title: Visual pathway study using in vivo diffusion tensor imaging tractography to complement classic anatomy.
abstract: BACKGROUND
  Knowledge of the individual course of the optic radiations (ORs) is important to avoid postoperative visual deficits. Cadaveric studies of the visual pathways are limited because it has not been possible to separate the OR from neighboring tracts accurately and results may not apply to individual patients. Diffusion tensor imaging studies may be able to demonstrate the relationships between the OR and neighboring fibers in vivo in individual subjects.
  
  
  OBJECTIVE
  To use diffusion tensor imaging tractography to study the OR and the Meyer loop (ML) anatomy in vivo.
  
  
  METHODS
  Ten healthy subjects underwent magnetic resonance imaging with diffusion imaging at 3 T. With the use of a fiducial-based diffusion tensor imaging tractography tool (Slicer 3.3), seeds were placed near the lateral geniculate nucleus to reconstruct individual visual pathways and neighboring tracts. Projections of the ORs onto 3-dimensional brain models were shown individually to quantify relationships to key landmarks.
  
  
  RESULTS
  Two patterns of visual pathways were found. The OR ran more commonly deep in the whole superior and middle temporal gyri and superior temporal sulcus. The OR was closely surrounded in all cases by an inferior longitudinal fascicle and a parieto/occipito/temporo-pontine fascicle. The mean left and right distances between the tip of the OR and temporal pole were 39.8 ± 3.8 and 40.6 ± 5.7 mm, respectively.
  
  
  CONCLUSIONS
  Diffusion tensor imaging tractography provides a practical complementary method to study the OR and the Meyer loop anatomy in vivo with reference to individual 3-dimensional brain anatomy.
authors.affiliation: Brigham and Women's Hospital, Department of Neurosurgery, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: Wentao
authors.initials: W
authors.lastname: Wu
authors.forename: Laura
authors.initials: L
authors.lastname: Rigolo
authors.forename: Lauren J
authors.initials: LJ
authors.lastname: O'Donnell
authors.forename: Isaiah
authors.initials: I
authors.lastname: Norton
authors.forename: Sargent
authors.initials: S
authors.lastname: Shriver
authors.forename: Alexandra J
authors.initials: AJ
authors.lastname: Golby
mesh_terms: D000328:Adult; D001931:Brain Mapping / Q000379:methods*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D005829:Geniculate Bodies / Q000033:anatomy & histology / Q000502:physiology; D006801:Humans; D020772:Internal Capsule / Q000033:anatomy & histology* / Q000502:physiology / Q000601:surgery; D008297:Male; D009445:Neuroanatomy / Q000379:methods*; D014795:Visual Pathways / Q000033:anatomy & histology* / Q000502:physiology / Q000601:surgery; D055815:Young Adult