The overall goal of the study is to determine whether imaging with the low-cost High Resolution Microendoscope(HRME) will increase the efficiency and yield of the current standard of endoscopic surveillance of Barrett's esophagus. We believe the HRME will provide an in-vivo "optical biopsy" that will be comparable to gold standard histopathology and allow the endoscopist to make a more informed decision about whether to obtain a biopsy or even perform endoscopic therapy (i.e. endoscopic mucosal resection, EMR).

Primary outcomes:

• the diagnostic yield (defined as the proportion of mucosal biopsy samples with neoplasia) of HRME with directed biopsy

  - compared to standard white-light endoscopy with 4-quadrant random biopsy (WL) for the diagnosis of BE-associated neoplasia in flat mucosa as well as mucosal lesions

• the clinical impact of HRME on the diagnosis and endoscopic surveillance of BE- associated neoplasia

  • does HRME alter the decision to obtain a mucosal biopsy or perform endoscopic mucosal resection (EMR)
  • the total number of total mucosal biopsies taken per procedure; does HRME alter the number of biopsies necessary?

Secondary outcomes:

• sensitivity, specificity, positive predictive value, and negative predictive value of HRME for the in-vivo diagnosis of neoplasia in a routine surveillance population of patients with BE (using histopathologic diagnosis of mucosal biopsies as the reference standard)
• the total procedure time for imaging and mucosal biopsy acquisition of HRME - compared with WL, stratified by length of BE (< 3 cm and > 3cm)

Inclusion Criteria:

• outpatients with > 1 cm biopsy-proven Barrett's Esophagus who are undergoing standard of care endoscopic surveillance for metaplasia, dysplasia, or neoplasia.

Exclusion Criteria:

• Allergy or prior reaction to the fluorescent contrast agent proflavine
• Patients who are unable to give informed consent.
• Known advanced adenocarcinoma of the distal esophagus, or dysplastic/suspected malignant esophageal lesion > 2 cm in size not amenable to EMR
• Patients with a history of a severe allergic reaction (anaphylaxis)
• Patients unable to undergo routine endoscopy with biopsy :
• Women who are pregnant or breastfeeding
• Prothrombin Time > 50% of control; PTT > 50 sec, or INR > 2.0)
• Inability to tolerate sedated upper endoscopy due to cardio-pulmonary instability or other
• Patients with known, untreated esophageal strictures, prior partial esophageal resection, or altered anatomy preventing passage of the endomicroscope
• Patients with known severe esophagitis
• Patients with suspected but no biopsy confirmed BE