Madsen Lasse Stensvig, Thomsen Malene Kaasing, Angleys Hugo, Mikkelsen Irene Klærke, Brooks David James, Eskildsen Simon Fristed, Østergaard Leif
Center of Functionally Integrative Neuroscience, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
Department of Nuclear Medicine and PET-Centre, Aarhus University Hospital, Aarhus, Denmark.
Imaging Neurosci (Camb). 2025 May 2;3. doi: 10.1162/imag_a_00562. eCollection 2025.
Oxygen availability in brain tissue is closely linked to local hemodynamics and even slight disturbances in the cerebral microcirculation may damage cells due to the brain's high energy demands. In addition to local cerebral blood flow, knowledge of the oxygen extraction fraction (OEF) is critical when assessing brain tissue oxygenation. A biophysical model that relates the brain's microvascular hemodynamics to OEF has previously been proposed. Here, we aimed to calibrate and compare this model with OEF measurements determined by [O]-based positron emission tomography imaging (PET). Local brain hemodynamics were assessed in 68 healthy elderly individuals using dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI). Average DSC-MRI-based mean transit time and capillary transit time heterogeneity were compared to PET OEF to calibrate the model parameters. The calibrated biophysical model produced OEF estimates in the range of PET OEF with a moderate correlation (r = 0.31, p = 0.009), albeit with a tendency to overestimate smaller PET OEF values and underestimate larger PET OEF values. We discuss the assumptions made when modeling oxygen transport in measurements of local hemodynamics and in [O]-based tracer uptake, respectively, and propose that the biophysical model provides a valuable tool to link hemodynamic changes to oxygen uptake in the human brain.
脑组织中的氧供应与局部血流动力学密切相关，由于大脑对能量的高需求，即使是脑微循环的轻微紊乱也可能损害细胞。除了局部脑血流量外，在评估脑组织氧合时，了解氧摄取分数（OEF）也至关重要。此前已提出一种将脑微血管血流动力学与OEF相关联的生物物理模型。在此，我们旨在校准该模型，并将其与基于[O]的正电子发射断层扫描成像（PET）测定的OEF测量值进行比较。使用动态磁敏感对比磁共振成像（DSC-MRI）对68名健康老年人的局部脑血流动力学进行评估。将基于DSC-MRI的平均通过时间和毛细血管通过时间异质性的平均值与PET OEF进行比较，以校准模型参数。校准后的生物物理模型产生的OEF估计值在PET OEF范围内，具有中等相关性（r = 0.31，p = 0.009），尽管有高估较小PET OEF值和低估较大PET OEF值的趋势。我们分别讨论了在局部血流动力学测量和基于[O]的示踪剂摄取中对氧运输进行建模时所做的假设，并提出生物物理模型为将血流动力学变化与人类大脑中的氧摄取联系起来提供了一个有价值的工具。
