title: Conditions for quantitative evaluation of injured spinal cord by in vivo diffusion tensor imaging and tractography: preclinical longitudinal study in common marmosets.
abstract: Conventional magnetic resonance imaging (MRI) can detect hemorrhage, edema, syrinx, and spinal cord atrophy, but not axonal disruption after spinal cord injury (SCI). We previously demonstrated that diffusion tensor tractography (DTT) could depict axonal disruption after hemisection SCI in common marmosets. In the present study, to determine the relationship between DTT results and functional recovery after contusive SCI, we performed longitudinal DTT, behavioral, and histological analyses before and after contusive SCI in common marmosets. By comparing the tract fiber estimate depicted by DTT with neuronal fibers labeled with RT97 and SMI-31, anti-neurofilament antibodies, we determined the optimal fractional anisotropy (FA) threshold for fiber tracking to be 0.40. The ratio of the number of tract fiber estimates at the lesion site to the number before SCI, determined by DTT, was significantly correlated with the functional recovery after SCI. Moreover, comparison of the longitudinal pre- and post-SCI FA and axial diffusivity (λ(‖)) values revealed that they decreased after injury at the sites caudal to the lesion epicenter in the corticospinal tract and rostral to the lesion epicenter in the dorsal column. The FA values, then, showed partial recovery in the dorsal column. FA-value-oriented color DTT was used to represent axonal sparing or regeneration of the different tracts. These findings indicated that DTT analysis might be a versatile non-invasive tool for evaluating the axonal disruption after SCI.
authors.affiliation: Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan.
authors.forename: Tsunehiko
authors.initials: T
authors.lastname: Konomi
authors.forename: Kanehiro
authors.initials: K
authors.lastname: Fujiyoshi
authors.forename: Keigo
authors.initials: K
authors.lastname: Hikishima
authors.forename: Yuji
authors.initials: Y
authors.lastname: Komaki
authors.forename: Osahiko
authors.initials: O
authors.lastname: Tsuji
authors.forename: Hirotaka James
authors.initials: HJ
authors.lastname: Okano
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Toyama
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Okano
authors.forename: Masaya
authors.initials: M
authors.lastname: Nakamura
mesh_terms: D000818:Animals; D016880:Anisotropy; D001522:Behavior, Animal; D002144:Callithrix / Q000502:physiology*; D056324:Diffusion Tensor Imaging; D005260:Female; D018737:Hand Strength / Q000502:physiology; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D008137:Longitudinal Studies; D009043:Motor Activity / Q000502:physiology; D016900:Neurofilament Proteins / Q000378:metabolism; D011597:Psychomotor Performance / Q000502:physiology; D013119:Spinal Cord Injuries / Q000473:pathology* / Q000523:psychology; D016707:Tissue Fixation
chemical_list: D016900:Neurofilament Proteins