Objective To explore the value of three-dimensional（3D） volume contrast-enhanced ultrasonography of stomach and iodinated water contrast-enhanced radiography of upper digestive tract in the evaluation of the effect of gastric peroralendoscopic pyloromyotomy（G-POEM）.Methods Ninety-four patients with gastroparesis who were indicative of G-POEM were divided into group A treated by 3D ultrasound（n=48） and group B treated by iodinated water contrast X-ray examination（n=46）.In group A

3D ultrasonography was proceeded at 5

15

30

60 and 90 min after oral administration of ultrasound contrast agent.In group B

the upper abdomen plain film was taken at the same time points as group A after taking iodized water contrast agent.The gastric volume after oral intake of contrast medium was estimated by 3D ultrasound and X-ray before and after G-POEM

respectively.The improvement of gastric emptying after G-POEM was evaluated and the results were compared and analyzed.Results①The success rate of 3D ultrasonography was 97.9%（47/48） in group A

and success rate of iodinated water contrast-enhanced radiography was 97.8%（45/46） in group B

there was no significant difference.②The gastric emptying time of 31 patients in each of group A and B were reduced compared with those before operation（all P<0.05）.③The gastric emptying time of 16 patients in group A was 90 min before and after operation.The gastric emptying rate of 8 patients were significantly improved in 90 min compared with that before operation and had statistical difference（all P<0.05）.The gastric emptying rate of 8 patients had no changes compared with that before operation with no statistical difference.The gastric emptying time of 14 patients in group B was 90 min before and after operation.The gastric emptying rate of 5 patients were significantly improved in 90 min compared with that before operation（all P<0.05）.The gastric emptying rate of 9 patients were not significantly improved compared with that before operation with no statistical difference.④In group A

31 of 47 patients were significantly improved by contrast-enhanced ultrasonography compared with those before operation

8 patients were not improved notably.In group B

31 of 45 patients were significantly improved by iodinated water contrast-enhanced radiography compared with those before operation

9 patients were not improved notably.There were no significant differences of gastric emptying rates between two groups（83% vs.80%）.Conclusion 3D volume contrast-enhanced ultrasonography of stomach and iodinated water contrastenhanced radiography of upper digestive tract can evaluate the gastric emptying before and after G-POEM.In clinic

3D volume contrast-enhanced ultrasonography of stomach is a first choice of evaluating the gastric emptying before and after G-POEM and improvement of gastric emptying function after operation.The iodinated water contrast-enhanced radiography of the upper digestive tract can be used as a supplementary method to provide objective imaging information in the clinical setting.