Data from: Microstructure and cerebral blood flow within white matter of the human brain: a TBSS analysis

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. Conclusion: 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.