title: In vivo DTI longitudinal measurements of acute sciatic nerve traction injury and the association with pathological and functional changes.
abstract: OBJECTIVE
  To explore the feasibility of longitudinally measuring acute traction injury to the sciatic nerve using 1.5 T clinical MRI scanner of diffusion tensor imaging (DTI) and to analyze the associations of the measurements [regarding fractional anisotropy (FA), apparent diffusion coefficient (ADC), eigenvalue (λ|| and λ⊥)] with limb function and pathology.
  
  
  METHODS
  Acute traction injuries to the sciatic nerve were created in the right hind limbs of 32 New Zealand white rabbits, the left hind limbs were chosen as sham operation nerves. MRI scans were performed at intervals from pre-operation through 8 weeks post-operation follow up. Scanning sequences included T2WI, STIR, and single shot spin echo DTI with single shot EPI acquisition (SE-DTI-SSEPI). Parameters of FA, ADC, axial diffusivity (λ||) and radial diffusivity (λ⊥) were then calculated from the DTI. The limb functions and pathologic changes were evaluated and compared.
  
  
  RESULTS
  Diffusion Tensor Tractography (DTT) only revealed the proximal portion of the injured nerves 1-3 days after traction injury but did not reveal the nerve of the distal and traction portions at all. Nerve fibers of the distal and traction portions were not revealed by DTT until after the 1st week. They were elongated gradually and recovered almost to the normal at 8th week. The value of FA and λ⊥of the injured nerves, which varied in different portions, were significantly different between the traction injury nerves and the sham operation nerves, whereas the value of ADC and λ|| were not significantly different. The curve lines of FA value-time for the proximal, traction and distal portions of the injured nerve correlated well to the functional and pathological changes of the limb affected, while the DTI parameters did not change that much in the sham-operated nerves.
  
  
  CONCLUSIONS
  DTI obtained on a 1.5 T clinical MRI scanner can demonstrate early abnormal changes following traction injury to the sciatic nerve in rabbits. The curve lines of FA-time and λ⊥-time for nerve traction injury are consistent with the pathological and functional changes of the limb affected. DTI may thus be a sensitive and reliable method to evaluate degeneration and regeneration of the nerve after traction injury.
authors: Department of Radiology, State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, 151 Yanjiangxi Road, Guangzhou 510120, PR China.
authors: Xinchun
authors: X
authors: Li
authors: Jingcong
authors: J
authors: Chen
authors: Goubin
authors: G
authors: Hong
authors: Congpeng
authors: C
authors: Sun
authors: Xiaomen
authors: X
authors: Wu
authors: Matthew Jianqiao
authors: MJ
authors: Peng
authors: Guangqiao
authors: G
authors: Zeng
mesh_terms: D000208:Acute Disease; D000818:Animals; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D059348:Peripheral Nerve Injuries / Q000175:diagnosis* / Q000503:physiopathology*; D011817:Rabbits; D020127:Recovery of Function; D015203:Reproducibility of Results; D020426:Sciatic Neuropathy / Q000175:diagnosis* / Q000503:physiopathology*; D012680:Sensitivity and Specificity; D014143:Traction
keywords: Diffusion tensor imaging; Functional assessment; Magnetic resonance imaging; Pathology; Sciatic nerve; Traction injury