title: Diffusion tensor imaging in polymicrogyria: a report of three cases.
abstract: BACKGROUND
  Polymicrogyria (PMG), a neuronal migration disorder, commonly manifests as a seizure disorder. The aim of this study was to look for the abnormalities in the underlying white matter using diffusion tensor imaging (DTI) that appeared normal on conventional magnetic resonance imaging (MRI) in patients with PMG.
  
  
  METHODS
  DTI was performed in three patients with PMG and eight age- and sex-matched healthy controls. Fractional anisotropy (FA) and mean diffusivity (MD) values were calculated for the cortex and adjoining subcortical white matter in both controls and patients.
  
  
  RESULTS
  We observed a significantly decreased mean FA value with no significant change in the MD value in subcortical white matter underlying polymicrogyric cortex (FA = 0.23+/-0.04, MD = 1.0+/-0.05 x 10(-3) mm(2)/s) as compared to both contralateral (FA = 0.32+/-0.04, MD = 1.0+/-0.05 x 10(-3) mm(2)/s) and normal control (FA = 0.32+/-0.04, MD = 1.0+/-0.06 x 10(-3) mm(2)/s) white matter. Significantly increased MD and decreased FA values were also observed in the polymicrogyric cortex (FA = 0.08+/-0.01, MD = 1.2+/-0.10 x 10(-3) mm(2)/s) as compared to normal contralateral (FA = 0.12+/-0.04, MD = 1.1+/-0.09 x 10(-3) mm(2)/s) and normal control (FA = 0.12+/-0.01, MD = 1.1+/-0.09 x 10(-3) mm(2)/s) cortex.
  
  
  CONCLUSIONS
  Significantly decreased FA values with no change in MD values in the subcortical white matter subjacent to polymicrogyric cortex reflect microstructural changes in the white matter probably due to the presence of ectopic neurons.
authors.affiliation: MR Section, Department of Radiodiagnosis, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, UP 226014, India.
authors.forename: R
authors.initials: R
authors.lastname: Trivedi
authors.forename: R K
authors.initials: RK
authors.lastname: Gupta
authors.forename: K M
authors.initials: KM
authors.lastname: Hasan
authors.forename: P
authors.initials: P
authors.lastname: Hou
authors.forename: K N
authors.initials: KN
authors.lastname: Prasad
authors.forename: P A
authors.initials: PA
authors.lastname: Narayana
mesh_terms: D000328:Adult; D016880:Anisotropy; D002540:Cerebral Cortex / Q000002:abnormalities*; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D008297:Male; D012640:Seizures / Q000473:pathology*