Static and functional MR urography as A comparison with renal scintigraphy in pediatric patients

AIM: In addition to the evaluation of the urinary system anatomy, MR urography examination provides the opportunity to calculate the function with image postprocessing methods in recent years. In this study, the urinary tract morphologies of pediatric patients with congenital renal and urinary malformations were examined through the MR urography scan currently available in our picture archiving and communication systems. After evaluating the relationships between morphological parameters, MR urography and MAG3 scintigraphy were compared in terms of functional parameters. MATERIALS AND METHODS: Renal size, parenchymal thickness, renal pelvis AP diameter, and ureter diameters were measured in 90 patients with dynamic contrast MR urography with 1.5 Tesla MR device who had previously obtained MAG3 scintigraphy, and their relations with each other were evaluated. Volumetric split renal functions, caliceal and renal transition times were calculated from the dynamic MR urography phases via CHOP-fMRU software in the remaining 76 patients after excluding of 14 patients with renal agenesis, multicystic dysplastic kidneys and whose kidney segmentation could not be performed. Split renal functions obtained by both examinations were compared. In addition, the agreement between the renal transit time (RTT) obtained by MR urography and the radionuclide half-life (T1/2) obtained by MAG3 kidney scintigraphy in demonstrating the obstruction was evaluated. While evaluating the study data, Student-t test and Mann-Whitney U test were used in comparison of quantitative variables between two groups, as well as descriptive statistical methods. Pearson and Spearman correlation analysis were used to evaluate the relationships between quantitative variables. RESULTS: The ages of the patients participating in the study ranged from 1 to 216 months (mean 76,82±62,59 months). Right and left kidney split functions obtained from MR urography and scintigraphy showed a statistically significant positive correlation (r=0.93, p=0.001). In the morphological evaluation, a negative correlation was observed between parenchymal thickness and AP diameter of the renal pelvis (p=0.001, r=-0.323). When the concordance between renal transit time and radionuclide half-life was evaluated, the sensitivity was 65%, the specificity was 83%, the positive predictive value was 90%, and the negative predictive value was 53%. CONCLUSION: MR urography examination is promising in functional evaluation with split renal function calculation similar to MAG3 scintigraphy. Compared to scintigraphy examinations, high anatomical detail, absence of radiation exposure stand out as positive aspects, motion artifact due to long exposure time and the need for sedation especially in patients under 6 years of age, are the parameters that limit its use. There are few literature data comparing the two techniques and functional MR urography is equally effective. Therefore, larger and deeper studies are needed to confirm the findings.