title: Circular air-filled space in the aortic knob: a rare radiologic finding.
authors.forename: Magdy M
authors.initials: MM
authors.lastname: El-Sayed Ahmed
authors.forename: Muhammad
authors.initials: M
authors.lastname: Aftab
authors.forename: Kim I
authors.initials: KI
authors.lastname: de la Cruz
authors.forename: Reynolds M
authors.initials: RM
authors.lastname: Delgado
authors.forename: Hari R
authors.initials: HR
authors.lastname: Mallidi
mesh_terms: D000368:Aged; D000388:Air; D001011:Aorta; D004868:Equipment Failure; D016027:Heart Transplantation / Q000009:adverse effects; D006801:Humans; D007423:Intra-Aortic Balloon Pumping / Q000295:instrumentation*; D008297:Male; D011859:Radiography; D012770:Shock, Cardiogenic / Q000000981:diagnostic imaging / Q000209:etiology / Q000628:therapy*