title: In vivo assessment of peripheral nerve regeneration by diffusion tensor imaging.
abstract: OBJECTIVE
  To evaluate the sensitivity of diffusion tensor imaging (DTI) in assessing peripheral nerve regeneration in vivo. We assessed the changes in the DTI parameters and histological analyses after nerve injury to examine degeneration and regeneration in the rat sciatic nerves.
  
  
  METHODS
  For magnetic resonance imaging (MRI), 16 rats were randomly divided into two groups: group P (permanently crushed; n = 7) and group T (temporally crushed; n = 9). Serial MRI of the right leg was performed before the operation, and then performed at the timepoints of 1, 2, 3, and 4 weeks after the crush injury. The changes in fractional anisotropy (FA), axial diffusivity (λ(∥)), and radial diffusivity (λ(⟂)) were quantified. For histological analyses, the number of axons and the myelinated axon areas were quantified.
  
  
  RESULTS
  Decreased FA and increased λ(⟂) were observed in the degenerative phase, and increased FA and decreased λ(⟂) were observed in the regenerative phase. The changes in FA and λ(⟂) were strongly correlated with histological changes, including axonal and myelin regeneration.
  
  
  CONCLUSIONS
  DTI parameters, especially λ(⟂) , can be good indicators for peripheral nerve regeneration and can be applied as noninvasive diagnostic tools for a variety of neurological diseases.
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Japan.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Morisaki
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kawai
authors.forename: Masahiro
authors.initials: M
authors.lastname: Umeda
authors.forename: Mayumi
authors.initials: M
authors.lastname: Nishi
authors.forename: Ryo
authors.initials: R
authors.lastname: Oda
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Fujiwara
authors.forename: Kei
authors.initials: K
authors.lastname: Yamada
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Higuchi
authors.forename: Chuzo
authors.initials: C
authors.lastname: Tanaka
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Kawata
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Kubo
mesh_terms: D000818:Animals; D016880:Anisotropy; D001369:Axons / Q000473:pathology; D004058:Diffusion; D056324:Diffusion Tensor Imaging / Q000379:methods*; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods; D015233:Models, Statistical; D009186:Myelin Sheath / Q000737:chemistry; D009416:Nerve Regeneration; D017933:Peripheral Nervous System / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012584:Sciatic Nerve / Q000473:pathology*; D013997:Time Factors