Diagnostic value of combined static-excretory MR Urography in children with hydronephrosis

The aim of this study was to determine the feasibility, accuracy and diagnostic potential of combined static-excretory MR Urography in children with sonographically detected hydronephrosis. We prospectively evaluated 28 children (11 girls and 17 boys), mean age 8.3 years (range 2 months-16 years). Static-excretory MR Urography was performed in all cases. The results of MR Urography were compared with the results of other imaging modalities, cystoscopy and surgery. In 28 children, 61 renal units were evaluated by MR Urography (the renal unit is the kidney and its draining ureter). The final diagnoses included: normal renal units (n = 23); uretropelvic junction obstruction (n = 14); megaureter (n = 8); midureteric stricture (n = 1), complicated duplicated systems (n = 5), post ESWL non-obstructive dilation (n = 2), extrarenal pelvis (n = 4), dysplastic kidney (n = 4). Complex pathology and more than one disease entity in were found in 7 children. The MRI diagnosis correlated with the final diagnosis in 57 units, with diagnostic accuracy 93.4%. In conclusions static and excretory MRU give both morphological and functional information in a single examination without exposure to ionizing radiation and iodinated contrast agent. It is a valuable imaging technique for children with upper urinary tract dilatation; especially in cases of complex congenital pathologies and severely hydronephrotic kidney.