Prediction of Split Renal Function and Obstruction with MR Urography in Comparison with Dynamic Renal Scintigraphy

Purpose: MR urography examinations allow the assessment of kidney functions through recently developed image post-processing techniques, in addition to providing detailed visualization of urinary system anatomy. MR urography and MAG3 scintigraphy were compared in terms of functional evaluation. Methods: Dynamic contrast-enhanced MR urography images of 90 children who had previously undergone MAG3 scintigraphy examinations were evaluated. Morphological parameters, volumetric split renal functions (SRF) and renal transit times (RTT) were calculated from the dynamic MR urography phases using the CHOP-fMRU software for a total of 76 patients. Results were compared with the half-time (T1/2) and SRF values obtained from MAG3 scintigraphy. Student's t-test and Mann-Whitney U test were used to compare quantitative variables, and correlation analysis was performed. Results: The ages of the patients included in the study ranged from 1 to 216 months, with a mean age of 76.82 ± 62.59 months. Statistically significant positive correlations (r > 0.9, p =0.001) were found between SRFs of the right and left kidneys, measured by MR urography and scintigraphy. When the agreement between RTT and radionuclide half-life was evaluated, the sensitivity, specificity, positive and negative predictive values ​​of RTT for urinary obstruction were 65%, 83%, 90% and 53%, respectively. Conclusion: MR urography based SRF calculations could to be an invaluable tool in the assessment of separate renal functions. Its high positive predictive value in detecting obstruction rivals that of MAG3 scintigraphy. Despite the lack of extensive comparative data, the potential benefits of MR urography justify the need for further studies.