In a preliminary PET study involving 4 Wt1-Igf2 mice, delayed acquisition of PET images up to 3 h post 18F-FDG administration resulted in a significant clearance of 18F-FDG from the kidneys and “unmasking” of areas or radioactivity accumulation in the tumor tissue (Fig. 2). The gene discussed is WT1; the disease is neoplasm.