title: Post-lung transplantation bronchiolitis obliterans syndrome: usefulness of expiratory thin-section CT for diagnosis.
abstract: OBJECTIVE
  To assess the usefulness of thin-section expiratory computed tomography (CT), as compared with that of thin-section inspiratory CT, in detecting airway obstruction and air trapping in pediatric lung transplant recipients with bronchiolitis obliterans syndrome (BOS).
  
  
  METHODS
  Thin-section CT scans were obtained at full inspiration and end expiration in 21 pediatric lung transplant recipients with proved BOS and in 41 transplant recipients with normal airways. True diagnosis was based on pulmonary function test results. Inspiration CT scans were scored for extent of decreased attenuation of the lung parenchyma; expiration CT scans were scored for extent of air trapping.
  
  
  RESULTS
  The sensitivity of inspiratory CT for enabling diagnosis of BOS was 71%; the specificity, 78%; the positive predictive value, 62%; and the negative predictive value, 84%. The sensitivity of expiratory CT for enabling diagnosis of BOS was 100%; the specificity, 71%; the positive predictive value, 64%; and the negative predictive value, 100%. Expiratory CT scores correlated more strongly (rho = 0.75, P <.01) with pulmonary function test-based scores than did inspiratory CT scores (rho = 0.48, P <.01). Nominal logistic regression analysis revealed that expiratory CT was a more powerful predictor of true diagnosis (P <.01) than was inspiratory CT (P =.10).
  
  
  CONCLUSIONS
  Expiratory CT is sensitive for depicting BOS-related airway abnormalities and may be more useful than inspiratory CT for diagnosis of small airway obstruction.
authors.affiliation: Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S Kingshighway Blvd, St Louis, MO 63110, USA. siegelm@mir.wustl.edu
authors.forename: M J
authors.initials: MJ
authors.lastname: Siegel
authors.forename: S
authors.initials: S
authors.lastname: Bhalla
authors.forename: F R
authors.initials: FR
authors.lastname: Gutierrez
authors.forename: C
authors.initials: C
authors.lastname: Hildebolt
authors.forename: S
authors.initials: S
authors.lastname: Sweet
mesh_terms: D000293:Adolescent; D001989:Bronchiolitis Obliterans / Q000000981:diagnostic imaging*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D016040:Lung Transplantation; D008297:Male; D011183:Postoperative Complications / Q000000981:diagnostic imaging; D012044:Regression Analysis; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013577:Syndrome; D014057:Tomography, X-Ray Computed / Q000379:methods*