title: Evaluation of the air bronchogram sign on CT in solitary pulmonary lesions.
abstract: OBJECTIVE
  Our goal was to evaluate the presence and the significance of the air bronchogram sign in solitary pulmonary lesions (SPL) on CT.
  
  
  METHODS
  One hundred thirty-two patients with SPL who underwent chest CT scans and had histological diagnosis were studied retrospectively. We reviewed all chest CT scans to assess for the presence of the air bronchogram sign in the SPL and recorded the distribution of this sign in malignant and benign lesions. The morphology of the aerated bronchi in the lesion and its significance in differential diagnosis were also evaluated.
  
  
  RESULTS
  Of 17 cases of benign lesions, only 1 (5.9%) had an air bronchogram; of 115 lung cancers, 33 (28.7%) had this sign (p < 0.05). The encased bronchi exhibited four morphologic patterns: normal, tortuous, ectatic, and cut-off. The morphology of the bronchus in the benign lesion was normal. However, bronchi in malignant lesions displayed all four types of morphology. The air bronchogram sign was seen in all histologic types of lung cancer (squamous cell 10, adenocarcinoma 9, bronchioloalveolar cell 12, small cell 1, non-small cell 1). Lesions of different sizes were noted to have air bronchograms, including those < 2 cm in diameter.
  
  
  CONCLUSIONS
  The CT air bronchogram sign in SPL is significantly more common in malignant than in benign lesions. The sign is seen in all lung cancer cell types and demonstrates varied bronchial morphology.
authors.affiliation: Department of Radiology, University of Maryland Medical System, Baltimore 21201, USA.
authors.forename: M
authors.initials: M
authors.lastname: Kui
authors.forename: P A
authors.initials: PA
authors.lastname: Templeton
authors.forename: C S
authors.initials: CS
authors.lastname: White
authors.forename: Z L
authors.initials: ZL
authors.lastname: Cai
authors.forename: Y X
authors.initials: YX
authors.lastname: Bai
authors.forename: Y Q
authors.initials: YQ
authors.lastname: Cai
mesh_terms: D001995:Bronchography; D003937:Diagnosis, Differential; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging*; D008175:Lung Neoplasms / Q000000981:diagnostic imaging; D011029:Pneumoradiography; D012189:Retrospective Studies; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed