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J Cereb Blood Flow Metab. 2017 Mar;37(3):1108-1119. doi: 10.1177/0271678X16653134. Epub 2016 Jul 21.

Anisotropic cerebral vascular architecture causes orientation dependency in cerebral blood flow and volume measured with dynamic susceptibility contrast magnetic resonance imaging.

Author information

1
1 Department of Pediatrics, Division of Neurology, University of British Columbia, Vancouver, Canada.
2
2 UBC MRI Research Centre, University of British Columbia, Vancouver, Canada.
3
3 Department of Physics, University of Heidelberg, Heidelberg, Germany.
4
4 Department of Radiology and Hotchkiss Brain Institute, University of Calgary, Calgary, Canada.
5
5 Department of Physics and Astronomy, University of British Columbia, Vancouver, Canada.
6
6 Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
7
7 Department of Radiology, University of British Columbia, Vancouver, Canada.
8
8 Division of Neurology, Department of Medicine, University of British Columbia, Vancouver, Canada.

Abstract

Measurements of cerebral perfusion using dynamic susceptibility contrast magnetic resonance imaging rely on the assumption of isotropic vascular architecture. However, a considerable fraction of vessels runs in parallel with white matter tracts. Here, we investigate the effects of tissue orientation on dynamic susceptibility contrast magnetic resonance imaging. Tissue orientation was measured using diffusion tensor imaging and dynamic susceptibility contrast was performed with gradient echo planar imaging. Perfusion parameters and the raw dynamic susceptibility contrast signals were correlated with tissue orientation. Additionally, numerical simulations were performed for a range of vascular volumes of both the isotropic vascular bed and anisotropic vessel components, as well as for a range of contrast agent concentrations. The effect of the contrast agent was much larger in white matter tissue perpendicular to the main magnetic field compared to white matter parallel to the main magnetic field. In addition, cerebral blood flow and cerebral blood volume were affected in the same way with angle-dependent variations of up to 130%. Mean transit time and time to maximum of the residual curve exhibited weak orientation dependency of 10%. Numerical simulations agreed with the measured data, showing that one-third of the white matter vascular volume is comprised of vessels running in parallel with the fibre tracts.

KEYWORDS:

Cerebral blood flow; anisotropy; blood vessels; cerebral blood volume; diffusion tensor imaging; multiple sclerosis; white matter

PMID:
27259344
PMCID:
PMC5363485
DOI:
10.1177/0271678X16653134
[Indexed for MEDLINE]
Free PMC Article

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