title: Lateral decubitus HRCT: a simple technique to replace expiratory CT in children with air trapping.
abstract: OBJECTIVE
  To evaluate the effectiveness of lateral decubitus high-resolution CT (HRCT) in detecting air trapping in children.
  
  
  METHODS
  HRCT scans of 21 children with heterogeneous lung attenuation caused by air trapping (n = 10) or with infiltrative lung disease (n = 11) were reviewed retrospectively. The air-trapping disease included bronchiolitis obliterans (n = 7), bronchial obstruction due to mediastinal lymphoma (n = 1), endobronchial haemangioma (n = 1) and foreign body aspiration (n = 1). HRCT was performed in both lateral decubitus positions as well as the supine position. The attenuation (Hounsfield units; HU) was measured in both the hypo- and adjacent hyper-attenuating areas of the heterogeneous lung portion, and the difference of attenuation between these two areas was calculated in the supine and both lateral decubitus scans, respectively. The attenuation differences of the three scans were compared in each group.
  
  
  RESULTS
  The attenuation difference was larger in the ipsilateral decubitus (207.95 +/- 105.24 HU) scans than in the contralateral (121.25 +/- 90.05 HU) or supine (162 +/- 94.01 HU) scans in the air-trapping group (P < 0.05). There were no significant differences among the three scans in the infiltrative lung disease group (P > 0.05).
  
  
  CONCLUSIONS
  Lateral decubitus HRCT is an effective adjunct to standard HRCT in the evaluation of air trapping as a cause of mosaic lung attenuation in uncooperative paediatric patients.
authors.affiliation: Department of Diagnostic Radiology, Asan Medical Centre, University of Ulsan College of Medicine, Seoul, South Korea.
authors.forename: Soo-Jung
authors.initials: SJ
authors.lastname: Choi
authors.forename: Byeong-Kyoo
authors.initials: BK
authors.lastname: Choi
authors.forename: Hyeon Joo
authors.initials: HJ
authors.lastname: Kim
authors.forename: Soo Hyun
authors.initials: SH
authors.lastname: Lee
authors.forename: Seong Hoon
authors.initials: SH
authors.lastname: Choi
authors.forename: Sang Joon
authors.initials: SJ
authors.lastname: Park
authors.forename: Hyun Woo
authors.initials: HW
authors.lastname: Goo
authors.forename: Jin Seong
authors.initials: JS
authors.lastname: Lee
authors.forename: Chong Hyun
authors.initials: CH
authors.lastname: Yoon
mesh_terms: D000402:Airway Obstruction / Q000000981:diagnostic imaging / Q000209:etiology; D001984:Bronchial Neoplasms / Q000150:complications; D001989:Bronchiolitis Obliterans / Q000000981:diagnostic imaging; D002648:Child; D002675:Child, Preschool; D005260:Female; D005547:Foreign Bodies / Q000150:complications; D006391:Hemangioma / Q000150:complications; D006801:Humans; D007223:Infant; D008168:Lung / Q000000981:diagnostic imaging*; D008171:Lung Diseases / Q000000981:diagnostic imaging*; D008223:Lymphoma / Q000150:complications; D008297:Male; D008479:Mediastinal Neoplasms / Q000150:complications; D011014:Pneumonia / Q000000981:diagnostic imaging; D012119:Respiration; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*