title: Cost function evaluation for the registration of clinical DTI images onto the ICBM DTI81 white matter atlas.
abstract: OBJECTIVE
  Various algorithms are available for the analysis of diffusion tensor (DTI) images. Many of these stand alone software packages require time-intensive user interactions not yet suited for routine clinical application Here, we demonstrate the use of the 'Analysis of Functional NeuroImages' (AFNI) software package, a standard for the analysis of functional magnetic resonance images (fMRI), to automatically align clinical DTI images onto the ICBM DTI81 atlas potentially enabling the combined presentation of fMRI and DTI results.
  
  
  METHODS
  Fractional anisotropy (FA) maps from seven patients diagnosed with video/EEG defined complex partial seizures were retrospectively analyzed. Affine transformations parameters for seven different cost functions provided by the 3dAllineate software tool were calculated. Alignment quality and variations of the transformation parameters were assessed.
  
  
  RESULTS
  Best alignment between the FA maps for each subject and the ICBM DTI81 atlas was achieved with cost functions utilizing the cost ratio (CR) (symmetrized* CR, symmetrized+ CR and unsymmetrized CR). Symmetrized* CR performed slightly better, in particular for lateral white matter structures. Relatively small variations in the transformation parameters emphasize the robustness of the transformations.
  
  
  CONCLUSIONS
  Good alignment of FA maps to the ICBM DTI81 white matter atlas can be achieved using an automated affine transformation with software tools provided by AFNI potentially enabling the combined presentation of fMRI and DTI information. This procedure maybe readily be applied in clinical practice.
authors.affiliation: The Methodist Hospital Neurological Institute, Houston, TX, USA. ckarmonik@tmhs.org
authors.forename: Christof
authors.initials: C
authors.lastname: Karmonik
authors.forename: Mario
authors.initials: M
authors.lastname: Dulay
authors.forename: Amit
authors.initials: A
authors.lastname: Verma
authors.forename: Robert G
authors.initials: RG
authors.lastname: Grossman
mesh_terms: D001271:Atlases as Topic; D001931:Brain Mapping / Q000379:methods*; D056324:Diffusion Tensor Imaging / Q000191:economics* / Q000379:methods*; D004569:Electroencephalography; D017029:Epilepsy, Complex Partial / Q000175:diagnosis*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D012189:Retrospective Studies