Value of Air Bronchogram Sign on CT in Diagnosis of Small Peripheral Lung Cancers

Objective:To study the pathology,the CT signs and the diagnostic value of the air bronchogram sign in small peripheral lung cancers.Methods:Forty-six patients with small peripheral lung cancer and twenty-two with solitary benign nodule undergone chest CT scans and with histological diagnosis were studied retrospectively.Results:Of 46 lung cancers,20 cases (43.5%) had air bronchogram.The frequency of this sign in various types of lung cancer was as follows:adenocarcinoma 17 of 31(54.8%);alveolar carcinoma 2 of 6; squamous cell carcinoma 1 of 5. This sign was not seen in other types of lung cancer.In these cases the bronchi mainly exhibited four morphologic patterns:irregular stenosis,tortuo- sity, ectasia and cut-off.Of 22 cases of benign lesions,only 1 (4.5%) had air bronchogram sign and the morphology of the bronchus was normal.Conclusion:The CT air bronchogram sign in solitary pulmonary nodules (SPN),especially the morphologic changes have important diagnostic values for evaluation of small peripheral lung cancer.