title: Main Pulmonary Artery-to-Ascending Aorta Diameter Ratio in Healthy Children on MDCT.
abstract: OBJECTIVE
  This study was performed to ascertain whether the adult ratio of 1:1 of the diameter of the main pulmonary artery (MPA) to the diameter of the ascending aorta (AA) (referred to hereafter as the MPA-to-AA ratio) on MDCT is applicable to children.
  
  
  METHODS
  Our hypothesis, which is based on experiential observation, is that the MPA-to-AA ratio would be higher than 1 in healthy children. A retrospective analysis of vessel calibers in a population of children without pulmonary hypertension who had undergone MDCT was performed.
  
  
  RESULTS
  The MPA-to-AA ratio was statistically significantly higher in children of all ages than in adults. We would, therefore, submit that the normal MPA-to-AA ratio in children on MDCT is greater than 1 and closer to 1.09.
  
  
  CONCLUSIONS
  The demonstration of an MPA segment that is slightly larger than the AA in children undergoing MDCT should not suggest a diagnosis of pulmonary arterial hypertension.
authors.affiliation: 1 Department of Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, ON, Canada.|2 Present address: Department of Radiology, Queensland X Ray, Mater Private Hospital, 21-37 Fulham Rd, Townsville, Queensland 4812, Australia.
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Compton
authors.affiliation: 1 Department of Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, ON, Canada.
authors.forename: Joshua
authors.initials: J
authors.lastname: Florence
authors.affiliation: 1 Department of Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, ON, Canada.
authors.forename: Cathy
authors.initials: C
authors.lastname: MacDonald
authors.affiliation: 1 Department of Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, ON, Canada.
authors.forename: Shi-Joon
authors.initials: SJ
authors.lastname: Yoo
authors.affiliation: 3 Department of Paediatrics, The Hospital for Sick Children, University of Toronto, ON, Canada.
authors.forename: Tilman
authors.initials: T
authors.lastname: Humpl
authors.affiliation: 1 Department of Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, ON, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Manson
mesh_terms: D000293:Adolescent; D001011:Aorta; D001027:Aortography / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011651:Pulmonary Artery / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: CT; pediatric; pulmonary hypertension