title: The effect of left-sided versus right-sided contrast infusion on attenuation of the main pulmonary artery when performing computed tomography angiograms of the chest.
abstract: OBJECTIVE
  This study assesses if the arm of contrast infusion influences attenuation of the main pulmonary artery in computed tomography (CT) angiograms to evaluate for pulmonary emboli.
  
  
  METHODS
  Four hundred seven consecutive CT angiograms performed to exclude pulmonary emboli were reviewed. Patient characteristics, study details, and interpretation results were collected. After exclusion criteria, 100 studies from each scanner (4, 16, and 64 slice) remained. A reader, blinded to injection side, measured the attenuation of the main pulmonary artery.
  
  
  RESULTS
  The average attenuation in the main pulmonary artery was similar if infused through the right (275.4 HU) or left (275.0 HU) arm when controlling for confounders with a multiple regression analysis (P = 0.82). There was no statistical difference (P > 0.05) in the number of scans with attenuation less than 250 (45.9% right, 42.9% left), 200 (25.3% right, 29.2% left), or 150 HU (11.6% right, 12.3% left) and interpreted as indeterminate (1.4% right, 3.9% left) or nondiagnostic (2.7% right, 2.6% left).
  
  
  CONCLUSIONS
  Main pulmonary artery attenuation is independent of the arm of infusion when evaluating mean attenuation, attenuation beneath 250, 200, or 150 HU, or indeterminate or nondiagnostic interpretations for patients undergoing CT angiograms of the chest to rule out pulmonary emboli.
authors.affiliation: Department of Diagnostic Radiology, Yale School of Medicine, New Haven, CT, USA. lars.grimm@gmail.com
authors.forename: Lars J
authors.initials: LJ
authors.lastname: Grimm
authors.forename: Daniel
authors.initials: D
authors.lastname: Cornfeld
authors.forename: Hamid R
authors.initials: HR
authors.lastname: Mojibian
mesh_terms: D001132:Arm / Q000098:blood supply*; D015331:Cohort Studies; D003287:Contrast Media; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D007472:Iohexol; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000000981:diagnostic imaging*; D011856:Radiographic Image Enhancement / Q000379:methods*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol