MR PERFUSION IMAGING FOR FUNCTIONAL BRAIN STUDIES

我们建议开发定量磁共振（MR）方法， 脑血流量（CBF）和血容量（CBV）成像， 基于幅度和相位的血液和组织信号的组合。 定量脑血流显像对脑血流的定量研究具有重要意义 在评估一些疾病过程中的重要性，特别是 涉及受试者内部和跨受试者的纵向测量。 同时，它也是理解大脑与大脑之间关系的基础。 对正常大脑中的大脑代谢起作用。 与正电子发射断层扫描定量方法比较 (PET)，使用钆（Gd）推注的MR，造影剂 智能体具有高空间分辨率、高信号强度、 信噪比（SNR），无电离辐射，高可用性， 成本然而，磁共振方法定量CBF和CBV的能力， 尚未完全实现。而磁化率效应 在弛豫速率（Δ R2或Δ R*2）变化时的团注Gd注射 信号）通常用于MR灌注成像，这些信号可能 取决于除组织GD浓度外的其他因素，例如 分隔（例如，血细胞比容）。CBV和CBF定量还 需要测量Gd动脉输入功能（AIF），其中 时间和空间分辨率、SNR、信号线性度 浓度，以及在广泛剂量和浓度范围内的反应 (dose动态范围）是至关重要的。 我们计划利用相移（delta-phi）信号， δ R2和δ R *2来定量CBV和CBF。在模型系统中， delta-phi信号是线性的，并且具有高信噪比和剂量动态范围。为 第一个目的是从理论上分析这些信号机制， 在血液和组织中进行实验。在第二个目标中，信号- 将通过实验确定血液中的浓度关系， 组织.最后，定量MR CBV和CBF测量的有效性 用不同的信号组合获得的结果将在 正常的狒狒和生理改变的狒狒。

We proposed to develop quantitative magnetic resonance (MR) methods of imaging cerebral blood flow (CBF) and blood volume (CBV) using combinations of magnitude- and phase-based blood and tissue signals. Quantitative CBV and CBF imaging in the human brain is of significant importance in the evaluation of a number of disease processes, especially those involving longitudinal measurements within and across subjects. Also, it is fundamental in understanding the relationship of brain function to brain metabolism in the normal brain. Compared with the quantitative method of positron emission tomography (PET), MR utilizing bolus administration of gadolinium (Gd), contrast agents has potential advantages of high spatial resolution, high signal- to-signal ratio (SNR), no ionizing radiation, high availability, and lower costs. However, the ability of MR methods to quantitate CBF and CBV has not yet been fully realized. While the magnetic susceptibility effect of bolus Gd injection on change in relaxation rate (deltaR2 or delta R*2 signals) is often used for MR perfusion imaging, these signals are likely dependent on other factors in addition to tissue GD concentration, such as compartmentation (e.g., hematocrit). CBV and CBF quantitations also require measurement of the Gd arterial input function (AIF), where temporal and spatial resolution, SNR, signal linearity with respect to concentration, and response over a wide range of doses and concentrations (dose dynamic range) are critical. We plan to utilize phase shift (delta-phi) signals in conjunction with deltaR2 and deltaR*2 to quantitate CBV and CBF. In model systems, the delta-phi signal is linear and has high SNR and dose dynamic range. As the first Aim, these signal mechanisms will be analyzed theoretically and experimentally in blood and tissue. In the second Aim, signal- concentrations relations will be experimentally determined in blood and tissue. Finally, the validity of quantitative MR CBV and CBF measurements obtained with different signal combinations will be tested against PET in baboons with normal and physiologically-altered flow.