title: A problem of consent.
authors: John W
authors: JW
authors: Norris
mesh_terms: D002339:Carotid Arteries / Q000000981:diagnostic imaging*; D006801:Humans; D007258:Informed Consent / Q000941:ethics*; D020521:Stroke / Q000209:etiology; D017585:Ultrasonography, Doppler, Transcranial / Q000009:adverse effects / Q000941:ethics* / Q000379:methods*