Parameter quantification for oxygen transport in the human brain

bioRxiv (Cold Spring Harbor Laboratory), Год журнала: 2024, Номер unknown

Опубликована: Апрель 15, 2024

Abstract Oxygen is carried to the brain by blood flow through generations of vessels across a wide range length scales. This multi-scale nature and oxygen transport poses challenges on investigating mechanisms underlying both healthy pathological states imaging techniques alone. Recently, models describing whole perfusion have been developed. Such rely effective parameters that represent microscopic properties. While characterised, those for are still lacking. In this study, we set quantify associated with their uncertainties. We first present multi-scale, multi-compartment model based porous continuum approach. then determine values parameters. By using statistically accurate capillary networks, geometric (vessel volume fraction surface area ratio) capture microvascular topologies found be 1.42% 627 [mm 2 /mm 3 ], respectively. These compare well obtained from human monkey vascular samples. addition, maximum consumption rates optimised uniquely define distribution over depth. Simulation results one-dimensional tissue column show qualitative agreement experimental measurements partial pressure in rats. highlight importance anatomical accuracy simulation performed within patient-specific mesh. Finally, one-at-a-time sensitivity analysis reveals not sensitive most its parameters; however, perturbations solubilities plasma concentration ratio considerable impact oxygenation. findings demonstrate validity approach organ-scale draw attention significance anatomy certain parameter values.

Язык: Английский

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Arterial arcades and collaterals regress under hemodynamics-based diameter adaptation: a computational and mathematical analysis

bioRxiv (Cold Spring Harbor Laboratory), Год журнала: 2024, Номер unknown

Опубликована: Июль 23, 2024

Segments in the arterial network have a >1000-fold span of radii. This is believed to result from adaptation each segment wall shear stress (WSS), with outward respectively inward remodeling if WSS higher or lower than some reference value. While this seems straightforward mechanism for tree design, not but contains numerous arcades, collaterals and other looping structures. In theoretical study, we analyzed stability structures networks under control. Simulation models were based on very simple topologies as well published human coronary mouse cerebral networks. Adaptation was implemented rate change structural radius that proportional deviation its WSS. A more generalized model large range local hemodynamic stimuli, including velocity, flow power dissipation. For over 12,000 tested parameter sets, simulations invariably predicted loss loops due regression one segments. small networks, case both model, initial conditions parameters. Loss loopiness also by included direction-dependent rates, heterogeneous rates among adapting segments, dynamic conditions. found artery subjected mathematical analysis proved direct consequence Kirchhoff's circuit law, which loop leads positive eigenvalue Jacobian matrix partial derivatives therefore unstable equilibria presence loops. an inherent property adapt hemodynamics. Additional mechanisms are needed explain their presence, communication between connected

Язык: Английский

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Modeling oxygen transport in the brain: An efficient coarse-grid approach to capture perivascular gradients in the parenchyma

PLoS Computational Biology, Год журнала: 2024, Номер 20(5), С. e1011973 - e1011973

Опубликована: Май 23, 2024

Recent progresses in intravital imaging have enabled highly-resolved measurements of periarteriolar oxygen gradients (POGs) within the brain parenchyma. POGs are increasingly used as proxies to estimate local baseline consumption, which is a hallmark cell activity. However, profile around given arteriole arises from an interplay between consumption and delivery, not only by this but also distant capillaries. Integrating such interactions across scales while accounting for complex architecture microvascular network remains challenge modelling perspective. This limits our ability interpret experimental maps constitutes key bottleneck toward inverse determination metabolic rates oxygen. We revisit problem parenchymal transport metabolism introduce simple, conservative, accurate scalable direct numerical method going beyond canonical Krogh-type models their associated geometrical simplifications. focus on two-dimensional formulation, concepts needed combine operator-splitting Green’s function approach. Oxygen concentration decomposed into slowly-varying contribution, discretized Finite Volumes over coarse cartesian grid, rapidly-varying approximated analytically grid-cells surrounding each vessel. Starting with simple test cases, we thoroughly analyze resulting errors comparison simulations original problem, showing considerable improvement computational-cost/accuracy balance compared previous work. then demonstrate model flexibly generate synthetic data reproducing spatial dynamics parenchyma, sub-grid resolution. Based these data, show that capillaries cannot be overlooked when interpreting POGs, thus reconciling recent cortical layers fundamental idea variations vascular density depth cortex may reveal underlying differences neuronal organization load.

Язык: Английский

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Parameter quantification for oxygen transport in the human brain

Computer Methods and Programs in Biomedicine, Год журнала: 2024, Номер 257, С. 108433 - 108433

Опубликована: Сен. 24, 2024

Oxygen is carried to the brain by blood flow through generations of vessels across a wide range length scales. This multi-scale nature and oxygen transport poses challenges on investigating mechanisms underlying both healthy pathological states imaging techniques alone. Recently, models describing whole perfusion have been developed. Such rely effective parameters that represent microscopic properties. While characterised, those for are still lacking. In this study, we set quantify associated with their uncertainties.

Язык: Английский

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