title: Assessment of airways with three-dimensional quantitative thin-section CT: in vitro and in vivo validation.
abstract: OBJECTIVE
  To prospectively validate the ability of customized three-dimensional (3D) software to enable bronchial tree skeletonization, orthogonal reconstruction of the main bronchial axis, and measurement of cross-sectional wall area (WA) and lumen area (LA) of any visible bronchus on thin-section computed tomographic (CT) images.
  
  
  METHODS
  Institutional review board approval and patient agreement and informed consent were obtained. Software was validated in a phantom that consisted of seven tubes and an excised human lung obtained and used according to institutional guidelines. In vivo validation was performed with multi-detector row CT in six healthy subjects (mean age, 47 years; range, 20-55 years). Intra- and interobserver agreement and reproducibility over time for bronchial tree skeletonization were evaluated with Bland-Altman analysis. Concordance in identifying bronchial generation was assessed with the kappa statistic. WA and LA obtained with the manual method were compared with WA and LA obtained with validated software by means of the Wilcoxon test and Bland-Altman analysis.
  
  
  RESULTS
  WA and LA measurements in the phantom were reproducible over multiple sessions (P > .90) and were not significantly different from WA and LA assessed with the manual method (P > .62). WA and LA measurements in the excised lung and the subjects were not different from measurements obtained with the manual method (intraclass correlation coefficient > 0.99). All lobar bronchi and 80.8% of third generation bronchi, 72.5% of fourth generation bronchi, and 37.7% of fifth generation bronchi were identified in vivo. Intra- and interobserver agreement and reproducibility over time for airway skeletonization and concordance in identifying bronchial generation were good to excellent (intraclass correlation coefficient > 0.98, kappa > 0.54, respectively).
  
  
  CONCLUSIONS
  This method enables accurate and reproducible measurement of WA and LA on reformatted CT sections perpendicular to the main axis of bronchi visible on thin-section CT scans.
authors.affiliation: Laboratory of Cellular Respiratory Physiology, Université Bordeaux 2, Bordeaux, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Montaudon
authors.forename: Patrick
authors.initials: P
authors.lastname: Berger
authors.forename: Gabriel
authors.initials: G
authors.lastname: de Dietrich
authors.forename: Achille
authors.initials: A
authors.lastname: Braquelaire
authors.forename: Roger
authors.initials: R
authors.lastname: Marthan
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Tunon-de-Lara
authors.forename: François
authors.initials: F
authors.lastname: Laurent
mesh_terms: D000328:Adult; D019412:Anatomy, Cross-Sectional; D001980:Bronchi / Q000033:anatomy & histology*; D001995:Bronchography / Q000379:methods*; D003198:Computer Simulation; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D019047:Phantoms, Imaging; D011446:Prospective Studies; D011856:Radiographic Image Enhancement; D012984:Software; D012986:Software Validation; D014057:Tomography, X-Ray Computed / Q000379:methods*