Objective To observe the imaging findings of congenital megaureter in order to enhance the understanding of this disease. Methods Image data of 5 patients with congenital megaureter and 2 misdiagnosed patients were analyzed

and image findings of congenital megaureter were summarized.Elscint Prestig 2.0T superconductive magnetic resonance urography (MRU) with conventional sequence (spin-echo

T1WI560 ms/16 ms; fast spin-echo

T2WI 9600 ms/96 ms ) was performed.Raw data were acquired with fastspin-echo sequence from heavy T2-weighted image (9600 ms/120 ms). Post-processing method of MRU was the maximum intensity projection with three-dimensional reconstruction in the workstation. Intravenous pyelography (IVP) was conducted

in which X-rayfilms were taken 7 minutes

15 minutes

and 30 minutes after injecting contrast agent

exceptthat in 2 patients the films were taken delayed at 60 and 90 minutes .X-ray retrograde pyelography was performed on 2 patients

successful in one butfailed in the other.Results The dilated ureter showed hypointensity on T1-weighted images and hyperintensity on T2-weighted images in conventional MRI. The mass wall was intact

uniform in thickness

and showing hypointensity on T1-weighted and T2-weighted images. The MRU images showed a retroperitoneal mass appearing as an elongated tubular cystic structure spreading from kidney to bladder. MRU also revealed dilated calices and renal pelvis

pelviureteric obstruction

and renal duplication. The main signs of congenital megaureter in X-urography was significant dilatation of ureter

or normal renal pelvis with ureter dilatation

hydronephrosis

deformity

and displacement. Conclusions MRU with X-urography could visualizethe characteristics of congenital megaureter

including the dilation of renal pelvis and ureter

calculi

urinary tract duplication

and stenosis location. The two techniques can complement each other in disease diagnosis and provide more detailed information for preoperative treatment.