title: High resolution diffusion tensor imaging of axonal damage in focal inflammatory and demyelinating lesions in rat spinal cord.
abstract: Inflammation, demyelination, gliosis and axonal degeneration are pathological hallmarks of multiple sclerosis (MS) and experimental autoimmune encephalomyelitis. Axonal damage is thought to contribute to irreversible damage and functional impairment, but is difficult to quantify. Conventional MRI has been used to assess the inflammatory and demyelinating aspects of MS lesions, but more sensitive and specific methods are needed to identify axonal damage to monitor disease progression and to determine efficacy of putative neuroprotective agents. We used high resolution diffusion tensor imaging (DTI) and fibre tracking to examine the spinal cord in rats with focal dorsal column inflammatory or demyelinating lesions to determine whether DTI measures can be used to detect pathology at the site of the focal lesion and to measure axonal damage in tracts distal to the focal lesion. Distant from the focal lesion, total axon counts, degenerating axon counts and SMI-31 staining, but not Luxol fast blue staining, were significantly correlated with fractional anisotropy, axial diffusivity and radial diffusivity, all of which are derived from the DTI data. These data suggest that high resolution DTI may be a more sensitive method than conventional imaging for detecting axonal damage at sites distant from inflammation.
authors.affiliation: Department of Neurology, Johns Hopkins University, School of Medicine, USA.
authors.forename: Cynthia A
authors.initials: CA
authors.lastname: DeBoy
authors.forename: Jiangyang
authors.initials: J
authors.lastname: Zhang
authors.forename: Sonny
authors.initials: S
authors.lastname: Dike
authors.forename: Irina
authors.initials: I
authors.lastname: Shats
authors.forename: Melina
authors.initials: M
authors.lastname: Jones
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Reich
authors.forename: Susumu
authors.initials: S
authors.lastname: Mori
authors.forename: Thien
authors.initials: T
authors.lastname: Nguyen
authors.forename: Brian
authors.initials: B
authors.lastname: Rothstein
authors.forename: Robert H
authors.initials: RH
authors.lastname: Miller
authors.forename: John T
authors.initials: JT
authors.lastname: Griffin
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Kerr
authors.forename: Peter A
authors.initials: PA
authors.lastname: Calabresi
mesh_terms: D000818:Animals; D001369:Axons / Q000473:pathology*; D002452:Cell Count; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D004195:Disease Models, Animal; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000473:pathology*; D005260:Female; D008854:Microscopy, Electron; D009103:Multiple Sclerosis / Q000473:pathology*; D009186:Myelin Sheath / Q000473:pathology; D010766:Phosphorylation; D051381:Rats; D011917:Rats, Inbred Lew; D013116:Spinal Cord / Q000473:pathology* / Q000648:ultrastructure