Biomedical subjects

John A Evans

Publications and source records attributed to John A Evans.

3 recordsLinked to original sources

PubMed2006

Optical coherence tomography to identify intramucosal carcinoma and high-grade dysplasia in Barrett's esophagus.

BACKGROUND & AIMS: Optical coherence tomography (OCT) is an optical technique that produces high-resolution images of the esophagus during endoscopy. OCT can distinguish specialized intestinal metaplasia (SIM) from squamous mucosa, but image criteria for differentiating intramucosal carcinoma (IMC) and high-grade dysplasia (HGD) from low-grade dysplasia (LGD), indeterminate-grade dysplasia (IGD), and SIM without dysplasia have not been validated. The purpose of this study was to establish OCT image characteristics of IMC and HGD in Barrett's esophagus. METHODS: Biopsy-correlated OCT images were acquired from patients with Barrett's esophagus undergoing endoscopic surveillance. Two pathologists rendered consensus diagnoses of the biopsy specimens. A blinded investigator reviewed the biopsy-correlated OCT images and scored each for surface maturation and gland architecture. For each image the scores were summed to determine an OCT "dysplasia index." RESULTS: A total of 177 biopsy-correlated images were analyzed. The corresponding histopathology diagnosis was IMC/HGD in 49 cases, LGD in 15, IGD in 8, SIM in 100, and gastric mucosa in 5. A significant relationship was found between a histopathologic diagnosis of IMC/HGD and scores for each image feature (dysplasia index [Spearman correlation coefficient, r = 0.50, P < .0001], surface maturation [r = 0.48, P < .0001], and gland architecture [r = 0.41, P < .0001]). When a dysplasia index threshold of >or=2 was used, the sensitivity and specificity for diagnosing IMC/HGD were 83% and 75%, respectively. CONCLUSIONS: An OCT image scoring system based on histopathologic characteristics has the potential to identify IMC and HGD in Barrett's esophagus.

Adult↗

PubMed2005

The use of optical coherence tomography in screening and surveillance of Barrett's esophagus.

Barrett's esophagus (BE) is defined as the presence of specialized intestinal metaplasia within the tubular esophagus. Recent studies suggest that performing endoscopic surveillance in patients with Barrett's esophagus is effective in preventing esophageal adenocarcinoma at an early stage. However, the accuracy of surveillance endoscopy is limited by sampling error and cost. Optical coherence tomography (OCT) is an optical analog of ultrasound, providing 10-microm resolution and real-time cross-sectional images of the luminal gastrointestinal tract. The literature describing the use of OCT in models of dysplasia and BE are reviewed. Three studies have examined the use of OCT in BE and models of dysplasia. These studies suggest that the currently achievable resolution combined with light-scattering properties of Barrett's mucosa is adequate to discern intestinal metaplasia and reliably detect high-grade dysplasia in patients with BE. Additional research to validate these findings is required.

Barrett Esophagus↗

PubMed2005

Endoscopic confocal microscopy.

PURPOSE OF REVIEW: Endoscopic confocal microscopy is a new endoscopic imaging technology that produces high-magnification cross-sectional images of the gastrointestinal epithelium during endoscopy. These high-magnification images might allow the endoscopist to make a tissue diagnosis during endoscopy without biopsy and histopathology. The purpose of this article is to review the salient features of endoscopic confocal microscopy, describe current clinical research areas using the technology, and depict its potential role in the management of gastrointestinal diseases. This review includes an overview of the technology, a review of recent publications describing its function, and a discussion of potential applications. RECENT FINDINGS: Endoscopic confocal microscopy has been technologically feasible only for a short time; therefore, the published experience is limited. Studies describing the use of endoscopic confocal microscopy for the detection of dysplastic tissue have been limited to a single paper in which endoscopic confocal microscopy was reported to be highly sensitive and specific for the detection of colonic dysplasia in a general screening population. Active areas of investigation include detecting dysplasia in ulcerative colitis and Barrett's esophagus. A recent case report detailed the ability of endoscopic confocal microscopy to detect gastric Helicobacter pylori in vivo. SUMMARY: Endoscopic confocal microscopy is a new imaging technology that produces high-magnification cross-sectional images of the gastrointestinal tract. Its role in detecting and managing diseases of the gastrointestinal tract has been studied in colon cancer screening and is currently being evaluated in a variety of premalignant conditions.

Endoscopes, Gastrointestinal↗