Magnetic resonance imaging for the evaluation of hydronephrosis, reflux and renal scarring in children

Purpose: We studied the effectiveness of magnetic resonance imaging (MRI) f or evaluating hydronephrosis, differential renal function, vesicoureteral r eflux and renal scarring in children. Materials and Methods: A total of 16 patients with hydronephrosis were eval uated with MRI. Coronal T1 and axial TI and T2-weighted images were obtaine d before and after the administration of intravenous contrast material. Pat ients with vesicoureteral reflux underwent magnetic resonance voiding cysto urethrography. Differential renal function was estimated from differential parenchymal volumes determined from MRI using computer software. The result s were compared to standard imaging modalities. Results: A total of 19 MRI studies were performed in 16 patients, including 3 for ureteropelvic junction obstruction, 11 for vesicoureteral reflux and 2 for other conditions. MRI provided the best anatomic detail and clear co rticomedullary differentiation. MRI identified renal scar-ring and cortical thinning in 8 cases, while mercaptoacetyltriglycine 3 scans did not show a ny renal scarring and single photon emission computerized tomography-dimerc apto-succinic acid nuclear scans diagnosed only 4 of 5 cases. There was goo d correlation between differential function obtained from nuclear scans and differential parenchymal volumes obtained from MRI (correlation coefficien t 0.86, r(2) = 0.74). Magnetic resonance voiding cystourethrography diagnos ed reflux in 4 of 5 patients in whom vesicoureteral reflux was previously d ocumented by standard voiding cystourethrography. Conclusions: MRI provides an alternative for the evaluation of hydronephros is in children by combining the information provided by functional and anat omic nuclear scans, voiding cystourethrography and ultrasonography in a sin gle study without ionizing radiation. MRI appears to be as good as existing modalities in the evaluation of renal scarring and cortical thinning.