title: Authors' reply.
authors.affiliation: University of Nebraska Medical Center, Omaha, Nebraska.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Porter
mesh_terms: D002983:Clinical Competence; D003287:Contrast Media; D004452:Echocardiography / Q000592:standards*; D006801:Humans; D017410:Practice Guidelines as Topic; D012955:Societies, Medical
chemical_list: D003287:Contrast Media