Identification and characterization of calyceal diverticula with MR urography (MRU) in children

Purpose To determine the MRU imaging findings of calyceal diverticula in a large cohort of children and to compare the frequency of calyceal diverticula in our cohort with what has been previously reported. Methods This was a HIPAA-compliant, IRB-approved retrospective study of all patients with suspected CD based on their medical records. All patients in this study underwent MRU at our institution between 2010 and 2017. Two pediatric radiologists reviewed each MRU blinded to clinical information and other urologic imaging regarding the presence, size, location, and morphology of the cyst and presence/absence of contrast within it. The time when contrast first appeared within the cystic mass was recorded, and a χ 2 test was used to determine significance on differences between the different characteristics of renal cysts and diverticula. Results Fifty children (29 girls and 21 boys; median age of 11.5 years, IQR 7–16) with a total of 66 individual cystic masses were included. 21 (21/66, 31.8%) Cystic masses demonstrated contrast filling and were characterized as diverticula, resulting in a frequency of 26.6 cases per 1000 patients (21/787). The remaining 45 cystic masses (45/66, 68.1%) were cysts. The median diameter of CD was 2.5 cm (IQR 1.5–3.7). Contrast was observed within the cystic mass on average at 4.6 min (SD ± 2.4; range 1.5–13 min). The agreement between both radiologists was 91% ( k = 0.78). 6 Cysts and 18 CD were confirmed surgically, MRU demonstrated accurate diagnosis in 100% of those cases. Conclusion Magnetic resonance urography is reliable in differentiating calyceal diverticula from renal cysts. On MRU, all diverticula were identified within 15 min of contrast administration; hence longer delays in imaging are unnecessary.