title: Bronchiolitis obliterans after lung transplantation: detection using expiratory HRCT.
abstract: OBJECTIVE
  The objective of this study was to determine if air trapping, as detected on expiratory high-resolution CT (HRCT), is useful as an indicator of bronchiolitis obliterans (BO) in lung transplant recipients.
  
  
  METHODS
  Corresponding inspiratory and expiratory HRCT images at five different levels and spirometry were obtained in 21 lung transplant recipients. Eleven patients had BO proved by transbronchial biopsy specimens; the remaining 10 patients had no pathologic or functional evidence of airways disease. Two "blinded" observers assessed the inspiratory images for the presence of bronchiectasis and mosaic pattern of lung attenuation, and the expiratory images for presence and extent of air trapping. Statistical comparison of the frequency of HRCT findings between patients with and without BO was performed using Fisher's Exact Test.
  
  
  RESULTS
  On inspiratory images, bronchiectasis and mosaic pattern of lung attenuation were present in 4 (36%) and 7 (64%) of 11 patients with BO, and 2 (20%) and 1 (10%) of 10 patients without BO (p>0.05 and p<0.05), respectively. The sensitivity, specificity, and accuracy of bronchiectasis and mosaic pattern for BO were 36%, 80%, and 57%, and 64%, 90%, and 70%, respectively. On expiratory images, air trapping was found in 10 of 11 (91%) patients with BO compared to 2 of 10 (20%) patients without BO (p<0.002). Air trapping was found to have a sensitivity of 91%, specificity of 80%, and accuracy of 86% for BO. Air trapping was identified in one patient with BO who had normal results of baseline spirometric function tests.
  
  
  CONCLUSIONS
  Air trapping, as detected on expiratory HRCT, was the most sensitive and accurate radiologic indicator of BO in the lung transplant population.
authors.affiliation: Department of Radiology, Stanford University Medical Center, Calif 94305-5105, USA.
authors.forename: A N
authors.initials: AN
authors.lastname: Leung
authors.forename: K
authors.initials: K
authors.lastname: Fisher
authors.forename: V
authors.initials: V
authors.lastname: Valentine
authors.forename: R E
authors.initials: RE
authors.lastname: Girgis
authors.forename: G J
authors.initials: GJ
authors.lastname: Berry
authors.forename: R C
authors.initials: RC
authors.lastname: Robbins
authors.forename: J
authors.initials: J
authors.lastname: Theodore
mesh_terms: D000328:Adult; D000388:Air; D001706:Biopsy; D001987:Bronchiectasis / Q000000981:diagnostic imaging / Q000209:etiology; D001989:Bronchiolitis Obliterans / Q000000981:diagnostic imaging* / Q000209:etiology / Q000473:pathology; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D001239:Inhalation; D008168:Lung / Q000000981:diagnostic imaging; D016040:Lung Transplantation / Q000009:adverse effects; D008297:Male; D008450:Maximal Midexpiratory Flow Rate; D008875:Middle Aged; D015588:Observer Variation; D011856:Radiographic Image Enhancement / Q000379:methods; D012119:Respiration; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D013147:Spirometry; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014797:Vital Capacity