title: Classification of fibroglandular tissue distribution in the breast based on radiotherapy planning CT.
abstract: BACKGROUND
  Accurate segmentation of breast tissues is required for a number of applications such as model based deformable registration in breast radiotherapy. The accuracy of breast tissue segmentation is affected by the spatial distribution (or pattern) of fibroglandular tissue (FT). The goal of this study was to develop and evaluate texture features, determined from planning computed tomography (CT) data, to classify the spatial distribution of FT in the breast.
  
  
  METHODS
  Planning CT data of 23 patients were evaluated in this study. Texture features were derived from the radial glandular fraction (RGF), which described the distribution of FT within three breast regions (posterior, middle, and anterior). Using visual assessment, experts grouped patients according to FT spatial distribution: sparse or non-sparse. Differences in the features between the two groups were investigated using the Wilcoxon rank test. Classification performance of the features was evaluated for a range of support vector machine (SVM) classifiers.
  
  
  RESULTS
  Experts found eight patients and 15 patients had sparse and non-sparse spatial distribution of FT, respectively. A large proportion of features (>9 of 13) from the individual breast regions had significant differences (p <0.05) between the sparse and non-sparse group. The features from middle region had most significant differences and gave the highest classification accuracy for all the SVM kernels investigated. Overall, the features from middle breast region achieved highest accuracy (91%) with the linear SVM kernel.
  
  
  CONCLUSIONS
  This study found that features based on radial glandular fraction provide a means for discriminating between fibroglandular tissue distributions and could achieve a classification accuracy of 91%.
authors.affiliation: North Sydney Cancer Center, Royal North Shore Hospital, Sydney, Australia.|Institute of Medical Physics, School of Physics, University of Sydney, Sydney, Australia.|Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, UK.
authors.forename: Prabhjot
authors.initials: P
authors.lastname: Juneja
authors.affiliation: Centre for Vision Speech and Signal Processing, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, UK.
authors.forename: Philip
authors.initials: P
authors.lastname: Evans
authors.affiliation: Centre for Vision Speech and Signal Processing, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, UK.
authors.forename: David
authors.initials: D
authors.lastname: Windridge
authors.affiliation: Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, UK. Emma.Harris@icr.ac.uk.
authors.forename: Emma
authors.initials: E
authors.lastname: Harris
mesh_terms: D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D060388:Support Vector Machine; D014018:Tissue Distribution; D014057:Tomography, X-Ray Computed / Q000379:methods*