title: Feasibility of multimodal deformable registration for head and neck tumor treatment planning.
abstract: OBJECTIVE
  To investigate the feasibility of using deformable registration in clinical practice to fuse MR and CT images of the head and neck for treatment planning.
  
  
  METHODS
  A state-of-the-art deformable registration algorithm was optimized, evaluated, and compared with rigid registration. The evaluation was based on manually annotated anatomic landmarks and regions of interest in both modalities. We also developed a multiparametric registration approach, which simultaneously aligns T1- and T2-weighted MR sequences to CT. This was evaluated and compared with single-parametric approaches.
  
  
  RESULTS
  Our results show that deformable registration yielded a better accuracy than rigid registration, without introducing unrealistic deformations. For deformable registration, an average landmark alignment of approximatively 1.7 mm was obtained. For all the regions of interest excluding the cerebellum and the parotids, deformable registration provided a median modified Hausdorff distance of approximatively 1 mm. Similar accuracies were obtained for the single-parameter and multiparameter approaches.
  
  
  CONCLUSIONS
  This study demonstrates that deformable registration of head-and-neck CT and MR images is feasible, with overall a significanlty higher accuracy than for rigid registration.
authors.affiliation: Biomedical Imaging Group Rotterdam, Department of Medical Informatics and Radiology, Erasmus MC University Medical Center, Rotterdam, The Netherlands. Electronic address: v.fortunati@erasmusmc.nl.
authors.forename: Valerio
authors.initials: V
authors.lastname: Fortunati
authors.affiliation: Hyperthermia Unit, Department of Radiation Oncology, Erasmus MC University Medical Center Cancer Institute, Rotterdam, The Netherlands.
authors.forename: René F
authors.initials: RF
authors.lastname: Verhaart
authors.affiliation: Istituto di Ricovero e Cura a Carattere Scientifico Foundation SDN for Research and High Education in Nuclear Diagnostics, Naples, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Angeloni
authors.affiliation: Department of Radiology, Erasmus MC University Medical Center, Rotterdam, The Netherlands.
authors.forename: Aad
authors.initials: A
authors.lastname: van der Lugt
authors.affiliation: Biomedical Imaging Group Rotterdam, Department of Medical Informatics and Radiology, Erasmus MC University Medical Center, Rotterdam, The Netherlands; Faculty of Applied Sciences, Delft University of Technology, Delft, The Netherlands.
authors.forename: Wiro J
authors.initials: WJ
authors.lastname: Niessen
authors.affiliation: Biomedical Imaging Group Rotterdam, Department of Medical Informatics and Radiology, Erasmus MC University Medical Center, Rotterdam, The Netherlands.
authors.forename: Jifke F
authors.initials: JF
authors.lastname: Veenland
authors.affiliation: Hyperthermia Unit, Department of Radiation Oncology, Erasmus MC University Medical Center Cancer Institute, Rotterdam, The Netherlands.
authors.forename: Margarethus M
authors.initials: MM
authors.lastname: Paulides
authors.affiliation: Biomedical Imaging Group Rotterdam, Department of Medical Informatics and Radiology, Erasmus MC University Medical Center, Rotterdam, The Netherlands.
authors.forename: Theo
authors.initials: T
authors.lastname: van Walsum
mesh_terms: D000465:Algorithms; D059925:Anatomic Landmarks / Q000000981:diagnostic imaging; D005240:Feasibility Studies; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000628:therapy*; D006801:Humans; D006979:Hyperthermia, Induced / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D064847:Multimodal Imaging / Q000379:methods*; D015588:Observer Variation; D056888:Patient Positioning / Q000379:methods; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D018709:Statistics, Nonparametric; D013813:Therapy, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*