title: Computer-aided segmentation and volumetry of artificial ground-glass nodules at chest CT.
abstract: OBJECTIVE
  The purpose of this study was to investigate a new software program for semiautomatic measurement of the volume and mass of ground-glass nodules (GGNs) in a chest phantom and to investigate the influence of CT scanner, reconstruction filter, tube voltage, and tube current.
  
  
  METHODS
  We used an anthropomorphic chest phantom with eight artificial GGNs with two different CT attenuations and four different volumes. CT scans were obtained with four models of CT scanner at 120 kVp and 25 mAs with a soft and a sharp reconstruction filter. On the 256-MDCT scanner, the tube current-exposure time product and tube voltage settings were varied. GGNs were measured with software that automatically segmented the nodules. Absolute percentage error (APE) was calculated for volume, mass, and density. Wilcoxon signed rank, Mann-Whitney U, and Kruskal-Wallis tests were used for analysis.
  
  
  RESULTS
  Volume and mass did not differ significantly from the true values. When measurements were expressed as APE, the error range was 2-36% for volume and 5-46% for mass, which was significantly different from no error. We did not find significant differences in APE between CT scanners with filters for lower tube current for volume or lower tube voltage for mass.
  
  
  CONCLUSIONS
  Computer-aided segmentation and mass and volume measurements of GGNs with the prototype software had promising results in this study.
authors.affiliation: Department of Radiology, University Medical Centre Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands. ethscholten@quicknet.nl
authors.forename: Ernst Th
authors.initials: ET
authors.lastname: Scholten
authors.forename: Colin
authors.initials: C
authors.lastname: Jacobs
authors.forename: Bram
authors.initials: B
authors.lastname: van Ginneken
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Willemink
authors.forename: Jan-Martin
authors.initials: JM
authors.lastname: Kuhnigk
authors.forename: Peter M A
authors.initials: PM
authors.lastname: van Ooijen
authors.forename: Matthijs
authors.initials: M
authors.lastname: Oudkerk
authors.forename: Willem P Th M
authors.initials: WP
authors.lastname: Mali
authors.forename: Pim A
authors.initials: PA
authors.lastname: de Jong
mesh_terms: D000465:Algorithms; D006801:Humans; D019047:Phantoms, Imaging; D011857:Radiographic Image Interpretation, Computer-Assisted; D012984:Software; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging*; D018709:Statistics, Nonparametric; D015898:Tomography Scanners, X-Ray Computed; D014057:Tomography, X-Ray Computed / Q000379:methods*