Chronic Urinary Obstruction: Evaluation of Dynamic Contrast-enhanced MR Urography for Measurement of Split Renal Function

Purpose: To evaluate if measurement of split renal function (SRF) with dynamic contrast material-enhanced (DCE) magnetic resonance (MR) urography is equivalent to that with renal scintigraphy (RS) in patients suspected of having chronic urinary obstruction. Materials and Methods: The study protocol was approved by the institutional ethics committee of the coordinating center on behalf of all participating centers. Informed consent was obtained from all adult patients or both parents of children. This prospective, comparative study included 369 pediatric and adult patients from 14 university hospitals who were suspected of having chronic or intermittent urinary obstruction, and data from 295 patients with complete data were used for analysis. SRF was measured by using the area under the curve and the Patlak-Rutland methods, including successive review by a senior and an expert reviewer and measurement of intra-and interobserver agreement for each technique. An equivalence test for mean SRF was conducted with an a of 5%. Results: Reproducibility was substantial to almost perfect for both methods. Equivalence of DCE MR urography and RS for measurement of SRF was shown in patients with moderately dilated kidneys (P < .001 with the Patlak-Rutland method). However, in severely dilated kidneys, the mean SRF measurement was underestimated by 4% when DCE MR urography was used compared with that when RS was used. Age and type of MR imaging device had no significant effect. Conclusion: For moderately dilated kidneys, equivalence of DCE MR urography to RS was shown, with a standard deviation of approximately 12% between the techniques, making substitution of DCE MR urography for RS acceptable. For severely dilated kidneys, a mean underestimation of SRF of 4% should be expected with DCE MR urography, making substitution questionable. (C) RSNA, 2014