title: Pulmonary nodule size evaluation with chest tomosynthesis.
abstract: OBJECTIVE
  To evaluate intra- and interobserver variability, as well as agreement for nodule size measurements on chest tomosynthesis and computed tomographic (CT) images.
  
  
  METHODS
  The Regional Ethical Review Board approved this study, and all participants gave written informed consent. Thirty-six segmented nodules in 20 patients were included in the study. Eight observers measured the left-to-right, inferior-to-superior, and longest nodule diameters on chest tomosynthesis and CT images. Intra- and interobserver repeatability, as well as agreement between measurements on chest tomosynthesis and CT images, were assessed as recommended by Bland and Altman.
  
  
  RESULTS
  The difference between the mean manual and the segmented diameter was -2.2 and -2.3 mm for left-to-right and -2.6 and -2.2 mm for the inferior-to-superior diameter for measurements on chest tomosynthesis and CT images, respectively. Intraobserver 95% limits of agreement (LOA) for the longest diameter ranged from a lower limit of -1.1 mm and an upper limit of 1.0 mm to -1.8 and 1.8 mm for chest tomosynthesis and from -0.6 and 0.9 mm to -3.1 and 2.2 mm for axial CT. Interobserver 95% LOA ranged from -1.3 and 1.5 mm to -2.0 and 2.1 mm for chest tomosynthesis and from -1.8 and 1.1 mm to -2.2 and 3.1 mm for axial CT. The 95% LOA concerning the mean of the observers' measurements of the longest diameter at chest tomosynthesis and axial CT were ±2.1 mm (mean measurement error, 0 mm). For the different observers, the 95% LOA between the modalities ranged from -2.2 and 1.6 mm to -3.2 and 2.8 mm.
  
  
  CONCLUSIONS
  Measurements on chest tomosynthesis and CT images are comparable, because there is no evident bias between the modalities and the repeatability is similar. The LOA between measurements for the two modalities raise concern if measurements from chest tomosynthesis and CT were to be used interchangeably.
authors.affiliation: Department of Radiology, the Sahlgrenska Academy at University of Gothenburg, and Department of Radiology, Sahlgrenska University Hospital, Bruna Straket 11, SE-413 45 Gothenburg, Sweden. ase.johns-son@gregion.se
authors.forename: Åse A
authors.initials: ÅA
authors.lastname: Johnsson
authors.forename: Erika
authors.initials: E
authors.lastname: Fagman
authors.forename: Jenny
authors.initials: J
authors.lastname: Vikgren
authors.forename: Valeria A
authors.initials: VA
authors.lastname: Fisichella
authors.forename: Marianne
authors.initials: M
authors.lastname: Boijsen
authors.forename: Agneta
authors.initials: A
authors.lastname: Flinck
authors.forename: Susanne
authors.initials: S
authors.lastname: Kheddache
authors.forename: Angelica
authors.initials: A
authors.lastname: Svalkvist
authors.forename: Magnus
authors.initials: M
authors.lastname: Båth
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011857:Radiographic Image Interpretation, Computer-Assisted; D013902:Radiography, Thoracic; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging* / Q000556:secondary; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*