Dynamic gadolinium‐enhanced magnetic resonance urography for assessing drainage in dilated pelvicalyceal systems with moderate renal function: preliminary results and comparison with diuresis renography

Abstract

administered, with a time-intensity curve of each kidney produced. Drainage was diagnosed by a clearly declining timeintensity curve and direct visualization of contrast medium within the ureter in several frames. High-grade or complete obstruction was diagnosed when drainage of contrast medium could not be detected. Gd-MRU results were compared with diuresis radionuclide (mercaptoacetyltriglycine, MAG3) renography within the same week. Unobstructive units detected by Gd-MRU were treated conservatively with a close follow-up by ultrasonography and radionuclide studies. RESULTSDiuresis MAG3 renography showed drainage in three dilated units and poor washout in five; in contrast, Gd-MRU showed drainage in seven dilated systems (three showed poor washout by MAG3), and obstruction in the remaining case. The unobstructed units detected by MRU under conservative treatment thus showed no further deterioration of renal function or progressive hydronephrosis in the subsequent follow-up (mean 18 months, range 15-23). CONCLUSIONThese preliminary results suggest that dynamic Gd-MRU is a useful noninvasive imaging method in distinguishing obstructive from unobstructive dilated systems, particularly in patients with hydronephrosis and reduced renal function.

Application of magnetic resonance urography in diagnosis of congenital urogenital anomalies in children

“…Excretory MRU imitates conventional IVU in that an intravenously injected gadolinium contrast agent is excreted by the kidneys and the gadolinium-enhanced urine is imaged with fast T1-weighted gradient echo sequences [10,15]. Low-molecular-weight gadolinium chelates have demonstrated a good safety profile after intravenous administration, and there has been an argument in favor of using contrast-enhanced MRU over iodinated contrastenhanced conventional excretory urography or CT, since the gadolinium-based contrast medium used in MRU is less toxic and with fewer adverse effects [11,13].…”

Impact of magnetic resonance urography and ultrasonography on diagnosis and management of hydronephrosis and megaureter in paediatric patients

“…[6,23,24] Avoiding exposure to ionizing radiation it might have the potential to replace MAG3 renography as gold standard investigation of patients suspected for ureter obstruction. [25] In our retrospective study the temporal resolution of the dynamic MRU sequence was not suited for a functional analysis. As a result, we could not use functional MRU data and therefore only morphologic data are presented in our study.…”

Dynamic MRI and isotope renogram in the functional evaluation of pelviureteric junction obstruction: A comparative study

“…However, even when isotope renogram results are compromised by reduced radiotracer uptake in the affected kidney, dMRI has proved to be a very good modality to differentiate between an obstructed dilated and a non-obstructed upper urinary tract. [19] However, a large multi-center study published in 2014 by Claudon et al [20] showed that dMRI was equivalent to renal scintigraphy in moderately dilated kidneys; but dMRI underestimated split renal function by 4% in severely dilated kidneys, making substitution of renal scintigraphy questionable. The advantages of MRI over other radiological techniques are exquisite soft tissue characterization, capability of direct multiplanar and three dimensional reformatting images, and lack of ionizing radiation.…”