How we do it: functional magnetic resonance urography in congenital anomalies of the kidney and urinary tract.

Abstract

Congenital anomalies of the kidney and urinary tract (CAKUT) are among the leading causes of chronic kidney disease in children. Early and accurate evaluation is essential to preserve nephron mass and guide appropriate management. Ultrasound represents the first-line imaging modality and acts as the gatekeeper for further diagnostic investigations, while vesicoureteral reflux should be evaluated with voiding cystourethrography or contrast-enhanced voiding urosonography. Functional magnetic resonance urography (functional MRU) is an advanced, non-ionizing "one-stop-shop" imaging technique that combines detailed anatomical assessment with quantitative functional evaluation. By using dynamic contrast-enhanced sequences and dedicated post-processing software, functional MRU enables comprehensive assessment of renal morphology, differential renal function, urinary drainage, excretory patterns, and urinary flow. Compared with renal scintigraphy, which has traditionally been used to evaluate split renal function and urinary drainage, functional MRU offers superior anatomical detail without exposing children to ionizing radiation. In pediatric practice, functional MRU has shown particular value in the assessment of CAKUT, especially in children with complex or bilateral anomalies, supporting surgical planning, treatment selection, and postoperative follow-up. Its ability to provide detailed functional characterization and longitudinal monitoring makes functional MRU a promising tool for personalized management. This review provides a practical guide for radiologists on the clinical applications of functional MRU in CAKUT evaluation.