title: Atlas-based versus individual-based fiber tracking of the corpus callosum in patients with multiple sclerosis: reliability and clinical correlations.
abstract: OBJECTIVE
  In multiple sclerosis (MS), the presence of lesions and normal-appearing white matter damage may affect the reliability of diffusion tensor (DT) magnetic resonance imaging (MRI)-based tractography. We compared the performance of an individual-based method for corpus callosum (CC) fiber tracking in MS with those of two atlas-based methods.
  
  
  METHODS
  Brain DT MRI scans were acquired from 35 patients with MS and 18 age-matched healthy volunteers (HV). DT-derived metrics from the CC-the mean diffusivity (MD) and fractional anisotropy (FA)-were calculated using an individual-based and two atlas-based methods with different types of subject registration (linear and nonlinear) to a CC atlas. Customized termination criteria were applied to stop the tracking algorithm when using the individual-based method.
  
  
  RESULTS
  All the methods were able to distinguish between MS patients and HV. Using the individual-based method, stronger relationships were found between CC DT-derived metrics and the subjects' clinical condition.
  
  
  CONCLUSIONS
  CC DT tractography using an individual-based method is more sensitive than the atlas-based ones to tract-specific alterations related to MS disability. An atlas-based method with nonlinear registration can be a valid alternative when an automated postprocessing is warranted, such as in the case of high volumes of data.
authors.affiliation: Department of Biomedical Engineering, Politecnico di Milano, Milan, Italy.
authors.forename: Maria Marcella
authors.initials: MM
authors.lastname: Laganà
authors.forename: Antonia
authors.initials: A
authors.lastname: Ceccarelli
authors.forename: Maria Giulia
authors.initials: MG
authors.lastname: Preti
authors.forename: Chiara
authors.initials: C
authors.lastname: Venturelli
authors.forename: Maria Pia
authors.initials: MP
authors.lastname: Sormani
authors.forename: Rosella
authors.initials: R
authors.lastname: Cavarretta
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Baselli
authors.forename: Pietro
authors.initials: P
authors.lastname: Cecconi
authors.forename: Domenico
authors.initials: D
authors.lastname: Caputo
authors.forename: Marco
authors.initials: M
authors.lastname: Rovaris
mesh_terms: D000328:Adult; D000465:Algorithms; D001271:Atlases as Topic; D003337:Corpus Callosum / Q000473:pathology*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000473:pathology*; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D015203:Reproducibility of Results