Magnetic resonance urography for the assessment of potential renal donors: comparison of the RARE technique with a low-dose gadolinium-enhanced magnetic resonance urography technique in the absence of pharmacological and mechanical intervention.

The aim of this study was to determine whether magnetic resonance urography without pharmacological (diuretic) stimulation and mechanical compression allows conclusive evaluation of the urinary system in potential renal donors. In 28 consecutive patients magnetic resonance urography (MRU) was performed on a 1.5-T system. Two techniques, rapid acquisition with relaxation enhancement (RARE) and a gadolinium (Gd)-enhanced 3D fast low angle shot (FLASH) sequence were compared in the absence of adjunctive measures. Two reviewers assessed image quality, presence of artifacts and completeness of visualization of the collecting systems and ureters. Among the 53 MR urograms, there was no difference in image quality and presence of artifacts between RARE and Gd-MRU. Despite high image quality, visualization of the urinary collecting system was insufficient. Continuous visualization from the collecting system to the distal ureter was demonstrated bilaterally in only 14% of the RARE and 26% of Gd-enhanced MR urograms, respectively. Overall, Gd-enhanced MRU was superior to the RARE technique in displaying the segments of the urinary collecting system, but this difference was not found to be statistically significant. Neither the RARE technique nor the gadolinium-enhanced MRU technique is accurate enough to allow the evaluation of the collecting system and ureters in potential renal donors in the absence of pharmacological intervention and compression.