title: Automated delineation of brain structures in patients undergoing radiotherapy for primary brain tumors: from atlas to dose-volume histograms.
abstract: OBJECTIVE
  To implement and evaluate a magnetic resonance imaging atlas-based automated segmentation (MRI-ABAS) procedure for cortical and sub-cortical grey matter areas definition, suitable for dose-distribution analyses in brain tumor patients undergoing radiotherapy (RT).
  
  
  METHODS
  3T-MRI scans performed before RT in ten brain tumor patients were used. The MRI-ABAS procedure consists of grey matter classification and atlas-based regions of interest definition. The Simultaneous Truth and Performance Level Estimation (STAPLE) algorithm was applied to structures manually delineated by four experts to generate the standard reference. Performance was assessed comparing multiple geometrical metrics (including Dice Similarity Coefficient - DSC). Dosimetric parameters from dose-volume-histograms were also generated and compared.
  
  
  RESULTS
  Compared with manual delineation, MRI-ABAS showed excellent reproducibility [median DSCABAS=1 (95% CI, 0.97-1.0) vs. DSCMANUAL=0.90 (0.73-0.98)], acceptable accuracy [DSCABAS=0.81 (0.68-0.94) vs. DSCMANUAL=0.90 (0.76-0.98)], and an overall 90% reduction in delineation time. Dosimetric parameters obtained using MRI-ABAS were comparable with those obtained by manual contouring.
  
  
  CONCLUSIONS
  The speed, reproducibility, and robustness of the process make MRI-ABAS a valuable tool for investigating radiation dose-volume effects in non-target brain structures providing additional standardized data without additional time-consuming procedures.
authors.affiliation: Department of Advanced Biomedical Sciences, Federico II University School of Medicine, Naples, Italy; Institute of Biostructure and Bioimaging, National Research Council (CNR), Naples, Italy.
authors.forename: Manuel
authors.initials: M
authors.lastname: Conson
authors.affiliation: Department of Advanced Biomedical Sciences, Federico II University School of Medicine, Naples, Italy; Institute of Biostructure and Bioimaging, National Research Council (CNR), Naples, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Cella
authors.affiliation: Department of Advanced Biomedical Sciences, Federico II University School of Medicine, Naples, Italy; Institute of Biostructure and Bioimaging, National Research Council (CNR), Naples, Italy. Electronic address: roberto.pacelli@unina.it.
authors.forename: Roberto
authors.initials: R
authors.lastname: Pacelli
authors.affiliation: Institute of Biostructure and Bioimaging, National Research Council (CNR), Naples, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Comerci
authors.affiliation: Department of Advanced Biomedical Sciences, Federico II University School of Medicine, Naples, Italy; Institute of Biostructure and Bioimaging, National Research Council (CNR), Naples, Italy.
authors.forename: Raffaele
authors.initials: R
authors.lastname: Liuzzi
authors.affiliation: Department of Advanced Biomedical Sciences, Federico II University School of Medicine, Naples, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Salvatore
authors.affiliation: Department of Advanced Biomedical Sciences, Federico II University School of Medicine, Naples, Italy; Institute of Biostructure and Bioimaging, National Research Council (CNR), Naples, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Quarantelli
mesh_terms: D000465:Algorithms; D001921:Brain / Q000000981:diagnostic imaging; D001931:Brain Mapping / Q000379:methods*; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000532:radiotherapy*; D001270:Cervical Atlas / Q000000981:diagnostic imaging; D005260:Female; D005910:Glioma / Q000175:diagnosis* / Q000532:radiotherapy*; D066128:Gray Matter / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011829:Radiation Dosage; D011859:Radiography; D011874:Radiometry / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000379:methods; D015203:Reproducibility of Results
keywords: Atlas-based segmentation; Brain tumors; DVH; MRI; Radiotherapy