title: How accurate is CT morphometry of airway? Phantom and clinical validation study.
abstract: OBJECTIVE
  To assess the reliability of CT airway measurement using phantom and to evaluate its reproducibility using clinical chest CT images.
  
  
  METHODS
  The phantom consisted of six tubes with different diameters and wall thicknesses was used. The wall area ratio (%WA) and wall thickness ratio (%WT) were calculated and the difference from the actual value (error ratio) was assessed. In vivo validation was performed with MDCT data of consecutive 10 patients and inter- and intra-rater agreements of the measurement were evaluated.
  
  
  RESULTS
  The error ratio of %WA and %WT increased for the phantom tube with a 1mm or thinner wall thickness. The FOV size has an influence on the airway measurement especially for the tube with 1mm wall thickness. Inter-rater reliabilities between two observers for %WA and %WT were excellent and good intra-class correlation coefficient for %WA and %WT were obtained as 0.825 and 0.811, respectively. Intra-rater reliabilities of measurement also showed good intra-class correlation coefficient for %WA and %WT as 0.822 and 0.800, respectively.
  
  
  CONCLUSIONS
  Although the phantom study showed there is a tendency to overestimate the wall area of an airway with a thickness 1mm or less, the software has a potential to be used in assessing longitudinal observation of the same patient, as well as, comparison among different patients due to good intra- and inter-rater reliability.
authors.affiliation: Department of Radiology, Shiga University of Medical Science, and Kusatsu General Hospital, Seta, Tsukinowa, Otsu, Shiga 520-2192, Japan. masashi@belle.shiga-med.ac.jp
authors.forename: Masashi
authors.initials: M
authors.lastname: Takahashi
authors.forename: Hiroki
authors.initials: H
authors.lastname: Okada
authors.forename: Naoko
authors.initials: N
authors.lastname: Oguni
authors.forename: Kiyosumi
authors.initials: K
authors.lastname: Maeda
authors.forename: Koji
authors.initials: K
authors.lastname: Segawa
authors.forename: Norihisa
authors.initials: N
authors.lastname: Nitta
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Murata
mesh_terms: D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*