Diagnostic Value of Optical Enhancement Technology in Early Esophageal Squamous Neoplasia

Inclusion Criteria:

1. Patients with high-risk factors for esophageal squamous cell carcinoma who meet any of follows：

   * Long term living in the high incidence area of esophageal squamous cell carcinoma ；
   * First degree relatives have a history of esophageal squamous cell carcinoma ；
   * Previous history of esophageal lesions （ esophageal squamous neoplasia ）；
   * The patients having a history of cancer；
   * A long history of smoking ；
   * A long history of drinking ；
   * Having bad eating habits such as eating fast, hot diet, high salt diet, eating pickles.
2. Patients aged between 40 to 74 years old.

Exclusion Criteria:

1. Having advanced esophageal carcinoma;
2. After esophageal surgery or endoscopic treatment ;
3. Known esophageal radiotherapy or chemotherapy ;
4. Esophageal stenosis;
5. Acute bleeding;
6. A known allergy to iodine;
7. Coagulopathy (prothrombin time \<50% of control, partial thromboplastin time \>50 seconds);
8. Having food retention;
9. Severe hepatic ,renal, cardiovascular or metabolic dysfunction ;
10. Being pregnant or lactating;