Grading Airway Stenosis Down to the Segmental Level Using Virtual Bronchoscopy: CT Scan Image Analysis

Grading Airway Stenosis Down to the Segmental Level Using Virtual Bronchoscopy: CT Scan Image AnalysisTable 1 shows the anatomic classification of the tracheobronchial tree, which was divided into 27 regions (9 central airway regions and 18 segmental airway regions). For image analysis, a virtual bronchoscopic fly-through of the tracheobronchial tree was performed in a central-to-peripheral direction by a fully board-certified radiologist specializing in chest radiology. For optimal orientation within the tracheobronchial tree and evaluation of the surrounding structures, virtual bronchoscopy was performed in the multiview mode in combination with dynamic axial and multiplanar reformatted imaging. The time for image analysis of a single patient ranged from 15 to 45 min. CT image analysis was performed in random order, and was blinded to flexible bronchoscopic findings and clinical history. Virtual bronchoscopy was evaluated using a flowsheet that listed all airways to the segmental level. For each airway region, the estimated grade of stenosis was recorded using a 3-point scale as follows: grade 0, no stenosis; grade 1, luminal narrowing of < 50%; or grade 2, luminal narrowing of > 50%.
Flexible Bronchoscopy
Flexible bronchoscopy was performed by a board-certified pulmonologist using a videobronchoscope (BF-1T200; Olympus Optical; Tokyo, Japan) under local anesthesia. The procedure time for bronchoscopy was about 30 min. The pulmonologist performing the procedure prospectively recorded the percentage of bronchial narrowing at all sites independent of CT scan data. Virtual bronchoscopic CT scan simulations of the airways were not available prior to flexible bronchoscopy, not directing the pulmonologist to particular areas of interest. Endobronchial photographs were obtained at stenotic sites. The presence and location of endoluminal mucus was routinely recorded on bronchoscopy reports. In retrospect, bronchoscopy reports were reviewed in random order without knowledge of the CT findings and clinical history, and for reasons of compatibility the grading of tracheobronchial narrowing was categorized as for virtual bronchoscopy using a 3-point scale as follows: grade 0, no stenosis; grade 1, luminal narrowing of < 50%; or grade 2, luminal narrowing of 50% or more.
Table 1—Anatomic Classification of the Central and Segmental Airways

Central Airways Segmental Airways
Trachea
Right main bronchus
Right upper lobe bronchus Apical segmental bronchus B I
Posterior segmental bronchus B II
Anterior segmental bronchus B III
Intermediate bronchus
Middle lobe bronchus Lateral segmental bronchus B IV
Medial segmental bronchus B V
Right lower lobe bronchus Superior segmental bronchus B VI
Medial basal segmental bronchus B VII
Anterior basal segmental bronchus B VIII
Lateral basal segmental bronchus B IX
Posterior basal segmental bronchus B X
Left main bronchus
Left upper lobe bronchus Apicoposterior segmental bronchus B I/II
Anterior segmental bronchus B III
Superior lingular bronchus B IV
Inferior lingular bronchus B V
Left lower lobe bronchus Superior segmental bronchus B VI
Anterior basal segmental bronchus B VIII
Lateral basal segmental bronchus B IX
Posterior basal segmental bronchus B X
anosiahuman.com