Delayed 18F-FDG PET (3-h post 18F-FDG administration) and dual-contrast CT (intravenous and intraperitoneal contrast) provided a more accurate anatomic and metabolic characterization of Wilms tumors in Wt1-Igf2 mice during early development and progression of renal tumors. This evidence concerns the gene WT1 and Nephroblastoma.