title: Letter from the guest editors.
authors.forename: Stephen C
authors.initials: SC
authors.lastname: O'Connor
authors.forename: Tara M
authors.initials: TM
authors.lastname: Catanzano
mesh_terms: D002648:Child; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D010372:Pediatrics / Q000379:methods*; D011829:Radiation Dosage; D014057:Tomography, X-Ray Computed / Q000379:methods*