Non-invasive optical detection of cerebral hemodynamics and metabolic transients

脑血流动力学和代谢瞬变的非侵入性光学检测

SERGIO FANTINI (2016-06-01 to 2018-05-31) $400,988

Project ID: R21EB020347 (NIBIB)

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Abstract

This project aims to demonstrate the feasibility of non-invasive optical measurements of the dynamic time courses of hemodynamic and metabolic changes associated with brain activation, systemic changes in mean arterial pressure, and spontaneous hemodynamic oscillations in human subjects. Functional near-infrared spectroscopy (fNIRS) is a non-invasive optical technique that measures the cerebral concentrations of oxy-hemoglobin (O) and deoxy-hemoglobin (D). The biological origin of O and D changes includes hemodynamic changes described by cerebral blood volume (CBV) and cerebral blood flow (CBF), and metabolic changes described by the cerebral metabolic rate of oxygen (CMRO2). We have recently introduced a novel hemodynamic model that translates dynamic changes in CBV, CBF, and CMRO2 into O and D changes that are measured by fNIRS. It is a multi-compartment model that takes into account the dynamic effects associated with capillary and venous blood transit times. Because our model predicts that fNIRS signals depend on the difference of CBF and CMRO2 changes, we propose to complement fNIRS with measurements of CBF with diffuse correlation spectroscopy (DCS), which is also a non-invasive optical technique. We propose to perform the analysis of concurrent and co-localized fNIRS and DCS data with our new hemodynamic model to generate dynamic traces of CBV, CBF, and CMRO2 that describe hemodynamic and metabolic transients and fluctuations. This is an innovative approach with respect to current methods in the fields of functional MRI and optical imaging that are commonly based on steady state models, which are intrinsically inadequate for the study of transient conditions. We also hypothesize that a universal dynamic relationship between optically measured CBV and CBF can be identified to allow for dynamic measurements of CBV, CBF, and CMRO2 with stand-alone fNIRS. We will perform human studies to demonstrate the feasibility of the proposed methods to characterize brain activation, controlled perturbations to the mean arterial pressure, and spontaneous hemodynamic oscillations at rest. This project will result in the development of a powerful optical tool for the functional study of the human brain to characterize brain activation conditions and resting state functional connectivity. Such a tool can significantly impact functional neuroimaging research and find clinical applications in the diagnosis and assessment of neurovascular disorders.

该项目旨在证明非侵入性光学测量动态时间过程的可行性，该动态时间过程与脑激活，平均动脉压的系统性变化和人类受试者的自发性血液动力学振荡相关的血液动力学和代谢变化。功能性近红外光谱（fNIRS）是一种非侵入性光学技术，可测量氧合血红蛋白（O）和脱氧血红蛋白（D）的脑浓度。 O和D变化的生物学起源包括由脑血容量（CBV）和脑血流（CBF）描述的血液动力学变化，以及由脑的氧代谢速率（CMRO2）描述的代谢变化。我们最近推出了一种新型血液动力学模型，将CBV，CBF和CMRO2的动态变化转换为由fNIRS测量的O和D变化。它是一种多室模型，考虑了与毛细血管和静脉血液传输时间相关的动态效应。因为我们的模型预测fNIRS信号取决于CBF和CMRO2变化的差异，我们建议用扩散相关光谱（DCS）测量CBF来补充fNIRS，这也是一种非侵入性光学技术。我们建议使用我们的新血液动力学模型对并发和共定位的fNIRS和DCS数据进行分析，以生成描述血液动力学和代谢瞬变和波动的CBV，CBF和CMRO2的动态痕迹。这是关于功能性MRI和光学成像领域中的当前方法的创新方法，其通常基于稳态模型，其本质上不足以用于瞬态条件的研究。我们还假设可以识别光学测量的CBV和CBF之间的通用动态关系，以允许使用独立的fNIRS动态测量CBV，CBF和CMRO2。我们将进行人体研究，以证明所提出的方法的可行性，以表征脑激活，平均动脉压的受控扰动和静息时的自发血流动力学振荡。该项目将为人类大脑的功能研究开发强大的光学工具，以表征大脑激活条件和静止状态功能连接。这种工具可以显着影响功能性神经影像学研究，并在神经血管疾病的诊断和评估中找到临床应用。