title: Diffusion tensor tractography analysis of the corpus callosum fibers in amyotrophic lateral sclerosis.
abstract: OBJECTIVE
  Involvement of the corpus callosum (CC) is reported to be a consistent feature of amyotrophic lateral sclerosis (ALS). We examined the CC pathology using diffusion tensor tractography analysis to identify precisely which fiber bundles are involved in ALS.
  
  
  METHODS
  Diffusion tensor imaging was performed in 14 sporadic ALS patients and 16 age-matched healthy controls. Whole brain tractography was performed using the multiple-region of interest (ROI) approach, and CC fiber bundles were extracted in two ways based on functional and structural relevance: (i) cortical ROI selection based on Brodmann areas (BAs), and (ii) the sulcal-gyral pattern of cortical gray matter using FreeSurfer software, respectively.
  
  
  RESULTS
  The mean fractional anisotropy (FA) values of the CC fibers interconnecting the primary motor (BA4), supplementary motor (BA6), and dorsolateral prefrontal cortex (BA9/46) were significantly lower in ALS patients than in controls, whereas those of the primary sensory cortex (BA1, BA2, BA3), Broca's area (BA44/45), and the orbitofrontal cortex (BA11/47) did not differ significantly between the two groups. The FreeSurfer ROI approach revealed a very similar pattern of abnormalities. In addition, a significant correlation was found between the mean FA value of the CC fibers interconnecting the primary motor area and disease severity, as assessed using the revised Amyotrophic Lateral Sclerosis Functional Rating Scale, and the clinical extent of upper motor neuron signs.
  
  
  CONCLUSIONS
  Our findings suggest that there is some degree of selectivity or a gradient in the CC pathology in ALS. The CC fibers interconnecting the primary motor and dorsolateral prefrontal cortices may be preferentially involved in ALS.
authors.affiliation: Department of Neurology, Seoul Medical Center, Seoul, Korea.
authors.forename: Jee-Eun
authors.initials: JE
authors.lastname: Kim
authors.affiliation: Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Jungsu S
authors.initials: JS
authors.lastname: Oh
authors.affiliation: Department of Neurology, Seoul National University Hospital, Seoul, Korea.
authors.forename: Jung-Joon
authors.initials: JJ
authors.lastname: Sung
authors.affiliation: Department of Neurology, Seoul National University Hospital, Seoul, Korea.
authors.forename: Kwang-Woo
authors.initials: KW
authors.lastname: Lee
authors.affiliation: Department of Radiology, Seoul National University Hospital, Seoul, Korea.
authors.forename: In Chan
authors.initials: IC
authors.lastname: Song
authors.affiliation: Department of Neurology, Seoul National University College of Medicine, Seoul Metropolitan Government Boramae Medical Center, Seoul, Korea.
authors.forename: Yoon-Ho
authors.initials: YH
authors.lastname: Hong
keywords: amyotrophic lateral sclerosis; corpus callosum; cortical parcellation; diffusion tensor imaging; motor neuron disease; tractography