title: The anterior bronchus sign: a new clue to hilar abnormality.
abstract: One hundred normal posteroanterior chest radiographs were reviewed to determine the frequency of appearance and characteristics of the anterior segmental bronchi of the upper lobes. The bronchus was visible as a sharp circle on the right in 45% of normals, and on the left in 50%. In 90% of normals, there is less than 3 mm of tissue lateral to the bronchus. In 10% of normals, pulmonary vessels may cause 3-5 mm of tissue lateral to the bronchus. Four cases of bronchogenic carcinoma were found to have more than 5 mm of tissue lateral to the bronchus. The presence of more than 5 mm of tissue lateral to the anterior segmental bronchus is termed the "anterior bronchus sign" and is a helpful clue to recognizing hilar region abnormality.
mesh_terms: D001980:Bronchi; D002283:Carcinoma, Bronchogenic / Q000000981:diagnostic imaging; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging; D013902:Radiography, Thoracic