title: Imaging software accuracy for 3-dimensional analysis of the upper airway.
abstract: BACKGROUND
  The aim of this study was to compare the precision and accuracy of 6 imaging software programs for measuring upper airway volumes in cone-beam computed tomography data.
  
  
  METHODS
  The sample consisted of 33 growing patients and an oropharynx acrylic phantom, scanned with an i-CAT scanner (Imaging Sciences International, Hatfield, Pa). The known oropharynx acrylic phantom volume was used as the gold standard. Semi-automatic segmentations with interactive and fixed threshold protocols of the patients' oropharynx and oropharynx acrylic phantom were performed by using Mimics (Materialise, Leuven, Belgium), ITK-Snap (www.itksnap.org), OsiriX (Pixmeo, Geneva, Switzerland), Dolphin3D (Dolphin Imaging & Management Solutions, Chatsworth, Calif), InVivo Dental (Anatomage, San Jose, Calif), and Ondemand3D (CyberMed, Seoul, Korea) software programs. The intraclass correlation coefficient was used for the reliability tests. A repeated measurements analysis of variance (ANOVA) test and post-hoc tests (Bonferroni) were used to compare the software programs.
  
  
  RESULTS
  The reliability was high for all programs. With the interactive threshold protocol, the oropharynx acrylic phantom segmentations with Mimics, Dolphin3D, OsiriX, and ITK-Snap showed less than 2% errors in volumes compared with the gold standard. Ondemand3D and InVivo Dental had more than 5% errors compared with the gold standard. With the fixed threshold protocol, the volume errors were similar (-11.1% to -11.7%) among the programs. In the oropharynx segmentation with the interactive protocol, ITK-Snap, Mimics, OsiriX, and Dolphin3D were statistically significantly different (P <0.05) from InVivo Dental. No statistical difference (P >0.05) was found between InVivo Dental and OnDemand3D.
  
  
  CONCLUSIONS
  All 6 imaging software programs were reliable but had errors in the volume segmentations of the oropharynx. Mimics, Dolphin3D, ITK-Snap, and OsiriX were similar and more accurate than InVivo Dental and Ondemand3D for upper airway assessment.
authors.affiliation: Department of Orthodontics, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Brazil. andre5051@hotmail.com
authors.forename: André
authors.initials: A
authors.lastname: Weissheimer
authors.forename: Luciane Macedo de
authors.initials: LM
authors.lastname: Menezes
authors.forename: Glenn T
authors.initials: GT
authors.lastname: Sameshima
authors.forename: Reyes
authors.initials: R
authors.lastname: Enciso
authors.forename: John
authors.initials: J
authors.lastname: Pham
authors.forename: Dan
authors.initials: D
authors.lastname: Grauer
mesh_terms: D000704:Analysis of Variance; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D009960:Oropharynx / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D011873:Radiology Information Systems / Q000592:standards*; D012986:Software Validation; D018709:Statistics, Nonparametric