title: Wallerian degeneration in central nervous system: dynamic associations between diffusion indices and their underlying pathology.
abstract: BACKGROUND
  Although diffusion tensor imaging has been used to monitor Wallerian degeneration, the exact relationship between the evolution of diffusion indices and its underlying pathology, especially in central nervous system, remains largely unknown. Here we aimed to address this question using a cat Wallerian degeneration model of corticospinal tract.
  
  
  RESULTS
  Twenty-five domestic mature Felis catus were included in the present study. The evolution of diffusion indices, including mean diffusivity (MD), fractional anisotropy (FA), primary (λ1) and transverse eigenvalues (λ23) of the degenerated corticospinal tract, were observed at baseline (before modeling) and at 2, 4, 6, 8, 10, 15, 20, 25, 30, 45 and 60 days after modeling in 4 cats. Pathological examinations were performed at eight time points mentioned above. Wallerian degeneration can be detected as early as the 2nd day after modeling by both diffusion tensor imaging and pathology. According to the evolution of diffusion indices, Wallerian degeneration can be classified into 2 stages. During the early stage (within 8 days after modeling), progressive disintegration of axons and myelin sheaths underlies the decreases in FA and λ1 and the increase in λ23. However, during the late stage (after 8 days), the gradual increases in FA, MD and λ1 and the unchanged λ23 seem to be a comprehensive reflection of the pathological processes including microglia activation, myelin clearance, and astrocytosis.
  
  
  CONCLUSIONS
  Our findings help the understanding of the altered diffusion indices in the context of pathology and suggest that diffusion tensor imaging has the potential to monitor the processes of Wallerian degeneration in the central nervous system in vivo after acute damage.
authors: Department of Radiology, Tianjin Medical University General Hospital, Tianjin, China.
authors: Wen
authors: W
authors: Qin
authors: Min
authors: M
authors: Zhang
authors: Yueshan
authors: Y
authors: Piao
authors: Deyu
authors: D
authors: Guo
authors: Zixin
authors: Z
authors: Zhu
authors: Xin
authors: X
authors: Tian
authors: Kuncheng
authors: K
authors: Li
authors: Chunshui
authors: C
authors: Yu
mesh_terms: D000818:Animals; D002415:Cats; D002490:Central Nervous System / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D008279:Magnetic Resonance Imaging; D008297:Male; D014855:Wallerian Degeneration / Q000473:pathology* / Q000503:physiopathology