The investigators hypothesize that careful examination of Barrett's esophagus by high-resolution endoscopy combined with virtual chromoendoscopy could replace the Seattle protocol for Barrett's esophagus monitoring and detection of dysplasic lesions, and thus modify existing recommendations.

Barrett's esophagus (BE) is a pre-neoplastic condition that predisposes to dysplasia and adenocarcinoma of the esophagus, a cancer with an increasing incidence and poor prognosis. However, when detected at an early stage, superficial lesions can be effectively treated by endoscopic resection. Although BE degeneration remains a rare event, the European Society for Gastrointestinal Endoscopy recommends that BE be followed according to its size. Follow-up consists of a digestive endoscopy with white light examination of the esophagus, targeted biopsies of any visible lesions and quadrantic biopsies every 2 centimeters from the esogastric junction to the top of the BE, at a frequency that depends on the presence of dysplasia and the size of the BE. However, physician adherence to this procedure, known as the Seattle Protocol, is low because : 1) it increases the time required for the endoscopist to examine the patient and therefore the duration of sedation, as well as the time needed to interpret the pathology, 2) the risk of sampling error is high because only a small portion of the esophageal mucosa can be biopsied and 3) this approach is costly because of the time spent on the Seattle protocol in the operating room and in the pathology department.

New optical tools such as high-resolution endoscopy combined with magnification and electronic chromoendoscopy can reveal subtle mucosal and microvascular changes in the BE, which could improve the detection of early neoplastic lesions. However, there is still insufficient evidence to recommend its use in routine BE surveillance.

The investigators hypothesize that careful examination of Barrett's Esophagus by high-resolution endoscopy combined with virtual chromoendoscopy could replace the Seattle protocol for BE monitoring and detection of dysplasic lesions, and thus modify existing recommendations.

In this study, each patient will be his(her) own control and have the two procedures :

• Firstly, an endoscopist called A will perform high-resolution endoscopy combined with virtual chromoendocopy and note on a scheme the biopsies/resection he would have done with this procedure.

• Secondly, another endoscopist called B will do the examination using white light modality of the endoscope and process as follows :

  1. He/she will describe all visible lesions with precise indications of their location on a virgin scheme;
  2. Then, he/she will be unblinded to endoscopist A findings, see the scheme of endoscopist A and perform biopsies/resection according to instructions of this scheme;
  3. He/she will perform the biopsies/resection he/she would have added (if any);
  4. Finally, he/she will perform the quadrantic biopsies according to Seattle Protocol.

Final histology results will serve as gold standard for the diagnosis of early esophageal adenocarcnoma or high grade displasia.

Inclusion Criteria:

• Male or Female with Age above ≥ years old;
• Female of childbearing potential must use appropriate method(s) of contraception during the clinical trial (i.e.: Intrauterine Device, pill, implant,sexual abstinence);
• Dysplastic Barrett's Esophagus preferably labelled "flat mucosal dysplasia";
• Patient requiring esophageal endoscopy as part of their regular monitoring;
• Affiliated to social security;
• Patient received Patient Information Form and accepted to participate to the study.

Exclusion Criteria:

• Previously treated Barrett's Esophagus;
• Known invasive esophageal adenocarcinoma;
• Contraindication to general anesthesia;
• Ongoing clopidogrel or anticoagulant therapy or coagulation disorder (platelet count < 50 000/mm3, Prothrombin time ratio <50%);
• Poor general health status precluding subsequent follow up of Barrett's Esophagus ;
• For female: pregnancy or breastfeeding;
• Adults under a legal protection regime (guardianship, trusteeship, "under judicial protection").
• Ongoing participation in another study requiring an intervention on Barrett's Esophagus during patient's participation in Converse study

The two endoscopists will be blinded to each other's findings when searching the lesions.