In vivo three-dimensional evaluation of the tracheobronchial tree.

Traditionally computed axial tomography has had limitations in evaluating diseases that affect the tracheobronchial tree because of respiratory-induced artifacts, with the likelihood of missing lesions as a result of misregistration. Spiral computed tomography (CT) differs from conventional CT in that the entire thorax can be rapidly imaged in the axial plane after a single breath-hold. Five patients underwent non-contrast-enhanced volumetric CT, with emphasis on three-dimensional reconstruction, and endoscopic evaluation with pathologic confirmation. In all cases, there was complete corroboration between volumetric CT and endoscopic evaluation. The use of selective thresholds allowed the air within the tracheobronchial tree to be used as a negative contrast agent. Thus with the integration of selective windowing, detailed three-dimensional tracheobronchial anatomy may be elucidated. The absence of respiratory registration artifact due to the single breath-hold technique raises the confidence that three-dimensional and multiplanar images generated from such studies are accurate representations of the pathologic conditions at hand. By the integration of volumetric CT techniques and rapid three-dimensional display of tracheobronchial structures, volumetric CT bronchography becomes practical.