1. From the Department of Clinical Radiology, Great Ormond Street Hospital, London, England (S.C.S.); Departments of Urology (A.J.L.), Oncology (A.A.G.), and Diagnostic Imaging (G.B.C.), The Hospital for Sick Children, 555 University Ave, Toronto, ON, Canada M5G 1X8; and Department of Medical Imaging, University of Toronto, Toronto, Ont, Canada (G.B.C.).