysplasia and early cancer in Barrett's oesophagus.

BACKGROUND: Barrett's surveillance is prone to sampling error. Aim To determine whether enhanced magnification endoscopy using acetic acid instillation improves diagnostic accuracy of specialized intestinal metaplasia/dysplasia in Barrett's oesophagus. METHODS: We examined the detection rate of the specialized intestinal metaplasia/dysplasia in 64 consecutive patients with Barrett's oesophagus using acetic acid to enhance mucosal pit patterns. Histology was compared with the previous findings at recent conventional surveillance in 62 patients. We also examined the inter-/intra-observer agreement in the assessment of the enhanced magnification endoscopy pit pattern findings. RESULTS: Histology revealed columnar-lined oesophagus in six (9%) patients, specialized intestinal metaplasia in 49 (77%), low-grade dysplasia in five (8%), high-grade dysplasia in one (2%), and adenocarcinoma in three (5%). There was discordance between the histologic findings from conventional surveillance with random biopsy. Fifteen patients (24%) had a histological upgrade with enhanced magnification endoscopy. There was a high detection rate of specialized intestinal metaplasia even in short segment Barrett's oesophagus (74%), and additionally, there were two cancers, one with 2-cm Barrett's oesophagus and one ultra-short (1 cm). The mean kappa values for inter- and intra-observer agreement in assessing the pit patterns were 0.571 (0.041) and 0.709 (0.038), respectively. CONCLUSIONS: Enhanced magnification endoscopy allows clear visualization of the epithelial pit patterns within Barrett's oesophagus, and targeted biopsy results in a high yield of specialized intestinal metaplasia and dysplasia.