Magnetic resonance urography in children: evaluation of suspected ureteral ectopia in duplex systems.

Objective: We evaluate the diagnostic accuracy of magnetic resonance urography in children with suspected ectopic ureters and ureteroceles in duplex systems.

Methods: A total of 14 children 4 weeks to 8 years old with a total of 18 duplex systems underwent magnetic resonance urography using a 1.5 tesla scanner. After injection of low dose furosemide, half-Fourier rapid acquisition with relaxation enhancement images were obtained for T2-weighted static fluid magnetic resonance urography. Respiratory gated 3-dimensional gradient echo images were acquired for T1-weighted excretory magnetic resonance urography 5 to 30 minutes after intravenously administered gadolinium.

Results: All magnetic resonance examinations were successfully performed without sedation. The diagnostic accuracy of T1-weighted excretory magnetic resonance urography depended on the renal function. Twelve duplex systems with a normal excretory function, including 6 bifid ureters and 6 upper moieties with inferomedial ectopic ureters, were analyzed correctly with the exception of a 6 mm. ureterocele in 1 case. In 6 duplex systems with poor or nonfunctioning upper moieties ectopic ureters were only demonstrated on T2-weighted magnetic resonance urograms.

Conclusions: Respiratory gated excretory and static fluid magnetic resonance urography complement each other in the evaluation of duplex systems in children and provide high accuracy in the evaluation of suspected ectopic ureters and ureteroceles.