title: Quantitative analysis of fiber tractography in cervical spondylotic myelopathy.
abstract: BACKGROUND
  Diffusion tensor fiber tractography is an emerging tool for the visualization of spinal cord microstructure. However, there are few quantitative analyses of the damage in the nerve fiber tracts of the myelopathic spinal cord.
  
  
  OBJECTIVE
  The aim of this study was to develop a quantitative approach for fiber tractography analysis in cervical spondylotic myelopathy (CSM).
  
  
  METHODS
  Prospective study on a series of patients.
  
  
  METHODS
  A total of 22 volunteers were recruited with informed consent, including 15 healthy subjects and 7 CSM patients. The clinical severity of CSM was evaluated using modified Japanese Orthopedic Association (JOA) score. The microstructure of myelopathic cervical cord was analyzed using diffusion tensor imaging. Diffusion tensor imaging was performed with a 3.0-T magnetic resonance imaging scanner using pulsed gradient, spin-echo, echo-planar imaging sequence. Fiber tractography was generated via TrackVis with fractional anisotropy threshold set at 0.2 and angle threshold at 40°. Region of interest (ROI) was defined to cover C4 level only or the whole-length cervical spinal cord from C1 to C7 for analysis. The length and density of tracked nerve bundles were measured for comparison between healthy subjects and CSM patients.
  
  
  RESULTS
  The length of tracked nerve bundles significantly shortened in CSM patients compared with healthy subjects (healthy: 6.85-77.90 mm, CSM: 0.68-62.53 mm). The density of the tracked nerve bundles was also lower in CSM patients (healthy: 086±0.03, CSM: 0.80±0.06, p<.05). Although the definition of ROI covering C4 only or whole cervical cord appeared not to affect the trend of the disparity between healthy and myelopathic cervical cords, the density of the tracked nerve bundle through whole myelopathic cords was in an association with the modified JOA score in CSM cases (r=0.949, p=.015), yet not found with ROI at C4 only (r=0.316, p=.684).
  
  
  CONCLUSIONS
  The quantitative analysis of fiber tractography is a reliable approach to detect cervical spondylotic myelopathic lesions compared with healthy spinal cords. It could be employed to delineate the severity of CSM.
authors.affiliation: Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, 12 Sandy Bay Rd, Pokfulam, Hong Kong.
authors.forename: Chun-Yi
authors.initials: CY
authors.lastname: Wen
authors.forename: Jiao-Long
authors.initials: JL
authors.lastname: Cui
authors.forename: Man Pan
authors.initials: MP
authors.lastname: Lee
authors.forename: Kin-Cheung
authors.initials: KC
authors.lastname: Mak
authors.forename: Keith Dip-Kei
authors.initials: KD
authors.lastname: Luk
authors.forename: Yong
authors.initials: Y
authors.lastname: Hu
mesh_terms: D000368:Aged; D002574:Cervical Vertebrae; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D013118:Spinal Cord Diseases / Q000209:etiology / Q000473:pathology*; D055009:Spondylosis / Q000150:complications / Q000473:pathology*