Objective:To study the best technological methods for high quality intravenous pyelography(IVP).Methods:300 patients undergoing nonpressurized IVP were chosen as study group;100 patients undergoing routine pressurized IVP were chosen as control group.The visualization effect and imaging quality of two groups were evaluated by senior technologist and doctor

and related data were processed statistically.Results:All of the 300 patients in the study group completed the examination successfully and painlessly.Of the 100 patients in the control group

5%(5/100) did not meet the diagnostic requirements

because they could not stand the pressurization because of old age

weakness

obesity and pelvis lesions

and had to be decompressed;13%(13/100) cases with poor image quality influenced the diagnostic results.In the study group

93.7%(281/300) cases were with clear visualization of pelvis and renal calices

conjunction of pelvis and the ureter

and the whole course of ureter.The remaining 6.3%(19/300)were with not-very-well visualization of the urinary system but met the diagnostic requirements.11.7%(35/300) patients in the study group needed to change position to gain multi-angle photographs for visualization of the details of the lesions

while 7%(7/100) patients in the control group needed multi-angle photographs but could not complete the examination.There was a significant difference in the whole course visualization of the urinary system(P<0.01

93.7% in the study group vs.43% in the control group).Conclusion:Non-pressurized IVP is better than pressurized IVP with advantage of painlessness

clear visualization of the anatomy of the whole course of the urinary system and details of lesions.