(1) dysphagia or symptoms of gastric outlet obstruction, suspected or known intestinal stenosis,overt gastrointestinal bleeding,fistulas and strictures; (2)history of upper gastrointestinal surgery or suspected delayed gastric emptying; (3) patients with poor general condition,asthma or claus trophobia; (4) implanted metallic devices such as pacemakers,defibrillators, artificial heart valves or joint prostheses; (5) pregnancy or mentally ill person; (6) currently participating in another clinical study;(7)communication obstacles persons.

(1) dysphagia or symptoms of gastric outlet obstruction, suspected or known intestinal stenosis,overt gastrointestinal bleeding,fistulas and strictures; (2)history of upper gastrointestinal surgery or suspected delayed gastric emptying; (3) patients with poor general condition,asthma or claus trophobia; (4) implanted metallic devices such as pacemakers,defibrillators, artificial heart valves or joint prostheses; (5) pregnancy or mentally ill person; (6) currently participating in another clinical study;(7)communication obstacles persons.