Bronchitis – The B6 Bronchus

History: 65 year old male with productive cough.

Frontal radiograph of the chest shows the bilateral B6 bronchi seen on end, with bronchial wall thickening, more so on the left, compatible with bronchitis.

This is a case of bronchitis. The bronchi seen on end near the hila are the B6 bronchi, which supply the superior segment of the lower lobes bilaterally. The B6 bronchi in the radiograph above are seen well because they are oriented perpindicular to the x-ray beam, and there is peribronchial cuffing/bronchial wall thickening indicating bronchitis. The B6 bronchus sign is usually an indicator of atelectasis or consolidation in the lung where an air bronchogram is seen in the B6 bronchus; however, this is not always true, as in the case above.