title: Tractography to depict three layers of visual field trajectories to the calcarine gyri.
abstract: OBJECTIVE
  Fiber-tracking by diffusion tensor magnetic resonance imaging (DT-MRI) is currently the only noninvasive in vivo method for white matter fiber-tracking in the human brain. We used this method in attempts to visualize the optic radiation and to examine the clinical applicability of this technique.
  
  
  METHODS
  Observational case series.
  
  
  METHODS
  DT-MRI scans for fiber-tracking were obtained in five healthy volunteers by use of a whole-body, 1.5 Tesla imager. DT-MRI data were transferred to an off-line workstation; PRIDE software was used for image analysis. We constructed 3 diopters fiber trajectories by tracking the direction of the fastest diffusion from the lateral geniculate nucleus, and then selected tracts on the basis of anatomical knowledge of the optic radiation.
  
  
  RESULTS
  Our method successfully reconstructed the macroscopic 3 diopters architecture of the three major groups of optic radiation in all subjects. Meyer's loop depicted by tractography was located more posterior than the known anatomical locations, although our results on the central and posterior bundles were in good agreement with them. DT-MRI scanning required 7 minutes; preliminary images of the optic radiation could be obtained in approximately 20 minutes.
  
  
  CONCLUSIONS
  Fiber-tracking enabled us to obtain information quickly on the 3 diopters course of the optic radiation in vivo. The finding that the fiber-tracking method underestimates the anterior extent of the optic radiations could prove to be an important limitation in the utility of this technique for preoperative planning. The time required for data acquisition and processing makes this method acceptable for routine clinical use.
authors.affiliation: Department of Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Takami
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Kei
authors.initials: K
authors.lastname: Yamada
authors.forename: Tsunehiko
authors.initials: T
authors.lastname: Nishimura
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kinoshita
mesh_terms: D000328:Adult; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D005829:Geniculate Bodies / Q000033:anatomy & histology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009900:Optic Nerve / Q000033:anatomy & histology*; D014793:Visual Cortex / Q000033:anatomy & histology*; D014795:Visual Pathways / Q000033:anatomy & histology*