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的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 通常认为，高氧大大改变了大脑的血液动力学，混淆了 尝试使用高氧造影剂测量血流动力学量。 然而研究 最近表明，脑血流量（CBF）仅经历小的（<4%）减少， 呼吸低至中等氧气浓度（FiO2d0.5）-流量变化太低，无法 产生的信号变化可以通过典型的BOLD T2* 加权EPI检测到。 高氧造影剂 已经显示出快速的冲洗时间，这使得精确测量 动态参数  比如血流--使用高氧造影剂。 我们最近观察到 在T2* 加权图像中，我们发现脑内动脉附近有明显的负对比度增强， 认为是由于血浆中过量溶解的顺磁性分子氧。 这种负面 对比增强提供了推断动脉中相对过量氧含量的手段 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）， 在稳态期间测量的高氧对比度增强。 我们目前正在调查 高氧洗脱期间动态测量CBV和CBF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.