Fast imaging MR assessment of ureterohydronephrosis during pregnancy

Purpose: to assess the value of the fast imaging sequence called RARE-MR-Urography (RMU) for the diagnosis of pathologic ureterohydronephrosis during pregnancy. Materials and Methods: 15 pregnant women with an acute flank pain were examined with RMU. Results were compared with those of ultrasonography (US), X-rays, and the evolution of symptoms. Results: the accuracy of RMU in the detection of urinary tract dilatation and the localization of the level of obstruction was excellent (100%). The determination of the type of obstruction, intrinsic vs. extrinsic, was always exact. RMU alone cannot specify the exact nature of the intrinsic obstruction. Ultrasonography gave less sensitive information in terms of level (60%) and type of obstruction (53%). Conclusion: RMU is able to differentiate a physiological from a pathologic ureterohydronephrosis during pregnancy. It could be considered as a procedure of choice for special cases when US failed to establish this differential diagnosis.