WILMS-TUMOR AND NEPHROBLASTOMATOSIS - IMAGING CHARACTERISTICS AT GADOLINIUM-ENHANCED MR-IMAGING

Twelve children with Wilms tumors were prospectively evaluated with 1. 5-T magnetic resonance (MR) imaging. Spin-echo images were obtained be fore and after administration of gadopentetate dimeglumine. Nine of th e 12 children had histologically proved nephroblastomatosis or nephrog enic rests involving a total of 14 kidneys. MR imaging depicted involv ement in eight of these kidneys, including five of five kidneys with l esions contralateral to the primary Wilms tumor. Overall sensitivity o f detection of nephrogenic rests was 43% on nonenhanced images and 58% when gadolinium-enhanced images were added. Nephrogenic rests admixed with Wilms tumors less than 4 mm in diameter were not depicted at MR imaging. On gadolinium-enhanced T1-weighted images, Wilms tumors and n ephrogenic rests were hypointense to normal renal tissue. On T2-weight ed images, Wilms tumors and hyperplastic nephrogenic rests were iso- o r slightly hyperintense to renal cortex, while sclerotic nephrogenic r ests were hypointense to renal cortex. On all images, including gadoli nium-enhanced T1-weighted images, the signal intensity of Wilms tumors was inhomogeneous, while the signal intensity of nephrogenic rests wa s homogeneous.