title: Computer-assisted quantification of interstitial lung disease associated with rheumatoid arthritis: preliminary technical validation.
abstract: OBJECTIVE
  To validate a threshold-based prototype software application (MeVis PULMO 3D) for quantification of chronic interstitial lung disease (ILD) in patients with rheumatoid arthritis (RA) using variable threshold settings for segmentation of diseased lung areas.
  
  
  METHODS
  Twenty-two patients with rheumatoid arthritis were included and underwent thin-section CT (4x1.25mm collimation). CT scans were assessed by two observers for extent of ILD (EoILD), and twice by MeVis PULMO 3D for each protocol. MeVis PULMO 3D used four segmentation threshold (ST) settings (ST=-740, -780, -800 and -840HU). Pulmonary function tests were obtained in all patients. Statistical evaluation used 95% limits of agreement (LoA) and linear regression analysis.
  
  
  RESULTS
  There was total concordance between the software measurements. Interobserver agreement was good (LoA=-28.36 to 17.58%). EoILD by readers correlated strongly with DL(CO) (r=-0.702, p<0.0001) and moderately with FVC (r=-0.523, p=0.018). There was close correlation between readers and MeVis PULMO 3D with best results for ST <780HU (EoILD vs. MeVis PULMO 3D: r=0.650 for ST=-800 and -840HU, respectively; p=0.002). MeVis PULMO 3D correlated best with DL(CO) at ST of -800HU (r=-0.44, -0.49, -0.58 and -0.57 for ST=-740, -780, -800 and -840, respectively; p=0.007-0.05) and moderately with FVC (r=-0.44, -0.51, -0.59 and -0.45 for ST=-740, -780, -800 and -840), respectively; p=0.007-0.05).
  
  
  CONCLUSIONS
  The MeVis PULMO 3D system used holds promise to become a valuable instrument for quantification of chronic ILD in patients with RA when using the threshold value of -800HU, with evidence of the closest correlations, both with human observers and physiologic impairment.
authors: Department of Radiology, Georg August University of Göttingen, Robert-Koch-Strasse 40, Göttingen, Germany.
authors: K
authors: K
authors: Marten
authors: V
authors: V
authors: Dicken
authors: C
authors: C
authors: Kneitz
authors: M
authors: M
authors: Hoehmann
authors: W
authors: W
authors: Kenn
authors: D
authors: D
authors: Hahn
authors: C
authors: C
authors: Engelke
mesh_terms: D000465:Algorithms; D001172:Arthritis, Rheumatoid / Q000150:complications* / Q000000981:diagnostic imaging*; D001185:Artificial Intelligence; D005260:Female; D006801:Humans; D017563:Lung Diseases, Interstitial / Q000150:complications* / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D010363:Pattern Recognition, Automated / Q000379:methods*; D010865:Pilot Projects; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012984:Software; D012986:Software Validation