title: Microstructure and Cerebral Blood Flow within White Matter of the Human Brain: A TBSS Analysis.
abstract: BACKGROUND
  White matter (WM) fibers connect different brain regions and are critical for proper brain function. However, little is known about the cerebral blood flow in WM and its relation to WM microstructure. Recent improvements in measuring cerebral blood flow (CBF) by means of arterial spin labeling (ASL) suggest that the signal in white matter may be detected. Its implications for physiology needs to be extensively explored. For this purpose, CBF and its relation to anisotropic diffusion was analyzed across subjects on a voxel-wise basis with tract-based spatial statistics (TBSS) and also across white matter tracts within subjects.
  
  
  METHODS
  Diffusion tensor imaging and ASL were acquired in 43 healthy subjects (mean age = 26.3 years).
  
  
  RESULTS
  CBF in WM was observed to correlate positively with fractional anisotropy across subjects in parts of the splenium of corpus callosum, the right posterior thalamic radiation (including the optic radiation), the forceps major, the right inferior fronto-occipital fasciculus, the right inferior longitudinal fasciculus and the right superior longitudinal fasciculus. Furthermore, radial diffusivity correlated negatively with CBF across subjects in similar regions. Moreover, CBF and FA correlated positively across white matter tracts within subjects.
  
  
  CONCLUSIONS
  The currently observed findings on a macroscopic level might reflect the metabolic demand of white matter on a microscopic level involving myelination processes or axonal function. However, the exact underlying physiological mechanism of this relationship needs further evaluation.
authors.affiliation: Center for Translational Research, University Hospital of Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Giezendanner
authors.affiliation: Center for Translational Research, University Hospital of Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland.
authors.forename: Melanie Sarah
authors.initials: MS
authors.lastname: Fisler
authors.affiliation: Center for Translational Research, University Hospital of Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland.
authors.forename: Leila Maria
authors.initials: LM
authors.lastname: Soravia
authors.affiliation: Center for Translational Research, University Hospital of Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Andreotti
authors.affiliation: University Hospital of Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Walther
authors.affiliation: Support Center for Advanced Neuroimaging (SCAN), Institute for Diagnostic and Interventional Neuroradiology, University Hospital Inselspital and University of Bern, Bern, Switzerland.
authors.forename: Roland
authors.initials: R
authors.lastname: Wiest
authors.affiliation: Center for Translational Research, University Hospital of Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Dierks
authors.affiliation: Center for Translational Research, University Hospital of Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland.
authors.forename: Andrea
authors.initials: A
authors.lastname: Federspiel
mesh_terms: D000328:Adult; D016880:Anisotropy; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D066128:Gray Matter / Q000033:anatomy & histology; D006801:Humans; D008297:Male; D008875:Middle Aged; D059629:Signal-To-Noise Ratio; D013223:Statistics as Topic; D066127:White Matter / Q000033:anatomy & histology* / Q000098:blood supply*; D055815:Young Adult