title: Computerized segmentation and measurement of malignant pleural mesothelioma.
abstract: OBJECTIVE
  The current linear method to track tumor progression and evaluate treatment efficacy is insufficient for malignant pleural mesothelioma (MPM). A volumetric method for tumor measurement could improve the evaluation of novel treatments, but a fully manual implementation of volume measurement is too tedious and time-consuming. This manuscript presents a computerized method for the three-dimensional segmentation and volumetric analysis of MPM.
  
  
  METHODS
  The computerized MPM segmentation method segments the lung parenchyma and hemithoracic cavities to define the pleural space. Nonlinear diffusion and a k-means classifier are then implemented to identify MPM in the pleural space. A database of 31 computed tomography scans from 31 patients with pathologically confirmed MPM was retrospectively collected. Three observers independently outlined five randomly selected sections in each scan. The Jaccard similarity coefficient (J) between each of the observers and between the observer-defined and computer-defined segmentations was calculated. The computer-defined and the observer-defined segmentation areas (averaged over all observers) were both calculated for each axial section and compared using Bland-Altman plots.
  
  
  RESULTS
  The median J value among observers averaged over all sections was 0.517. The median J between the computer-defined and manual segmentations was 0.484. The difference between these values was not statistically significant. The area delineated by the computerized method demonstrated variability and bias comparable to the tumor area calculated from manual delineations.
  
  
  CONCLUSIONS
  A computerized method for segmentation and measurement of MPM was developed. This method requires minimal initialization by the user and demonstrated good agreement with manually drawn outlines and area measurements. This method will allow volumetric tracking of tumor progression and may improve the evaluation of novel MPM treatments.
authors.affiliation: Department of Radiology, The University of Chicago, 5841 South Maryland Avenue, Chicago, Illinois 60637, USA. wfsensak@uchicago.edu
authors.forename: William F
authors.initials: WF
authors.lastname: Sensakovic
authors.forename: Samuel G
authors.initials: SG
authors.lastname: Armato
authors.forename: Christopher
authors.initials: C
authors.lastname: Straus
authors.forename: Rachael Y
authors.initials: RY
authors.lastname: Roberts
authors.forename: Philip
authors.initials: P
authors.lastname: Caligiuri
authors.forename: Adam
authors.initials: A
authors.lastname: Starkey
authors.forename: Hedy L
authors.initials: HL
authors.lastname: Kindler
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D008654:Mesothelioma / Q000000981:diagnostic imaging*; D008875:Middle Aged; D010997:Pleural Neoplasms / Q000000981:diagnostic imaging*; D013902:Radiography, Thoracic; D015203:Reproducibility of Results; D012189:Retrospective Studies