Imaging in ureteral complications of renal transplantation: value of static fluid MR urography

Ureteral obstruction is an infrequent complication after renal transplantat ion that may cause rapid loss of transplant function. We tested static flui d MR urography for determining the cause of graft hydronephrosis. Magnetic resonance urography was performed in nine transplants with dilated collecti ng systems on ultrasound. A heavily T2-weighted 3D turbo spin-echo sequence on a 1.5-T scanner was used and maximum intensity projections were ob:obta ined. The patients also underwent excretory urography (n = 1), renal scinti graphy (n = 1), antegrade pyelography (n = 3), voiding cystourethrography ( n = 4), and non-enhanced CT (n = 2). Six patients had pathologic conditions including ureteral stricture, compression by lymphoceles, implantation ste nosis, vesicoureteral reflux, and late-occurring transitional cell carcinom a at the implantation site. Static MRU was able to diagnose or exclude a di lation of the graft collecting system. It visualized the course of the uret ers and localized the obstruction site in four of five obstructed transplan ts. In one case the ureter was obscured by lymphoceles, which were demonstr ated by hydrographic MRU as well. The definite cause for obstruction was pr ovided in only 2 of 5 cases. Dilation due to vesicoureteral reflux could no t be differentiated. The current multimodality approach to renal transplant imaging already provides Comprehensive assessment of graft hydronephrosis. Static MRU may be useful in some cases since complications associated with intravenous iodinated contrast or antegrade pyelography can be avoided. It s main drawback, the lack of functional information, may be overcome by com bining it with contrast-enhanced MRU.