3-DIMENSIONAL HELICAL CT OF THE TRACHEOBRONCHIAL TREE - EVALUATION OFIMAGING PROTOCOLS AND ASSESSMENT OF SUSPECTED STENOSES WITH BRONCHOSCOPIC CORRELATION

OBJECTIVE. To assess the accuracy of three-dimensional (3D) helical CT of normal airways, we evaluated different imaging protocols in test o bjects and patients, The clinical value of 3D helical CT was compared with bronchoscopy in patients with suspected stenoses, especially befo re and after endobronchial procedures. SUBJECTS AND METHODS. Solid tes t objects-one of central airways and one of peripheral airways-were sc anned and assessed for volume defects and stairstep artifacts. Fifty h elical studies were performed in 36 patients. We evaluated these image s for visualization of segmental bronchi, frequency of artifacts; and presence, localization, and degree of stenoses. Bronchoscopic correlat ion was available for 40 CT examinations. Follow-up 3D helical CT afte r endobronchial procedures was performed in nine patients. RESULTS. In test objects, thin sections reduced volume artifacts. Overlapping sec tions mainly diminished stairstep artifacts. In vivo, overlapping sect ions were superior to contiguous sections for good visualization of th e origin (96% versus 89%, p < .01) and of the course (75% versus 54%, p < .001) of segmental bronchi. Three-dimensional helical CT allowed u s to assess accurately 36 of 36 central stenoses that were seen on bro nchoscopy; however, on 3D helical CT, we missed two of three segmental stenoses. At bronchoscopy, 18 stenoses could not be passed, whereas 3 D helical CT provided details for possible endobronchial procedures: l ength of stenosis, patency (12/18), and spatial orientation of distal bronchi. Follow-up 3D helical CT documented the efficacy of endobronch ial treatment. CONCLUSION. Three-dimensional helical CT based on thin overlapping sections accurately visualized the normal airways down to the origin of the segmental bronchi and central stenoses. When it comp lements bronchoscopy, 3D helical CT allows visualization beyond stenos es. supports planning of endobronchial procedures, and may even substi tute for bronchoscopy after endobronchial procedures.