Magnetic resonance urography in children: Evaluation of suspected ureteralectopia in duplex systems

Purpose: We evaluate the diagnostic accuracy of magnetic resonance urograph y in children with suspected ectopic ureters and ureteroceles in duplex sys tems. Materials and 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 rap id acquisition with relaxation enhancement images were obtained for T2-weig hted static fluid magnetic resonance urography. Respiratory gated 3-dimensi onal gradient echo images were acquired for T1-weighted excretory magnetic resonance urography 5 to 30 minutes after intravenously administered gadoli nium. Results: All magnetic resonance examinations were successfully performed wi thout sedation. The diagnostic accuracy of T1-weighted excretory magnetic r esonance urography depended on the renal function. Twelve duplex systems wi th a normal excretory function, including 6 bifid ureters and 6 upper moiet ies with inferomedial ectopic ureters, were analyzed correctly with the exc eption of a 6 mm. ureterocele in 1 case. In 6 duplex systems with poor or n onfunctioning upper moieties ectopic ureters were only demonstrated on T2-w eighted magnetic resonance urograms. Conclusions: Respiratory gated excretory and static fluid magnetic resonanc e urography complement each other in the evaluation of duplex systems in ch ildren and provide high accuracy in the evaluation of suspected ectopic ure ters and ureteroceles.