Pediatric MR urography: Indications, techniques and role in uroradiology

Abstract

The aim of writing the article is to bring closer to readers the role of this specific procedure in uroradiology. Functional magnetic resonance urography (fMRU) gives us an insight into the morphology of the urinary system with functional parameters similar to nuclear medicine (renal scintigraphy). MR urography (MRU) and functional (fMRU) provide both morphological and functional information by means of different sequences with or without injection of gadolinium. Combined static and dynamic contrast-enhanced MR urography is particularly advantageous in the pediatric population, offering high spatial resolution, morphological imaging of the urinary tract with reliable information about kidney function and urinary excretion in a single examination, without exposure to ionizing radiation. An fMRU scan requires external postprocessing using special dedicated software. The functional analysis is based primarily on the post-contrast sequences. Dynamic scans are repeated over 15 minutes with increasing pauses between acquisitions. The analytical results include: calyceal transit time, renal transit time, time-to-peak, whole (renal) volume, parenchymal (renal) volume, differential renal function, enhancement curves, excretion curves, and patlak plots. Conclusion - This is a noninvasive procedure without the use of ionizing radiation, providing a very detailed urinary tract anatomy and functional analysis of kidney function and urinary excretion.