title: Spiral CT scanning technique in the detection of aspiration of LEGO foreign bodies.
abstract: BACKGROUND
  Radiolucent foreign bodies (FBs) such as plastic objects and toys remain difficult to identify on conventional radiographs of the neck and chest. Children may present with a variety of respiratory complaints, which may or may not be due to a FB.
  
  
  OBJECTIVE
  To determine whether radiolucent FBs such as plastic LEGOs and peanuts can be seen in the tracheobronchial tree or esophagus using low-dose spiral CT, and, if visible, to determine the optimal CT imaging technique.
  
  
  METHODS
  Multiple spiral sequences were performed while varying the CT parameters and the presence and location of FBs in either the trachea or the esophagus first on a neck phantom and then a cadaver. Sequences were rated by three radiologists blinded to the presence of a FB using a single scoring system.
  
  
  RESULTS
  The LEGO was well visualized in the trachea by all three readers (both lung and soft-tissue windowing: combined sensitivity 89 %, combined specificity 89 %) and to a lesser extent in the esophagus (combined sensitivity 31 %, combined specificity 100 %). The peanut was not well visualized (combined sensitivity < 35 %). The optimal technique for visualizing the LEGO was 120 kV, 90 mA, 3-mm collimation, 0.75 s/revolution, and 2.0 pitch. This allowed for coverage of the cadaver tracheobronchial tree (approximately 11 cm) in about 18 s. Although statistical power was low for detecting significant differences, all three readers noted higher average confidence ratings with lung windowing among 18 LEGO-in-trachea scans.
  
  
  CONCLUSIONS
  Rapid, low-dose spiral CT may be used to visualize LEGO FBs in the airway or esophagus. Peanuts were not well visualized.
authors.affiliation: Department of Radiology, Cleveland Clinic Foundation, 11 106 Euclid Avenue, Cleveland, OH 44196, USA. kiappleg@iupui.edu
authors.forename: K E
authors.initials: KE
authors.lastname: Applegate
authors.forename: J T
authors.initials: JT
authors.lastname: Dardinger
authors.forename: M L
authors.initials: ML
authors.lastname: Lieber
authors.forename: B R
authors.initials: BR
authors.lastname: Herts
authors.forename: W J
authors.initials: WJ
authors.lastname: Davros
authors.forename: N A
authors.initials: NA
authors.lastname: Obuchowski
authors.forename: A
authors.initials: A
authors.lastname: Maneker
mesh_terms: D010367:Arachis; D002102:Cadaver; D004947:Esophagus / Q000000981:diagnostic imaging*; D005260:Female; D005547:Foreign Bodies / Q000175:diagnosis / Q000000981:diagnostic imaging*; D006801:Humans; D019047:Phantoms, Imaging; D010988:Play and Playthings; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014132:Trachea / Q000000981:diagnostic imaging*