title: Fractional anisotropy levels derived from diffusion tensor imaging in cervical syringomyelia.
abstract: BACKGROUND
  Syringomyelia can result in major functional disability. Conventional imaging techniques frequently fail to detect the underlying cause of syringomyelia. The prediction as to whether syringomyelia might lead to neurological deficits is still challenging.
  
  
  OBJECTIVE
  We hypothesized that fractional anisotropy (FA) derived from diffusion tensor imaging (DTI) is a parameter to detect dynamic forms of syringomyelia.
  
  
  METHODS
  Six patients with cervical syringomyelia, all comparable in size, shape, and location, were examined, along with 2 volunteers. Patients underwent electrophysiological recordings (somatosensory evoked potentials, motor evoked potentials, silent periods). Magnetic resonance imaging (1.5 T) was performed with a 6-element spine coil. Anatomic images were acquired with a 3-dimensional, constructive interference in steady-state sequence, and DTI with an echo-planar imaging sequence (5-mm thickness, b value 800 s/mm) using the generalized autocalibrating partially parallel acquisitions technique. The positions were centered on the syrinx in the volunteers between the C2 and Th1. DTI data were interpolated to a spatial resolution of 0.5 mm. After calculation of a diffusion tensor in each pixel, an FA map was calculated and profiles of the FA values across the spinal cord were calculated in all slices.
  
  
  RESULTS
  FA values were lower at the level of all examined syrinxes and reached normal values beyond them. Electrophysiological results correlated with the decrease in FA value. There were no presyrinx changes in the white matter tracts in terms of signs of FA changes beneath the syrinx.
  
  
  CONCLUSIONS
  DTI of syringomyelia can demonstrate white matter fiber tracts around and beyond the syrinx consistent with electrophysiological values. DTI of the cervical spine can provide quantitative information about the pathological characteristics beyond the abnormalities visible on magnetic resonance imaging.
authors.affiliation: Department of Neurosurgery, University of Tübingen, Tübingen, Germany. f.roser@gmx.de
authors.forename: Florian
authors.initials: F
authors.lastname: Roser
authors.forename: Florian H
authors.initials: FH
authors.lastname: Ebner
authors.forename: Florian
authors.initials: F
authors.lastname: Ebner
authors.forename: Gottlieb
authors.initials: G
authors.lastname: Maier
authors.forename: Marcos
authors.initials: M
authors.lastname: Tatagiba
authors.forename: Thomas
authors.initials: T
authors.lastname: Nägele
authors.forename: Uwe
authors.initials: U
authors.lastname: Klose
mesh_terms: D016880:Anisotropy; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D004569:Electroencephalography / Q000379:methods; D019054:Evoked Potentials, Motor / Q000502:physiology; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005500:Follow-Up Studies; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D012445:Sacrococcygeal Region / Q000473:pathology; D013595:Syringomyelia / Q000175:diagnosis* / Q000503:physiopathology*; D013997:Time Factors