MEASUREMENT OF CBF AND CBV IN HUMANS USING WASHOUT OF HYPEROXIC CONTRAST

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 通常认为，高氧会实质上改变大脑的血液动力学，令人困惑。 尝试用高氧造影剂测量血流动力学参数。然而，研究表明 最近的研究表明，脑血流量(CBF)仅有轻微(4%)的减少。 呼吸低到中等的氧气浓度(FiO2d0.5)--流量变化太低，不可能 产生典型的粗体T2*加权EPI可以检测到的信号变化。高氧对比度 已经显示出快速的冲刷时间，这使得准确测量 动态参数，如血流--使用高氧对比。我们最近观察到 在大脑动脉附近的T2*加权图像中，我们发现显著的负对比增强 Believe是由于血浆中溶解的顺磁分子氧过多所致。这张底片 对比剂增强提供了推断动脉中相对过剩氧含量的方法 补充大脑，从而测量定量血流所需的动脉输入功能(AIF 价值观。此外，高氧造影剂可用于测量脑血容量(CBV)。 在稳定状态下测量高氧对比增强。我们目前正在调查 高氧冲刷过程中动态测量脑血流量和脑血流量的准确性 以类似于动态磁化率对比MRI的方式使用指示剂稀释理论进行对比 (DSC-MRI)测量。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. It is typically assumed that hyperoxia substantially alters the hemodynamics of the brain, confounding attempts to measure hemodynamic quantities with hyperoxic contrast. However, studies have recently shown that cerebral blood flow (CBF) experiences only a small (<4%) reduction upon breathing low to moderate oxygen concentrations (FiO2d0.5) -- flow changes that are too low to be produce signal changes that can be detected by typical BOLD T2*-weighted EPI. Hyperoxic contrast has been shown to exhibit fast washout times, which make feasible the accurate measurements of dynamic parameters  such as blood flow -- using hyperoxic contrast. We have recently observed substantial negative contrast enhancement in T2*-weighted images near arteries in the brain that we believe is due to excess dissolved paramagnetic molecular oxygen in the plasma. This negative contrast enhancement provides the means to infer the relative excess oxygen content in the arteries feeding the brain and thereby measure an arterial input function (AIF) necessary for quantitative flow values. In addition, hyperoxic contrast can be used to measure cerebral blood volume (CBV) using hyperoxic contrast enhancement measured during steady-state. We are currently investigating the accuracy of measurements of CBV and CBF made dynamically during the washout of hyperoxic contrast using indicator-dilution theory in a manner akin to dynamic susceptibility contrast MRI (DSC-MRI)measurements.