Data for: On the identification of hypoxic regions in subject-specific cerebral vasculature by combined CFD/MRI

A long-time exposure to lack of oxygen (hypoxia) in some regions of the
cerebrovascular system is believed to be one of the causes of cerebral
neurological disease. Performing {\em in vivo} studies on the human brain
is complicated and can be highly risky for patients. In the present study,
we show how a combination of Magnetic Resonance Imaging (MRI) and
Computational Fluid Dynamics (CFD) can provide a non-invasive alternative
for studying blood flow and transport of oxygen within the cerebral
vasculature. We perform computer simulations of oxygen mass transfer in
the subject-specific geometry of the Circle of Willis. The computational
domain and boundary conditions are based on 4D flow MRI measurements. Two
different oxygen mass transfer models are considered: passive (where
oxygen is treated as a dilute chemical species in plasma) and active
(where oxygen is bonded to hemoglobin) models. We show that neglecting
hemoglobin transport results in a significant underestimation of the
arterial wall-mass transfer of oxygen. We identified the hypoxic regions
along the arterial walls by introducing the critical thresholds that are
obtained by comparison of the estimated range of Damk\"{o}hler number
($Da\subset\langle9;57\rangle$) with the local Sherwood number. Finally,
we recommend additional validations of the combined MRI/CFD approach
proposed here for larger groups of subject- or patient-specific brain
vasculature systems.