Endoscopic Raman spectroscopy enables objective diagnosis of dysplasia in Barrett's esophagus

Background: Early detection and targeted endoscopic resection of Barrett's esophagus-associated high-grade dysplasia (HGD) can prevent progression to invasive esophageal malignancy. Raman spectroscopy, a highly sophisticated analytical technique, has been translated into an endoscopic tool to facilitate rapid, objective diagnosis of dysplasia in the esophagus. Objective: To evaluate the ability of endoscopic Raman spectroscopy (ERS) to objectively detect esophageal HGD and adenocarcinoma. Design: A total of 798 one-second spectra were measured from 673 ex vivo esophageal tissue samples, collected from patients with Barrett's esophagus by using a novel endoscopic Raman probe. Spectra were correlated with consensus histopathology. Multivariate analysis was used to evaluate the classification accuracy of ERS ex vivo. Setting: Probe measurements were conducted in the laboratory. Tissue specimens were collected from the operating theatre and endoscopy unit. Patients: Tissue from 62 patients was included in the study. Interventions: Endoscopic biopsy/resection or esophagectomy was performed where indicated clinically. Main Outcome Measurement: Diagnostic performance of ERS for detection of HGD and esophageal adenocarcinoma. Results: ERS demonstrated a sensitivity of 86% and a specificity of 88% for detecting HGD and adenocarcinoma. The ability to grade dysplasia and differentiate intestinal metaplasia from nonintestinal metaplasia columnar-lined esophagus was also demonstrated. Diagnostic classification was based on objective measurement of the biochemical profile of different tissue types. The potential for combination ERS and narrow-band imaging was also demonstrated. Limitations: Measurements were taken from ex vivo tissue. Conclusion: ERS enables rapid, accurate, objective diagnosis of superficial esophageal disease (metaplasia, dysplasia, intramucosal cancer) in clinically applicable time scales.