The aims of the present study：

1. To investigate the diagnosing value of optical enhancement technology for early esophageal squamous neoplasia.
2. To assess the detection rate of early esophageal squamous neoplasia by virtual chromoendoscopy with optical enhancement technology .

Detection and differentiation of esophageal squamous neoplasia (ESN) are of value in improving patient outcomes.Optical enhancement technology can serves in the diagnosis of GI neoplasia. However, its performance in ESN has not yet been reported.The aims of the present study is:

1. To investigate the diagnosing value of optical enhancement technology for early esophageal squamous neoplasia.
2. To assess the detection rate of early esophageal squamous neoplasia by virtual chromoendoscopy with optical enhancement technology .

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;

Consecutive patients screened that fulfill the eligibility criteria at Qilu Hospital, Shandong University will be enrolled into the study.